Method for determining mangiferin in mango extract

Abstract

The invention discloses a method for determining mangiferin in a mango extract, and belongs to the technical field of plant detection. The determination method comprises the following steps: firstly, ionizing sample ions from a target material, enabling at least part of the sample ions to enter a mobility pool, capturing the sample ions to generate mass spectrum data, and extracting first sampling data and second sampling data from the mass spectrum data; according to the method, the mangiferin and other xanthone derivatives in the mango extract are separated according to a mobility pool, and then the content of the mangiferin is determined through flight mass spectrometry. According to the method, the migration interval of the to-be-detected component is adjusted according to the actually measured signal peak, the corresponding sampling data is intercepted from the migration interval, and then the electric field parameters are adjusted, so that the signal peak interval is prevented from being too small, the mangiferin and other xanthone derivatives can be distinguished, and the testability of the sampling data is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of plant detection, and particularly relates to a method for determining mangiferin in mango extract. Background Art

[0002] Mango extract contains mango polyphenols. When studying mango polyphenols, the content of its iconic component mangiferin is usually used as a standard. As a xanthone C-glycoside, the mass-to-charge ratio of mangiferin is 421.11, and its content can be determined by mass spectrometry technology, as described in Chinese Patent Publication No. CN105866285A, etc. Mango extract contains a variety of macromolecules similar to mangiferin, especially other xanthone derivatives, which have similar mass-to-charge ratios. In order to avoid signal overlap, it is necessary to separate mangiferin from other xanthone derivatives first in order to more accurately determine the content of mangiferin. For this reason, Chinese Patent Publication No. CN112461913A discloses a method for improving the identification ability of isomeric compounds. This method increases the potential difference between the inlet and outlet of the mobility cell, reduces the coexistence conformation number of isomeric ions, and improves the separation degree of similar macromolecules in the ion mobility spectrum. Although the increase in potential difference improves the resolution of substances with similar mass-to-charge ratios, it will significantly reduce the signal peak spacing, resulting in signal overlap and increasing the measurement difficulty. Therefore, there is a need for further improvement in the prior art. Summary of the Invention

[0003] In order to solve the defects existing in the above technology, the present invention proposes a method for determining mangiferin in mango extract. This method corrects the migration interval where the component to be measured is located and then intercepts the corresponding sampling data, and adjusts the electric field parameters of the mobility cell according to the peak width and peak spacing of the signal peak to avoid too small signal peak spacing and ensure the measurability of the sampling data.

[0004] The technical solution of the present invention is realized as follows: A method for determining mangiferin in mango extract, comprising the following steps: Step 1: The mango extract has a first component and a second component. Calculate a first migration interval and a second migration interval based on the first attribute of the first component and the second component, and calculate a first flight interval and a second flight interval based on the second attribute of the first component and the second component; Step 2: Mix the mango extract with a matrix to make a target, introduce the target and a first medium into the ionization channel, and introduce the first medium into the mobility cell; Step 3: Ionize sample ions from the target, start the inlet gate at the starting moment, and at least part of the sample ions enter the mobility cell; Step 4: The sample ions pass through the flight channel, generate mass spectrometry data after capturing the sample ions, and extract first sampling data and second sampling data from the mass spectrometry data based on the first flight interval and the second flight interval; Step 5: Extract the measured signal peaks of the first sampling data and the second sampling data, adjust the first migration interval and the second migration interval according to the measured signal peaks, and adjust the electric field parameters of the mobility cell according to the peak width and peak spacing of the measured signal peaks; Step 6: Calculate the measured signal-to-noise ratio based on the first sampling data and the second sampling data, adjust the ionization parameters of the ionization channel. If the ionization parameters are greater than the voltage upper limit, extract the first medium in the mobility cell and introduce the second medium, and return to Step 2; otherwise, proceed to Step 7; Step 7: Repeat Steps 1 to 4, and predict the contents of the first component and the second component in the mango extract based on the first sampling data and the second sampling data respectively.

[0005] In the present invention, the matrix is composed of acetonitrile at a mass ratio of 50%, water at 49.9%, and trifluoroacetic acid at 0.1%. The first medium is nitrogen, and the second medium is argon.

