Residual monitoring

Abstract

The present invention relates to a method for determining the residue of an analyte from a previous sample into a target sample on a liquid chromatography mass spectrometer (LC-MS) device, the method comprising the steps of: (a) determining at least one chromatogram of the target sample on the LC-MS device (2, 4); (b) determining the background height of the chromatogram (3, 5); and (c) determining the residue of the analyte from the previous sample into the target sample based on the background height. The present invention also relates to a method, a system and a computer program product related to the above method.

Description

Technical Field

[0001] The present invention relates to a method for determining the residue of an analyte from a previous sample to a target sample on a liquid chromatography mass spectrometer (LC-MS) device, the method comprising the steps of: (a) determining at least one chromatogram of the target sample on the LC-MS device; (b) determining the background height of the chromatogram; and (c) determining the residue of the analyte from the previous sample to the target sample based on the background height. The present invention also relates to methods, systems and computer program products related to the above method. Background Art

[0002] The residue of an analyte from sample to sample is one of the main limitations associated with liquid chromatography, but also exists in primary sample handling and sample preparation. The state-of-the-art methods for assessing the degree or risk of residue are described in regulatory guidelines such as CLSI C62-A (Lynch (2020), Clinical Chemistry 62(1):24–299). These guidelines recommend assessing residue by using blank samples after high-concentration samples during method development as well as validation and verification phases. The resulting peak areas of these blank samples are used to calculate potential residues. Zeng et al. (2006), Rapid Comm Mass Spectrom 20:635 teaches estimating the impact of a previous sample on the peak area of an analyte in a subsequent sample based on the concentration of the analyte in the previous sample in an HPLC-MS system.

[0003] The assessment of residue during method development gives an overall overview of the risk and its degree of residue. However, this method is not suitable for providing information about the current sample measurement. For batch-mode analysis, re-analysis of samples after high-concentration samples is usually triggered, but this is not feasible in the case of random access where the analyte of the previous sample is different from that of the current sample.

[0004] Problem to be Solved

[0005] Therefore, there is still a need in the art for devices and methods that assist in detecting and, if possible, correcting residues in LC-MS measurements. Summary of the Invention

[0006] This problem is solved by a method, system, computer program product, computer or computer network, computer-loadable data structure, computer program and storage medium having the features of the independent claims. Advantageous embodiments that may be implemented in isolation or in any arbitrary combination are listed in the dependent claims.

[0007] Accordingly, the present invention relates to a method for determining the residue of an analyte from a previous sample into a target sample on a liquid chromatography mass spectrometer (LC-MS) device, the method comprising the steps of:

[0008] (a) providing at least one chromatogram of the target sample on the LC-MS device;

[0009] (b) determining the background height of the chromatogram; and

[0010] (c) determining the residue of the analyte from the previous sample into the target sample based on the background height.

[0011] The terms used herein are broad terms and are given the ordinary and customary meanings to those of ordinary skill in the art; thus, unless otherwise specified, the terms used herein are not limited to special or custom meanings. As used hereinafter, the terms "having", "including" or "comprising" or any arbitrary grammatical variations thereof are used in a non-exclusive manner. Thus, these terms can refer to both cases where there are no additional features in the entity described in this context other than the features introduced by these terms, and cases where there are one or more additional features. As an example, the expressions "A has B", "A includes B" and "A comprises B" can refer to both cases where there are no other elements in A other than B (i.e., cases where A consists of B alone and uniquely), and cases where there are one or more additional elements in entity A in addition to B (such as element C, elements C and D or even additional elements). Further, as understood by those skilled in the art, the expressions "comprising a" and "comprising an" preferably mean "comprising one or more", i.e., equivalent to "comprising at least one". Similarly, the term "determine X" means determining one X, as well as determining more than one X, such as two, three or four Xs. Further, the term "plurality" relates to a large number, in one embodiment, at least two of the indicated items, in a further embodiment, at least three, in a further embodiment, at least four, in a further embodiment, at least five.

[0012] In addition, as used hereinafter, the terms "preferably", "more preferably", "most preferably", "particularly", "more particularly", "specifically", "more specifically" or similar terms are used in conjunction with optional features without limiting other possibilities. Thus, the features introduced by these terms are optional features and are not intended to limit the scope of the claims in any way. As will be recognized by those skilled in the art, the present invention can be carried out by using alternative features. Similarly, features introduced by "in one embodiment" or similar expressions are intended to be optional features without any limitation on other embodiments of the present invention, without any limitation on the scope of the present invention, and without any limitation on the possibility of combining the features introduced in such a way with other optional or non-optional features of the present invention.

[0013] As used herein, the term "about" refers to an indicated value with the technical precision recognized in the relevant art, preferably to within ±20% of the indicated value, more preferably ±10%, and most preferably ±5%. In addition, the term "substantially" means the absence of deviations that affect the indicated result or use, i.e., the potential deviation does not cause the indicated result to deviate by more than ±20%, more preferably ±10%, and most preferably ±5%. Thus, "consisting essentially of" means including the specified components, but excluding other components, except for materials present as impurities, inevitable materials resulting from the process for providing the components, and components added for purposes other than achieving the technical effects of the present invention. For example, a composition defined using the phrase "consisting essentially of" encompasses any known acceptable additives, excipients, diluents, carriers, etc. Preferably, a composition consisting essentially of a group of components will contain less than 5% by weight, more preferably less than 3% by weight, even more preferably less than 1% by weight, and most preferably less than 0.1% by weight of non-specified components. As described herein, the measured and calculated parameters are described on an exemplary basis; as will be understood by those skilled in the art, these parameters can be modified by standard mathematical operations, particularly by multiplication, division, addition, subtraction, reciprocal formation, scaling, and other operations known to those skilled in the art; in one embodiment, the reference is correspondingly adjusted, particularly by applying the same mathematical operations. The measured and calculated parameters can also be used in the calculation of fractions, which can be calculated based on one or more parameter values; optionally weighted, and / or calculated by further mathematical operations, particularly as specified above, such as scaling.

[0014] The method for determining the residue is an in vitro method. In addition, it may also include steps other than those explicitly mentioned above. For example, further steps may involve, for example, providing a sample for step a), or further calculations in steps b) and / or c). In addition, one or more of these steps may be performed by an automated device. In one embodiment, in particular steps b) and c) are performed by a processor, in particular by a computer, which may be configured as an evaluation device as specified elsewhere herein.

[0015] As used herein, the term "provide" refers to making the indicated information or object available. Thus, in the case of providing a chromatogram, the chromatogram may be provided as data, for example as a graphical representation, as a list of measured values, for example as value pairs (such as elution time / quantification factor value pairs and / or elution time / qualification factor value pairs) or as a mathematical model. The chromatogram may be provided via any medium considered suitable by a person skilled in the art, in particular via an operative connection between the MS device and the evaluation device, via a data connection (such as a data network) or via a data storage medium. In one embodiment, the provision is a determination as specified below.

[0016] The term "determine" is understood by a person skilled in the art to mean selecting, concluding or establishing a fact and / or data. Thus, in one embodiment, the determination involves a qualitative determination; in a further embodiment, it involves a semi-quantitative determination; in a further embodiment, it involves a quantitative determination. Thus, "determining a residue" includes verifying the fact that the residue occurs (qualitative determination); verifying whether the extent of the residue is within an acceptable limit (semi-quantitative determination); and verifying the amount of the residue (quantitative determination). In one embodiment, the determination involves a quantitative determination. In addition, "determining a chromatogram" involves measuring the chromatogram, specifically recording and optionally storing on a suitable storage device data points representing the signals of the LC / MS device recorded during an LC / MS run. As understood by a person skilled in the art, in the case of determining a chromatogram, the determination in one embodiment is quantitative. Similarly, in one embodiment, "determining the background height" is quantitatively determining the value of the background height as specified elsewhere herein; however, the term may also involve a semi-quantitative determination of the background height, for example by determining whether the background height exceeds a predetermined exclusion criterion.

