A mass spectrometry cracking analysis method of nesiritide analogues based on esi-ms / ms mode

Abstract

This invention discloses a mass spectrometry fragmentation and resolution method for nixacin analogs based on ESI-MS / MS mode. The structural formula of the nixacin analog is shown below. The method includes the following steps: (1) obtaining the characteristic fragment ion sequence D of the suspected substance in ESI-MS / MS mode; (2) sorting the sequence D to obtain the sequence D. ′ Determine sequence D ′ The largest fragment D ′ n and the smallest fragment D ′ 1. Does it meet the conditions for nitric acid analogues? (3) Search sequence D ′ The largest fragment D with a mass-to-charge ratio less than 107 ′ i And the smallest fragment D with a mass-to-charge ratio greater than 107 ′ j (4) Based on i and D ′ i (5) Based on the mass-to-charge ratio of R1 and R2, deduce the structure of R1 and R2; ′ j Based on the mass-to-charge ratio of R4, the structure of R4 can be deduced; (6) Based on D ′ i D ′ j D ′ n By analyzing the mass-to-charge ratio of R3, the structure and alkyl length of R3 were deduced, and the molecular structure of the suspected substance was reduced.

Description

Technical Field

[0001] This invention relates to a method for identifying nicotin analogs, and more particularly to a mass spectrometry fragmentation and analysis method for nicotin analogs based on ESI-MS / MS mode. Background Technology

[0002] Nizoxins are a new class of synthetic opioids (NSOs) with 2-benzylbenzimidazole as the core. Their addictiveness, acute toxicity, and risk of death from overdose are far greater than those of morphine. The pharmacological activity of most varieties far exceeds that of fentanyl, making them the most promising new synthetic opioid psychoactive substances after fentanyl.

[0003] The core structure of nicotinic acid analogs is 2-benzylbenzimidazole. The parent nucleus is surrounded by four groups: R1, R2, R3, and R4. R1 and R2 are carbon chains, or may be combined into a carbon ring structure, without carbon-carbon double bonds; R3 is located on the left side of the benzene ring of the parent nucleus and is either hydrogen or a nitro group; R4 is a halogen (fluorine, chlorine, bromine, etc.), a hydroxyl group, or an alkoxy group. The overall structure is as follows: Additionally, an alkylene group (-(CH2)) may be present on the right side of the parent nucleus. n -).

[0004] However, due to the diverse structures of nicotin analogs, traditional analytical methods struggle to rapidly and accurately identify their structures. Mass spectrometry, as a highly sensitive and selective analytical technique, has been widely applied to the structural analysis of organic compounds.

[0005] In the existing technology, the mass spectrometry analysis of nicotin analogs mainly relies on the comparison of standard spectral libraries, lacking an in-depth understanding of their fragmentation rules. Due to the rapid update speed, wide variety of nicotin analogs, and difficulty in obtaining reference standards, there are certain limitations in the analysis of unknown compounds, resulting in low accuracy and efficiency in the analysis of nicotin-like structural analogs. Summary of the Invention

[0006] The purpose of this invention is to provide a mass spectrometry fragmentation and resolution method for nicotin analogs based on ESI-MS / MS mode. This invention improves the accuracy and efficiency of nicotin analog analysis.

[0007] The technical solution of this invention: a mass spectrometry fragmentation and resolution method for nixacin analogs based on ESI-MS / MS mode, wherein the structural formula of the nixacin analog is... Its characteristic is that it includes the following steps:

[0008] (1) Obtain the characteristic fragment ion sequence D of the suspected substance in ESI-MS / MS mode;

[0009] (2) Sort the sequence D in ascending order to obtain the sequence D ′ , and judge the sequence D ′ to determine whether the fragment D ′ n with the largest mass-to-charge ratio and the fragment D ′ 1 with the smallest mass-to-charge ratio in the sequence D satisfy the conditions of the nitenpyram analog. If they satisfy, go to step (3); otherwise, it is considered that the suspect is not a nitenpyram analog, and go to step (7);

[0010] (3) Search for the largest fragment D ′ i in the sequence D' with a mass-to-charge ratio less than 107 and the smallest fragment D ′ j with a mass-to-charge ratio greater than 107;

[0011] (4) According to the condition of i and the mass-to-charge ratio relationship between D ′ i , R1 and R2, infer the structures of R1 and R2;

[0012] (5) According to the mass-to-charge ratio relationship between D ′ j and R4, infer the structure of R4;

[0013] (6) According to the mass-to-charge ratio relationships between D ′ i , D ′ j , D ′ n and R3, infer the structure and alkyl length of R3, and restore the molecular structure of the suspect;

[0014] (7) The analysis is completed.