[0006] In the present invention, the ionized sample ions enter the first collimation channel. The first collimation channel modulates the sample ions into a first ion beam. After the exit gate is opened, at least part of the sample ions enter the second collimation channel. The second collimation channel modulates the sample ions into a second ion beam, and the second ion beam is introduced into the flight channel.

[0007] In the present invention, in Step 1, the first component is mangiferin, the second component is xanthone derivatives, the first property is the ion collision cross section, and the second property is the mass-to-charge ratio.

[0008] In the present invention, the migration duration T1 is calculated based on the ion collision cross section of the first component, the migration duration T2 is calculated based on the ion collision cross section of the second component, and then the first migration interval [T1 - ΔT1, T1 + ΔT1] and the second migration interval [T2 - ΔT1, T2 + ΔT1] are obtained in combination with the detection width ΔT1.

[0009] In the present invention, the flight duration T3 is calculated based on the mass-to-charge ratio of the first component, and then the first flight interval [T3 - ΔT2, T3 + ΔT2] is calculated. The flight duration T4 is calculated based on the mass-to-charge ratio of the second component, and then the second flight interval [T4 - ΔT2, T4 + ΔT2] is calculated. ΔT2 is the half measurement interval.

[0010] In the present invention, in Step 4, the sampling interval of the first component is calculated based on the first migration interval and the first flight interval, and then the minimum sampling time and the maximum sampling time of the first component are obtained in combination with the starting time and the sampling interval. The first sampling data is intercepted from the mass spectrometry data according to the minimum sampling time and the maximum sampling time.

[0011] In the present invention, in step 5, the center line of the measured signal peak of the first sampled data is extracted, and the first migration interval is translated until the midpoint of the sampling interval corresponding to the first migration interval coincides with the center line of the measured signal peak.

[0012] In the present invention, in step 5, the electric field parameters include the electric field strength, the fitting peak width constraint coefficient to obtain the lower limit of the electric field strength, the fitting peak spacing constraint coefficient to obtain the upper limit of the electric field strength, and the target electric field strength is calculated based on the upper limit and the lower limit of the electric field strength.

[0013] In the present invention, in step 6, the ionization parameters include the spray voltage, the ionization efficiency constant of the mango extract is fitted, the effective spray voltage of the ionization channel and the noise growth coefficient are calculated, then the theoretical spray voltage and the corresponding theoretical signal-to-noise ratio are calculated, the measured signal-to-noise ratio is calculated, the adjustment step size is calculated according to the theoretical spray voltage, the current spray voltage, the theoretical signal-to-noise ratio and the measured signal-to-noise ratio, and the spray voltage of the ionization channel is adjusted based on the current spray voltage and the adjustment step size.

[0014] Implementing the method for determining mangiferin in mango extract of the present invention has the following beneficial effects: The present invention separates mangiferin and other xanthone derivatives in mango extract according to the mobility cell, and then determines the content of mangiferin by time-of-flight mass spectrometry. The present invention adjusts the migration interval where the component to be measured is located according to the measured signal peak, intercepts the corresponding sampled data from the migration interval, and then adjusts the electric field parameters to avoid too small signal peak spacing and ensure the measurability of the sampled data. Further, the sampled data of the present invention can be corrected according to the center line of the signal peak, and the ionization parameters are adjusted according to the measured signal-to-noise ratio to improve the degree of ion fragmentation and limit the noise level. The present invention uses the first medium as the environmental gas of the ionization channel and the mobility cell, and at the same time, to avoid damage to the molecular structure due to too high ionization parameters, the medium of the mobility cell is replaced in time to ensure the resolution. Description of the Drawings

[0015] Figure 1 is a flow chart of the method for determining mangiferin in mango extract of the present invention; Figure 2 is a schematic diagram of the principle of the method for determining mangiferin in mango extract of the present invention; Figure 3 is a mass spectrum of a preferred mango extract of the present invention; Figure 4 is a schematic diagram of the principle of calculating the sampling interval of the present invention; Figure 5 is a distribution diagram of the arrival time of sample ions of the present invention; Figure 6 is a schematic diagram of the content of mangiferin and the response ratio of the present invention; Figure 7 is a flow chart of a preferred method for adjusting the electric field parameters of the mobility cell of the present invention; Figure 8 This is a preferred method flowchart for adjusting the ionization parameters of the ionization channel of the present invention.

