Discrimination of amphetamine-type stimulant tablets based on capillary zone electrophoresis and chemometrics

Abstract

The present application relates to a kind of amphetamine tablet source discrimination method based on zone capillary electrophoresis and chemometrics.The method comprises: taking the tablet to be tested, dissolving, obtaining first sample group sample solution and second sample group solution;Using zone capillary electrophoresis method, first sample group sample solution and second sample group solution are separated and detected analysis, obtain the percentage content of methamphetamine, the relative migration time of first separation component and the relative absorbance value of first separation component;Normalization processing is carried out, and the Euclidean distance is calculated, when Euclidean distance≤0.01, it is determined that the same source.The technical problem to be solved is how to provide a kind of amphetamine tablet source discrimination method based on zone capillary electrophoresis and chemometrics, which can overcome the technical problems that it is difficult to use multi-dimensional chemical parameters obtained by capillary electrophoresis combined with chemometrics model to objectively and quantitatively distinguish the homology of different amphetamine tablets in prior art.

Description

Technical Field

[0001] This invention belongs to the field of analytical identification technology, and in particular relates to a method for determining the source of amphetamine tablets based on zone capillary electrophoresis and chemometrics. Background Technology

[0002] Cases involving methamphetamine tablets are frequent, and tablets from different sources or batches vary in terms of ingredient content and additives. Analyzing the chemical characteristics of methamphetamine tablet samples to determine whether tablets seized in different cases share the same origin is a key technical means for tracing the source of methamphetamine tablets and linking related cases.

[0003] Currently, qualitative and quantitative analysis of drug samples mainly relies on instrumental analysis methods such as gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography (HPLC), and Fourier transform infrared spectroscopy (FTIR). However, these methods still have certain limitations in the application of amphetamine tablet source inference: GC-MS requires high sample pretreatment and is difficult to effectively separate trace adulterants that are highly polar or non-volatile; HPLC analysis is time-consuming and the column cost is high; although FTIR can achieve rapid and non-destructive detection, its response sensitivity to low-content components in mixtures is low, making it difficult to meet the needs of trace evidence mining. Therefore, capillary zone electrophoresis (CZE) has attracted widespread attention. This technology has advantages such as high separation efficiency, small injection volume, low operating cost, and simple and environmentally friendly buffer system, and can achieve efficient separation based on the difference in the mass-charge ratio of the analytes, making it particularly suitable for the analysis of charged components in complex matrices. Existing studies have shown that CZE can be used for the separation and detection of heroin, amphetamine drugs, and their adulterants. However, existing CZE methods mostly focus on the qualitative and quantitative analysis of the main components of drugs, and cannot comprehensively extract and identify the source of multidimensional chemical parameters. As a result, the subtle differences in chemical characteristics between amphetamine tablets seized in different cases are difficult to capture and evaluate objectively and quantitatively, and cannot achieve homology source inference based on multidimensional parameters. This seriously restricts the practical application value of CZE technology in drug tracing and case linkage. Summary of the Invention

[0004] The main objective of this invention is to provide a method for determining the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics. The technical problem to be solved is how to provide a method for determining the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics. This method can overcome the technical problem in the prior art that it is difficult to use multidimensional chemical parameters (methamphetamine content, relative migration time, relative absorbance) obtained by capillary electrophoresis combined with chemometric models to objectively and quantitatively determine the homology of amphetamine tablets from different cases.

[0005] The objective of this invention and the technical problem it solves are achieved through the following technical solution. According to this invention, a method for identifying the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics is proposed. The amphetamine tablets are tablets containing amphetamine and its derivatives. The components of the amphetamine tablets include methamphetamine. The method for identifying the source of amphetamine tablets includes: S100. Take the tablets to be tested, divide them into a first sample group and a second sample group, each group containing at least 3 tablets to be tested, and then dissolve them with a solvent to obtain the first sample group sample solution and the second sample group solution.

[0006] S200. Use zone capillary electrophoresis to separate and detect the sample solutions of the first sample group and the second sample group, respectively, to obtain the first electrophoretic pattern of the first sample group and the second electrophoretic pattern of the second sample group.

[0007] S300. Analyze the first electrophoresis pattern to obtain the percentage content A of methamphetamine, the relative migration time A of the first separated component, and the relative absorbance value A of the first separated component. Analyze the second electrophoresis pattern to obtain the percentage content B of methamphetamine, the relative migration time B of the first separated component, and the relative absorbance value B of the first separated component.

[0008] S400. Normalize the percentage content A of methamphetamine, the relative migration time A of the first separated component, the relative absorbance value A of the first separated component, the percentage content B of methamphetamine, the relative migration time B of the first separated component, and the relative absorbance value B of the first separated component, respectively.

[0009] S500. Calculate the Euclidean distance between the first sample group and the second sample group. The calculation method is as follows: Wherein, Euclidean Distance is the Euclidean distance between the first and second sample groups, x1 is the percentage content of methamphetamine after normalization A, y1 is the relative elution time of the first separated component after normalization A, z1 is the relative absorbance value after normalization A, x2 is the percentage content of methamphetamine after normalization B, y2 is the relative elution time of the first separated component after normalization B, and z2 is the relative absorbance value after normalization B.