[0015] In the above-mentioned mass spectrometry fragmentation analysis method of nitenpyram analog based on the ESI-MS / MS mode, in step (1): the sequence D = {D1, D2, D3,... D m}, where m is a positive integer greater than 3. For any two fragments D i and D j in the sequence D, there is always D i ≠ D j , where 0 < i < j ≤ m, and both i and j are positive integers.

[0016] In the above-mentioned mass spectrometry fragmentation analysis method of nitenpyram analog based on the ESI-MS / MS mode, in step (2), the sequence D ′ = {D ′ 1, D ′ 2, D ′ 3,... D ′n}, for sequence D ′ For any two fragments D ′ i and D ′ j in it, there is always D ′ i > D ′ j , where 0 < i < j ≤ n ≤ m, and both i and j are positive integers. [[ID=~16]] [[ID=~17]]

[0017] In the above-mentioned method for mass spectrometry fragmentation analysis of nizatidine analogs based on the ESI-MS / MS mode, in step (2), the conditions for nizatidine analogs are condition (a): [[ID=~19]] [[ID=~20]]. [[ID=~21]] [[ID=~22]]

[0018] In the above-mentioned method for mass spectrometry fragmentation analysis of nizatidine analogs based on the ESI-MS / MS mode, in step (3), 0 < i < j ≤ n, and both i and j are positive integers. [[ID=~24]] [[ID=~25]]

[0019] In the above-mentioned method for mass spectrometry fragmentation analysis of nizatidine analogs based on the ESI-MS / MS mode, step (4) specifically includes: If i = 1, solve the equation (b): 14x = D[[ID=~27]] ′ [[ID=~28]] i - 56; [[ID=~30]] [[ID=~31]]

[0020] If x has a non-negative integer solution, it indicates that the chemical formula of R1 is -(CH2)[[ID=~33]] x H; the chemical formula of R2 is -CH2CH3, and go to step (5); [[ID=~35]] E[[ID=~36]]

[0021] If i > 1, solve the equation (c): 14x = D[[ID=~38]] ′ [[ID=~39]] i - 72, where x is a non-negative integer; [[ID=~41]] [[ID=~42]]

[0022] If x has a non-negative integer solution, it indicates that the chemical formula of R1 is -(CH2)[[ID=~44]] x H, the chemical formula of R2 is -CH2CH3, and go to step (5); [[ID=~46]] [[ID=~47]]

[0023] If x has no non-negative integer solution, solve the equation (d): 14y = D[[ID=~49]] ′ [[ID=~50]] i - D[[ID=~52]] ′ [[ID=~53]] i-1 ; [[ID=~55]] [[ID=~56]]

[0024] If y has a positive integer solution, it indicates that R1 and R2 together form a carbon ring, and the chemical formula is -(CH2)[[ID=~58]] y+1 , and go to step (5). [[ID=~60]] [[ID=~61]]

[0025] In the above-mentioned method for mass spectrometry fragmentation analysis of nizatidine analogs based on the ESI-MS / MS mode, step (5) specifically includes: According to D[[ID=~63]] ′j The mass-to-charge ratio relationship between R and R4 is solved by solving equation (e):

[0026] ;

[0027] Where a, b, c, d, e, and f represent the quantities of alkyl, oxygen (hydroxyl), fluorine, chlorine, bromine, and iodine, respectively; a is a non-negative integer, and b, c, d, e, and f are 0 or 1.

[0028] If we find a=0 and b=1, it indicates that the chemical formula of the side chain R4 is -OH;

[0029] If we find that a > 0 and b = 1, then the chemical formula of side chain R4 is -O(CH2). a-1 CH3;

[0030] If the solution is c=1, it indicates that the chemical formula of the side chain R4 is -F;

[0031] If the solution is d=1, it indicates that the chemical formula of the side chain R4 is -Cl;

[0032] If the solution is e=1, it indicates that the chemical formula of the side chain R4 is -Br;

[0033] If the solution f=1, it indicates that the chemical formula of the side chain R4 is -I.