[0016] Reference numerals in the drawings: ionization channel 100, first pipeline 101, second pipeline 102, first collimation channel 200, mobility cell 300, inlet gate 301, outlet gate 302, third pipeline 303, second collimation channel 400, flight channel 500, repulsion region 501, acceleration region 502, field-free region 503, first reflection region 504, second reflection region 505, exhaust pipeline 506, analysis device 600. Detailed implementation manners

[0017] To understand the purpose, technical solution and advantages of the present application more clearly, the present application will be described and explained below with reference to the drawings and embodiments.

[0018] In the existing mobility mass spectrometry technology, the electric field strength of the mobility cell is a fixed value, generally 100–500 V / cm. The spray voltage is also a fixed value, generally 1–3 kV. The present invention corrects the migration interval where the component to be measured (such as mangiferin) is located and then intercepts the corresponding sampling data, adjusts the electric field strength of the mobility cell according to the peak width and peak spacing of the signal peak, and adjusts the spray voltage according to the signal-to-noise ratio of the sampling data, avoids the signal peak spacing being too small, ensures the measurability of the sampling data, and at the same time improves the ion fragmentation degree and limits the noise level. Embodiment 1

[0019] As Figures 1 to 6 shown, a method for determining mangiferin in a mango extract of the present invention includes the following steps.

[0020] Step 1: The mango extract has a first component and a second component. Calculate a first migration interval and a second migration interval based on a first property of the first component and the second component, and calculate a first flight interval and a second flight interval based on a second property of the first component and the second component. The mango extract of the present invention can be a polyphenol-enriched extract obtained by liquid phase separation extraction of mango pulp. The first component is mangiferin, the second component is other xanthone derivatives (such as mangiferin), the first property is the ion collision cross section, and the second property is the mass-to-charge ratio. The ion collision cross section of mangiferin is 210 Ų, and the mass-to-charge ratio is 421.11. The ion collision cross section of xanthone derivatives (such as isomangiferin) is 225 Ų, and the mass-to-charge ratio is 421.11. Calculate the migration duration T1 based on the ion collision cross section of the first component, calculate the migration duration T2 based on the ion collision cross section of the second component, and then combine the detection width ΔT1 to obtain the first migration interval [T1 - ΔT1, T1 + ΔT1] and the second migration interval [T2 - ΔT1, T2 + ΔT1]. Calculate the flight duration T3 based on the mass-to-charge ratio of the first component, and then combine the first migration interval to calculate the first flight interval [T3 - ΔT2, T3 + ΔT2]. Calculate the flight duration T4 based on the mass-to-charge ratio of the second component, and then combine the second migration interval to calculate the second flight interval [T4 - ΔT2, T4 + ΔT2]. ΔT2 is the half measurement interval, refer to the detailed description of Example 2 and Example 3.

[0021] Step 2: Mix the mango extract with a matrix to form a target, introduce the target and a first medium into the ionization channel, and introduce the first medium into the mobility cell. The matrix consists of acetonitrile at a mass ratio of 50%, water at 49.9%, and trifluoroacetic acid at 0.1%. The concentration of the matrix is usually 10–20 mg / mL (a supersaturated solution to promote the formation of a microcrystalline target). The first medium is nitrogen, and the second medium is argon. The first medium enters the ionization channel from the first pipe 101, and the target enters the ionization channel 100 from the second pipe 102. Nitrogen has a low cost and can be used for both the mobility cell and the ionization channel at the same time. Using nitrogen can reduce the difficulty of gas introduction and discharge. Argon can provide higher resolution. The first medium enters the mobility cell 300 from the third pipe 303.

