Method of acquiring characteristic peaks of compounds, method of calculating signal-to-noise ratios of characteristic peaks, and server host for implementing the methods

Abstract

To provide a method of acquiring characteristic peaks of a compound.SOLUTION: Characteristic peaks of one or more compounds are obtained from a mass spectrometry file based on a filter parameter table. The filter parameter table records a filter parameter set for each compound. Selection of characteristic peaks for each compound is determined by filtering rules defined by its own filter parameter set. Another method for obtaining characteristic peaks of compounds is based on the positions of the characteristic peaks obtained from the mass spectrometry file, from which one or more characteristic peaks of compounds are obtained from another mass spectrometry file.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to mass spectrum data analysis, and in particular to a method for obtaining characteristic peaks of compounds. [Background technology]

[0002] Mass spectrometry can be used to determine what compounds are contained in a sample, for example, what pesticide residues are present in a vegetable sample. Common mass spectrometers include liquid chromatography tandem mass spectrometry (LC-MS / MS) and gas chromatography tandem mass spectrometry (GC-MS / MS).

[0003] A bottleneck in conventional compound detection work is that an experienced technician must spend a tremendous amount of time and effort analyzing the mass spectrum file generated by the mass spectrometer in order to obtain characteristic peak data for each compound in the mass spectrum file (e.g., the total area, signal-to-noise ratio, and area ratio of the quantitative / qualitative characteristic peaks of each compound). This not only leads to problems such as inefficiency in the entire compound detection work, but also makes errors due to human error more likely to occur. Furthermore, it takes two to three years for technicians to be trained and able to perform the work independently, resulting in frequent technician shortages. Summary of the Invention [Means for solving the problem]

[0004] The present invention provides a method for acquiring a characteristic peak of a compound, the method including: reading mass spectrum data from a mass spectrum file, the mass spectrum data including a plurality of ion pairs belonging to the compound and all of their peaks; reading a selection parameter set for the compound from a selection parameter table; selecting, from the ion pairs of the compound, an ion pair having the highest or lowest peak based on a quantitative ion pair selection parameter in the selection parameter set, as the quantitative ion pair of the compound; and selecting, from all peaks of the quantitative ion pairs of the compound, the Nth peak in height from the front based on a characteristic peak number parameter in the selection parameter set, as the quantitative characteristic peak of the compound, where the value of N is determined by the characteristic peak number parameter.

[0005] In one embodiment, the method of the present invention includes, before reading the selection parameter table, first searching and acquiring the names of the compounds from a compound list based on the ion pairs of the mass spectrum data, wherein the compound list records the names and ion pairs of each compound to be detected by the mass spectrometer, and the selection parameter table records the names and selection parameter sets of each compound in the compound list.

[0006] In one embodiment, the selection parameter table in the present invention is created for each mass spectrometer that generates the mass spectrum file.

[0007] In one embodiment, the method of the present invention includes finding a peak having the same or similar position from all peaks of ion pairs other than the quantitative ion pair based on the position of the quantitative characteristic peak of the compound, and determining the peak as the qualitative characteristic peak of the compound.

[0008] In one embodiment, the method of the present invention includes defining an allowable position range for each quantitative characteristic peak found based on the position parameters of the selection parameter set, and selecting, from all peaks of each ion pair other than the quantitative ion pair in the compound, peaks whose positions fall within the allowable position range as qualitative characteristic peaks of the compound.

[0009] In one embodiment, the method of the present invention includes, after obtaining the qualitative characteristic peak of the compound, if the quantitative ion pair is selected from the ion pair having the lowest peak, subsequently performing a swapping operation to swap the quantitative characteristic peak and the qualitative characteristic peak of the compound with each other.

[0010] In one embodiment, the method of the present invention includes, when selecting the quantitative feature peak, determining whether to maintain the current selection or to change it so as to select the M-th peak in position among the N-th peaks from the front as the quantitative feature peak of the compound, based on a quantitative feature peak change parameter in the selection parameter set for the compound, where the value of M is determined by the quantitative feature peak change parameter.

[0011] In one embodiment, the method of the present invention includes, before selecting the quantitative characteristic peak, first deleting the first and last peaks of all peaks of the quantitative ion pair based on the deletion parameters of the selection parameter set.

[0012] In one embodiment, the method of the present invention includes determining whether the value of the feature peak number parameter is 2 or greater, and if the determination result is "YES," performing a pass / fail determination operation for the quantitative ion pair based on a peak ratio parameter of the selection parameter set. The pass / fail determination operation includes obtaining one or more height ratios by dividing the height of each subsequent quantitative feature peak by the height of the first quantitative feature peak, determining whether each height ratio is greater than the peak ratio parameter, and determining the quantitative ion pair as a pass ion pair if the determination result is "YES," or as a fail ion pair if the determination result is "YES."