[0034] In the aforementioned mass spectrometry fragmentation and resolution method for nixacin analogues based on ESI-MS / MS mode, step (6) specifically includes: according to D ′ i D ′ j D ′ n The mass-to-charge ratio relationship between R and R3 is given by solving equation (f): ;

[0035] Where a, b, and c are 0 or 1, and d is a non-negative integer;

[0036] If we find a=1, b=0, c=0, then the chemical formula of the side chain R3 is -H;

[0037] If we find a=0, b=1, c=0, then the chemical formula of the side chain R3 is -NO2;

[0038] If we find a=0, b=0, c=1, then the chemical formula of the side chain R3 is -CN;

[0039] If the solution yields d≥0, then the link on the right side of the mother nucleus is -(CH2). d -

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] This invention primarily utilizes computer language to apply the mass spectrometry fragmentation rules of novel nixacin analogs to the structural analysis of these compounds. It enables rapid and direct inference and identification of the molecular structures of nixacin analogs based on mass spectrometry data, effectively addressing the identification challenges caused by the rapid iteration of novel nixacin analogs, the wide variety of their structures, and the scarcity of reference standards. Furthermore, this method reduces human intervention, lowers identification costs, shortens the detection cycle, minimizes detection errors, and significantly improves the efficiency and accuracy of identification work. It offers advantages such as precise detection, rapid and efficient operation, low cost, and strong versatility. Furthermore, this invention enables high-throughput rapid screening of unknown nicotinic acid analogues, further improving the identification technology system for novel psychoactive substances, enhancing the consistency and standardization of test results from different laboratories, and providing key technical support for rapid characterization, evidence collection, and source tracing in drug-related cases. It can also serve dynamic monitoring of drug conditions and analysis of structural evolution trends, reducing reliance on scarce standard samples. Applicable to the detection of various complex matrix samples such as blood, urine, hair, and sewage, it can meet the law enforcement and supervision needs of multiple departments including drug control, customs, and border inspection, providing data support for dynamic updates to the controlled substance list and the implementation of pre-emptive control measures. It also lays the foundation for the development of subsequent intelligent and automated identification systems, comprehensively improving the scientific and forward-looking nature of drug source control. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the process of the present invention;

[0043] Figure 2 A schematic diagram of the decomposition pathway of nicotin analogues.

[0044] Figure 3 The decomposition path diagram of metoprin in ESI-MS / MS mode.

[0045] Figure 4 The mass spectrum of metoprin in ESI-MS / MS mode.

[0046] Figure 5 Mass spectrometric decomposition pathway of denitroetoxin in ESI-MS / MS mode;

[0047] Figure 6 Mass spectrum of denitroetotenidine in ESI-MS / MS mode;

[0048] Figure 7 This is the mass spectrometric decomposition pathway diagram of phenethyletotenidine in ESI-MS / MS mode.

[0049] Figure 8 This is the mass spectrum of phenethyletotenidine in ESI-MS / MS mode.

[0050] Figure 9Mass spectrometry decomposition pathway diagram of clonitazene in ESI-MS / MS mode.

[0051] Figure 10 Mass spectrometry diagram of clonitazene in ESI-MS / MS mode. Detailed implementation manners

[0052] The present invention will be further described below with reference to the accompanying drawings and embodiments, but it shall not be used as a basis for limiting the present invention.

[0053] As Figure 1 and Figure 2 shown, a mass spectrometry fragmentation analysis method for nitazine analogs based on the ESI-MS / MS mode includes the following steps:

[0054] (1) Obtain the characteristic fragment ion sequence D = {D1, D2, D3,... D m} in the ESI-MS / MS mode of the suspect, where m is a positive integer greater than 3. For any two fragments D i and D j in the sequence D, there is always D i ≠D j , where 0 < i < j ≤ m, and both i and j are positive integers.