[0010] S600. Determine whether the first sample group and the second sample group have the same source based on the calculated Euclidean distance: when the Euclidean distance is ≤0.01, the first sample group and the second sample group are determined to have the same source.

[0011] In one possible implementation, the normalization formula in step S400 is as follows: Where δ is the result after normalization and square root processing, x i For the parameters to be normalized, x min x is the minimum value of the parameter. max This represents the maximum value of the parameter. The parameter is either the percentage content of methamphetamine A, the relative migration time of the first separated component A, the relative absorbance value of the first separated component A, the percentage content of methamphetamine B, the relative migration time of the first separated component B, or the relative absorbance value of the first separated component B.

[0012] In one possible implementation, in step S300, the first separated component is the component with the shortest migration time in the electrophoretic pattern.

[0013] In one possible implementation, in step S100, the solvent is distilled water. The concentration of the first sample group solution is 0.25–1 mg / L. The concentration of the second sample group solution is 0.25–1 mg / L.

[0014] In one possible implementation, the concentration of the first sample group solution and the concentration of the second sample group solution are both 1 mg / L.

[0015] In one possible implementation, in step S300, the percentage content A and percentage content B of methamphetamine are obtained by the following method: First, a working solution of methamphetamine standard sample is prepared, and then data is collected on the working solution of methamphetamine standard sample using zone capillary electrophoresis to obtain a working curve. Then, the first electrophoresis pattern and the second electrophoresis pattern of the second sample group are compared with the working curve to obtain the percentage content A and percentage content B of methamphetamine.

[0016] In one possible implementation, the concentration of the methamphetamine standard working solution is 0.25–1 mg / mL.

[0017] In one possible implementation, in step S200, the separation conditions for zone capillary electrophoresis are: using boric acid at a concentration of 85–95 mmol / L and a pH of 8.4 as the separation buffer.

[0018] In one possible implementation, the specific method for zone capillary electrophoresis in step S200 is as follows: S210. Filter boric acid, a 0.1 mol / L sodium hydroxide aqueous solution, and water, and then place them sequentially into the buffer tray of the capillary electrophoresis apparatus. Place the sample solution of the first sample group or the sample solution of the second sample group into the sample tray of the capillary electrophoresis apparatus.

[0019] S220. Rinse the capillary tube with boric acid for 2 minutes, then rinse it with sodium hydroxide aqueous solution for 5 minutes, and finally rinse it with water for 1 minute.

[0020] S230. Set the scanning wavelength of the capillary electrophoresis detector to 190-300 nm, the operating voltage to 25 kV, the sample injection time to 5 s, the borate buffer to be used as the separation buffer, and the separation time to 10 min. The capillary electrophoresis instrument collects data while separating.

[0021] By employing the above technical solution, the present invention proposes a method for determining the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics, which has at least the following advantages: The technical solution disclosed in this application combines zone capillary electrophoresis (CZE) with chemometrics to systematically extract three core chemical characteristic parameters from the CZE electrophoresis pattern: the percentage content of methamphetamine, the relative migration time of the first separated component, and the relative absorbance value. This overcomes the shortcomings of existing CZE methods that only focus on the qualitative and quantitative results of the principal components and ignore the potential evidence information of multidimensional parameters, thus realizing the comprehensive extraction and utilization of multidimensional chemical characteristic parameters. In the data processing of this application, the percentage content of methamphetamine, the relative migration time and relative absorbance value of the first separated component are normalized. Then, the multidimensional parameter distance between different samples is calculated using Euclidean distance, achieving objective quantitative identification of sample origin and avoiding the subjectivity and low repeatability of traditional manual comparison of electrophoresis patterns. Furthermore, because the scanning band setting of the capillary electrophoresis detector is relatively wide, it will cause a decrease in detector sensitivity, resulting in most samples showing only a single response in the 201-280 nm range, with less response to trace components other than methamphetamine. Therefore, in order to improve the sensitivity of CZE technology, this application does not directly detect trace additives during the detection process. Instead, it indirectly reflects the differences in chemical characteristics between samples by extracting stable parameters such as the relative migration time and relative absorbance of the main component and the first separated component, effectively expanding the application scope of CZE technology in source inference.

[0022] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Attached Figure Description