[0013] The present invention provides a method for calculating the S / N ratio of a quantitative feature peak. The method includes: setting any quantitative feature peak of the compound as a target signal; cutting out peaks within a certain time ahead of or behind the position of any quantitative feature peak of the compound as background noise based on an S / N ratio parameter of the selection parameter set; and calculating the S / N ratio based on the intensity of the target signal and the intensity of the background noise. Preferably, the method of the present invention further includes determining whether to inspect the S / N ratio based on an S / N ratio pass / fail judgment parameter of the selection parameter set.

[0014] The present invention provides a method for calculating the S / N ratio of a qualitative feature peak. The method includes: setting any of the qualitative feature peaks of the compound as a target signal; cutting out peaks within a certain time ahead of or behind the position of any of the qualitative feature peaks of the compound as background noise based on an S / N ratio parameter of the selection parameter set; and calculating the S / N ratio based on the intensity of the target signal and the intensity of the background noise. Preferably, the method of the present invention further includes determining whether to inspect the S / N ratio of the qualitative feature peak based on an S / N ratio pass / fail judgment parameter of the selection parameter set.

[0015] The present invention also provides another method for acquiring characteristic peaks of compounds, the method including: receiving a first mass spectral file and a second mass spectral file; acquiring characteristic peaks of a plurality of compounds from the first mass spectral file; reading one or more mass spectral data from the second mass spectral file, each mass spectral data including a group of ion pairs belonging to the compound and all of its peaks; and performing a characteristic peak extraction operation on the peaks read from the second mass spectral file based on the characteristic peaks of the compounds acquired from the first mass spectral file, thereby acquiring characteristic peaks of each compound in the second mass spectral file.

[0016] The present invention further provides a server host, which includes a feature peak processing program and is capable of executing any of the above methods based on the program code of the feature peak processing program. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 shows a schematic flow chart of the method of the present invention. [Figure 2] Figure 2 shows the mass spectrum of one compound. [Figure 3] FIG. 3 shows the mass spectrum of another compound. [Figure 4] FIG. 4 shows the mass spectrum of another compound. [Figure 5] FIG. 5 shows a schematic flow chart of another method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention discloses a method for obtaining characteristic peaks of compounds from a mass spectrum file. The mass spectrum file is generated by testing a test solution using a mass spectrometer. The mass spectrum file records mass spectrum data of one or more compounds contained in the test solution. The test solution may be a solution for a different purpose. The compounds may also be multiple types of pesticides (e.g., 410 types) or veterinary drugs. For the preparation of the solution and the names of the pesticides, please refer to "Testing Method for Pesticide Residues in Food - Multi-residue Analysis Method (5)" (hereinafter referred to as the "promulgated method") published in 2022 by the Taiwan Food and Drug Administration (Ministry of Health and Welfare).

[0019] Mass spectral data for each compound includes multiple ion pairs in the compound and all peaks for each ion pair. Each peak has a height (i.e., signal intensity) and a position (i.e., retention time). Each ion pair consists of the mass-to-charge ratio of a precursor ion and the mass-to-charge ratio of a product ion. For example, one ion pair for iprodione consists of a precursor ion with a mass-to-charge ratio of 314 and a product ion with a mass-to-charge ratio of 56. Therefore, the ion pair is represented by 314>56. The other two ion pairs for iprodione are 314>245 and 314>271, respectively.

[0020] For convenience of explanation, the execution steps of the method of the present invention will be explained here by taking as an example the case of acquiring a characteristic peak of one compound. As shown in Figure 1, the method of the present invention includes the following steps a to d.

[0021] a) Reading mass spectrum data from the mass spectrum file, the mass spectrum data including multiple ion pairs belonging to the compound and all of their peaks.

[0022] b) Reading a selection parameter set for the compound from a selection parameter table.

[0023] c) Based on the quantitative ion pair selection parameters of the selection parameter set, an ion pair having the highest or lowest peak is selected from the ion pairs of the compound as a quantitative ion pair of the compound.

[0024] d) Based on the feature peak number parameter of the selection parameter set, the Nth peak in height from the front is selected from all the peaks of the quantitative ion pairs in the compound as quantitative feature peaks of the compound, where the value of N is determined by the feature peak number parameter.

[0025] The mass spectrum data read in step a includes only the ion pairs and their peaks, but does not include the names of the compounds to which they belong. If it is necessary to know the names of the compounds to which they belong, it is possible to search for the names of the compounds from a compound list using any of the ion pairs in the mass spectrum data. The compound list records the names and ion pairs of each compound to be detected by the mass spectrometer. Typically, the compound list is generated by the mass spectrometer together with the mass spectrum file, but it may also be created separately and manually.

[0026] In step b, the selection parameter table records selection parameter sets for multiple compounds, for example, a selection parameter set for each compound in the compound list. For example, if the compound list records 410 pesticide names and ion pairs, the selection parameter table must also create names and selection parameter sets for these 410 pesticides. The names of the 410 pesticides can be determined by referring to the method published above.