[0022] Step 3: Ionize sample ions from the target, start the inlet gate at the starting moment, and at least part of the sample ions enter the mobility cell. The starting moment is the initial moment of ion movement. The mobility cell 300 has an inlet gate 301 and an outlet gate 302. After the inlet gate 301 and the outlet gate 302 are opened, the sample ions can freely enter and exit. Refer to Figure 2, the ionized sample ions enter the first collimation channel 200. The first collimation channel 200 modulates the sample ions into a first ion beam. After the exit gate 302 is opened, at least part of the sample ions enter the second collimation channel 400. The second collimation channel 400 modulates the sample ions into a second ion beam and guides the second ion beam into the flight channel 500. To reduce other interferences, an exhaust duct 506 can be provided on the side wall of the flight channel 500 to reduce the internal air pressure.

[0023] Step 4: The sample ions pass through the flight channel. After capturing the sample ions, mass spectrometry data is generated. Based on the first flight interval and the second flight interval, the first sampling data and the second sampling data are extracted from the mass spectrometry data. The sampling interval of the first component is calculated based on the first migration interval and the first flight interval, and then combined with the starting time and the sampling interval to obtain the minimum sampling time and the maximum sampling time of the first component. The first sampling data is intercepted from the mass spectrometry data according to the minimum sampling time and the maximum sampling time.

[0024] Similarly, the sampling interval of the second component is calculated based on the second migration interval and the second flight interval, and then combined with the starting time and the sampling interval to obtain the minimum sampling time and the maximum sampling time of the second component. The second sampling data is intercepted from the mass spectrometry data according to the minimum sampling time and the maximum sampling time. The ranges of the first sampling data and the second sampling data are affected by the first migration interval and the second migration interval. In the subsequent steps of the present invention, the migration interval is adjusted to improve the accuracy of extracting the sampling data.

[0025] Step 5: Extract the measured signal peaks of the first sampling data and the second sampling data. Adjust the first migration interval and the second migration interval according to the measured signal peaks, and adjust the electric field parameters of the mobility cell according to the peak width and the peak spacing of the measured signal peaks. The measured signal peak of the first sampling data refers to the maximum signal intensity within the range of the first sampling data. As Figure 5 shown, the present invention extracts the center line of the measured signal peak of the first sampling data and translates the first migration interval until the midpoint of the sampling interval corresponding to the first migration interval coincides with the center line of the measured signal peak. The electric field parameters of the present invention include the electric field intensity, the fitting peak width constraint coefficient to obtain the lower limit of the electric field intensity, the fitting peak spacing constraint coefficient to obtain the upper limit of the electric field intensity. Calculate the target electric field intensity based on the upper limit of the electric field intensity and the lower limit of the electric field intensity, and adjust the electric field intensity of the mobility cell to the target electric field intensity, as described in Embodiment 4.

[0026] Step 6: Calculate the measured signal-to-noise ratio based on the first sampling data and the second sampling data, and adjust the ionization parameters of the ionization channel. If the ionization parameters are greater than the voltage upper limit, extract the first medium in the drift cell and introduce the second medium, then return to Step 2; otherwise, proceed to Step 7. The ionization parameters at least include the spray voltage, and the voltage upper limit can take a value of 5 kV. The present invention fits the ionization efficiency constant of the mango extract, the effective spray voltage of the ionization channel, and the noise growth coefficient, and then calculates the theoretical spray voltage and the corresponding theoretical signal-to-noise ratio. Calculate the measured signal-to-noise ratio based on the measured fragment intensity and background intensity of the first sampling data and the second sampling data. Refer to Figure 3 As shown, in this embodiment, the measured fragment intensity is the average intensity value of the first sampling data and the second sampling data, representing the signal response of the ion fragments. The background intensity is the smaller value between the minimum intensity value of the first sampling data and the minimum intensity value of the second sampling data. The background intensity represents the noise signal existing due to equipment factors when the ion signal is weak. In a simpler embodiment, the background intensity is preset to 10 counts / s. The present invention can calculate the adjustment step based on the theoretical spray voltage, the current spray voltage, as well as the theoretical signal-to-noise ratio and the measured signal-to-noise ratio, and adjust the spray voltage of the ionization channel based on the current spray voltage and the adjustment step, as described in Embodiment Five.