[0017] As used herein, the term "sample", also referred to as "test sample", relates to any type of substance composition; thus, the term can refer to, but is not limited to, any arbitrary sample, such as a biological sample. In one embodiment, the sample is a liquid sample, and in a further embodiment, an aqueous sample. In one embodiment, the test sample is selected from the group consisting of: physiological fluids, including blood, serum, plasma, saliva, aqueous humor, tears, cerebrospinal fluid, sweat, urine, milk, ascites, mucus, synovial fluid, peritoneal fluid, and amniotic fluid; lavage fluids; tissues, cells, etc. However, the sample can also be a natural or industrial liquid, particularly surface water or groundwater, sewage, industrial wastewater, process fluids, soil eluates, etc. In one embodiment, the sample comprises or is suspected of comprising at least one target chemical compound, i.e., the chemical substance to be determined, which is referred to as the "analyte". The sample can comprise one or more additional chemical compounds, which are not determined and are generally referred to as the "matrix". The sample can be used directly upon obtaining from the corresponding source, or can be subjected to one or more pre-treatment and / or sample preparation steps. Thus, the sample can be pre-treated by physical and / or chemical methods, in one embodiment by centrifugation, filtration, mixing, homogenization, chromatography, precipitation, dilution, concentration, contact with binding and / or detection reagents, and / or any other method considered suitable by a person skilled in the art. In the sample preparation step, i.e., before, during, and / or after the sample preparation step, one or more internal standards can be added to the sample. The sample may be spiked with internal standards. For example, the internal standard can be added to the sample at a predefined concentration. The internal standard can be selected such that it can be readily identified under the normal operating conditions of a mass spectrometry device. The concentration of the internal standard can be predefined and significantly higher than the concentration of the analyte.

[0018] As described above, the term "analyte" as used herein refers to any chemical compound or group of compounds to be determined in a sample. In one embodiment, the analyte is a macromolecule, i.e., a compound having a molecular mass greater than 1000 u (i.e., greater than 1 kDa). In a further embodiment, the analyte is a biological macromolecule, particularly a polypeptide, polynucleotide, polysaccharide or a fragment of any of the foregoing. In one embodiment, the analyte is a small molecule chemical compound, i.e., a compound having a molecular mass of at most 1000 u (1 kDa). In a further embodiment, the analyte is a compound metabolized by the body of a subject, particularly a human subject, or a compound administered to a subject to induce a change in the subject's metabolism. Thus, in one embodiment, the analyte is a prohibited drug or its metabolite, such as amphetamine; cocaine; methadone; ethyl glucuronide; ethyl sulfate; opium, particularly buprenorphine, 6-monoacetylmorphine, codeine, dihydrocodeine, morphine, morphine-3-glucuronide and / or tramadol; and / or an opioid, particularly acetylfentanyl, carfentanil, fentanyl, hydrocodone, norfentanyl, oxycodone and / or oxymorphone.

[0019] In one embodiment, the analyte is a therapeutic drug, such as valproic acid; clonazepam; methotrexate; voriconazole; mycophenolic acid (total); mycophenolic acid - glucuronide; acetaminophen; salicylic acid; theophylline; digoxin; immunosuppressants, particularly cyclosporine, everolimus, sirolimus and / or tacrolimus; analgesics, particularly pethidine, norpethidine, tramadol and / or O - demethyl - tramadol; antibiotics, particularly gentamicin, tobramycin, amikacin, vancomycin, piperacillin (tazobactam), meropenem and / or linezolid; antiepileptic drugs, particularly phenytoin, valproic acid, free phenytoin, free valproic acid, levetiracetam, carbamazepine, carbamazepine - 10,11 - epoxide, phenobarbital, primidone, gabapentin, zonisamide, lamotrigine and / or topiramate. In one embodiment, the analyte is a hormone, particularly cortisol, estradiol, progesterone, testosterone, 17 - hydroxyprogesterone, aldosterone, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA - S), dihydrotestosterone and / or cortisone; in one embodiment, the sample is a serum or plasma sample and the analyte is cortisol, DHEA - S, estradiol, progesterone, testosterone, 17 - hydroxyprogesterone, aldosterone, DHEA, dihydrotestosterone and / or cortisone; in one embodiment, the sample is a saliva sample and the analyte is cortisol, estradiol, progesterone, testosterone, 17 - hydroxyprogesterone, androstenedione and / or cortisone; in one embodiment, the sample is a urine sample and the analyte is cortisol, aldosterone and / or cortisone. In one embodiment, the analyte is a vitamin, in one embodiment vitamin D, particularly ergocalciferol (vitamin D2) and / or cholecalciferol (vitamin D3) or derivatives thereof, such as 25 - hydroxy - vitamin - D2, 25 - hydroxy - vitamin - D3, 24,25 - dihydroxy - vitamin - D2, 24,25 - dihydroxy - vitamin - D3, 1,25 - dihydroxy - vitamin - D2 and / or 1,25 - dihydroxy - vitamin - D3. In a further embodiment, the analyte is a metabolite of the subject.

[0020] The term "carryover" in principle relates to any transfer of at least one component from a first sample to a second sample, and in one embodiment is the transfer of a component from a first sample to a second sample. In the context of the present specification, said transfer is the transfer of a sample component from a sample processed at a first time point in an analytical device, in particular an LC-MS device as specified elsewhere herein, to a second sample processed at a subsequent second time point in said analytical device, and in one embodiment, directly after the first sample in said analytical device. It will be understood that the second sample above is the sample for which carryover is to be determined; and at least the second sample above is the sample for which an analyte is to be determined. In summary, the first sample above is also referred to as the "previous sample", and the second sample above is also referred to as the "target sample". As will be understood by those skilled in the art, in LC-MS measurements, carryover may occur prior to the LC step, essentially resulting in an unwanted increase in analyte peaks caused by analytes from the previous sample (peak carryover). However, carryover may also occur after the LC step, resulting in an increase in the background in the chromatogram (background carryover). As surprisingly found in the fundamental work of the present invention, the two types of carryover are correlated, in particular are proportional, such that measuring background carryover can be used to determine and, if necessary, correct peak carryover.

[0021] The term "liquid chromatography mass spectrometer device", abbreviated as "LC-MS device", is understood by those skilled in the art. In one embodiment, the term relates to a device configured to perform a combination of liquid chromatography (LC) and mass spectrometry (MS). Thus, in one embodiment, the device includes at least one LC unit and at least one MS unit, wherein the LC unit and the MS unit are coupled via at least one interface. As used herein, the term "liquid chromatography (LC) unit" in one embodiment relates to a unit configured to separate one or more analytes of a target sample from other components of the sample via liquid chromatography, in one embodiment for detection of one or more analytes with a mass spectrometry device. LC can be based on any separation principle considered suitable by those skilled in the art; in one embodiment, LC is reverse phase chromatography, hydrophobic interaction chromatography, ion exchange chromatography, size exclusion chromatography, affinity chromatography or chiral chromatography; in a further embodiment, LC is reverse phase chromatography. The LC device can include at least one LC column. For example, the LC device can be a single-column LC device or a multi-column LC device having multiple LC columns. The LC column can have a stationary phase through which the mobile phase is pumped in order to separate and / or elute and / or transfer the target analyte. The LC unit can be or can include at least one high performance liquid chromatography (HPLC) unit and / or at least one microfluidic liquid chromatography (μLC) device. As used herein, in one embodiment, the term "mass spectrometry unit" relates to a mass analyzer configured to detect at least one analyte based on the mass-to-charge ratio of the analyte or its fragment. The mass spectrometry unit can be or can include at least one quadrupole mass spectrometry device. The interface coupling the LC unit and the MS unit can include at least one ionization source configured to generate molecular ions and to transfer the molecular ions into the gas phase. In one embodiment, the MS unit is a tandem mass spectrometry (MS / MS) unit, in a further embodiment, a triple quadrupole MS / MS, and in a further embodiment in the multiple reaction monitoring (MRM) mode.