[0027] In the above example, the mass spectrum file contains mass spectrum data for only one compound. Therefore, only the selection parameter set for this compound is read from the selection parameter table to select the quantitative ion pairs and quantitative feature peaks for that compound. However, if the mass spectrum file contains mass spectrum data for multiple compounds, the selection parameter sets for these compounds must be read from the selection parameter table. In other words, for each compound, the selection parameter set for that compound is used to select the quantitative ion pairs and quantitative feature peaks for that compound from its mass spectrum data.

[0028] In the selection parameter table, some compounds have the same selection parameter set, while some compounds have different selection parameter sets. In any case, each selection parameter set includes one or more of a smoothing parameter, the quantitative ion pair selection parameter, the feature peak number parameter, a position parameter, a quantitative feature peak modification parameter, a deletion parameter, and a peak ratio parameter. Preferably, the selection parameter table further includes an SNR parameter and an SNR pass / fail parameter.

[0029] Preferably, for each ion pair peak read in step a, it is possible to determine the degree of smoothing to be applied to the coordinate points of the peak of each ion pair based on the smoothing parameter. By smoothing, peaks due to noise are removed, thereby smoothing the signal curves of each ion pair (e.g., signal curves 11 to 13 in FIG. 2) plotted based on all the peaks of each ion pair as much as possible. For example, if the smoothing parameter is null, this means that no smoothing is required. Furthermore, if the smoothing parameter is a numerical value, a larger numerical value indicates that a higher degree of smoothing is required, and conversely, a lower degree of smoothing is required.

[0030] In step c, the ion pair having the highest peak or the lowest peak can be selected as the quantitative ion pair of the compound based on the quantitative ion pair selection parameter. For example, when the value of the quantitative ion pair selection parameter is a first value (e.g., null), the ion pair having the highest peak is selected as the quantitative ion pair of the compound. When the value of the quantitative ion pair selection parameter is a second value (e.g., −1), the ion pair having the lowest peak is selected as the quantitative ion pair of the compound.

[0031] For example, as shown in FIG. 2, the first signal curve 11 is plotted based on all peaks of the first ion pair (314>56) of iprodione, the second signal curve 12 is plotted based on all peaks of the second ion pair (314>245) of iprodione, and the third signal curve 13 is plotted based on all peaks of the third ion pair (314>271) of iprodione. If the value of the quantitative ion pair selection parameter for iprodione is read as the first value from the selection parameter table, the first ion pair (314>56) of iprodione is determined to be the quantitative ion pair of iprodione. This is because, of these three curves 11 to 13, the first ion pair (314>56) has the highest peak 111. The remaining two ion pairs (314>245 and 314>271) can be determined to be two qualitative ion pairs of iprodione. Based on this, the first signal curve 11 is the signal curve for the quantitative ion pair, and the second and third signal curves 12 and 13 are the signal curves for the qualitative ion pairs, respectively. Thus, one quantitative ion pair (314>56) and two qualitative ion pairs (314>245 and 314>271) of iprodione are selected.

[0032] Similarly, as shown in FIG. 3, among the three signal curves 14-16 plotted based on all the peaks of the three ion pairs of allethrin, the one with the highest peak 141 is the first ion pair (123>81). Therefore, the selection program module 36 can designate this ion pair (123>81) as the quantitative ion pair of allethrin, and the remaining two ion pairs (107>91 and 136>93) as the two qualitative ion pairs of allethrin. Based on this, signal curve 14 becomes the signal curve of the quantitative ion pair, and signal curves 15 and 16 become the signal curves of the qualitative ion pairs, respectively. Thus, the selection of one quantitative ion pair (123>81) and two qualitative ion pairs (107>91 and 136>93) of allethrin is completed.

[0033] In step c, if the value of the quantitative ion pair selection parameter for cypermethrin is read from the selection parameter table as the second value, the third ion pair of cypermethrin (181>152.1) is tentatively designated as the quantitative ion pair (tentative) of cypermethrin, and the other two ion pairs (163>91 and 163>127) are "tentatively" designated as the two qualitative ion pairs of cypermethrin. This is because, as shown in FIG. 4, of the three signal curves 17-19 plotted based on all peaks of the three ion pairs of cypermethrin, the one with the lowest peak 191 is the third ion pair (181>152.1). Next, in accordance with step d, quantitative characteristic peaks 191-194 (tentative) and qualitative characteristic peaks 181-184 (tentative) of cypermethrin are found and then swapped. As a result, the quantitative characteristic peaks 191-194 (tentative) and the qualitative characteristic peaks 181-184 (tentative) of the compound (cypermethrin) are swapped with each other to obtain the true quantitative characteristic peaks 181-184 and true qualitative characteristic peaks 191-194 of cypermethrin. Accordingly, the above-mentioned tentative quantitative ion pair (181>152.1) is changed to a qualitative ion pair, and the original tentative qualitative ion pair (163>127) is changed to a quantitative ion pair. Therefore, in FIG. 4, 163>127 is the quantitative ion pair of cypermethrin, and 181>152.1 is the qualitative ion pair of cypermethrin. The quantitative ion pair curve and qualitative ion pair curve of cypermethrin are denoted by symbols 18 and 19, respectively. Although signal curve 17 has the highest peak 171, this is merely the signal curve of one ion pair (163>91) in cypermethrin, and is neither a quantitative nor a qualitative ion pair curve.