[0055] (2) Sort the characteristic fragment ion sequence D in ascending order to obtain the sequence D ′ = {D ′ 1, D ′ 2, D ′ 3,... D ′ n}. For any two fragments D ′ and D ′ i in the sequence D ′ j , there is always D ′ i > D ′ j , where 0 < i < j ≤ n ≤ m, and both i and j are positive integers;

[0056] Judge whether the sequence D ′ meets the mass-to-charge ratio condition (a) of the fragment sequence of nitazine analogs: , if it meets, go to step (3); otherwise, it is considered that the suspect is not a nitazine analog, and go to step (7);

[0057] (3) Search for the largest fragment D ′ with a mass-to-charge ratio less than 107 and the smallest fragment D ′ i with a mass-to-charge ratio greater than 107 in the sequence D′ j , where 0 < i < j ≤ n, and both i and j are positive integers;

[0058] (4) If i = 1, solve equation (b): 14x = D ′ i -56;

[0059] Among them, 14 represents the mass-to-charge ratio of CH2, and 56 is the smallest mass-to-charge ratio of the current nitenpyram analog in ESI / MS.

[0060] If x has a non-negative integer solution, it indicates that R1 is a hydrocarbon group or hydrogen, and the chemical formula of R1 is -(CH2) x H; R2 is ethyl, and the chemical formula of R2 is -CH2CH3, go to step (4);

[0061] If i > 1, solve equation (c): 14x = D ′ i -72, where x is a non-negative integer;

[0062] If x has a non-negative integer solution, it indicates that R1 is a hydrocarbon group or hydrogen, and the chemical formula of R1 is -(CH2) x H, R2 is ethyl, and the chemical formula of R2 is -CH2CH3, go to step (4);

[0063] If x has no non-negative integer solution, it is necessary to consider the case where R1 and R2 jointly form a carbon ring, and solve equation (d): 14y = D ′ i -D ′ i-1 ;

[0064] If y has a positive integer solution, it indicates that R1 and R2 jointly form a carbon ring, and the chemical formula is -(CH2) y+1 , go to step (5).

[0065] If the above equations (b), (c), and (d) have no solutions, it is considered that the suspect is not a nitenpyram analog, and go to step (7);

[0066] (5) According to the mass-to-charge ratio relationship between D ′ j and R4, solve equation (e):

[0067] ;

[0068] Among them, a, b, c, d, e, and f respectively represent the numbers of alkyl, oxygen (hydroxyl), fluorine, chlorine, bromine, and iodine; a is a non-negative integer, and b, c, d, e, f are 0 or 1.

[0069] If it is solved that a = 0 and b = 1, it indicates that the side chain R4 is a hydroxyl group, that is, -OH;

[0070] If we find that a > 0 and b = 1, it indicates that the side chain R4 is an alkoxy group, i.e., -O(CH2). a-1 CH3;

[0071] If the solution is c=1, it indicates that the side chain R4 is a fluorine group, i.e., -F;

[0072] If the solution is d=1, it indicates that the side chain R4 is a chlorine group, i.e., -Cl;

[0073] If the solution is e=1, it indicates that the side chain R4 is a bromine group, i.e., -Br;

[0074] If the solution is f=1, it indicates that the side chain R4 is an iodine group, i.e., -I.

[0075] If equation (e) has no non-negative integer solutions, then the suspected object is not a Nizin analogue and proceeds to step (7).

[0076] (6) According to D ′ i D ′ j D ′ n The mass-to-charge ratio relationship between R and R3 is given by solving equation (f):

[0077] ;

[0078] Where a, b, c, and d represent the number of hydrogen (-H), nitro (-NO2), cyano (-CN), and alkylene groups, respectively, a, b, and c are 0 or 1, and d is a non-negative integer.

[0079] If we find a=1, b=0, c=0, then it indicates that the side chain R3 is a hydrogen group, i.e. -H;

[0080] If we find a=0, b=1, c=0, it indicates that the side chain R3 is a nitro group, i.e. -NO2;

[0081] If we find a=0, b=0, c=1, it indicates that the side chain R3 is a cyano group, i.e., -CN;

[0082] If the solution yields d ≥ 0, it indicates that the number of alkyl groups on the right side of the parent nucleus is d, meaning that an alkylene group (-(CH2)) is attached to the right side of the parent nucleus. d -;

[0083] Otherwise, the substance is considered not to be a nizumab analogue, and proceed to step (7).

[0084] (7) End of analysis.