[0023] Figure 1 This is the standard working curve of methamphetamine described in Example 1 of the present invention; Figure 2 The infrared spectra of methamphetamine in Example 1 and Comparative Example 1 of this invention are shown below. Figure 3 The infrared spectra of samples 1-a of Example 1 and Comparative Example 1 of this invention are shown below. Figure 4 This is a frequency distribution diagram of the three-dimensional Euclidean distance of the percentage content of methamphetamine, the separation time of the first separated component, and the relative absorbance value in Example 1 of the present invention. Figure 5 These are the electrophoretic separation spectra of samples 1-a, 1-b, and 1-c from Example 1 of the present invention; Figure 6 The electrophoretic separation spectra of samples 2-a, 2-b, and 2-c of Example 1 of this invention are shown. Figure 7 The electrophoretic separation spectra of samples 3-a, 3-b, and 3-c of Example 1 of this invention are shown. Figure 8 The electrophoretic separation spectra of samples 4-a, 4-b, and 4-c in Example 1 of this invention are shown. Figure 9 The electrophoretic separation spectra of samples 5-a, 5-b, and 5-c from Example 1 of this invention are shown. Figure 10 The electrophoretic separation spectra of samples 6-a, 6-b, and 6-c from Example 1 of this invention are shown. Figure 11 The electrophoretic separation spectra of samples 7-a, 7-b, and 7-c of Example 1 of this invention are shown. Figure 12 The electrophoretic separation spectra of samples 8-a, 8-b, and 8-c from Example 1 of this invention are shown. Figure 13 The electrophoretic separation spectra of samples 9-a, 9-b, and 9-c from Example 1 of this invention are shown. Figure 14 These are the electrophoretic separation spectra of samples 10-a, 10-b, and 10-c from Example 1 of the present invention; Figure 15 The electrophoretic separation spectra of samples 11-a, 11-b, and 11-c in Example 1 of this invention are shown. Figure 16 The electrophoretic separation spectra of samples 12-a, 12-b, and 12-c in Example 1 of this invention are shown. Figure 17 The electrophoretic separation spectra of samples 13-a, 13-b, and 13-c in Example 1 of this invention are shown. Figure 18 These are the electrophoretic separation spectra of samples 14-a, 14-b, and 14-c from Example 1 of the present invention; Figure 19 These are the electrophoretic separation spectra of samples 15-a, 15-b, and 15-c from Example 1 of the present invention; Figure 20 The electrophoretic separation spectra of samples 16-a, 16-b, and 16-c from Example 1 of this invention are shown. Figure 21 These are the electrophoretic separation spectra of samples 17-a, 17-b, and 17-c from Example 1 of the present invention; Figure 22 The electrophoretic separation spectra of samples 18-a, 18-b, and 18-c in Example 1 of this invention are shown. Figure 23 These are the electrophoretic separation spectra of samples 19-a, 19-b, and 19-c from Example 1 of the present invention; Figure 24 These are the electrophoretic separation spectra of samples 20-a, 20-b, and 20-c from Example 1 of this invention; Figure 25 The electrophoretic separation spectra of samples 21-a, 21-b, and 21-c of Example 1 of the present invention are shown. Figure 26 The electrophoretic separation spectra of samples 22-a, 22-b, and 22-c of Example 1 of this invention are shown. Figure 27 The electrophoretic separation spectra of samples 23-a, 23-b, and 23-c of Example 1 of this invention are shown. Figure 28 The electrophoretic separation spectra of samples 24-a, 24-b, and 24-c of Example 1 of this invention are shown. Figure 29 The images show the electrophoretic separation spectra of samples 25-a, 25-b, and 25-c from Example 1 of this invention. Detailed Implementation To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a method for determining the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics proposed according to the present invention. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0024] This invention proposes a method for identifying the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics. Amphetamine tablets are tablets containing amphetamine and its derivatives. The components of amphetamine tablets include methamphetamine. The method for identifying the source of amphetamine tablets includes: S100. Take the tablets to be tested, divide them into a first sample group and a second sample group, each group containing at least 3 tablets to be tested, and then dissolve them with a solvent to obtain the first sample group sample solution and the second sample group solution.

[0025] In the technical solution disclosed in this application, the tablets to be tested are divided into two groups, with at least three tablets taken from each group. This effectively reduces measurement errors caused by batch-to-batch inhomogeneity in single samples, improving sample representativeness and result reliability. Furthermore, the grouping design facilitates subsequent comparison of Euclidean distance between the two groups, providing a statistical basis for source identification.

[0026] In this step, the first sample group and the second sample group can be a combination of a sample from an unknown source and a sample from a known source, or a combination of two samples from unknown sources. If it is necessary to determine whether a sample from an unknown source is homologous to a sample from a known source, then the sample from the known source is designated as the first sample group, and the sample from the unknown source is designated as the second sample group. If it is only necessary to determine whether the seized samples in two cases come from the same source, then both groups are samples from unknown sources, and homology is determined directly by calculating the Euclidean distance.

[0027] It is worth noting that the first and second sample groups described in this application are only used as examples to illustrate the comparison process between the two sample groups. In practical applications, the sample groups to be judged can be dozens or even hundreds of groups. By calculating the Euclidean distance between each group, pairwise comparisons and source clustering analysis of batch samples can be achieved.

[0028] S200. Use zone capillary electrophoresis to separate and detect the sample solutions of the first sample group and the second sample group, respectively, to obtain the first electrophoretic pattern of the first sample group and the second electrophoretic pattern of the second sample group.

[0029] In this step, this application uses CZE technology to detect the sample solutions of the first and second sample groups, respectively, to obtain two CZE electrophoresis patterns. The two CZE electrophoresis patterns are then analyzed.

[0030] S300. Analyze the first electrophoresis pattern to obtain the percentage content A of methamphetamine, the relative migration time A of the first separated component, and the relative absorbance value A of the first separated component. Analyze the second electrophoresis pattern to obtain the percentage content B of methamphetamine, the relative migration time B of the first separated component, and the relative absorbance value B of the first separated component.