[0022] The term "chromatogram" is known to the person skilled in the art. In one embodiment, the term relates to a correlative plot of the quantitative measure of a signal obtained from a sample over time, such as retention time and / or elution volume, and determined by an MS detector, against the progress of chromatographic separation. In one embodiment, the quantitative measure of the signal is associated with the concentration of at least a portion of the sample components, in particular with the concentration of the analyte; thus, the quantitative measure of the signal can in particular be the signal intensity. Thus, in one embodiment, the chromatogram is an MS chromatogram, and in a further embodiment an MS / MS chromatogram. As the person skilled in the art will understand, the above representation can be but is not necessarily a graphical representation; however, the representation can also be provided, for example, as a list of value pairs (such as elution time / quantitative factor value pairs and / or elution time / qualitative factor value pairs) or as a mathematical model. In one embodiment, the quantitative measure of the signal includes the analyte signal intensity and / or the internal standard signal intensity. In one embodiment, the quantitative measure of the signal includes the analyte quantitative factor, the internal standard quantitative factor, the analyte qualitative factor and / or the internal standard qualitative factor. Thus, in one embodiment, in particular in the case where MS is tandem MS, determining at least one chromatogram includes measuring at least one of the analyte quantitative factor, the internal standard quantitative factor, the analyte qualitative factor and / or the internal standard qualitative factor over time and / or elution time as specified above. As the person skilled in the art will understand, the elution time can be replaced by any other measure of LC progress considered suitable by the person skilled in the art, in particular by the elution volume or the retention time.

[0023] In the context of the present specification, the terms "quantitative factor" and "qualitative factor" are understood by the person skilled in the art. In one embodiment, these terms relate to signals of analyte fragments generated in tandem MS, where the analyte is typically quantified using the most abundant and / or most reliably detected fragment (analyte quantitative factor), while a second transition (fragment) is used to confirm the identity of the analyte (analyte qualitative factor). The corresponding terms are often abbreviated as AQN (analyte quantitative factor) and AQL (analyte qualitative factor). The values of these two parameters are typically determined as the signal intensity of ions having the corresponding m / z values, particularly, for example, as the peak area determined after peak integration. These values can be associated with the LC process to generate the chromatograms of the present specification. As will be understood by the person skilled in the art, the terms "qualitative factor" and "quantitative factor" and their values are used in the art to refer to the raw values measured as signal intensity, but also to values derived therefrom, particularly by peak integration. Thus, unless otherwise stated, the terms quantitative factor and qualitative factor are used for the measured signal intensity, including values derived therefrom by standard mathematical operations, particularly multiplication, ratio calculation, curve smoothing, or mean value calculation, but excluding the derived integral values, which are referred to as "integrated qualitative factor" and "integrated quantitative factor" respectively. Thus, in one embodiment, these values (particularly if used for calculating the quantitative factor / qualitative factor ratio) are single-cycle values, i.e., intensities determined in one scan cycle, selective ion monitoring (SIM) cycle, or multiple reaction monitoring (MRM) cycle. The expression "determining the ratio of the quantitative factor to the qualitative factor" involves calculating the ratio by dividing the value of the qualitative factor by the value of the quantitative factor; similarly, the expression "determining the ratio of the integrated quantitative factor to the integrated qualitative factor" involves calculating the ratio by dividing the value of the integrated qualitative factor by the value of the integrated quantitative factor. In one embodiment, the integrated AQN / AQL ratio is a compound-specific and measurement method-specific parameter for the analyte. As will be understood, the above details apply, mutatis mutandis, to the measurement of the quantitative factor and qualitative factor of the internal standard.

[0024] In one embodiment, step b) comprises steps b1) identifying the peak corresponding to the analyte in the chromatogram; b2) determining the upper peak boundary and the lower peak boundary of said peak. In a further embodiment, step b) comprises step b3) determining at least one minimum signal intensity value within the upper peak boundary and the lower peak boundary.

[0025] As used herein, the term "peak" refers to at least one local maximum of a chromatogram. Accordingly, peak integration involves at least one mathematical operation and / or mathematical algorithm for determining the peak area enclosed by the peaks of a chromatogram. Specifically, the integration of a peak can include the identification and / or measurement of the curve characteristics of a chromatogram. Peak integration can include one or more of the following: peak detection, peak finding, peak identification, peak fitting, peak evaluation, determination of peak start and / or peak end, determination of background, and determination of baseline. Peak integration can allow for the determination of one or more of the following: peak area, retention time, peak height, and peak width. In one embodiment, peak integration is automated peak integration, i.e., peak integration performed by at least one computer and / or computer network and / or machine. Specifically, automated peak integration can be performed without manual operation or interaction with a user.

[0026] The term "background" is known to those skilled in the art. In one embodiment, the term refers to a signal measured by a detection device, such as an MS device, that is not caused by a peak as specified above. Thus, the term "background height" refers to a quantitative measure of the background in a chromatogram; thus, the term background height can also refer to the value of the background height. Those skilled in the art are in principle able to determine the background height, for example by determining the offset of the chromatogram from the zero line, by determining the area under the baseline, etc. In one embodiment, the background height is determined close to the analyte peak, in particular as at least one minimum signal intensity value within the upper and lower peak boundaries of the analyte peak. In a further embodiment, the background height is determined near the upstream of the upper peak boundary and / or near the downstream of the lower peak boundary, the term "near" in each case referring to up to 1 peak width upstream or downstream, up to 1 / 2 peak width in one embodiment, and up to 1 / 4 peak width in a further embodiment. In one embodiment, the background height is determined as part of a peak integration process, which is preferably performed by an automated device. In one embodiment, the background height is determined as the average of these values, such as the median, mean, or another parameter indicating an average considered appropriate by those skilled in the art. In one embodiment at least two, in a further embodiment at least five, in a further embodiment at least ten single-cycle values are used for the average calculation; in one embodiment 2 to 1000, in a further embodiment 5 to 250, in a further embodiment 10 to 100 single-cycle background values are used for the average calculation, the term "single-cycle" referring to a single cycle of signal intensity measurement for generating a recorded signal by an MS unit.

[0027] According to step c) of the method, determining the residue of the analyte from at least one previous sample into the target sample is based on the background height, i.e., based on the value of the background height determined in step b). Thus, in one embodiment, the background height determined as specified above is associated with the residue. In one embodiment, the correlation is a quantitative relationship, in one embodiment a direct proportionality relationship, and in further embodiments includes at least one linear function, at least one quadratic function, at least one rational function, and / or at least one sigmoid function. Thus, the correlation can be represented by any mathematical, graphical, or other representation reflecting the above correlation. In one embodiment, the relationship is linear above a lower threshold of the background height. The method for determining the above correlation and for establishing its appropriate representation is described below and in particular in the embodiments. In one embodiment, the peak area of the analyte peak is determined after step a), i.e., after establishing the specified chromatogram. In this case, a correlation can be established between the peak area and the background height and a corrected peak area or a value derived therefrom, such that the corrected analyte value can be directly determined from this three-parameter correlation.