[0027] Step 7: Repeat Steps 1 to 4 to predict the contents of the first component and the second component in the mango extract based on the first sampling data and the second sampling data respectively. The signal intensity of the first sampling data is ρ, the total signal intensity of the spectral data is ρ0, and the response ratio h of the first component is h = ρ / ρ0. Collect the response ratios at multiple different calibration contents, establish a coordinate system with the response ratio h as the abscissa and the content l as the ordinate, and mark the response ratio of this component and the corresponding calibration content in the coordinate system. Fit these points into a smooth curve through a relevant fitting algorithm to obtain the relationship between the content ω and the response ratio h, that is, the response function ω = f(h). The response function is only related to the characteristics of the system itself. The present invention does not limit the relevant fitting algorithm. In this embodiment, the least squares method is used to fit into a straight line, and the fitting result is as Figure 7 shown. The present invention integrates the signal intensity at each moment in the first sampling data to obtain the signal intensity ρ of the first sampling data, calculates the ratio ρ / ρ0 of it to the total signal intensity ρ0 to obtain the response ratio h of the first component, and substitutes it into the response function ω = f(h) to obtain the content of the first component in the mango extract. The content of the second component can be determined in the same way. Embodiment Two

[0028] This embodiment further discloses a preferred method for calculating the first migration interval and the second migration interval.

[0029] First, calculate the mobility k3 based on the ion collision cross-section of the first component. The ion collision cross-section of mangiferin is 210 Ų. In this embodiment, according to the principle of Ion Mobility-Mass Spectrometry (IM-MS), . z is the ion charge, e is the electron charge, n is the number density of the drift gas, which refers to the number of drift gas molecules per unit volume, usually taken as 10 21 to 10 23 per m 3 . μ is the reduced mass of the drift substance, μ = m1m2 / (m1 + m2), m1 is the mass of the first medium or the second medium, usually 28 Da. m2 is the mass of the first component, usually 500 Da. T' is the gas temperature of the mobility cell. k1 is the Boltzmann constant, i.e., 1.38×10 −23 J / cal, k2 is the ion collision cross-section of the first component, (the mobility measured at standard temperature and pressure). Then calculate the migration time T1, T1 = L / (k3E), L is the length of the migration tube, usually 5–30 cm, and E is the electric field strength.

[0030] Then, combine the detection width ΔT1 to obtain the first migration interval [T1 - ΔT1, T1 + ΔT1]. The detection width ΔT1 can be 100 to 200 μs. Since the ion mobility is measured at a specific temperature and pressure, in order to avoid the influence of the actual temperature and gas pressure on the integrity of data acquisition, in a more preferred embodiment, the detection width ΔT1 = ΔT0 + K4. ΔT0 is, for example, 10 μs. . T' is the gas temperature, p' is the current pressure, and β is the fitted temperature-pressure ratio.

[0031] Similarly, calculate the migration time T2 based on the ion collision cross-section of the second component. The second component is a xanthone derivative, such as isomangiferin. The ion collision cross-section of isomangiferin is 225 Ų. Combine the detection width ΔT1 to obtain the second migration interval [T2 - ΔT1, T2 + ΔT1]. Example 3

[0032] This embodiment further discloses a preferred method for calculating the first flight interval and the second flight interval.

[0033] First, calculate the flight duration T3 based on the mass-to-charge ratio of the first component. t1, t2, t3, t4, and t5 are the motion times of the first component in the repulsion region 501, acceleration region 502, field-free region 503, first reflection region 504, and second reflection region 505, respectively. When the ion enters the flight channel 500, its vertical velocity is first accelerated through the repulsion region 501 and acceleration region 502. When the ion enters the field-free region 503, it maintains a constant velocity. Then, under the action of the first reflection region 504 and second reflection region 505, it first decelerates to 0 and then accelerates in the opposite direction. When it enters the field-free region 503 again, it maintains a constant velocity until the ion lands on the analysis device 600. However, its horizontal velocity remains constant throughout the flight. Therefore, the flight duration T3 = t1 + t2 + 2(t3 + t4 + t5).

