GB 31658.23-2022 English PDF

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GB 31658.23-2022: (National food safety standards-Determination of nitroimidazole drug residues in animal foods-liquid chromatography-tandem mass spectrometry)
Status: Valid

Standard ID	USD	BUY PDF	Lead-Days	Standard Title (Description)	Status
GB 31658.23-2022	219	Add to Cart	3 days	(National food safety standards-Determination of nitroimidazole drug residues in animal foods-liquid chromatography-tandem mass spectrometry)	Valid

Similar standards

GB 31650.1   GB/T 37517   GB/T 30636   GB 31658.20   GB 31658.21   GB 31658.19   

Basic data

Standard ID: GB 31658.23-2022 (GB31658.23-2022)
Description (Translated English): (National food safety standards-Determination of nitroimidazole drug residues in animal foods-liquid chromatography-tandem mass spectrometry)
Sector / Industry: National Standard
Classification of Chinese Standard: X04
Word Count Estimation: 11,120
Date of Issue: 2022-09-20
Date of Implementation: 2023-02-01
Issuing agency(ies): National Health Commission of the People's Republic of China, State Administration for Market Regulation

GB 31658.23-2022: (National food safety standards-Determination of nitroimidazole drug residues in animal foods-liquid chromatography-tandem mass spectrometry)

---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
National Health Commission of the People's Republic of China National food safety standard Nitrate in animal food Determination of residues of imidazoles Liquid Chromatography-Tandem Mass Spectrometry National Standards of People's Republic of China release State Administration for Market Regulation Ministry of Agriculture and Rural Affairs of the People's Republic of China

foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for Standardization Work Part 1.Structure and Drafting Rules for Standardization Documents" drafting. This document is published for the first time. National Food Safety Standards Determination of nitroimidazole drug residues in animal food Liquid chromatography-tandem mass spectrometry

1 Scope

This document specifies the sample preparation and liquid chromatography for the detection of metronidazole, hydroxymetronidazole, demetonidazole and hydroxydemenidazole residues in food of animal origin. Chromatography-tandem mass spectrometry method. This document applies to the muscle, liver and kidney tissue of pigs, cattle, sheep and chickens for metronidazole, hydroxymetronidazole, demetonidazole and hydroxydemetrazol Determination of azole residues.

2 Normative references

The content in the following documents constitutes the essential provisions of this document through normative references in the text. Among them, the dated reference documents, Only the version corresponding to the date applies to this document; for undated references, the latest version (including all amendments) applies to this document document. GB/T 6682 Analytical laboratory water specifications and test methods

3 Terms and Definitions

This document does not have terms and definitions that need to be defined.

4 principles

The residual nitroimidazoles in the sample were extracted with ethyl acetate, degreased by n-hexane liquid-liquid extraction, purified by solid-phase extraction column, and liquid chromatography-serial. Mass spectrometry was used for detection, and matrix-matched internal standard method was used for quantification.

