CN-122017064-A - Oxidized triglyceride mass spectrometry analysis method based on thermal oxidation reaction mechanism and mass spectrometry fragmentation rule prediction spectrum library

CN122017064ACN 122017064 ACN122017064 ACN 122017064ACN-122017064-A

Abstract

The invention relates to the technical field of food chemistry, and particularly discloses a mass spectrometry analysis method of oxidized triglyceride based on a thermal oxidation reaction mechanism and mass spectrometry fragmentation rule prediction spectrum library, which comprises the following steps of P1 constructing possible oxidized acyl chains based on an oxidation mechanism of unsaturated fatty acid type and different double bond sites of molecules in common vegetable oil, predicting the molecular structure of the oxidized triglyceride according to the composition of the acyl chains and Cartesian product, calculating molecular formula, molecular mass and adduct ion mass of the oxidized triglyceride, P2 calculating mass spectrometry collision induced dissociation core fragments according to the general rule of different types of the oxidized triglyceride, constructing a primary and secondary prediction spectrum library of the oxidized triglyceride, P3 acquiring sample data based on a non-targeted liquid chromatography-mass spectrometry, and P4 annotating and identifying oxidized triglyceride molecules in a vegetable oil sample.

Inventors

WEI FANG
QIN ZUOJIAN
LV XIN
WANG DAN
CHEN HONG

Assignees

中国农业科学院油料作物研究所

Dates

Publication Date: 20260512
Application Date: 20260130

Claims (5)

1. The method for mass spectrometry analysis of oxidized triglyceride based on a thermal oxidation reaction mechanism and mass spectrometry fragmentation rule prediction spectrum library is characterized by comprising the following steps of: P1, constructing a possible oxidized acyl chain based on an oxidation mechanism of unsaturated fatty acid type and different double bond sites of molecules in common vegetable oil, predicting the molecular structure of oxidized triglyceride according to the combination of the acyl chain composition of the oxidized triglyceride and Cartesian product of the oxidized triglyceride, and calculating molecular formula, molecular mass and adduct ion mass ([ M+NH4] + ) of the oxidized triglyceride; p2, calculating mass spectrum collision induced dissociation core fragments according to the general rules of different types of oxidized triglyceride, and constructing a primary and a secondary prediction spectrum library of the oxidized triglyceride; P3, collecting sample data based on non-targeted liquid chromatography-mass spectrometry; and P4, carrying out annotation identification on oxidized triglyceride molecules in the vegetable oil sample, namely carrying out matching and secondary spectrum similarity calculation on the oxidized triglyceride molecules in the sample by utilizing the predicted oxidized triglyceride molecular mass, the adduct mass and the secondary prediction spectrum library in the step 2) so as to realize the structural annotation of the oxidized triglyceride molecules.
2. The method for mass spectrometry analysis of oxidized triglyceride based on thermal oxidation reaction mechanism and mass spectrometry fragmentation rule prediction spectrum library according to claim 1, wherein in the step P1, the fatty acid acyl chain oxidation mechanism comprises free radical chain reaction, peroxidation, epoxidation, beta cleavage and dehydration reaction, and the unsaturated fatty acid acyl chain type comprises palmitoleic acid with carbon atom 16, double bond 1, double bond position omega-7, oleic acid with carbon atom 18, double bond 1, double bond position omega-9, linoleic acid with carbon atom 18, double bond 2, double bond position omega-6, carbon atom 20, double bond 1, and eicosenoic acid with double bond position omega-9.
3. The method according to claim 1, wherein in the step P2, the library of oxidized triglyceride fragmentation patterns predicted based on mass spectrometry collision induced dissociation cleavage comprises fragments characterized by the formation of diglyceride fragments [ M-R 1 COOH] + 、[M-R 2 COOH] + 、[M-R 3 COOH] + ] by neutral loss of acyl chains in oxidized triglycerides, and acyl chain fragment [R 1 COOH-H 2 O] + 、[R 2 COOH-H 2 O] + 、[R 3 COOH-H 2 O] + ; adduct deamination fragments [ M+NH 4 -17] + .
4. The method for mass spectrometry of oxidized triglycerides based on thermal oxidation reaction mechanism and mass spectrometry fragmentation rule prediction spectrum library according to claim 1, characterized in that in step P3, the chromatographic conditions and the mass spectrometry conditions are as follows: the chromatographic elution condition is that a C18 chromatographic column is adopted, a mobile phase A is a mixed solution of water, methanol and acetonitrile in a volume ratio of 1:1, a mobile phase B is a mixed solution of isopropanol and acetonitrile in a volume ratio of 5:1, and 5mM ammonium acetate is respectively added; Chromatographic elution procedure, initial fluidity B of 20% B, 0.5min for 0.5min-1.5min mobile phase B linearly increasing to 40% B, mobile phase B of 1.5 min-2 min to mobile phase 60%, mobile phase of 2 min-10 min linearly increasing to 95%, mobile phase B of 13 min decreasing to 20% B; in the mass spectrum condition, an electrospray mass spectrum positive ion mode is adopted, the mass-to-charge ratio mass scanning range is 200-1200, MS2 adopts a dependent acquisition mode, and 15 candidate high-abundance precursor ions are preferably selected for each scanning interval to trigger the acquisition of a secondary spectrogram.
5. The method for mass spectrometry analysis of oxidized triglyceride based on the prediction spectrum library of the thermal oxidation reaction mechanism and the mass spectrometry fragmentation rule according to claim 4, wherein a C18 chromatographic column is used in the chromatography analysis, the length of the filler is 100mm, the inner diameter is 2.1mm, the flow rate is 0.4 mL/min, the column temperature is 60 ℃, and the sample injection amount is 3ul.