[0034] In step d, the number N of quantitative feature peaks of the compound can be determined based on the feature peak number parameter. For example, if the value of the feature peak number parameter is null or 1, the value of N is 1. In this case, of all the peaks of the quantitative ion pair in the compound, the peak with the highest height (i.e., the first peak) is determined as the only quantitative feature peak of the quantitative ion pair in the compound. Also, if the value of the feature peak number parameter is 2, the value of N is 2. In this case, of all the peaks of the quantitative ion pair in the compound, the peaks with the second highest height (i.e., the first and second peaks) are determined as the two quantitative feature peaks of the quantitative ion pair in the compound. Also, if the value of the feature peak number parameter is 3, the value of N is 3. In this case, of all the peaks of the quantitative ion pair in the compound, the peaks with the highest height (i.e., the first to third peaks) are determined as the three quantitative feature peaks of the quantitative ion pair in the compound. The same applies below.

[0035] For example, if the value of the characteristic peak number parameter for iprodione is read as null from the selection parameter table, this means N=1. In this case, as shown in FIG. 2, the highest peak 111, which has the highest height among all the peaks of the quantitative ion pair (314>56) in iprodione, is determined to be the only quantitative characteristic peak of the quantitative ion pair (314>56) in iprodione. Furthermore, if the value of the characteristic peak number parameter for allethrin is read as 2 from the selection parameter table, this means N=2. In this case, as shown in FIG. 3, the heights of peaks 141 to 143 of the quantitative ion pair (123>81) in allethrin are all clear, but because the value of the characteristic peak number parameter is 2, only peaks 141 and 142, which have the highest height among all the peaks of the quantitative ion pair (123>81) in allethrin, are determined to be the two quantitative characteristic peaks of allethrin. Furthermore, when the value of the characteristic peak number parameter for cypermethrin is read as 4 from the selection parameter table, it means that N = 4. In this case, as shown in Fig. 4, of all the peaks of the quantitative ion pair (181>152.1, tentative) for cypermethrin, peaks 191 to 194 having the first to fourth highest heights are provisionally defined as four quantitative characteristic peaks of cypermethrin.

[0036] After selecting the quantitative ion pairs and quantitative feature peaks of the compound, it is possible to find the qualitative feature peaks of the compound based on their positions. More specifically, for the found quantitative feature peaks, an allowable position range is defined based on the position parameter, and peaks whose positions fall within the allowable position range can be selected as the qualitative feature peaks of the compound from all peaks of ion pairs other than the quantitative ion pairs (i.e., qualitative ion pairs) in the compound. For example, when the value of the position parameter is null or 1, the allowable position range of each quantitative feature peak is within 1 second before and after the position of that quantitative feature peak. Furthermore, when the value of the position parameter is 1.5, the allowable position range of each quantitative feature peak is within 1.5 seconds before and after the position of that quantitative feature peak. Furthermore, when the value of the position parameter is 2, the allowable position range of each quantitative feature peak is within 2 seconds before and after the position of that quantitative feature peak. The same applies below.

[0037] For example, in FIG. 2 , the quantitative feature peak (i.e., the highest peak 111) of iprodione is located at t1. If the value of the location parameter for iprodione is read from the selection parameter table as 1, the range between t1-1 and t1+1 becomes the allowable location range for the quantitative feature peak 111. Next, by searching downward from the quantitative feature peak 111 along a dotted line (a virtual line that does not exist in the mass spectrum) passing through location t1, a peak 121 located at t1 and a peak 131 located close to t1 are found. Because the locations of these two peaks 121 and 131 are both within the allowable location range for the quantitative feature peak 111, these can be determined as the two qualitative feature peaks 121 and 131 of iprodione. As a result, a total of three feature peaks are obtained for iprodione: one quantitative feature peak 111 and two qualitative feature peaks 121 and 131.

[0038] Similarly, it is possible to find qualitative characteristic peaks of allethrin based on the positions of the two quantitative characteristic peaks 141 and 142 of allethrin. As is clear from FIG. 3 , the positions of peaks 151 and 152 are the same as those of the two quantitative characteristic peaks 141 and 142, respectively. Therefore, the selection program module 36 identifies peaks 151 and 152 as two qualitative characteristic peaks of one qualitative ion pair (107>91) in allethrin. Furthermore, the positions of peaks 161 and 162 are also within the allowable position ranges of the two quantitative characteristic peaks 141 and 142, respectively. Therefore, the selection program module 36 identifies peaks 161 and 162 as two qualitative characteristic peaks of another qualitative ion pair (136>93) in allethrin. As a result of the above, a total of six characteristic peaks are obtained for allethrin, including two quantitative characteristic peaks 141 and 142 and four qualitative characteristic peaks 151 and 152 and 161 and 162.