[0034] The mass of the first component ion is m, the magnitude of the charge it carries is q, and the mass-to-charge ratio is m / q. L1, L2, L3, and L4 represent the lengths of the repulsion region 501, acceleration region 502, field-free region 503, and first reflection region 504, respectively. E1, E2, E4, and E5 represent the magnitudes of the electric field strengths in the repulsion region 501, acceleration region 502, field-free region 503, first reflection region 504, and second reflection region 505, respectively. According to the ion motion relationship, it can be determined that: ; ; ; ; .

[0035] Then, in combination with the first migration interval, calculate the first flight interval [T3 - ΔT2, T3 + ΔT2]. ΔT2 is the half-measurement interval to ensure that ions with this mass-to-charge ratio can be measured. ΔT2 is usually taken as 10 to 50 μs. Using the above method, calculate the mass-to-charge ratio from the mass and the magnitude of the charge carried by the first component ion, then calculate the flight duration T4, and in combination with the second migration interval, calculate the second flight interval [T4 - ΔT2, T4 + ΔT2].

[0036] Furthermore, the sampling interval of the first component is [T1 - ΔT1 + T3 - ΔT2, T1 + ΔT1 + T3 + ΔT2], the starting moment is t6, the minimum sampling moment is t6 + T1 - ΔT1 + T3 - ΔT2, and the maximum sampling moment is t6 + T1 + ΔT1 + T3 + ΔT2. Intercept the first sampling data from the mass spectrometry data according to this minimum sampling moment and maximum sampling moment. In a simpler embodiment, the system clock can be calibrated and the starting moment can be preset to 0.

[0037] Similarly, the sampling interval of the second component is [T2 - ΔT1 + T4 - ΔT2, T4 + ΔT1 + T3 + ΔT2], the starting time is t6, the minimum sampling time is t6 + T2 - ΔT1 + T4 - ΔT2, and the maximum sampling time is t6 + T4 + ΔT1 + T3 + ΔT2. The first sampling data is intercepted from the mass spectrometry data according to the minimum sampling time and the maximum sampling time. Example 4

[0038] As Figure 7 , this embodiment further discloses a preferred method for adjusting the electric field parameters of the mobility cell. The electric field parameters of this embodiment include the electric field strength.

[0039] First, fit the peak width constraint coefficient, and then obtain the lower limit of the electric field strength. To ensure the signal resolution, a maximum allowable peak width W0 is preset, for example, 0.5 ms 1 / 2 . The peak width is mainly caused by ion diffusion. For the same detection environment (constant temperature, mobility, and mobility cell length), the diffusion variance σ 2 is proportional to the migration time, and the migration time is inversely proportional to the electric field strength. Therefore, the peak width W (i.e., the standard deviation) is inversely proportional to the square root of the electric field strength. W = (λ1 / E) 1 / 2 , where λ1 is the peak width constraint coefficient. By measuring the electric field strength and the peak width multiple times, the peak width constraint coefficient λ1 of the same device can be fitted. Then calculate the lower limit of the electric field strength E min = λ1 / W0 2 .

[0040] Then fit the peak spacing constraint coefficient, and then obtain the upper limit of the electric field strength. To fully display the signal peaks of different ion components, a minimum measurable peak spacing T0 is preset, for example, 2 ms. The peak spacing is the migration time difference between adjacent signal peaks. According to, the peak spacing is inversely proportional to the electric field strength. The peak spacing T = λ2 / E, where λ2 is the peak spacing constraint coefficient. By measuring the electric field strength and the peak spacing multiple times, the peak spacing constraint coefficient λ2 of the same device can be fitted. Then calculate the lower limit of the electric field strength E max = λ2 / T0.

[0041] Finally, calculate the target electric field strength based on the upper limit and the lower limit of the electric field strength. If E max <E min , the target electric field strength has no real solution, and the task ends. Readjust the device (for example, adjust the length L of the mobility cell) to meet the detection requirements. If E max ≥E min , the target electric field strength is the geometric mean of the upper limit and the lower limit of the electric field strength, that is, the target electric field strength E = (E max ×E min ) 1 / 2 .