[0028] As shown below, depending on the result determined in step c), the method for determining the residue may further include the following steps: in the case where the result of step c) indicates that the residue of the analyte from the at least one previous sample exceeds a predetermined threshold, the step of marking the result of step a) as unreliable, and optionally starting a rerun of the target sample. Thus, the LC-MS device may not provide a determination of the analyte, may indicate that the determined result is unreliable, and / or may result in repeating at least the chromatogram determination, and in one embodiment repeating all steps a) to c) of the method for the affected sample. In one embodiment, the repetition is performed directly after a control sample lacking the analyte, or directly after a sample with a known low concentration of the analyte. In further embodiments, the resulting amount or concentration determined from the chromatogram established in step a) may be corrected for the residue of the analyte from the at least one previous sample. As specified above, step b) of the method provides a background height associated with the residue, enabling the person skilled in the art to correct the amount or concentration of the analyte determined from the chromatogram established in step a) for the occurring residue. Thus, the corrected amount or concentration of the analyte can be calculated. Exemplary methods for quantifying the above correlation are described elsewhere herein.

[0029] In one embodiment, the method further comprises at least one confirmation step, wherein the confirmation step includes determining the reliability of the background height; that is, in one embodiment, the method further comprises the step of providing an assessment of whether the increased background value is caused by residue. As will be appreciated, the confirmation step is optional, as for quality control purposes, it may be sufficient to determine that residue may confound the values measured for the analyte. In one embodiment, determining the reliability of the background height includes analyzing the quantitative factor signal and / or qualitative factor signal of the background data points, and in one embodiment, analyzing the quantitative factor signal and / or qualitative factor signal of the background data points used to determine the background height of the chromatogram. In a further embodiment, determining the reliability of the background height includes analyzing the quantitative factor signal and qualitative factor signal of the background data points, in particular the ratio of the quantitative factor signal to the qualitative factor signal, i.e., the quantitative factor / qualitative factor ratio, and in one embodiment, analyzing the quantitative factor signal and qualitative factor signal of the background data points used to determine the background height of the chromatogram. In one embodiment, determining the reliability of the background height includes determining the quantitative factor / qualitative factor ratio near the upstream of the upper peak boundary and / or near the downstream of the lower peak boundary, near the upstream of the upper peak boundary in one embodiment, and near the downstream of the lower peak boundary in a further embodiment, the term "near" having the meaning as specified above. In one embodiment, these values, especially if the values used to calculate the quantitative factor / qualitative factor ratio are single-cycle values as specified above.

[0030] In one embodiment, determining the reliability of the background height includes determining a reliability parameter from the above signals and / or parameters. It is found that due to the increase in residue, the values determined for the analyte quantitative factor (AQN) and analyte qualitative factor (AQL) in the background measurement increase, and the value of the quantitative factor / qualitative factor ratio approaches the reference quantitative factor / qualitative factor ratio, which is analyte-specific and system-specific, i.e., assay-specific. In one embodiment, the reference quantitative factor / qualitative factor ratio is the quantitative factor / qualitative factor ratio determined for a substantially pure analyte and / or in an analysis run without residue, and in a further embodiment, the reference quantitative factor / qualitative factor ratio is the integrated quantitative factor / qualitative factor ratio determined for a substantially pure analyte and / or in an analysis run without residue. Thus, in one embodiment, the reliability of the background height determination is confirmed in the case where the value of the quantitative factor / qualitative factor ratio approaches the reference quantitative factor / qualitative factor ratio.

[0031] Also due to the increase in the residue, it is found that the variability of the values determined for the analyte quantification factor (AQN) and the analyte qualification factor (AQL) in the background measurement is reduced. Therefore, in one embodiment where the variability of the quantification factor / qualification factor ratio is lower than the reference as specified elsewhere herein, the reliability of the background height determination is confirmed in one embodiment. Thus, in one embodiment, determining the reliability of the background height includes determining the average value of the quantification factor / qualification factor ratio of the background data points, which is the mean in one embodiment, particularly the median, arithmetic mean, or geometric mean. In one embodiment, the average value of the quantification factor / qualification factor ratio of the background data points used to determine the background height of the chromatogram is determined, and these values may be reliability parameters. In one embodiment, the said average value is compared with a predetermined reference. In a further embodiment, a measure of the variability of the background data points is provided, which is particularly a reliability parameter of the quantification factor signal, the qualification factor signal, and / or the quantification factor / qualification factor ratio in one embodiment; the measure of the variability of the background data points can be any variability parameter considered suitable by a person skilled in the art, particularly the coefficient of variation. However, it is also conceivable to determine, for example, the standard deviation or an equivalent parameter.

[0032] As used herein, the term "reference" refers to an identifying sub - entity that allows the assessment of the reliability of a residual determination. This identifying sub - entity can be a reliability parameter, e.g., the value of an average or a variability parameter as specified elsewhere herein, indicative of the residual. In one embodiment, the reference is a quantitative metric, and in a further embodiment is a value (e.g., a threshold), a range (e.g., a range of values indicative of a reliable residual determination), a fraction, or any other value or range deemed appropriate by a person skilled in the art. In one embodiment, depending on the type of reference selected, the reference is an analyte - specific, device - specific, and / or method - specific parameter, and in a further embodiment is an analyte - specific parameter. Methods for determining an appropriate reference are provided elsewhere herein on an exemplary basis. In view of the foregoing, the reference is, in one embodiment, determined using the same type of LC - MS device as that used in the methods specified herein. In one embodiment, in the case of analyzing the quantitative factor signal and / or the qualitative factor signal of background data points, the reference is a quantitative metric of the variability of the quantitative factor signal and / or the qualitative factor signal and / or a value of the deviation of the quantitative factor signal and / or the qualitative factor signal from an expected value. Thus, in the case of determining a quantitative factor / qualitative factor ratio, the reference can be the quantitative factor / qualitative factor ratio or the integrated quantitative factor / qualitative factor ratio determined for a pre - purified or substantially pure analyte and / or in a residue - free analysis run. A person skilled in the art can, for example, determine an appropriate reference during assay development; on an exemplary basis, in one embodiment, e.g., in the case of determining a quantitative factor / qualitative factor ratio, the reference is a threshold or a reference range. Thus, in the case of determining an average, particularly a median, the reference can be the (internal) quantitative factor / qualitative factor ratio determined for a substantially pure analyte and / or in a residue - free analysis run ± up to 10 times, in a further embodiment ± up to 2 times, in a further embodiment ± up to 1.5 times, in a further embodiment ± up to 1 time, in a further embodiment ± up to 0.5 times, in a further embodiment ± up to 0.1 times; thus, the reference range can be, for example, the (internal) quantitative factor / qualitative factor ratio determined for a substantially pure analyte and / or in a residue - free analysis run ± 1000%, in one embodiment ± 100%, in a further embodiment ± 50%, in a further embodiment ± 20%, in a further embodiment ± 10%. In this case, in one embodiment, a value below or corresponding to the threshold or within the reference range indicates a reliable residual determination. In a further exemplary embodiment, in the case where the coefficient of variation is determined as the variability parameter, the reference is a threshold of at most 0.5, in one embodiment at most 0.4, in a further embodiment at most 0.3, or a mathematically corresponding value; in this case, in one embodiment, a value below or equal to the threshold indicates a reliable residual determination.

[0033] As used herein, the term "quality control" is known to those skilled in the art. In one embodiment, quality control is the process of ensuring that the processes performed by an entity and / or the goods produced meet predefined quality standards. In a further embodiment, in sample measurements, particularly in the measurement of medical samples (such as patient samples), for example in clinical diagnostics and / or clinical chemistry, quality control includes ensuring that the analytical results obtained using a specific measurement method correspond to the results obtained using a gold standard method and thus, in one embodiment, correspond to the results that are theoretically obtainable within a predefined range. Thus, in one embodiment, the method for determining a residue includes, depending on the determination result of step c), one or more of the following as one or more further steps: i) marking the result of step a) as unreliable if the result of step b) indicates that the background height exceeds a predefined threshold and optionally starting a rerun of the target sample; ii) marking the result of step a) as unreliable if the result of step c) indicates that the residue of the analyte from the at least one previous sample exceeds a predefined threshold and optionally starting a rerun of the target sample; iii) in an embodiment as specified elsewhere herein, correcting the result of step a) for the residue of the analyte from the at least one previous sample.