[0039] Similarly, a tentative qualitative characteristic peak can be found based on the positions of the four tentative quantitative characteristic peaks 191-194 of cypermethrin. As shown in FIG. 4 , searching upward along the dotted line passing through the quantitative characteristic peaks 191-194 reveals peaks 181-184 on the qualitative ion pair curve 18, which can be tentatively determined as the four qualitative characteristic peaks of one qualitative ion pair (163 > 127) for cypermethrin. Subsequently, the sorting program module 36 performs the above-described swapping operation to obtain eight characteristic peaks for cypermethrin: the four quantitative characteristic peaks 181-184 and the four qualitative characteristic peaks 191-194.

[0040] As is clear from the above description, the method of the present invention makes it possible to reliably obtain characteristic peaks of one or more compounds from any mass spectrum file. The characteristic peaks of each compound include quantitative characteristic peaks of quantitative ion pairs. Preferably, the characteristic peaks may further include qualitative characteristic peaks of one or more qualitative ion pairs. The number of characteristic peaks of each quantitative or qualitative ion pair may be one, two, or more.

[0041] In step d above, for some compounds, it may be inappropriate to designate all peaks found based on the feature peak number parameter (i.e., the Nth peak in height from the top) as quantitative feature peaks. Therefore, the method of the present invention may further include determining, based on the quantitative feature peak change parameter, whether to maintain the policy of "designating all peaks up to the Nth peak in height as quantitative feature peaks of the compound" or to change the policy to select "the Mth peak among the Nth peak in height as quantitative feature peak of the compound." The value of M is determined by the quantitative feature peak change parameter. For example, if the value of the quantitative feature peak change parameter is blank, M is null. In this case, all peaks up to the Nth peak in height from the top are designated as quantitative feature peaks of the compound. However, if the quantitative feature peak change parameter is not null, the Mth peak among the Nth peak in height is designated as quantitative feature peak of the compound. For example, if the value of the quantitative feature peak change parameter is 1, M is equal to 1. In this case, the sorting program module 36 determines the first peak among the N-th peaks in height as the sole quantitative feature peak of the compound. Furthermore, if the value of the quantitative feature peak change parameter is 2, M is equal to 2. In this case, the sorting program module 36 determines the second peak among the N-th peaks in height as the sole quantitative feature peak of the compound. The same applies below. Assume that the value of the quantitative feature peak change parameter for cypermethrin is read as 2 from the sorting parameter table. In this case, as shown in FIG. 4 , of the four peaks 191 to 194 in height, peak 192 is located second from the left, and therefore peak 192 alone is determined to be the sole (provisional) quantitative feature peak of cypermethrin.

[0042] The highest peak of the quantitative ion pair for some compounds may be the first or last peak. This means that the starting point or ending point of the quantitative ion pair curve for those compounds may be the highest peak. In this case, when performing step d, the first or last peak may be considered one of the quantitative feature peaks of one of the compounds, which is an error. To avoid such an error, the method of the present invention may further include deleting the first and last peaks of all quantitative ion pair peaks for the compound based on the deletion parameter, and then subsequently performing step d. For example, when the deletion parameter is a first value (e.g., null), the first and last peaks of all quantitative ion pair peaks for the compound are deleted, and then step d is subsequently performed. However, when the deletion parameter is a second value (e.g., −1), this means that no peaks need to be deleted. Furthermore, when the feature peak count parameter is ≧2, no peaks need to be deleted (i.e., the deletion parameter may be ignored).

[0043] In step c above, after the quantitative ion pairs of some compounds have been selected, it may be necessary to further determine whether they pass or fail. Therefore, the method of the present invention may further include the following: Determining whether the value of the feature peak number parameter for the compound is 2 or greater. If the determination result is "YES," performing a pass / fail determination operation for the quantitative ion pairs of the compound based on the peak ratio parameter for the compound. The pass / fail determination operation includes the following: Obtaining one or more height ratios by dividing the height of the first quantitative feature peak by the height of each subsequent quantitative feature peak, and determining whether each height ratio is greater than the peak ratio parameter. If the determination result is "YES," the quantitative ion pair is determined to be a pass ion pair; otherwise, determining the quantitative ion pair to be a fail ion pair.

[0044] In the method of the present invention described above, when selecting quantitative ion pairs and quantitative characteristic peaks for each compound, the selection is performed for each compound using rules defined by the selection parameter set for that compound, thereby significantly improving the accuracy of the resulting characteristic peaks. In addition, the selection parameter table is created for each mass spectrometer that generates the mass spectrum file. That is, a dedicated selection parameter table is created for each mass spectrometer from a different manufacturer, and even for each mass spectrometer of the same manufacturer and same model number but owned by a different user. This further improves the accuracy of the resulting characteristic peaks by fully taking into account the characteristics of the instrument and, ultimately, the user's usage habits.

