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GB 31659.1-2021: National food safety standard--Determination of xylazine residue in milk by liquid chromatography -tandem mass spectrometric method
Status: Valid
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National food safety standard--Determination of xylazine residue in milk by liquid chromatography -tandem mass spectrometric method
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GB 31659.1-2021
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Basic data | Standard ID | GB 31659.1-2021 (GB31659.1-2021) | | Description (Translated English) | National food safety standard--Determination of xylazine residue in milk by liquid chromatography -tandem mass spectrometric method | | Sector / Industry | National Standard | | Classification of Chinese Standard | X16 | | Classification of International Standard | 67.100 | | Word Count Estimation | 12,139 | | Date of Issue | 2021-09-16 | | Date of Implementation | 2022-02-01 | | Issuing agency(ies) | National Health Commission of the People's Republic of China, State Administration for Market Regulation | | Summary | This standard specifies the sample preparation and liquid chromatography tandem mass spectrometry method for the detection of xylazine residues in milk. This standard applies to the qualitative and quantitative detection of xylazine residues in milk. | GB 31659.1-2021: National food safety standard--Determination of xylazine residue in milk by liquid chromatography -tandem mass spectrometric method
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National food safety standards
Determination of xylazine residues in milk
Liquid chromatography-tandem mass spectrometry
National Standards of People's Republic of China
Released by the National Health Commission of the People's Republic of China
State Administration for Market Regulation
Ministry of Agriculture and Rural Affairs of the People's Republic of China
Foreword
This document is drafted in accordance with the provisions of GB/T 1:1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents":
This document is published for the first time:
1 Scope
This document specifies the sample preparation and liquid chromatography-tandem mass spectrometry determination methods for the detection of xylazine residues in milk:
This document is suitable for the qualitative and quantitative detection of xylazine residues in milk:
2 Normative reference documents
The contents of the following documents constitute essential provisions of this document through normative citations in the text: Among them, the cited documents with dates are:
Only the version corresponding to the date applies to this document; for undated referenced documents, the latest version (including all amendments) applies to this document:
document:
GB/T 6682 Specifications and test methods for water used in analytical laboratories
3 Terms and definitions
There are no terms or definitions that need to be defined in this document:
4 Principles
The residual xylazine in milk was extracted with acetonitrile and protein precipitated, purified with a solid phase extraction column, measured by liquid chromatography-tandem mass spectrometry, and matrix matched:
Quantification by external standard method with standard solution:
5 Reagents and materials
Unless otherwise specified, all reagents are of analytical grade and the water is first-grade water that complies with GB/T 6682:
5:1 Reagents
5:1:1 Methanol (CH3OH): chromatographically pure:
5:1:2 Acetonitrile (CH3CN): chromatographically pure:
5:1:3 Concentrated ammonia (NH3:H2O):
5:1:4 Formic acid (HCOOH):
5:2 Preparation of solution
5:2:1 2% formic acid in methanol solution: Take 2mL of formic acid, add methanol to dilute to 100mL, mix well, and get it:
5:2:2 0:5% ammonia solution: Take 0:5 mL of concentrated ammonia solution, add water to dilute to 100 mL, mix well, and it is ready:
5:2:3 20% acetonitrile solution: Take:200mL of acetonitrile, add water to dilute to 1000mL, mix well, and it is ready:
5:2:4 Mobile phase A: 0:1% formic acid in acetonitrile solution: Take 0:1 mL of formic acid, add acetonitrile to dilute to 100 mL, and mix well:
5:2:5 Mobile phase B: 0:1% formic acid solution: Take 0:1mL of formic acid, add water to dilute to 100mL, mix well, and get it:
5:3 Standard products
Xylazine (C12H16N2S, CAS number: 7361-61G7), content ≥ 98:0%:
5:4 Preparation of standard solutions
5:4:1 Standard stock solution (1mg/mL): Take about 10mg of xylazine standard, weigh it accurately, dissolve it in acetonitrile and dilute it to a 10mL volumetric flask, shake it well, and store it below -18℃: The validity period 3 months:
5:4:2 Standard intermediate solution (10 μg/mL): Precisely measure 100 μL of the above standard stock solution, put it into a 10 mL volumetric flask, add acetonitrile to dilute to the mark, shake well, and get it: Store at 2℃~8℃, valid period 1 months:
5:4:3 Standard working solution (100ng/mL): Precisely measure 100μL of the above standard intermediate solution, put it into a 10mL volumetric flask, add 20% acetonitrile solution to dilute to the mark, shake well, and store at 2℃~8℃ , valid for 1 month:
5:5 Materials
5:5:1 Solid phase extraction column: HLB (60mg/3mL), or equivalent:
5:5:2 Microporous filter membrane: 0:22μm:
6 Instruments and equipment
6:1 Liquid chromatography-tandem mass spectrometer: equipped with electrospray ion source:
6:2 Balance: sensitivity 0:01g:
6:3 Analytical balance: sensitivity 0:00001g:
6:4 Vortex mixer:
6:5 Oscillator:
6:6 Centrifuge:
6:7 Nitrogen blower:
6:8 Ultrasonic instrument:
7: Preparation and preservation of samples
7:1 Preparation of samples
Sample preparation includes:
a) Take the mixed test sample as the test material;
b) Take the mixed blank sample as the blank sample;
c) Take the mixed blank sample, add the standard working solution of appropriate concentration, and add the sample as a blank:
7:2 Storage of samples
Store below -18℃:
8 Measurement steps
8:1 Extraction
Weigh 2 (±0:02) g of the sample, add 8 mL of acetonitrile, vortex and mix for 20 s, oscillate and extract for 5 min, centrifuge at 8000 r/min for 5 min at 5°C, put the supernatant into a 10mL centrifuge tube, and concentrate in a 40°C water bath under nitrogen flow: to less than 2 mL, add 4 mL of 0:5% ammonia solution, vortex to mix, and set aside:
8:2 Purification
Activate the solid phase extraction column with 3 mL of methanol, 3 mL of water, and 3 mL of 0:5% ammonia solution in sequence: Pass all the reserve solution through the column and add 3 mL of water:
Rinse, vacuum dry, and elute with 3 mL of 2% formic acid in methanol solution: Dry the eluate with nitrogen in a 40°C water bath, add 0:5 mL of 20% acetonitrile solution to the residue, vortex, and dissolve with ultrasonic for 5 min: After filtration through a 0:2 μm filter membrane, it was analyzed by liquid chromatography-tandem mass spectrometer:
8:3 Preparation of matrix matching standard curve
Precisely measure an appropriate amount of standard working solution and dilute it with 20% acetonitrile solution to 0:5ng/mL, 1:0ng/mL, 2:0ng/mL,
A series of working solutions of 5:0ng/mL, 10ng/mL, 20ng/mL, and 50ng/mL: After the blank milk sample was extracted, purified, and dried with nitrogen, it was dissolved in 0:5mL of the above series of standard working solutions to make a series of Concentration matrix matching standard solution: Use liquid chromatography-tandem mass spectrometry
For measurement, take the characteristic ion mass chromatographic peak area of the analyte as the ordinate and the concentration of the matrix-matched standard solution as the abscissa, draw a standard working curve, and calculate the linear equation and regression coefficient:
8:4 Determination
8:4:1 Liquid chromatography reference conditions
a) Chromatographic column: C18 chromatographic column (50mm×2:1mm, 1:7μm) or equivalent;
GB 31659:1-2021
b) Mobile phase: A is 0:1% formic acid acetonitrile solution, B is 0:1% formic acid solution;
c) Flow rate: 0:3mL/min;
d) Injection volume: 10μL;
e) Column temperature: 30℃;
f) Mobile phase gradient elution program: 0min~2:5min, phase A changes linearly from 5% to 50%; 2:5min~3min, maintain phase A
The proportion is 100%; 3min~4:5min, keep the proportion of phase A at 5%:
8:4:2 Tandem mass spectrometry reference conditions
a) Ion source: electrospray ion source;
b) Scanning method: positive ion scanning
c) Detection method: multiple reaction monitoring (MRM);
d) The reference values of qualitative ion pairs, quantitative ion pairs, cone voltage and collision energy are shown in Table 1:
8:4:3 Determination
The retention time of the drug to be tested in the sample solution is within ±2:5% of the retention time of the drug to be tested in the matrix-matched standard solution:
Compared with the relative ion abundance in the matrix-matched standard solution, the relative ion abundance should meet the requirements of Table 2:
8:5 Blank test
Take a blank sample and perform the measurement using exactly the same measurement steps except that no drug is added:
9 Calculation and presentation of results
The residual amount of xylazine in the sample is calculated according to the standard curve or formula (1):
10 Sensitivity, accuracy and precision of detection methods
10:1 Sensitivity
The detection limit of xylazine in milk is 0:2 μg/kg, and the limit of quantification is 0:5 μg/kg:
10:2 Accuracy
This method has a recovery rate of 70% to 120% within the added concentration range of 0:5μg/kg~5μg/kg:
10:3 Precision
The intra-batch relative standard deviation of this method is ≤15%, and the inter-batch relative standard deviation is ≤20%:
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