[0031] In this step, this application analyzes the two obtained CZE electrophoresis patterns to obtain two sets of data: the percentage content A of methamphetamine in the sample solution of the first sample group, the relative migration time A of the first separated component, and the relative absorbance value A of the first separated component; and the percentage content B of methamphetamine in the solution of the second sample group, the relative migration time B of the first separated component, and the relative absorbance value B of the first separated component.

[0032] While traditional Fourier transform infrared spectroscopy (FTIR) is simple and rapid for analyzing mixed samples, its ability to analyze trace components in mixtures is relatively weak. Therefore, this application employs zone capillary electrophoresis (CZE). CZE can achieve good separation of the main component of the sample, methamphetamine, and has the advantage of requiring a small sample volume; however, the small sample volume also leads to a decrease in its sensitivity to detect trace components in the sample.

[0033] To address the aforementioned shortcomings, this application selects three parameters from the CZE electrophoresis pattern to comprehensively characterize the chemical features of the sample from three dimensions: the relative migration time of the first separated component, the percentage content of methamphetamine, and the relative absorbance value of the first separated component. This approach provides strong information complementarity and effectively overcomes the problem of insufficient discrimination ability of a single parameter.

[0034] It is worth noting that the "first separated component" disclosed in this application is defined as the component with the shortest migration time in the electrophoretic pattern. This component is less affected by fluctuations in experimental conditions and has good stability.

[0035] S400. Normalize the percentage content A of methamphetamine, the relative migration time A of the first separated component, the relative absorbance value A of the first separated component, the percentage content B of methamphetamine, the relative migration time B of the first separated component, and the relative absorbance value B of the first separated component, respectively.

[0036] S500. Calculate the Euclidean distance between the first sample group and the second sample group. The calculation method is as follows: Wherein, Euclidean Distance is the Euclidean distance between the first and second sample groups, x1 is the percentage content of methamphetamine after normalization A, y1 is the relative elution time of the first separated component after normalization A, z1 is the relative absorbance value after normalization A, x2 is the percentage content of methamphetamine after normalization B, y2 is the relative elution time of the first separated component after normalization B, and z2 is the relative absorbance value after normalization B.

[0037] In this application, the normalized data is further calculated using Euclidean distance. This step integrates the three dimensions of chemical characteristic parameters into a single value, which can indirectly reflect the differences in chemical characteristics between different samples even when trace additives are not directly detected during the CZE detection process. This effectively compensates for the loss of evidence information caused by the insufficient sensitivity of CZE technology for trace detection, and provides a stable and quantifiable objective basis for sample source identification.

[0038] This application discloses the formula for calculating Euclidean distance, as follows: Wherein, Euclidean Distance is the Euclidean distance between the first and second sample groups, x1 is the percentage content of methamphetamine after normalization A, y1 is the relative elution time of the first separated component after normalization A, z1 is the relative absorbance value after normalization A, x2 is the percentage content of methamphetamine after normalization B, y2 is the relative elution time of the first separated component after normalization B, and z2 is the relative absorbance value after normalization B.

[0039] Furthermore, the Euclidean distance disclosed in this application can not only perform overall data analysis on the three parameters of the first and second sample groups, but also perform individual analysis on any single parameter, as detailed below: The percentage content of methamphetamine was analyzed separately using Euclidean distance, as follows: The calculation formula is: Wherein, Euclidean Distance2 is the Euclidean distance between the percentage content of methamphetamine in the first sample group and the second sample group, x1 is the percentage content of methamphetamine A after normalization, and x2 is the percentage content of methamphetamine B after normalization.

[0040] If the calculated Euclidean Distance2 value approaches 0 infinitely, it indicates that the first and second sample groups are homologous in terms of the percentage content of methamphetamine. Preferably, when Euclidean Distance2 ≤ 0.01, it indicates that the first and second sample groups are homologous in terms of the percentage content of methamphetamine.

[0041] A separate Euclidean distance analysis was performed on the relative elution times of the first separated component, as detailed below: The calculation formula is: Wherein, Euclidean Distance3 represents the relative elution time of the first separated component in the first sample group and the second sample group, y1 represents the relative elution time A of the first separated component after normalization, and y2 represents the relative elution time B of the first separated component after normalization. If the calculated Euclidean Distance3 value approaches 0 infinitely, it indicates that the first sample group and the second sample group are homologous in terms of the relative elution time of the first separated component. Preferably, when Euclidean Distance3 ≤ 0.01, it indicates that the first sample group and the second sample group are homologous in terms of the relative elution time of the first separated component.

[0042] A separate Euclidean distance analysis was performed on the relative absorbance values, as follows: The calculation formula is: Wherein, Euclidean Distance4 is the Euclidean distance between the relative absorbance values ​​of the first sample group and the second sample group, z1 is the relative absorbance value A after normalization, and z2 is the relative absorbance value B after normalization.

[0043] If the calculated Euclidean Distance4 value approaches 0 infinitely, it indicates that the first and second sample groups are homologous in terms of relative absorbance. Preferably, if Euclidean Distance4 ≤ 0.01, it indicates that the first and second sample groups are homologous in terms of relative absorbance.