[0045] The present invention further discloses a method for calculating the signal-to-noise ratio, the method including:

[0046] Based on the S / N ratio parameter in the selection parameter set for the compound, peaks within a certain time (e.g., 10 seconds) before or after the position of the characteristic peak of the compound are cut out as background noise, and the characteristic peak of the compound is set as a target signal. The characteristic peak may be a quantitative characteristic peak or a qualitative characteristic peak.

[0047] An SN ratio is calculated based on the intensity of the target signal and the intensity of the background noise, and is set as the SN ratio of the characteristic peak.

[0048] Preferably, the method for calculating the SN ratio may further include determining whether to inspect the SN ratio of the characteristic peak based on the SN ratio pass / fail judgment parameter in the selection parameter set for the compound. Typically, a quantitative characteristic peak of any compound is considered to pass if its SN ratio is 10 or more, and is considered to fail if it is not. Also, a qualitative characteristic peak of any compound is considered to pass if its SN ratio is 2 or more, and is considered to fail if it is not.

[0049] In the method of the present invention, the characteristic peaks of a compound are obtained by filtering a mass spectrum file using the filtering parameter table, but below, another method of the present invention is disclosed, in which the characteristic peaks of a compound are obtained by peak comparison.

[0050] Another method for acquiring characteristic peaks of a compound from a mass spectrum file is shown in Figure 5. This method includes the following steps a' to d'.

[0051] a') Receive the first mass spectrum file and the second mass spectrum file.

[0052] b') Characteristic peaks of a plurality of compounds are obtained from the first mass spectrum file.

[0053] c') One or more mass spectral data are read from the second mass spectral file, each mass spectral data including a plurality of ion pairs belonging to a compound and all of their peaks.

[0054] d') Extracting characteristic peaks from the peaks read from the second mass spectrum file based on the characteristic peaks of the compounds obtained from the first mass spectrum file, thereby obtaining characteristic peaks of each compound in the second mass spectrum file.

[0055] In step a', the first mass spectrum file and the second mass spectrum file are preferably generated by the same mass spectrometer, but may be generated by different mass spectrometers. The first mass spectrum file records one or more mass spectrum data generated by the mass spectrometer examining the first test solution. The second mass spectrum file records one or more mass spectrum data generated by the mass spectrometer examining the second test solution. Each mass spectrum data includes multiple ion pairs belonging to a compound and all peaks of each ion pair.

[0056] In one embodiment, the first test solution may be a standard solution, and the second test solution may be a sample solution, in which case the first and second mass spectral files generated by the mass spectrometer are a standard mass spectral file and a sample mass spectral file, respectively.

[0057] The standard solution contains a substrate and a compound standard solution of a predetermined concentration (e.g., 50 ppb). The substrate does not contain any compound samples. The substrate is obtained from agricultural crops or food that does not contain pesticides or other chemicals. The compound standard solution also contains one or more types of compound standards, for example, pesticide standard solutions of multiple types of pesticide standards such as abamectin, acephate, etc. If the standard solution contains 216 types of pesticide standards (but is not limited to this), the standard mass spectrum file (i.e., first mass spectrum file) generated by the mass spectrometer testing the standard solution contains mass spectrum data of these 216 types of pesticide standards. The sample solution also contains a test sample. The sample solution is obtained from agricultural crops or food. If the sample solution contains multiple types of compounds (e.g., pesticides or veterinary drugs), the mass spectrum data of these multiple types of compounds will be recorded in the sample mass spectrum file (i.e., the second mass spectrum file) generated by the mass spectrometer when examining the sample solution.

[0058] In step b', the characteristic peaks of each compound are preferably obtained using the method shown in Figure 1 of the present invention (although this is not limitative), but will not be described in detail here. When the first mass spectrum file is the standard mass spectrum file, simply by executing step b', the characteristic peaks of the 216 pesticide standard samples can be obtained as comparison standards for use in the subsequent characteristic peak extraction process.

[0059] In step c', the reading of the second mass spectrum file is almost the same as in step a shown in FIG. 1, and therefore will not be described in detail here.

[0060] In step d', the characteristic peak extraction process involves searching for peaks having the same or similar positions from the peaks read from the second mass spectrum file based on the positions of the characteristic peaks (e.g., quantitative characteristic peaks) of each compound, and designating the peaks found as characteristic peaks.

[0061] The term "same or similar position" as used herein refers to a position within a certain time interval (e.g., 3 seconds). For example, if the position of one quantitative characteristic peak in allethrin from the first mass spectrum file (e.g., the standard mass spectrum file) is t, three peaks at position t are searched for among all the peaks of the three ion pairs in allethrin from the second mass spectrum file (e.g., the sample mass spectrum file). The peak with the highest height among these three peaks is designated as one quantitative characteristic peak of one quantitative ion pair in allethrin, and the other two peaks are designated as one qualitative characteristic peak of two qualitative ion pairs in allethrin. However, if such a peak is not found, the search continues within the position range between t-3 and t+3. Once found, these peaks are designated as the quantitative characteristic peak and qualitative characteristic peak as described above. Other quantitative characteristic peaks and qualitative characteristic peaks in allethrin from the second mass spectrum file can also be found using the above method. Similarly, quantitative and qualitative characteristic peaks of other compounds from the second mass spectrum file can be found according to the above method.