[0085] Example 1:

[0086] A mass spectrometric fragmentation analysis method for nixacin analogues based on ESI-MS / MS mode, to Figure 3 Taking topiramate as an example, combined with Figure 1 , Figure 2 The present invention will be described in further detail, including the following analytical steps:

[0087] (1) Obtain the characteristic fragment ion sequence of the suspected substance in ESI-MS mode: D={D1=56,D2=381,D3=121,D4=98}, m=4;

[0088] (2) Sort sequence D in ascending order to obtain sequence D ′ ={D ′ 1=56,D ′ 2=98,D ′ 3=121,D ′ 4=381}, n=4;

[0089] Determine sequence D ′ The following condition (a) must be met: ;

[0090] (3) Search sequence D ′ The largest fragment with a mass-to-charge ratio less than 107 is D. ′ 2=98, the smallest fragment with a mass-to-charge ratio greater than 107 is D. ′ 3 = 121, meaning i = 2, j = 3;

[0091] (4) If i>0, then solve equation (c): 14x=D ′ i -72=98-72=26;

[0092] If x has no positive integer solutions, then solve the equation (d): 14y=D ′ i -D ′ i-1 =98-56=42;

[0093] If y=3, and there are positive integer solutions, it indicates that R1 and R2 together form a carbon ring with the chemical formula -(CH2)4.

[0094] (5) Solve equation (e):

[0095] ;

[0096] Solving for a and b, we get a = 1 > 0, b = 1, and c, d, e, and f are all 0. This indicates that the side chain R4 contains an alkoxy group, i.e., -OCH3.

[0097] (6) Solve equation (f):

[0098] ;

[0099] Solving for a=0, b=1, c=0, d=0, we get that the side chain R3 is a nitro group, i.e. -NO2, and that no alkylene group is attached to the right side of the parent core.

[0100] Based on the results of R1, R2, R3, and R4, the structure of the suspected object is reconstructed as follows: The suspected substance is metoprin.

[0101] (7) End of analysis.

[0102] Example 2:

[0103] A mass spectrometric fragmentation analysis method for nixacin analogues based on ESI-MS / MS mode, to Figure 5 Taking denitroetenidin as an example, combined with Figure 1 , Figure 2 The present invention will be described in further detail, including the following analytical steps:

[0104] (1) Obtain the characteristic fragment ion sequence of the suspected substance in ESI-MS mode: D={D1=72,D2=100,D3=107,D4=352,D5=135}, m=5;

[0105] (2) Sort sequence D in ascending order to obtain sequence D ′ ={D ′ 1=72,D ′ 2=100,D ′ 3=107,D ′ 4=135,D ′ 5=352}, n=5;

[0106] Determine sequence D ′ The following condition (a) must be met: ;

[0107] (3) Search sequence D ′ The largest fragment with a mass-to-charge ratio less than 107 is D. ′ 2=100, the smallest fragment with a mass-to-charge ratio greater than 107 is D. ′ 4 = 135, which means i = 2 and j = 4;

[0108] (4) If i>0, then solve equation (c): 14x=D ′ i -72=100-72=28;

[0109] Solving for x, we get x=2. Therefore, R1 is an ethyl group with the chemical formula -CH2CH3; R2 is an ethyl group with the chemical formula -CH2CH3.

[0110] (5) Solve equation (e):

[0111] ;

[0112] Solving for a and b, we get a = 2 > 0, b = 1, and c, d, e, and f are all 0. This indicates that the side chain R4 contains an alkoxy group, i.e., -OCH2CH3.

[0113] (6) Solve equation (f):

[0114] ;

[0115] Solving for a=1, b=0, c=0, d=0, we get that the side chain R3 is a hydrogen group, i.e. -H; and the right side of the parent core is not connected to an alkylene group.

[0116] Based on the results of R1, R2, R3, and R4, the structure of the suspected object is reconstructed as follows: The suspected substance is denitroetotenidine.

[0117] (7) End of analysis.

[0118] Example 3:

[0119] A mass spectrometric fragmentation analysis method for nixacin analogues based on ESI-MS / MS mode, to Figure 7 Taking phenethyletophenonezine as an example, combined with Figure 1 , Figure 2 The present invention will be described in further detail, including the following analytical steps:

[0120] (1) Obtain the characteristic fragment ion sequence of the suspected substance in ESI-MS mode: D={D1=72,D2=100,D3=411,D4=338,D5=135}, m=5;

[0121] (2) Sort sequence D in ascending order to obtain sequence D ′ ={D ′ 1=72,D ′ 2=100,D ′ 3=135,D ′ 4=338,D ′ 5=411}, n=5;

[0122] Determine sequence D ′ The following condition (a) must be met: ;

[0123] (3) Search sequence D ′ The largest fragment with a mass-to-charge ratio less than 107 is D. ′ 2=100, the smallest fragment with a mass-to-charge ratio greater than 107 is D. ′3 = 135, which means i = 2, j = 3;

[0124] (4) If i>0, then solve equation (c): 14x=D ′ i -72=100-72=28;

[0125] Solving for x, we get x=2. Therefore, R1 is an ethyl group with the chemical formula -CH2CH3; R2 is an ethyl group with the chemical formula -CH2CH3.