[0034] As used herein, in one embodiment, the term "internal standard" refers to an analyte present in a sample at a defined concentration. Thus, in one embodiment, the concentration of the internal standard is known; however, it is also conceivable that the concentration of the internal standard is unknown but at least the same for the target sample and at least one calibration sample; in this case, in one embodiment, the concentration of the internal standard is the same for all analyzed samples. In one embodiment, the internal standard is structurally similar to the analyte, and in a further embodiment, is structurally identical to the analyte. Particularly in the latter case, in one embodiment, the internal standard is an isotopically labeled molecule, particularly an isotopically labeled form of the analyte, such as 2 H (deuterated), 15 N and / or 13 C-labeled derivatives. An internal standard sample can be a sample that includes at least one internal standard substance with a known (e.g., predefined) concentration. For more details on standard samples, see, for example, EP 3425369 A1.

[0035] Advantageously, in the basic work of the present invention, it has been found that the degree of residue between two samples can be determined by measuring the background height as described herein, such that samples affected by an intolerable degree of residue can be detected by determining the background height. In addition, a proportional relationship has been found between peak residue and background height, making it feasible to perform a quantitative correction for the residue based on the background height. Further, it has been found that background height data, particularly single-cycle background data points, can be used to verify the reliability of residue determination.

[0036] The definitions made above apply mutatis mutandis to the following. Additional definitions and explanations made below also apply mutatis mutandis to all embodiments described in this specification.

[0037] The present invention further relates to a system for determining the concentration of at least one analyte in a sample, comprising:

[0038] (I) at least one liquid chromatography mass spectrometer (LC-MS) device, wherein the LC-MS device is configured to measure the analyte in the sample and to determine at least one chromatogram, and

[0039] (II) at least one evaluation device, wherein the evaluation device is configured to determine the background height of the chromatogram and to determine the residue based on the background height.

[0040] As used herein, the term "system" relates to different devices that are operatively connected to each other. The devices can be implemented in a single physical unit or can be physically separated units that are operatively connected to each other. Suitable components and their properties are described elsewhere below and also above in the context of the method for determining residue. Thus, the method of the present invention can be implemented by the system specified herein. Thus, in one embodiment, the device is configured to perform the method for determining the residue of an analyte as specified elsewhere herein, the method for performing at least one measurement as specified elsewhere herein, and / or the method for determining the relationship between the background height and the residue of an analyte as specified elsewhere herein. The system can include additional devices or units, particularly a data collector, an output unit, a communication interface, and / or any other device or unit that a person skilled in the art deems suitable.

[0041] The LC-MS device and the device and method for determining at least one chromatogram have been described above in the context of the method for determining residue.

[0042] The term "evaluation device" generally refers to any device suitable for performing the method steps described above, in one embodiment by using at least one data processing device, and in a further embodiment by using at least one processor and / or at least one application-specific integrated circuit. Thus, by way of example, at least one evaluation device may include at least one data processing unit having software code stored thereon, the software code including a plurality of computer commands. The evaluation device may provide one or more hardware elements for performing one or more of the indicated operations, and / or may provide software running thereon to one or more processors for performing one or more method steps.

[0043] As used herein, the term "data collector" relates to any storage unit configured to store data, in particular data points, chromatograms, determined background heights, results of residue determinations, and / or provided recommendations and / or decisions made for further procedures of a sample, determined by an LC-MS device. In one embodiment, the data collector includes at least one database configured to receive and / or store at least one chromatogram. In one embodiment, the data collector includes at least one database including one or more references. In one embodiment, the data collector includes at least one database including data on the correlation between background height and residue.

[0044] As used herein, the term "output unit" relates to any unit configured to transfer information from the system to another entity, where the other entity may be another data processing device and / or a user. Thus, the output device may include a user interface (such as a suitably configured display), or may be a printer. However, the output unit may also be an indicator, such as an indicator light, indicating, for example, the detection of a residue.

[0045] The term "communication interface" is understood by those skilled in the art to relate to any interface configured for information exchange, in particular data exchange. Such data exchange may be achieved by a permanent or temporary physical connection, such as a coaxial cable, a fiber cable, an optical fiber or a twisted pair cable, a 10BASE-T cable, a storage unit connector (such as USB, FireWire and similar connectors). Alternatively, it may be achieved by using a temporary or permanent wireless connection, such as radio waves, such as Wi-Fi, LTE, LTE Advanced or Bluetooth, etc.

[0046] The present invention also relates to a method for performing at least one measurement of an analyte in a sample using at least one liquid chromatography mass spectrometry device, the method comprising the following steps:

[0047] (A) Performing at least one first measurement on a first sample;

[0048] (B) Perform at least one second measurement on a second sample;

[0049] (C) Determine the residue from the first sample to the second sample using the method for determining residue according to the present invention.

[0050] The method for performing at least one measurement is an in vitro method. Additionally, it may include steps other than the specifically mentioned steps. Further steps may involve, for example, sample pretreatment steps before step (A), such as the quality control steps specified above, or steps for correcting the measurement results of the analyte for residue as specified above. Additionally, one or more steps may be assisted by an automated device. However, it is also contemplated to perform the complete method in an automated manner, for example, in a high-throughput analysis setup.

[0051] The term "measurement of an analyte in a sample" is understood by a person skilled in the art. In one embodiment, the term relates to the quantitative, semi-quantitative, or qualitative determination of an analyte in a sample, and in one embodiment, to the quantitative determination of the amount of an analyte in a sample. As used herein, the term "amount" of an analyte relates to any quantitative measure of the analyte and is equivalent to other corresponding measures (such as mass fraction, concentration), which can be calculated from this amount when the sample mass or sample volume is known. Thus, the measurement results of the analyte in the sample can be expressed in any unit considered appropriate by a person skilled in the art, including arbitrary units, weight measures, mass fractions, concentrations, etc., or measures derived therefrom, such as according to predefined international units. Thus, the expressions "perform at least one first measurement" and "perform at least one second measurement" respectively relate to measuring the analyte in the first and second samples as specified above.

[0052] The method for determining the amount of an analyte by LC-MS is in principle known to a person skilled in the art. In one embodiment, the method includes quantitatively determining the amount of an analyte in a sample by determining the peak area of the analyte (analyte peak area); in a further embodiment, further determining the peak area of an internal standard (IS peak area) and determining the ratio of the analyte peak area to the IS peak area, and in one embodiment, comparing the said ratio with a calibration function to determine a concentration value. The corresponding methods are known to a person skilled in the art. In a further embodiment, the said amount of the analyte is corrected by performing at least steps b) and c) of the method for determining residue, and in one embodiment, by subtracting the determined residue from the amount of the analyte determined for the second sample, the amount determined for the determined residue is corrected.

[0053] The present invention further relates to a method for determining the relationship between the background height and the residue of an analyte on a liquid chromatography mass spectrometer device, the method comprising the following steps:

[0054] (i) Perform at least one first measurement on a first sample;

[0055] (ii) Perform at least one second measurement on a second sample and determine at least one chromatogram thereof, wherein the second sample does not contain the analyte and is, in one embodiment, a control sample and, in a further embodiment, a buffer control sample, a blank control sample or a matrix control sample;

[0056] (iii) Determine the apparent amount of the analyte in the second sample or the signal corresponding thereto;

[0057] (iv) Determine the background height of the chromatogram; and

[0058] (v) Repeat steps (i) to (iv) for at least two additional first samples, the first samples comprising different concentrations of the analyte,

[0059] (vi) Correlate the apparent amount of the analyte determined in step (iii) or the signal corresponding thereto with the background height determined in step (iv),

[0060] (vii) Thereby determine the relationship between the background height and the residue of the analyte.