[0062] The quantitative or qualitative characteristic peaks of each compound from the second mass spectrum file can be obtained by the above steps a' to d'. However, the qualitative characteristic peaks of each compound from the second mass spectrum file may be obtained by using the positions of the found quantitative characteristic peaks.

[0063] As is clear from the above explanation, by using characteristic peaks obtained from one mass spectrum file to compare with peaks of a compound in another mass spectrum file, it is possible to quickly and accurately find characteristic peaks from peaks of a compound in the other mass spectrum file, regardless of whether they are quantitative or qualitative characteristic peaks.

[0064] 5, it is possible to obtain the characteristic peaks of the 216 pesticide standards from the standard mass spectral file and use these characteristic peaks as comparison standards to obtain the characteristic peaks of one or more pesticides from the sample mass spectral file. Similarly, it is also possible to obtain the characteristic peaks of one or more compounds from other mass spectral files using the characteristic peaks of various pesticide standards obtained from the standard mass spectral file.

[0065] After obtaining the characteristic peaks of a compound using the method of the present invention shown in FIG. 1 or FIG. 5, it is possible to calculate the total area and signal-to-noise ratio (S / N) of the quantitative characteristic peaks, the total area and S / N ratio of the qualitative characteristic peaks, and the area ratio for each compound based on the obtained characteristic peaks. The total area of ​​the quantitative characteristic peaks and the total area of ​​the qualitative characteristic peaks can both be calculated using, but are not limited to, the composite trapezoidal rule. The S / N ratio of a quantitative characteristic peak is the ratio of the signal intensity of the quantitative characteristic peak to that of the surrounding background noise. The S / N ratio of a qualitative characteristic peak is the ratio of the signal intensity of the qualitative characteristic peak to that of the surrounding background noise. The area ratio = (total area of ​​qualitative characteristic peaks) / (total area of ​​quantitative characteristic peaks).

[0066] When calculating the total area of ​​any characteristic peak, the method of the present invention first sets a reference line (see L1 to L5 in Figures 2 to 4) for that characteristic peak, and then calculates the total area of ​​that characteristic peak using the trapezoidal rule. The reference line is a line connecting the lowest points on both the left and right sides of that characteristic peak. In this example, the method of the present invention sets one reference line for each quantitative and qualitative characteristic peak of each compound. As shown in Figure 2, the quantitative ion pair curve 11 and qualitative ion pair curve 12 for iprodione overlap at their lowest points, so only one reference line L1 is present in the figure. Furthermore, as shown in Figure 3, the quantitative ion pair curve 14 and qualitative ion pair curve 15 for allethrin each have one reference line L2 and L3, respectively. Furthermore, as shown in Figure 4, the quantitative ion pair curve 18 and qualitative ion pair curve 19 for cypermethrin each have one reference line L4 and L5, respectively.

[0067] The present invention further discloses a server host. The server host is connected to a client computer, and the mass spectrometer is connected to the client computer. The mass spectrometer can be a liquid chromatography-tandem mass spectrometer (LC / MS / MS), a gas chromatography-tandem mass spectrometer (GC / MS / MS), or other types of mass spectrometer. The mass spectrum file generated by the mass spectrometer is created on the client computer and uploaded from the client computer to the server host via a network. Typically, the server host consists of one or more computer hosts and one or more storage devices at a server level, but is not limited to this.

[0068] The server host has a feature peak processing program installed therein and is capable of executing any of the above methods of the present invention based on the program code of the feature peak processing program. Preferably, a conversion program is also installed in the server host. The conversion program is used to convert the file format of the mass spectrum file into a file format required by the feature peak processing program. For example, commonly known standard mass spectrum file formats are mzData, mzXML, or mzML. In one embodiment, the file format required by the feature peak processing program is mzML. In another embodiment, if the original file format of the mass spectrum file generated by the mass spectrometer is the file format required by the feature peak processing program, there is no need to set up the conversion program, and naturally there is no need to perform the above file format conversion work.