[0126] (5) Solve equation (e):

[0127] ;

[0128] Solving for a and b, we get a = 2 > 0, b = 1, and c, d, e, and f are all 0. This indicates that the side chain R4 contains an alkoxy group, i.e., -OCH2CH3.

[0129] (6) Solve equation (f):

[0130] ;

[0131] Solving for a=0, b=1, c=0, and d=1 indicates that the side chain R3 is a nitro group, i.e., -NO2; and that the right side of the parent core is connected to an alkylene group -CH2-.

[0132] Based on the results of R1, R2, R3, and R4, the structure of the suspected object is reconstructed as follows: The suspected substance is phenethyletotenidine.

[0133] (7) End of analysis.

[0134] Example 4:

[0135] A mass spectrometric fragmentation analysis method for nixacin analogues based on ESI-MS / MS mode, to Figure 9 Taking chlorpheniramine as an example, combined with Figure 1 , Figure 2 The present invention will be described in further detail, including the following analytical steps:

[0136] (1) Obtain the characteristic fragment ion sequence of the suspected substance in ESI-MS mode: D={D1=72,D2=100,D3=387,D4=314,D5=125}, m=5;

[0137] (2) Sort sequence D in ascending order to obtain sequence D ′ ={D ′ 1=72,D ′ 2=100,D ′ 3=125,D ′ 4=314,D ′5=387}, n=5;

[0138] Determine sequence D ′ The following condition (a) must be met: ;

[0139] (3) Search sequence D ′ The largest fragment with a mass-to-charge ratio less than 107 is D. ′ 2=100, the smallest fragment with a mass-to-charge ratio greater than 107 is D. ′ 3 = 125, which means i = 2 and j = 3;

[0140] (4) If i>0, then solve equation (c): 14x=D ′ i -72=100-72=28;

[0141] Solving for x, we get x=2. Therefore, R1 is an ethyl group with the chemical formula -CH2CH3; R2 is an ethyl group with the chemical formula -CH2CH3.

[0142] (5) Solve equation (e):

[0143] ;

[0144] Solving for a, d, and b, c, e, and f, we get a=0, d=1, and b, c, e, and f are all 0, which indicates that the side chain R4 is a chlorine group, i.e., -Cl.

[0145] (6) Solve equation (f):

[0146] ;

[0147] Solving for a=0, b=1, c=0, d=0, we get that the side chain R3 is a nitro group, i.e. -NO2, and there is no alkyl group attached to the right side of the parent core.

[0148] Based on the results of R1, R2, R3, and R4, the structure of the suspected object is reconstructed as follows: The suspected substance is chlorpheniramine.

[0149] (7) End of analysis.

[0150] The parts of this invention not described in detail are prior art and therefore will not be specifically described here.

Claims

1. A mass spectrometric fragmentation and resolution method for nicotin analogs based on ESI-MS / MS mode. The structural formula of the nicotin analog is: Its characteristics are, It includes the following steps: (1) Obtain the characteristic fragment ion sequence D of the suspicious substance under the ESI-MS / MS mode; (2) Sort sequence D in ascending order to obtain sequence D ′ Determine sequence D ′ Fragment D with the highest mass-to-charge ratio ′ n The fragment D with the smallest mass-to-charge ratio ′ 1. Does it meet the criteria for a nitric acid analogue? If it does, proceed to step (3); otherwise, the suspect is considered not to be a nitric acid analogue and proceed to step (7). (3) Search sequence D ′ The largest fragment D with a mass-to-charge ratio less than 107 ′ i And the smallest fragment D with a mass-to-charge ratio greater than 107 ′ j ; (4) Based on the conditions of i and D ′ i By analyzing the mass-to-charge ratio between R1 and R2, the structures of R1 and R2 can be deduced. (5) According to D ′ j Based on the mass-to-charge ratio relationship between R4 and R4, the structure of R4 can be deduced; (6) According to D ′ i D ′ j D ′ n By analyzing the mass-to-charge ratio relationship between R3 and R3, the structure and alkyl length of R3 can be deduced, and the molecular structure of the suspected substance can be reduced. (7) The parsing ends.