Description

Oxidized triglyceride mass spectrometry analysis method based on thermal oxidation reaction mechanism and mass spectrometry fragmentation rule prediction spectrum library Technical Field The invention relates to the technical field of food chemistry, in particular to a mass spectrometry analysis method for oxidized triglyceride based on a thermal oxidation reaction mechanism and mass spectrometry fragmentation rule prediction spectrum library. Background The edible oil undergoes thermal oxidation during the thermal processing/cooking process, resulting in complex oxidation products, wherein the oxidized triglycerides are primary oxidation products during the thermal oxidation of the edible oil and are also important oxidation intermediates, and analysis of the oxidized triglycerides can be used to monitor the oxidation degree and safety of the edible oil. Oxidized triglycerides are cytotoxic and tend to affect human health as a result of the ingestion of fats and oils, and therefore analysis of oxidized triglycerides in edible oils has received considerable attention from researchers. Oxidized triglycerides are very complex in type and structure due to their oxidation of all three fatty acyl chains. Oxidized triglycerides mainly include hydroxyl groups, peroxidic hydroxyl groups, epoxy groups, ketone groups, and groups containing polyoxidative groups. Currently, the detection means of oxidized triglyceride molecules mainly adopt liquid chromatography mass spectrometry, and the separation of chromatography and the structural analysis capability of mass spectrometry enable researchers to accurately analyze oxidized triglyceride in different oil samples. Oxidized triglycerides are unstable, commercially available standards are very limited, and there is no comprehensive secondary mass spectrometry database of oxidized triglycerides, resulting in analysis and identification of oxidized triglycerides in edible oils becoming a challenge. Disclosure of Invention In order to solve the problems mentioned in the background art, the invention aims to provide an oxidized triglyceride mass spectrometry analysis method based on a thermal oxidation reaction mechanism and a mass spectrometry fragmentation rule prediction spectrum library. In order to achieve the above object, the technical scheme of the present invention is as follows: The method for mass spectrometry analysis of oxidized triglyceride based on a thermal oxidation reaction mechanism and mass spectrometry fragmentation rule prediction spectrum library comprises the following steps: P1, according to the general rule and oxidation mechanism of unsaturated oxidized fatty acid thermal oxidation, 1) unsaturated double bond side alpha carbon is easy to generate hydrogen extraction reaction to combine oxygen to generate peroxidized hydroxyl fatty acid, the peroxidized hydroxyl generates dehydration reaction to generate ketone-based fatty acid, the peroxidized hydroxyl provides hydroxyl, double bond alpha carbon provides hydrogen atom, dehydration is performed to form epoxy-based fatty acid, and 2) fatty acid containing oxidation group generates beta cracking to generate short-chain alkane and broken fatty acid structure. Based on the combination of the reaction mechanism and the Cartesian product of the oxidized triglyceride, the molecular structure of the oxidized triglyceride is predicted, and the molecular formula, the molecular mass and the information of the adduct ion mass of the oxidized triglyceride are calculated. And P2, calculating mass spectrum collision induced dissociation core fragments according to the general rules of different types of oxidized triglyceride, and constructing a primary and secondary prediction spectrum library of the oxidized triglyceride. P3, performing chromatographic-mass spectrometry non-targeted analysis on the oxidized vegetable oil sample. And P4, matching the oxidized triglyceride in the sample and calculating the secondary spectrum similarity by using the predicted molecular mass of the oxidized triglyceride, the adduct mass and the predicted secondary spectrum library, so as to realize the structural annotation of the oxidized triglyceride molecules. Further, in the step P1, the fatty acid acyl chain oxidation mechanism comprises free radical chain reaction, peroxidation, epoxidation, beta cracking, dehydration reaction and the like, and the unsaturated fatty acid acyl chain type comprises palmitoleic acid with 16 carbon atoms, 1 double bond and omega-7 double bond positions, oleic acid with 18 carbon atoms, 1 double bond and omega-9 double bond positions, linoleic acid with 18 carbon atoms, 2 double bond and omega-6 double bond positions, 20 carbon atoms, 1 double bond and omega-9 double bond positions. Further, in step P2, the prediction spectrum library based on the fragmentation law of the oxidized triglyceride of the mass spectrum collision induced dissociation cleavage comprises characteristic fragments, namely digl