[0044] S600. Determine whether the first sample and the second sample have the same origin based on the calculated Euclidean distance: when the Euclidean distance is ≤0.01, the first sample and the second sample are determined to have the same origin.

[0045] After the above data processing, the obtained Euclidean distance result is compared with a preset threshold. If the Euclidean distance approaches 0 infinitely, the first sample and the second sample are determined to be from the same source. Furthermore, if the Euclidean distance is ≤0.01, the first sample and the second sample are determined to be from the same source.

[0046] This application establishes a clear preset threshold, which makes source identification operable and repeatable, avoids ambiguous judgments, and thus improves the accuracy of the judgment.

[0047] In one possible implementation, the normalization formula in step S400 is as follows: Where δ is the result after normalization and square root processing, x i For the parameters to be normalized, x min x is the minimum value of the parameter. maxThis represents the maximum value of the parameter. The parameter is either the percentage content of methamphetamine A, the relative migration time of the first separated component A, the relative absorbance value of the first separated component A, the percentage content of methamphetamine B, the relative migration time of the first separated component B, or the relative absorbance value of the first separated component B.

[0048] This application discloses a specific method for normalization processing, and the specific calculation formula is as follows: Where δ is the result after normalization and square root processing. The specific result needs to be determined according to the specific meaning of x. For example, if x is the percentage content A of methamphetamine, then δ is the result after normalization and square root processing of the percentage content A of methamphetamine. i The parameter to be normalized is x, which can be the percentage content of methamphetamine, the relative migration time of the first separated component, or the relative absorbance value of the first separated component. The specific value can be selected according to the actual calculation needs. min x is the minimum value of this parameter. max This is the maximum value of the parameter. For x min and x max This value represents the maximum and minimum values ​​of this parameter across all sample groups. This application divides the samples into a first sample group and a second sample group, solely for illustrative purposes to illustrate the comparison process between the two sample groups. However, in practical applications, the samples to be tested can number in the dozens or even hundreds, while x... min and x max The value is the minimum and maximum value among all samples. For example: if there are 50 sample groups to be tested, and x is the percentage content of methamphetamine, then x i x represents the percentage of methamphetamine to be normalized. min This represents the minimum percentage content of this type of methamphetamine in the 50 sample groups. max The maximum percentage content of methamphetamine in the 50 samples is the maximum value, and the relative migration time or relative absorbance value of the first separated component can be deduced accordingly.

[0049] In one possible implementation, in step S300, the first separated component is the component with the shortest migration time in the electrophoretic pattern.

[0050] In one possible implementation, in step S100, the solvent is distilled water. The concentration of the first sample group solution is 0.25–1 mg / L. The concentration of the second sample group solution is 0.25–1 mg / L.

[0051] In one possible implementation, the concentration of the first sample group solution and the concentration of the second sample group solution are both 1 mg / L.

[0052] In one possible implementation, in step S300, the percentage content A and percentage content B of methamphetamine are obtained by the following method: First, a working solution of methamphetamine standard sample is prepared, and then data is collected on the working solution of methamphetamine standard sample using zone capillary electrophoresis to obtain a working curve. Then, the first electrophoresis pattern and the second electrophoresis pattern of the second sample group are compared with the working curve to obtain the percentage content A and percentage content B of methamphetamine.

[0053] This application discloses a method for obtaining the percentage content data of methamphetamine, as follows: First, accurately weigh methamphetamine standard, dissolve and dilute it with distilled water to prepare a series of standard working solutions with concentration gradients, preferably 0.25 mg / mL, 0.5 mg / mL, 0.7 mg / mL and 1.0 mg / mL.

[0054] Then, the above-mentioned standard working solution was analyzed using the same zone capillary electrophoresis conditions as the test sample. Each concentration point was tested in parallel at least three times, and the peak area of ​​methamphetamine at each concentration was recorded. A standard working curve for methamphetamine was plotted with concentration on the x-axis and peak area on the y-axis, as shown below. Figure 1 As shown.

[0055] Finally, by comparing the first electrophoresis pattern and the second electrophoresis pattern of the second sample group with the working curve, the percentage content of methamphetamine can be obtained.

[0056] In one possible implementation, the concentration of the methamphetamine standard working solution is 0.25–1 mg / mL.

[0057] In one possible implementation, in step S200, the separation conditions for zone capillary electrophoresis are: using boric acid at a concentration of 85–95 mmol / L and a pH of 8.4 as the separation buffer.

[0058] In one possible implementation, the specific method for zone capillary electrophoresis in step S200 is as follows: S210. Filter boric acid, a 0.1 mol / L sodium hydroxide aqueous solution, and water, and then place them sequentially into the buffer tray of the capillary electrophoresis apparatus. Place the sample solution of the first sample group or the sample solution of the second sample group into the sample tray of the capillary electrophoresis apparatus.

[0059] S220. Rinse the capillary tube with boric acid for 2 minutes, then rinse it with sodium hydroxide aqueous solution for 5 minutes, and finally rinse it with water for 1 minute.

[0060] S230. Set the scanning wavelength of the capillary electrophoresis detector to 190-300 nm, the operating voltage to 25 kV, the sample injection time to 5 s, the borate buffer to be used as the separation buffer, and the separation time to 10 min. The capillary electrophoresis instrument collects data while separating.