2. The mass spectrometry fragmentation and resolution method for nicotinic acid analogs based on ESI-MS / MS mode according to claim 1, characterized in that, In step (1): sequence D = {D1, D2, D3,... D m}, where m is a positive integer greater than 3. For any two fragments D i and D j in sequence D, there is always D i ≠ D j , where 0 < i < j ≤ m, and both i and j are positive integers.

3. The mass spectrometry fragmentation and resolution method for nicotinic acid analogs based on ESI-MS / MS mode according to claim 1, characterized in that, In step (2), sequence D ′ ={D ′ 1, D ′ 2, D ′ 3,... D ′ n}, for any two fragments D ′ in sequence D ′ i and D ′ j , there is always D ′ i > D ′ j , where 0 < i < j ≤ n ≤ m, and both i and j are positive integers.

4. The mass spectrometry fragmentation and resolution method for nicotinic acid analogs based on ESI-MS / MS mode according to claim 1, characterized in that, In step (2), the condition for nizoamine analogues is condition (a): .

5. The mass spectrometry fragmentation and resolution method for nicotinic acid analogs based on ESI-MS / MS mode according to claim 1, characterized in that, In step (3), 0 < i < j ≤ n, and both i and j are positive integers.

6. The mass spectrometric fragmentation and resolution method for nicotinic acid analogs based on ESI-MS / MS mode according to claim 1, characterized in that, Step (4) specifically includes: If i=1, solve equation (b): 14x=D ′ i -56; If x has non-negative integer solutions, it indicates that the chemical formula of R1 is -(CH2). x H; The chemical formula of R2 is -CH2CH3, proceed to step (5); If i > 1, solve equation (c): 14x = D ′ i -72, where x is a non-negative integer; If x has non-negative integer solutions, it indicates that the chemical formula of R1 is -(CH2). x H, R2 has the chemical formula -CH2CH3, proceed to step (5); If x has no non-negative integer solutions, then solve the equation (d): 14y=D ′ i -D ′ i-1 ; If y has positive integer solutions, it indicates that R1 and R2 together form a carbon ring with the chemical formula -(CH2). y+1 Proceed to step (5).

7. The mass spectrometry fragmentation and resolution method for nicotinic acid analogs based on ESI-MS / MS mode according to claim 1, characterized in that, Step (5) specifically includes: according to D ′ j The mass-to-charge ratio relationship between R and R4 is solved by solving equation (e): ； Among them, a, b, c, d, e, and f respectively represent the numbers of alkyl, oxygen (hydroxyl), fluorine, chlorine, bromine, and iodine; a is a non-negative integer, and b, c, d, e, and f are 0 or 1. If it is solved that a = 0 and b = 1, it indicates that the chemical formula of the side chain R4 is -OH; If we find that a > 0 and b = 1, then the chemical formula of side chain R4 is -O(CH2). a-1 CH3; If it is solved that c = 1, it indicates that the chemical formula of the side chain R4 is -F; If it is solved that d = 1, it indicates that the chemical formula of the side chain R4 is -Cl; If it is solved that e = 1, it indicates that the chemical formula of the side chain R4 is -Br; If it is solved that f = 1, it indicates that the chemical formula of the side chain R4 is -I.

8. The mass spectrometric fragmentation and resolution method for nicotinic acid analogs based on ESI-MS / MS mode according to claim 1, characterized in that, Step (6) specifically includes: according to D ′ i D ′ j D ′ n The mass-to-charge ratio relationship between R and R3 is given by solving equation (f): ; Among them, a, b, and c are 0 or 1, and d is a non-negative integer; If it is solved that a = 1, b = 0, and c = 0, it indicates that the chemical formula of the side chain R3 is -H; If it is solved that a = 0, b = 1, and c = 0, it indicates that the chemical formula of the side chain R3 is -NO2; If it is solved that a = 0, b = 0, and c = 1, it indicates that the chemical formula of the side chain R3 is -CN; If the solution yields d≥0, then the link on the right side of the mother nucleus is -(CH2). d -

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