[0069] In summary, the present invention enables the server host to execute the above method to automatically and quickly obtain characteristic peaks of one or more compounds from a mass spectrum file, thereby improving the overall detection speed and avoiding human error, thereby resolving the problem of personnel shortages. [Explanation of symbols]

[0070] Steps a~d a'~d' steps

Claims

1. A method for acquiring a characteristic peak of a compound, comprising: reading mass spectrum data from a mass spectrum file, the mass spectrum data including a plurality of ion pairs belonging to the compound and all of their peaks; reading a selection parameter set for said compound from a selection parameter table; selecting an ion pair having the highest or lowest peak from the ion pairs of the compound as a quantitative ion pair of the compound based on a quantitative ion pair selection parameter of the selection parameter set; and selecting, from among all peaks of the quantitative ion pairs in the compound, the N-th peaks in height from the front as quantitative characteristic peaks of the compound based on a characteristic peak number parameter of the selection parameter set, and the value of N is determined by the characteristic peak number parameter; A method comprising:

2. before reading the selection parameter table, first, searching for and acquiring the name of the compound from a compound list based on the ion pair of the mass spectrum data; The method according to claim 1, wherein the compound list records the name and ion pair of each compound to be detected by the mass spectrometer, and the selection parameter table records the name and selection parameter set of each compound in the compound list.

3. The method of claim 1 , wherein the selection parameter table is created for each mass spectrometer that generates the mass spectrum file.

4. The method according to claim 1, further comprising: finding a peak having the same or a similar position from all peaks of ion pairs other than the quantitative ion pair based on the position of the quantitative characteristic peak of the compound, and determining the peak as the qualitative characteristic peak of the compound.

5. defining an allowable position range for each of the found quantitative characteristic peaks based on the position parameters of the selection parameter set; and selecting, from all peaks of each ion pair other than the quantitative ion pair in the compound, peaks whose positions fall within the allowable position range as qualitative characteristic peaks of the compound; 10. The method of claim 1, comprising:

6. 6. The method according to claim 4 or 5, wherein after obtaining the qualitative characteristic peak of the compound, if the quantitative ion pair is selected from the ion pair having the lowest peak, a swapping operation is subsequently performed to swap the quantitative characteristic peak and the qualitative characteristic peak of the compound with each other.

7. When selecting the quantitative feature peak, it is determined whether to maintain the current selection or to change the selection so as to select the M-th peak among the N-th peaks in height as the quantitative feature peak of the compound based on a quantitative feature peak change parameter in the selection parameter set for the compound, The method of claim 1 , wherein the value of M is determined by the quantitative feature peak change parameter.

8. The method of claim 1, further comprising first deleting the first and last peaks of all the peaks of the quantitative ion pair based on a deletion parameter of the selection parameter set before selecting the quantitative characteristic peak.

9. determining whether the value of the characteristic peak number parameter is 2 or greater; If the result of the determination is "YES", performing a pass / fail determination operation for the quantitative ion pair based on the peak ratio parameters of the selection parameter set; Including, The pass / fail determination process is as follows: obtaining one or more height ratios by dividing the height of each subsequent quantitative feature peak by the height of the first quantitative feature peak; determining whether each height ratio is greater than the peak ratio parameter; and If the result of the determination is "YES", the quantitative ion pair is determined as a passing ion pair, and if the result of the determination is "YES", the quantitative ion pair is determined as a failing ion pair.

10. The method of claim 1, comprising:

10. 1. A method for calculating a signal to noise ratio of a quantitative feature peak, comprising: Obtaining a quantitative characteristic peak of the compound using the method of claim 1; A quantitative characteristic peak of any one of the compounds is used as a target signal; Based on the S / N ratio parameter of the selection parameter set, cutting out a peak within a certain time period before or after the position of any of the quantitative characteristic peaks of the compound as background noise; and calculating a signal-to-noise ratio based on the intensity of the target signal and the intensity of the background noise; A method comprising:

11. 11. The method of claim 10, further comprising determining whether to test the signal-to-noise ratio based on a signal-to-noise ratio pass / fail parameter of the screening parameter set.

12. 1. A method for calculating a signal-to-noise ratio of a qualitative feature peak, comprising: Obtaining a qualitative characteristic peak of the compound using the method according to claim 4 or 5; any qualitative characteristic peak of the compound is used as a target signal; Based on the S / N ratio parameter of the selection parameter set, cutting out peaks within a certain time period ahead of or behind the position of any of the qualitative characteristic peaks of the compound as background noise; and calculating a signal-to-noise ratio based on the intensity of the target signal and the intensity of the background noise; A method comprising:

13. The method of claim 12, further comprising determining whether to inspect the signal-to-noise ratio of the qualitative feature peak based on a signal-to-noise ratio pass / fail parameter of the selection parameter set.

14. A method for acquiring a characteristic peak of a compound, comprising: receiving a first mass spectral file and a second mass spectral file; acquiring characteristic peaks of a plurality of compounds from the first mass spectrum file; One or more mass spectral data are read from the second mass spectral file, and each mass spectral data contains a group of ion pairs belonging to a compound and all of their peaks; and acquiring characteristic peaks of each compound in the second mass spectrum file by performing a characteristic peak extraction operation on peaks read from the second mass spectrum file based on the characteristic peaks of the compound acquired from the first mass spectrum file; A method comprising:

15. A server host comprising a feature peak processing program and capable of carrying out the method of any one of claims 1 to 14 based on the program code of said feature peak processing program.

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