[0061] This application discloses a specific implementation method for CZE technology. During operation, although the detector scanning wavelength of the capillary electrophoresis apparatus is set to 190–300 nm, in actual testing, most samples only show a single signal response around 200 nm. This is mainly due to the decreased detector sensitivity during wide-band scanning and the weak response of trace chemical components in tablet methamphetamine samples. Therefore, this application selects the percentage content of methamphetamine in the test sample as one of the criteria for determining chemical characteristics.

[0062] In one possible implementation, after performing step S500, the obtained Euclidean distance is further normalized twice, as shown in the following formula: in, The results are the result of the second normalization process. x1 is the percentage content of methamphetamine after the first normalization process, y1 is the relative elution time of the first separated component after the first normalization process, and z1 is the relative absorbance value of the first separated component after the first normalization process.

[0063] Then, the Euclidean distance is calculated from the result of the second normalization process, as shown in the following formula: in, The Euclidean distance is calculated from the result of the second normalization process. The percentage content of methamphetamine after secondary normalization. The relative elution times of the first separated component after secondary normalization are given. The relative absorbance value of the first separated component after secondary normalization is given.

[0064] The present invention will be further described below with reference to specific embodiments, but this should not be construed as a limitation on the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention still fall within the scope of protection of the present invention.

[0065] Unless otherwise specified, all materials and reagents mentioned below are commercially available products well known to those skilled in the art; unless otherwise specified, all methods described are methods known in the art. Unless otherwise defined, the technical or scientific terms used should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0066] Example 1 A method for determining the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics, the method comprising: 1. Reagents and instruments: Reagents: distilled water, borate buffer (concentration 80-90 mmol / L, pH 8.4), sodium hydroxide aqueous solution (concentration 0.1 mol / L), methamphetamine standards (concentrations of 0.25 mg / mL, 0.5 mg / mL, 0.7 mg / mL and 1.0 mg / mL), 25 groups of amphetamine tablets to be tested, 3 tablets in each group.

[0067] Instrument: Capillary electrophoresis apparatus (such as Beckman P / ACEMDQ) 2. Experimental Procedure: S100. Grind 25 groups of 3 tablets each into powder and prepare sample solutions with a concentration of 1 mg / L.

[0068] S210. Filter the boric acid, sodium hydroxide aqueous solution, and water, and then place them sequentially into the buffer tray of the capillary electrophoresis apparatus. Place the sample solution into the sample tray of the capillary electrophoresis apparatus.

[0069] S220. Rinse the capillary tube with boric acid for 2 minutes, then rinse it with sodium hydroxide aqueous solution for 5 minutes, and finally rinse it with water for 1 minute.

[0070] S230. Set the scanning wavelength of the capillary electrophoresis detector to 190–300 nm, the operating voltage to 25 kV, the injection time to 5 s, and the separation buffer to borate buffer (90 mmol / L, pH=8.4) for 10 min. Collect data simultaneously during capillary electrophoresis to obtain CZE electrophoresis patterns, and then analyze the electrophoresis patterns. The results of 25 sets of electrophoresis patterns are as follows: Figures 5 to 25 As shown.

[0071] S300. Compare the obtained electrophoretic pattern with the standard working curve of methamphetamine ( Figure 1 The percentage content of methamphetamine was obtained. Then, the electrophoretic pattern was analyzed to obtain the relative migration time and relative absorbance value of the first separated component.

[0072] S400. The percentage content of methamphetamine, the relative migration time of the first separated component, and the relative absorbance value of the first separated component were normalized respectively. The calculation method is as follows: Where δ is the result after normalization and square root processing, x iFor the parameters to be normalized, x min x is the minimum value of this parameter among the 25 samples. max This represents the maximum value of this parameter among the 25 sample groups. The parameters are the percentage content of methamphetamine, the relative migration time of the first separated component, and the relative absorbance value of the first separated component.

[0073] S500. Calculate the Euclidean distance between any sample group and other sample groups. The calculation method is as follows: Wherein, Euclidean Distance is the Euclidean distance between any sample group and other sample groups, x1 is the percentage content A of methamphetamine in any sample group after normalization, y1 is the relative elution time A of the first separated component in any sample group after normalization, z1 is the relative absorbance value A of any sample group after normalization, x2 is the percentage content B of methamphetamine in other sample groups after normalization, y2 is the relative elution time B of the first separated component in other sample groups after normalization, and z2 is the relative absorbance value B of other sample groups after normalization.

[0074] S600. Based on the calculated Euclidean distance, if the Euclidean distance is ≤0.01, the two samples are determined to be from the same source.

[0075] Comparative Example 1 Compared with Example 1, Comparative Example 1 used a Smith Detection Target-ID portable Fourier transform infrared spectrometer to test 25 groups of samples.