[0061] The method for determining the relationship is an in vitro method; furthermore, the method may include further steps not specifically addressed. In particular, the method may include performing steps i) to iv) on a first sample that does not contain the analyte. Some or all steps of the method may be assisted or performed by an automated device.

[0062] The term "apparent amount" of an analyte refers to the amount detected by an LC-MS method. Thus, the apparent amount is the amount measured for the analyte without correcting for residues.

[0063] The term "determine the relationship between the background height and the residue" is understood by a person skilled in the art in view of the present disclosure. In one embodiment, the term refers to a graphical and / or mathematical representation of establishing the correlation between the background height and the residue as specified above and in the examples. In one embodiment, the relationship is a linear relationship and, in a further embodiment, the relationship is linear above a threshold.

[0064] The present invention further discloses and provides a computer program, which includes computer-executable instructions to perform the method according to the present invention in one or more of the embodiments attached herein when the program is executed on a computer or a computer network. Specifically, the computer program can be stored on a computer-readable data carrier. Thus, specifically, one, more, or even all of the method steps as shown above can be assisted or performed by using a computer or a computer network, preferably by using the computer program.

[0065] The present invention further discloses and provides a computer program product having program code means for performing the method according to the present invention in one or more of the embodiments attached herein when the program is executed on a computer or a computer network. Specifically, the program code means can be stored on a computer-readable data carrier.

[0066] Furthermore, the present invention discloses and provides a data carrier having a data structure stored thereon, which can perform the method according to one or more of the embodiments disclosed herein after being loaded into a computer or a computer network, such as after being loaded into the working memory or main memory of a computer or a computer network.

[0067] The present invention further provides and discloses a computer program product having program code means stored on a machine-readable carrier for performing the method according to one or more of the embodiments disclosed herein when the program is executed on a computer or a computer network. As used herein, a computer program product refers to a program as a tradable product. The product can generally exist in any format (such as in a paper format) or on a computer-readable data carrier. Specifically, the computer program product can be distributed on a data network.

[0068] Furthermore, the present invention provides and discloses a modulated data signal containing instructions readable by a computer system or a computer network for performing the method according to one or more of the embodiments disclosed herein.

[0069] In one embodiment, with reference to the computer-implemented aspect of the present invention, one or more or even all of the method steps of the method according to one or more of the embodiments disclosed herein can be performed by using a computer or a computer network. Thus, generally speaking, any method step including providing and / or processing data can be performed by using a computer or a computer network. Generally speaking, these method steps can include any method steps except those that usually require manual operations (such as providing samples and / or performing certain aspects of actual measurements).

[0070] Specifically, the present invention further discloses:

[0071] A computer or computer network comprising at least one processor, wherein the processor is adapted to execute a method according to one of the embodiments described in this specification,

[0072] A computer-loadable data structure adapted to execute a method according to one of the embodiments described in this specification when the data structure is executed on a computer,

[0073] A computer program, wherein the computer program is adapted to execute a method according to one of the embodiments described in this specification when the program is executed on a computer,

[0074] A computer program comprising program means for executing a method according to one of the embodiments described in this specification when the computer program is executed on a computer or on a computer network,

[0075] A computer program comprising program means according to the previous embodiment, wherein the program means are stored on a computer-readable storage medium,

[0076] A storage medium on which a data structure is stored and wherein the data structure is adapted to execute a method according to one of the embodiments described in this specification after being loaded into the main memory and / or working memory of a computer or computer network, and

[0077] A computer program product having program code means, wherein the program code means can be stored or are stored on a storage medium for executing a method according to one of the embodiments described in this specification when the program code means are executed on a computer or computer network.

[0078] In summary, the following embodiments are particularly contemplated.

[0079] Embodiment 1: A method for determining the residue of an analyte from a previous sample to a target sample on a liquid chromatography-mass spectrometry (LC-MS) device, the method comprising the steps of:

[0080] (a) Providing at least one chromatogram of the target sample on the LC-MS device;

[0081] (b) Determining the background height of the chromatogram; and

[0082] (c) Determining the residue of the analyte from the previous sample to the target sample based on the background height.

[0083] Example 2: The method according to Example 1, wherein in one embodiment of the analyte quantification factor signal intensity over elution time, the chromatogram is a representation of the intensity of the analyte-specific signal over elution time.

[0084] Example 3: The method according to Example 1 or 2, wherein the measuring step a) includes determining data points representing at least one of the quantification factor signal and the qualification factor signal over elution time and optionally storing the data points on a storage medium.

[0085] Example 4: The method according to any one of Examples 1 to 3, wherein step c) includes using a predetermined relationship between the background height and a parameter associated with the residue.

[0086] Example 5: The method according to Example 5, wherein the relationship includes at least one linear function, at least one quadratic function, at least one rational function, and / or at least one sigmoid function.

[0087] Example 6: The method according to any one of Examples 1 to 4, wherein step b) includes:

[0088] b1) identifying the peak corresponding to the analyte in the chromatogram; and

[0089] b2) determining the upper peak boundary and the lower peak boundary of the peak.

[0090] Example 7: The method according to Example 6, further comprising the step

[0091] b3) determining at least one minimum signal intensity value within the upper peak boundary and the lower peak boundary.

[0092] Example 8: The method according to any one of Examples 1 to 7, wherein the background height is determined near the upstream of the upper peak boundary and / or near the downstream of the lower peak boundary.

[0093] Example 9: The method according to any one of Examples 1 to 8, wherein the method further includes at least one confirmation step, and the confirmation step includes determining the reliability of the background height.

[0094] Example 10: The method according to Example 9, wherein the reliability of the background height is determined by calculating a reliability parameter and comparing the reliability parameter with a predefined reference.

[0095] Example 11: The method according to Example 9 or 10, wherein the reliability of the background height is determined by analyzing background data points, preferably the quantitative factor signal and the qualitative factor signal of the background data points used to determine the background height of the chromatogram.

[0096] Example 12: The method according to any one of Examples 9 to 11, wherein in the confirmation step, the quantitative factor / qualitative factor ratio of the background data points is determined.

[0097] Example 13: The method according to any one of Examples 8 to 12, wherein in the confirmation step, the median of the quantitative factor / qualitative factor ratio of the background data points is determined and compared with a predefined reference.

[0098] Example 14: The method according to Example 13, wherein if the median of the quantitative factor / qualitative factor ratio differs by at most ±100%, in one embodiment at most ±50%, and in one embodiment at most ±20% from the value of the quantitative factor / qualitative factor ratio determined for a substantially pure analyte and / or in a residue-free analysis run, the residue determined in step c) is classified as reliable.

[0099] Example 15: The method according to any one of Examples 9 to 14, wherein the confirmation step includes determining the coefficient of variation of the background data points, preferably the background data points used to determine the background height of the chromatogram.

[0100] Example 16: The method according to Example 15, wherein if the coefficient of variation of the background data points is at most a predetermined reference, in one embodiment ≤0.5, the residue determined in step c) is classified as reliable.

[0101] Example 17: The method according to any one of Examples 1 to 16, wherein the at least one previous sample is the at least one sample measured immediately before the target sample on the liquid chromatography mass spectrometer, preferably wherein the at least one previous sample is the sample measured immediately before the target sample on the liquid chromatography mass spectrometer.

[0102] Example 18: The method according to any one of Examples 1 to 17, wherein method steps b) and c) are performed by a computer.

[0103] Example 19: The method according to any one of Examples 1 to 17, wherein the method is a quality control method or is included in a quality control method.