[0042] Further, the electric field parameters further include the medium pressure of the drift cell, and the medium pressure of the drift cell is generally 5 Torr. To ensure stable operation and avoid arc discharge, the electric field intensity and the medium pressure are maintained within a safe range. The drift cell of the present invention has two gas types, namely a first medium and a second medium. The Paschen's law is used to plot the relationship between the electric field intensity and the medium pressure of each gas type in the current environment or to formulate a matching table of the electric field intensity and the medium pressure. A feedback control system is used to adjust the gas pressure in real time according to the target electric field intensity, which will not be elaborated in this embodiment. Embodiment 5

[0043] As Figure 8 , this embodiment further discloses a preferred method for adjusting the ionization parameters of the ionization channel. The ionization parameters include the spray voltage.

[0044] First, fit the ionization efficiency constant of the mango extract, the effective spray voltage of the ionization channel, and the noise growth coefficient. The ion fragment intensity usually increases non-linearly with the increase of voltage and finally tends to saturate. It can be described by a negative exponential model. Thus, the measured fragment intensity S of the ion and the spray voltage U can be expressed as: S = I max {1 - exp[-k6(U - U0)]}, I max is the theoretical intensity (plateau value), generally taken as 10 5 counts / s. U0 is the minimum effective spray voltage. k6 is the ionization efficiency constant, usually 0.1 to 2 kV -1 . The background noise is caused by random events in the ionization process (such as discharge, solvent cluster fragmentation) and usually has a weak exponential relationship with the voltage. Thus, the background noise N and the spray voltage U can be expressed as: N = N0exp - k5(U - U0). N0 is the baseline noise (noise level when not ionized), generally taken as 10 counts / s. k5 is the noise growth coefficient, usually 10 to 50 V -1 . Measuring the ion intensity and background noise multiple times can fit the ionization efficiency constant k6, the effective spray voltage U0 of the ionization channel, and the noise growth coefficient k5.

[0045] Then, calculate the theoretical spray voltage and the theoretical signal-to-noise ratio. Specifically, the signal-to-noise ratio S / N = I max {1 - exp[-k6(U - U0)]} / N0×exp(-k6(U - U0)). Calculate the derivative extreme value of the signal-to-noise ratio, d(S / N) / dU = 0, and the theoretical spray voltage U opt = U0 + 1 / k6×ln(1 + k6 / k5) can be obtained. Substitute the theoretical spray voltage into I max {1 - exp[-k6(U - U0)]} / {N0×exp[-k6(U - U0)]}, and the theoretical signal-to-noise ratio S / N can be obtained opt。

[0046] Then, according to the theoretical spray voltage and the current spray voltage U act and the theoretical signal-to-noise ratio and the measured signal-to-noise ratio, calculate the adjustment step size. Specifically, detect the current fragment intensity and the current background signal based on the spectral data, and calculate the measured signal-to-noise ratio S / N accordingly act . The adjustment coefficient is [ln(S / N act ) / U act -ln(S / N opt ) / U opt / ln(S / N act ), and the target adjustment amount is (U max -U act ). The adjustment step size is (U max -U act )×[ln(S / N act ) / U act -ln(S / N opt ) / U opt / ln(S / N act ).

[0047] Finally, based on the current spray voltage and the adjustment step size, adjust the ionization parameters of the ionization channel. Specifically, the spray voltage for the next cycle finally determined in this embodiment is U act +(U max -U act )×[ln(S / N act ) / U act -ln(S / N opt ) / U opt / ln(S / N act ).