[0076] The results of the analysis of Comparative Example 1 are shown in Table 1: Table 1: Main components of 25 samples analyzed by Fourier transform infrared spectroscopy Table 1 shows that Fourier transform infrared spectroscopy analysis of the 25 samples revealed the most frequently detected main components as follows: caffeine (100% detection), dihydroxypropyltheophylline (detected in 30 samples, accounting for 40%), and nortriptyline hydrochloride (detected in 22 samples, accounting for 29%). Some samples had identical main components in all three samples. For example, caffeine, 2-aminobutane, and theophylline were detected in all three samples of sample #9; caffeine, dihydroxypropyltheophylline, and deoxyephedrine hydrochloride were detected in all three samples of sample #13. Therefore, it can be inferred that the three samples of sample #9 and sample #13 in the same case may have the same source. Furthermore, ten samples (1-a, 2-b, 2-c, 6-a, 11-a, 12-a, 17-a, 17-b, 19-c, and 21-b) all contained caffeine, dihydroxypropyltheophylline, and nortriptyline hydrochloride; three samples (16-a and 13#) all contained caffeine, dihydroxypropyltheophylline, and deoxyephedrine hydrochloride. Therefore, these ten samples, as well as samples 13-a, 13-b, 13-c, and 16-a, may share a common origin. These results indicate that using infrared spectroscopy to analyze the main components of samples is feasible for uncovering hidden information about similar types of drugs.

[0077] However, according to the standard infrared characteristics of methamphetamine, such as Figure 2 As shown, 2458 cm⁻¹ is the characteristic peak of methamphetamine hydrochloride. However, the main active ingredient in "Ma Gu" (methamphetamine pills) could not be clearly detected using a portable infrared spectrometer. For example, sample 1-a in group 25, such as... Figure 3 and Figure 4 As shown, it only has a small absorption peak near 2500 cm⁻¹, suggesting the presence of methamphetamine, but the signal is weak and cannot be used as an accurate basis for identification.

[0078] Therefore, through Table 1, Figure 2 , Figure 3 and Figure 4 It is evident that Fourier transform infrared spectroscopy (FTIR) has a significant limitation in the analysis of amphetamine tablets: it measures overtone and combination frequency absorption. When the concentration of a component in the sample is low, its absorption signal weakens significantly, resulting in insufficient detection sensitivity. Therefore, although Fourier transform infrared spectroscopy has advantages such as simple operation, no reagents required, and fast testing speed, its response to low-concentration components in mixtures is weak, making it unsuitable for trace analysis. For amphetamine tablets containing multiple additives and where the main component and excipients coexist, relying solely on infrared spectroscopy is insufficient to fully extract all evidentiary information; therefore, it is urgently necessary to combine it with more sensitive separation and analysis techniques. The analysis results of Example 1 are as follows: Table 2: Percentage content of methamphetamine in 25 samples analyzed using the method in Example 1 Table 3: Component migration time and absorbance of 25 sample groups In Table 3, component 1 is the component that is the first to elute in the electrophoresis pattern, that is, the component with the shortest migration time.

[0079] The data in Tables 2 and 3 were normalized, and the results are shown in Table 4: Table 4: Results after normalization Then, the data in Table 4 is further normalized using the following formula: in, To further normalize the results, x1 represents the percentage content of methamphetamine after one normalization process, y1 represents the relative elution time of the first separated component after one normalization process, and z1 represents the relative absorbance value of the first separated component after one normalization process. The specific calculation results are shown in Table 5. Table 5: Results of further normalization Then, based on the calculation results in Table 5, the Euclidean distance between each sample and other samples was calculated. The results were then compared with those in Table 1. It can be seen that, according to the detection results of the Fourier transform infrared spectrometer, samples 1-a, 2-b, 2-c, 6-a, 11-a, 12-a, 17-a, 17-b, 19-c, and 21-b all contain caffeine, dihydroxypropyltheophylline, and nortriptyline hydrochloride. Samples 16-a, 13-a, 13-b, and 13-c all contain caffeine, dihydroxypropyltheophylline, and deoxyephedrine hydrochloride. Therefore, it is preliminarily inferred that the above 10 samples and samples 13-a, 13-b, 13-c, and 16-a may have the same source. However, after extracting the three-dimensional chemical feature parameters and calculating the Euclidean distance using CZE technology, it was found that only the Euclidean distances of 2-b, 2-c, 17-a, and 19-c were close to 0 (see Table 6), indicating that these four samples were truly homologous. In the comparison of 13-a, 13-b, 13-c, and 16-a, only the Euclidean distance between 13-a and 13-b was close to 0 (see Table 8), indicating that they were from the same source. Although the other samples had the same main components, their chemical features were substantially different, and they were not homologous.

[0080] Table 6: Euclidean distance of three-dimensional parameters for samples 1-a, 2-b, 2-c, 6-a, 11-a, 12-a, 17-a, 17-b, 19-c and 21-b Table 8: Euclidean distances between samples 13-a, 13-b, 13-c and 16-a In summary, while Fourier transform infrared spectroscopy can rapidly identify the main components in amphetamine tablets, its sensitivity for detecting low-content components is relatively low, making it difficult to accurately determine whether samples are homologous based solely on identical component types. This application, however, combines zone capillary electrophoresis (CZE) with chemometrics. By extracting chemical characteristic parameters in three dimensions—methamphetamine percentage, relative migration time of the first separated component, and relative absorbance—and calculating the Euclidean distance between samples, it achieves an objective quantitative determination of sample homology.