[0104] Example 20: A system for determining the concentration of at least one analyte in a sample, comprising:

[0105] (I) At least one liquid chromatography mass spectrometer (LC-MS) device, wherein the LC-MS device is configured to measure the analyte in the sample and to determine at least one chromatogram, and

[0106] (II) At least one evaluation device, wherein the evaluation device is configured to determine the background height of the chromatogram and to determine the residue based on the background height.

[0107] Example 21: The system according to the previous example, which is configured to perform the method for determining the residue of an analyte according to any one of Examples 1 to 19.

[0108] Example 22: The system according to Example 20 or 21, wherein the evaluation device is adapted to perform the method for determining the residue of an analyte according to any one of Examples 1 to 9.

[0109] Example 23: A method for performing at least one measurement on an analyte in a sample using at least one liquid chromatography mass spectrometer device, the method comprising the following steps:

[0110] (A) Performing at least one first measurement on a first sample;

[0111] (B) Performing at least one second measurement on a second sample;

[0112] (C) Determining the residue from the first sample to the second sample using the method for determining the residue according to any one of Examples 1 to 19.

[0113] Example 24: The method according to Example 23, wherein for the analyte in the second sample, (i) no determination is provided, (ii) the determination result is indicated as unreliable, and / or (iii) the measurement is repeated; in the case where the residue of the analyte from the first sample to the second sample is determined to exceed a predetermined threshold.

[0114] Example 25: The method according to Example 23 or 24, which includes quantitatively determining the amount of the analyte in the second sample.

[0115] Example 26: The method according to any one of Examples 23 to 25, wherein the peak area ratio of the analyte and the internal standard quantitative factor is determined, and wherein the amount of the analyte in the sample is determined by a calibration function.

[0116] Example 27: The method according to any one of Examples 23 to 26, wherein by performing at least steps b) and c) of Example 1, and correcting the amount by subtracting the determined residue from the quantitative result of the analyte in the second sample.

[0117] Example 28: A method for determining the relationship between the background height and the residue of an analyte on a liquid chromatography mass spectrometry device, the method comprising the steps of:

[0118] (i) Performing at least one first measurement on a first sample;

[0119] (ii) Performing at least one second measurement on a second sample and determining at least one chromatogram thereof, wherein the second sample does not contain the analyte and is, in one embodiment, a control sample and, in a further embodiment, a buffer control sample, a blank control sample or a matrix control sample;

[0120] (iii) Determining the apparent amount of the analyte in the second sample or the signal corresponding thereto;

[0121] (iv) Determining the background height of the chromatogram; and

[0122] (v) Repeating steps (i) to (iv) for at least two additional first samples, the first samples comprising different concentrations of the analyte,

[0123] (vi) Correlating the apparent amount of the analyte determined in step (iii) or the signal corresponding thereto with the background height determined in step (iv),

[0124] (vii) Thereby determining the relationship between the background height and the residue of the analyte.

[0125] Example 29: A database tangibly embedded on a data carrier, comprising: one or more references for performing reliability determination according to the method of any one of Examples 9 to 19, and / or data on the correlation between the background height and the residue determined according to the method of Example 28 in one embodiment.

[0126] Example 30: The database according to Example 29 is tangibly embedded in a data collector of the system according to any one of Examples 20 to 22.

[0127] Example 31: A computer or computer network comprising at least one processor, wherein the processor is adapted to execute at least steps b) and c) of the method according to any one of Examples 1 to 19 and / or at least step (vi) of the method according to Example 28.

[0128] Example 32: A computer-loadable data structure adapted to perform at least steps b) and c) of the method according to any one of Examples 1 to 19 and / or at least step (vi) of the method according to Example 28, while the data structure is being executed on a computer.

[0129] Example 33: A computer program, wherein the computer program is adapted to perform at least steps b) and c) of the method according to any one of Examples 1 to 19 and / or at least step (vi) of the method according to Example 28, while the program is being executed on a computer.

[0130] Example 34: A computer program comprising program means for performing at least steps b) and c) of the method according to any one of Examples 1 to 19 and / or at least step (vi) of the method according to Example 28, while the computer program is being executed on a computer or a computer network.

[0131] Example 35: A computer program comprising the program means according to Example 34, wherein the program means are stored on a computer-readable storage medium.

[0132] Example 36: A storage medium, wherein a data structure is stored on the storage medium, and wherein the data structure, after having been loaded into the main storage and / or working memory of a computer or a computer network, is adapted to perform at least steps b) and c) of the method according to any one of Examples 1 to 19 and / or at least step (vi) of the method according to Example 28.

[0133] Example 37: A computer program product having program code means, wherein the program code means are capable of being stored on or are stored on a storage medium, the computer program product for performing at least steps b) and c) of the method according to any one of Claims 1 to 19 and / or at least step (vi) of the method according to Example 28 when the program code means are executed on a computer or a computer network.

[0134] The entire disclosure of all references cited in this specification and the disclosures specifically mentioned in this specification are incorporated herein by reference. BRIEF DESCRIPTION OF THE DRAWINGS

[0135] Figure 1 : Correlation between the analyte quantification factor (AQN) peak area of a previous sample (x-axis) and the analyte quantification factor (AQN) peak area of a blank sample (current sample, y-axis).

[0136] Figure 2: Example of an AQN quality trace showing residual effects; 1: blank sample; 2: sample with medium analyte content; 3: blank sample; 4: sample with high analyte content; 5: blank sample; the arrow indicates that sample 4 was measured immediately after sample 3 and sample 5 was measured immediately after sample 4; the lower row shows the same chromatogram as the upper row but with a higher magnification (different scale on the y-axis).

[0137] Figure 3 : Correlation of two types of residues - background height (x-axis) and AQN peak area (y-axis).

[0138] Figure 4 : Single-cycle ratio used as a confirmation measure of residues. Upper row: exemplary chromatograms of signal intensity over time (AQN (upper line) and AQL (lower line) respectively); Middle row: individual values and median over time of the AQN / AQL ratio of the data points in the upper row; Lower row: coefficient of variation of the AQN / AQL ratio of the data points in the upper row.

[0139] Figure 5 : Linear calibration function of testosterone (40 pg / mL - 200 ng / mL) in the LC-MS method.

[0140] Figure 6 : Correlation between background height and residual peak area in the testosterone measurement of Example 3.

[0141] The following examples are intended to illustrate the invention only. In no way should they be construed as limiting the scope of the invention.

[0142] Example 1: Correlation between residue and background height

[0143] In an experimental LC-MS setup, data of blank samples were generated after generating data of high-concentration samples; as Figure 1 shown, a correlation was observed between the analyte peak area of the blank sample and the analyte peak area of the previous sample. The slope of this function is a measure of the degree of residue. Analyte residues generally appear in two forms: as peaks from residues before the LC column and as a broad baseline increase (background signal) from residues after the LC column ( Figure 2 ).

[0144] Although both types of residues can be measured in analyte-free samples (such as blank samples, double blank samples, or solvent samples), the background increase can only be measured in real patient samples. Therefore, the result deviation caused by residues cannot be directly measured. Unexpectedly, it was found that both types of residues showed a rather obvious correlation ( Figure 3)。Therefore, the background signal can be used to monitor the residues in the measured sample. Using this correlation, the calculation of the impact of the residues on the quantitative results of the patient sample can be estimated.

[0145] Example 2: Confirming residue measurement

[0146] In principle, there can be several reasons for an increase in the background signal. Typical contributing factors are chemical noise (interference), background interference, instrument noise, and residues. In particular, instrument noise varies over time as it is a function of ion source aging and detector aging / voltage. To distinguish the effects arising from non-specific sources of increased background signal, the quantitative factor / qualitative factor ratio (single-cycle ratio) of each individual data point can be used to confirm this finding by comparison with a target value. In addition, the coefficient of variation (cv) of the single-cycle ratio can also be used to confirm ( Figure 4 ).