[0048] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for determining mangiferin in mango extract, characterized in that, It includes the following steps: Step 1: The mango extract has a first component and a second component. Calculate a first migration interval and a second migration interval based on the first attribute of the first component and the second component, and calculate a first flight interval and a second flight interval based on the second attribute of the first component and the second component; Step 2: Mix the mango extract with a matrix to make a target, introduce the target and a first medium into the ionization channel, and introduce the first medium into the mobility cell; Step 3: Ionize sample ions from the target, start the inlet gate at the starting moment, and at least part of the sample ions enter the mobility cell; Step 4: The sample ions pass through the flight channel, generate mass spectrometry data after capturing the sample ions, and extract first sampling data and second sampling data from the mass spectrometry data based on the first flight interval and the second flight interval; Step 5: Extract the measured signal peaks of the first sampling data and the second sampling data, adjust the first migration interval and the second migration interval according to the measured signal peaks, and adjust the electric field parameters of the mobility cell according to the peak width and peak spacing of the measured signal peaks; Step 6: Calculate the measured signal-to-noise ratio according to the first sampling data and the second sampling data, adjust the ionization parameters of the ionization channel. If the ionization parameters are greater than the voltage upper limit, extract the first medium in the mobility cell and introduce a second medium, and return to Step 2, otherwise enter Step 7; Step 7: Repeat Steps 1 to 4, and predict the contents of the first component and the second component in the mango extract according to the first sampling data and the second sampling data respectively.

2. The method for determining mangiferin in mango extract according to claim 1, characterized in that, The matrix is composed of acetonitrile at a mass ratio of 50%, water at 49.9%, and trifluoroacetic acid at 0.1%. The first medium is nitrogen, and the second medium is argon.

3. The method for determining mangiferin in mango extract according to claim 1, characterized in that, The ionized sample ions enter a first collimation channel, the first collimation channel modulates the sample ions into a first ion beam. After the outlet gate is opened, at least part of the sample ions enter a second collimation channel, the second collimation channel modulates the sample ions into a second ion beam, and the second ion beam is introduced into the flight channel.

4. The method for determining mangiferin in mango extract according to claim 1, wherein In Step 1, the first component is mangiferin, the second component is xanthone derivatives, the first attribute is the ion collision cross section, and the second attribute is the mass-to-charge ratio.

5. The method for determining mangiferin in mango extract according to claim 1, characterized in that, Calculate the migration duration T1 based on the ion collision cross section of the first component, calculate the migration duration T2 based on the ion collision cross section of the second component, and then combine the detection width ΔT1 to obtain the first migration interval [T1 - ΔT1, T1 + ΔT1] and the second migration interval [T2 - ΔT1, T2 + ΔT1].

6. The method for determining mangiferin in the mango extract according to claim 5, characterized in that, Calculate the flight duration T3 based on the mass-to-charge ratio of the first component, and then calculate the first flight interval [T3 - ΔT2, T3 + ΔT2]. Calculate the flight duration T4 based on the mass-to-charge ratio of the second component, and then calculate the second flight interval [T4 - ΔT2, T4 + ΔT2]. ΔT2 is the half measurement interval.

7. The method for determining mangiferin in mango extract according to claim 6, characterized in that, In Step 4, calculate the sampling interval of the first component based on the first migration interval and the first flight interval, and then combine the starting moment and the sampling interval to obtain the minimum sampling moment and the maximum sampling moment of the first component, and intercept the first sampling data from the mass spectrometry data according to the minimum sampling moment and the maximum sampling moment.

8. The method for determining mangiferin in mango extract according to claim 1, characterized in that, In step 5, extract the center line of the measured signal peak of the first sampled data, and translate the first migration interval until the midpoint of the sampling interval corresponding to the first migration interval coincides with the center line of the measured signal peak.

9. The method for determining mangiferin in mango extract according to claim 8, characterized in that, In step 5, the electric field parameters include the electric field strength, the fitting peak width constraint coefficient to obtain the lower limit of the electric field strength, the fitting peak spacing constraint coefficient to obtain the upper limit of the electric field strength, and calculate the target electric field strength based on the upper limit and the lower limit of the electric field strength.

10. The method for determining mangiferin in mango extract according to claim 1, characterized in that, In step 6, the ionization parameters include the spray voltage, fitting the ionization efficiency constant of the mango extract, the effective spray voltage of the ionization channel, and the noise growth coefficient, then calculate the theoretical spray voltage and the corresponding theoretical signal-to-noise ratio, calculate the measured signal-to-noise ratio, calculate the adjustment step based on the theoretical spray voltage, the current spray voltage, and the theoretical signal-to-noise ratio and the measured signal-to-noise ratio, and adjust the spray voltage of the ionization channel based on the current spray voltage and the adjustment step.

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