[0081] The above comparison shows that among the multiple samples initially inferred to be potentially homologous by infrared spectroscopy, only those samples with an Euclidean distance close to 0 (≤0.01) were verified as truly homologous. The remaining samples, although sharing the same main components, exhibited substantial differences in chemical characteristics. Therefore, the method provided in this application effectively overcomes the limitations of insufficient sensitivity and subjective judgment inherent in traditional infrared spectroscopy, significantly improving the accuracy and reliability of identifying the source of amphetamine tablets. It provides an objective and quantifiable technical means for drug tracing and case linking.

[0082] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for determining the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics, characterized in that, The amphetamine tablets are tablets containing amphetamine and its derivatives; the amphetamine tablets contain methamphetamine; the methods for determining the source of the amphetamine tablets include: S100. Take the test tablets and divide them into a first sample group and a second sample group, each containing at least 3 test tablets. Then dissolve them with a solvent to obtain a first sample group sample solution and a second sample group solution. S200. Use zone capillary electrophoresis to separate and detect the sample solutions of the first sample group and the second sample group respectively, to obtain the first electrophoretic pattern of the first sample group and the second electrophoretic pattern of the second sample group; S300. Analyze the first electrophoretic pattern to obtain the percentage content A of methamphetamine, the relative migration time A of the first separated component, and the relative absorbance value A of the first separated component; analyze the second electrophoretic pattern to obtain the percentage content B of methamphetamine, the relative migration time B of the first separated component, and the relative absorbance value B of the first separated component. S400. Normalize the percentage content A of the methamphetamine, the relative migration time A of the first separated component, the relative absorbance value A of the first separated component, the percentage content B of the methamphetamine, the relative migration time B of the first separated component, and the relative absorbance value B of the first separated component, respectively. S500. Calculate the Euclidean distance between the first sample group and the second sample group, using the following method: Wherein, Euclidean Distance is the Euclidean distance between the first sample group and the second sample group, x1 is the percentage content A of the methamphetamine after normalization, y1 is the relative elution time A of the first separated component after normalization, z1 is the relative absorbance value A after normalization, x2 is the percentage content B of the methamphetamine after normalization, y2 is the relative elution time B of the first separated component after normalization, and z2 is the relative absorbance value B after normalization. S600. Determine whether the first sample group and the second sample group have the same source based on the calculated Euclidean distance: when the Euclidean distance is ≤0.01, determine that the first sample group and the second sample group have the same source.

2. The method for determining the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics according to claim 1, characterized in that, In step S400, the normalization formula is as follows: Where δ is the result after normalization and square root processing, x i For the parameters to be normalized, x min x is the minimum value of the parameter. max The parameter is the maximum value of the parameter; the parameter is the percentage content A of the methamphetamine, the relative migration time A of the first separated component, the relative absorbance value A of the first separated component, the percentage content B of the methamphetamine, the relative migration time B of the first separated component, or the relative absorbance value B of the first separated component.

3. The method for determining the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics according to claim 1, characterized in that, In step S300, the first separated component is the component with the shortest migration time in the electrophoretic pattern.

4. The method for determining the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics according to claim 1, characterized in that, In step S100, the solvent is distilled water; the concentration of the first sample group solution is 0.25–1 mg / L; and the concentration of the second sample group solution is 0.25–1 mg / L.

5. The method for determining the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics according to claim 1, characterized in that, The concentration of the sample solution in the first sample group and the concentration of the sample solution in the second sample group are both 1 mg / L.

6. The method for determining the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics according to claim 5, characterized in that, In step S300, the percentage content A and percentage content B of methamphetamine are obtained by the following method: First, a methamphetamine standard sample working solution is prepared, and then the methamphetamine standard sample working solution is subjected to zone capillary electrophoresis to obtain a working curve. Then, the first electrophoresis pattern and the second electrophoresis pattern of the second sample group are compared with the working curve to obtain the percentage content A and percentage content B of methamphetamine.

7. The method for determining the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics according to claim 6, characterized in that, The concentration of the methamphetamine standard sample working solution is 0.25–1 mg / mL.

8. The method for determining the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics according to claim 7, characterized in that, In step S200, the separation conditions for the zone capillary electrophoresis are as follows: boric acid with a concentration of 85-95 mmol / L and a pH of 8.4 is used as the separation buffer.

9. The method for determining the source of amphetamine tablets based on zonal capillary electrophoresis and chemometrics according to claim 8, characterized in that, In step S200, the specific method for zonal capillary electrophoresis is as follows: S210. Filter the boric acid, the 0.1 mol / L sodium hydroxide aqueous solution and water, and then place them sequentially into the buffer tray of the capillary electrophoresis apparatus; place the sample solution of the first sample group or the sample solution of the second sample group into the sample tray of the capillary electrophoresis apparatus; S220. Rinse the capillary with the boric acid for 2 min, then rinse the capillary with the sodium hydroxide aqueous solution for 5 min, and finally rinse the capillary with water for 1 min. S230. Set the scanning wavelength of the capillary electrophoresis detector to 190-300 nm, the operating voltage to 25 kV, the sample injection time to 5 s, the borate buffer to be used as the separation buffer, and the separation time to 10 min. The capillary electrophoresis instrument collects data while separating.

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