[0147] Example 3: Application in testosterone measurement

[0148] The concentration of testosterone in the patient sample can be determined using a calibration function by reading the concentration value of the measured peak area ratio of the analyte quantitative factor to the internal standard quantitative factor (AQN / IQN) ( Figure 5 ).

[0149] Three different samples are compared. Sample 1 with a very low analyte concentration is measured after a sample with a very high concentration. Sample 2 with a low analyte concentration is measured after a high-concentration sample, and Sample 3 with a medium concentration is measured after a sample with a very high concentration.

[0150] Using the correlation shown according to Figure 6 , the measured values can be verified to determine the residues; the results are summarized in Table 1:

[0151] Column 2 shows the peak area AQN, the peak area IQN, the AQN / IQN ratio calculated therefrom, and the background height determined for the corresponding sample. Column 3 shows the analyte concentration calculated from the AQN / IQN ratio in Column 2.

[0152] Column 4 shows the apparent AQN peak area contributed by the residues, which is determined based on the background height and according to the correlation shown in Figure 6 , as well as the contribution of the residues to the absolute concentration and the fraction of this contribution relative to the calculated concentration. In summary, in Sample 1, 62% of the measured concentration is actually caused by residues.

[0153] The fifth column of Table 1 shows the confirmation measures: the upper row shows the median of the single-cycle AQN / AQL ratio calculated for the data points near the peak boundary, the predetermined reference range, and the comparison result between the corresponding value and the reference. OK means that the measured value is within the reference range, that is, the confirmed residue. NO indicates that the value is outside the reference range, that is, the unconfirmed residue. The lower row shows the coefficient of variation (cv) of the single-cycle AQN / AQL ratio calculated for the data points near the peak boundary, the predetermined reference range, and the comparison result between the corresponding value and the reference. OK and NO have the meanings as shown above.

[0154] As shown in Table 6, interference caused by residues was confirmed in Samples 1 and 3, although there was only a small interference in Sample 3. In contrast, there was no obvious residue in the measurement of Sample 2.

[0155] Literature:

[0156] EP 3 425 369 A1

[0157] Lynch(2020), Clinical Chemistry 62(1):24–299

[0158]

Claims

1. A method for determining the residue of an analyte from a previous sample into a target sample on a liquid chromatography mass spectrometry (LC-MS) device, the method comprising the following steps: (a) Determining at least one chromatogram of the target sample on the LC-MS device; (b) Determining the background height of the chromatogram; and (c) Determining the residue of the analyte from the previous sample into the target sample based on the background height, wherein the background height is associated with the residue.

2. The method according to claim 1, wherein in one embodiment of the signal intensity of the analyte quantification factor over elution time, the chromatogram is a representation of the intensity of the analyte-specific signal over elution time.

3. The method according to claim 1 or 2, wherein step c) comprises using a predefined relationship between the background height and a parameter associated with the residue.

4. The method according to claim 1 or 2, wherein step b) comprises: b1) Identifying the peak corresponding to the analyte in the chromatogram; and b2) Determining the upper peak boundary and the lower peak boundary of the peak.

5. The method according to claim 4, further comprising the step b3) Determining at least one minimum signal intensity value within the upper peak boundary and the lower peak boundary.

6. The method according to claim 4, wherein the background height is determined near the upstream of the upper peak boundary and / or near the downstream of the lower peak boundary.

7. The method according to claim 1 or 2, wherein the method further comprises at least one confirmation step, wherein the confirmation step comprises determining the reliability of the background height.

8. The method according to claim 7, wherein the reliability of the background height is determined by calculating a reliability parameter and comparing the reliability parameter with a predefined reference.

9. The method according to claim 8, wherein: (i) By determining the average of the quantification factor / qualification factor ratios of the background data points and comparing the average with a predefined average reference; (ii) By determining the variation parameter of the background data points and comparing the variation parameter with a predefined variation reference, wherein the most abundant and / or most reliably detected fragment is used to quantify the analyte, i.e., the analyte quantification factor, while the second transition is used to confirm the identity of the analyte, i.e., the analyte qualification factor.

10. The method according to claim 8, wherein (i) By determining the average of the quantification factor / qualification factor ratios of the background data points used to determine the background height of the chromatogram and comparing the average with a predefined average reference; and / or (ii) By determining the variation parameter of the background data points used to determine the background height of the chromatogram and comparing the variation parameter with a predefined variation reference, wherein the most abundant and / or most reliably detected fragment is used to quantify the analyte, i.e., the analyte quantification factor, while the second transition is used to confirm the identity of the analyte, i.e., the analyte qualification factor.

11. The method according to claim 1 or 2, wherein the method is a quality control method or is included in a quality control method.

12. The method according to claim 1 or 2, wherein the LC-MS device is an LC tandem MS device, and wherein the ratio of the quantification factor to the qualification factor is determined by dividing the intensity of the fragment used for quantifying the analyte by the intensity of the fragment used for determining the identity of the analyte.

13. A system for determining the concentration of at least one analyte in a sample, which comprises: (I) at least one liquid chromatography mass spectrometer LC-MS device, wherein the LC-MS device is configured to measure the analyte in the sample and to determine at least one chromatogram, and (II) at least one evaluation device, wherein the evaluation device is configured to determine the background height of the chromatogram and to determine the residue based on the background height, wherein the background height is associated with the residue.

14. The system according to claim 13, which is configured to perform the method according to any one of claims 1 to 11.

15. The system according to claim 13 or 14, wherein the evaluation device is adapted to perform the method according to any one of claims 1 to 11.

16. A method for performing at least one measurement on an analyte in a sample using at least one liquid chromatography mass spectrometer device, the method comprising the following steps: (A) performing at least one first measurement on a first sample; (B) performing at least one second measurement on a second sample; (C) using the method according to any one of claims 1 to 11 to determine the residue from the first sample to the second sample.

17. The method according to claim 16, wherein in the case where the residue of the analyte from the first sample to the second sample is determined to exceed a predetermined threshold, for the analyte in the second sample, (i) no determination is provided, (ii) the result of the determination is indicated as unreliable, and / or (iii) the measurement is repeated.

18. The method according to claim 16, which includes quantitatively determining the amount of the analyte in the second sample.

19. The method according to claim 18, wherein the amount is corrected by performing at least steps a) to c) of the method according to any one of claims 1 to 11 and subtracting the determined residue from the quantitative result of the analyte in the second sample.

20. A method for determining the relationship between the background height and the residue of an analyte on a liquid chromatography mass spectrometer device, the method comprising the following steps: (i) performing at least one first measurement on a first sample; (ii) performing at least one second measurement on a second sample and determining at least one chromatogram thereof, wherein the second sample does not contain the analyte; (iii) determining the apparent amount of the analyte in the second sample or the signal corresponding thereto; (iv) determining the background height of the chromatogram; and (v) repeating steps (i) to (iv) for at least two additional first samples, the first samples including different concentrations of the analyte, (vi) Correlate the apparent amount of the analyte determined in step (iii) or the signal corresponding thereto with the background height determined in step (iv), (vii) thereby determining the relationship between the background height and the residue of the analyte.

21. The method according to claim 20, wherein the second sample is a control sample.

22. The method according to claim 20, wherein the second sample is a buffer control sample, a blank control sample or a matrix control sample.

23. A computer program product having program code means, wherein the program code means can be stored on or in a storage medium, the computer program product being operative to perform at least steps b) and c) of the method according to any one of claims 1 to 11 and / or at least step (vi) of the method according to claim 20 when the program code means are executed on a computer or a computer network.

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