5 Reagents and materials

Unless otherwise specified, all reagents are of analytical grade, and the water is first-class water in accordance with GB/T 6682. 5.1 Reagents 5.1.1 Ethyl acetate (C4H8O2). chromatographically pure. 5.1.2 Acetonitrile (CH3CN). chromatographically pure. 5.1.3 Methanol (CH3OH). chromatographically pure. 5.1.4 n-Hexane (C6H14). chromatographically pure. 5.1.5 Formic acid (HCOOH). chromatographically pure. 5.1.6 Ammonia (NH3.H2O). 5.1.7 Hydrochloric acid (HCl). 5.2 Solution preparation 5.2.11 0.1mol/L hydrochloric acid solution. take 8.3mL of concentrated hydrochloric acid, add water to dilute to 1L, and mix well. 5.2.2 2% ammonia solution. Take 2mL of ammonia water, dilute it with water to 100mL, mix well, and prepare immediately. 5.2.3 Eluent. Take 80 mL of methanol, add 15 mL of water and 5 mL of ammonia water, mix well, and prepare immediately after use. 5.2.4 0.1% formic acid aqueous solution. Take 500 mL of water, add 500 μL of formic acid, and mix well. 5.2.5 0.1% formic acid in acetonitrile solution. take 500 mL of acetonitrile, add 500 μL of formic acid, and mix well. 5.3 Standards Metronidazole, demetonidazole, hydroxymetronidazole, hydroxydemetronidazole, metronidazole-D3, demetronidazole-D3, hydroxymetronidazole-D2, hydroxydemetronidazole azole-D3, the contents were ≥95%. See Appendix A for details. 5.4 Preparation of standard solution 5.4.1 Standard stock solution. take an appropriate amount of metronidazole, demetonidazole, hydroxymetronidazole, and hydroxydemenidazole standard (equivalent to 10mg), accurately weighed, dissolved in methanol and diluted to volume in a 10mL volumetric flask to prepare metronidazole and demetrazol with a concentration of 1mg/mL azole, hydroxymetronidazole and hydroxydemenidazole standard stock solutions. Stored below -18 ℃, valid for 6 months. 5.4.2 Internal standard stock solution. Take an appropriate amount of standard substances of metronidazole-D3, demetonidazole-D3, hydroxymetronidazole-D2 and hydroxydemetrinidazole-D3 (equivalent to 10 mg of each active ingredient), accurately weighed, dissolved in methanol and diluted to a volume in a 10 mL volumetric flask, to prepare methylnitrate with a concentration of 1 mg/mL azole-D3, demetonidazole-D3, hydroxymetronidazole-D2 and hydroxymetronidazole-D3 internal standard stock solutions. Stored below -18 ℃, valid for 6 months. 5.4.3 10μg/mL mixed standard working solution. Accurately measure 0.1mL of each standard stock solution into a 10mL volumetric flask, dilute with methanol to the mark, and prepared into a mixed standard working solution with a concentration of 10 μg/mL. Stored below -18°C, the validity period is 6 months. 5.4.4 1μg/mL mixed standard working solution. accurately measure 10μg/mL mixed standard working solution 1mL into a 10mL volumetric flask, Diluted with alcohol to the mark, and prepared a mixed standard working solution with a concentration of 1 μg/mL. Stored below -18°C, the validity period was 3 months. 5.4.5 0.1μg/mL mixed standard working solution. accurately measure 1mL of 1μg/mL mixed standard working solution into a 10mL volumetric flask, Diluted with alcohol to the mark, and prepared a mixed standard working solution with a concentration of 0.1 μg/mL. Stored below -18°C, the validity period was 1 month. 5.4.6 10 μg/mL mixed internal standard working solution. Accurately measure 0.1 mL of each internal standard stock solution into a 10 mL volumetric flask, dilute with methanol To the mark, it was prepared into a mixed internal standard working solution with a concentration of 10 μg/mL. Stored below -18°C, the validity period was 6 months. 5.4.7 1 μg/mL mixed internal standard working solution. accurately measure 1 mL of 10 μg/mL internal standard working solution in a 10 mL volumetric flask, dilute with methanol The mixture was released to the mark, and prepared into a mixed internal standard working solution with a concentration of 1 μg/mL. Stored below -18°C, the validity period was 3 months. 5.5 Materials 5.5.1 Mixed strong cation exchange reversed-phase solid-phase extraction column. 60mg/3mL, or equivalent. 5.5.2 Microporous membrane. 0.2 μm, water phase.

6 Instruments and equipment

6.1 Liquid chromatography-tandem mass spectrometer. with electrospray ion source. 6.2 Analytical balance. Sensitivity 0.00001g and 0.01g. 6.3 Nitrogen blowing instrument. 6.4 Vortex mixer. 6.5 Centrifuge. 6.6 Tissue homogenizer. 6.7 Solid phase extraction device.

7 Preparation and storage of samples

7.1 Preparation of samples Take an appropriate amount of fresh or thawed blank or test tissue, mince it, and homogenize it. a) Take the homogenized test sample as the test sample; b) Take the homogenized blank sample as the blank sample; c) Take the homogenized blank sample, add a standard solution of appropriate concentration, and add the sample as a blank. 7.2 Storage of samples Store below -18°C.

8 Measurement steps

8.1 Extraction Weigh 2g of the sample (accurate to ±0.05g), put it in a 50mL plastic centrifuge tube, add 10μL of 1μg/mL mixed internal standard working solution, and vortex for 30s Mix well and let stand for 10min. Add 15mL of ethyl acetate, vortex for 2min, and centrifuge at 10000r/min for 5min. Take the supernatant in another 50mL centrifuge Add 15 mL of ethyl acetate to the residue, repeat the extraction once, combine the two extracts, and dry them in a water bath with nitrogen at 25 °C. 8.2 Purification Add 5 mL of 0.1 mol/L hydrochloric acid solution to the residue, vortex for 1 min to fully dissolve, add 5 mL of n-hexane, shake for 1 min, 5000 r/min Centrifuge for 5 min, discard the n-hexane layer. Add 5 mL of n-hexane to the lower layer and repeat degreasing once, discard the n-hexane layer, and set aside. The solid-phase extraction column was activated successively with 2 mL of methanol and 2 mL of 0.1 mol/L hydrochloric acid solution, and the spare liquid was passed through the column, followed by 0.1 mol/L hydrochloric acid solution. Rinse with 2 mL of hydrochloric acid solution, 1 mL of methanol and 1 mL of 2% ammonia water, and elute with 2 mL of eluent. After drying, 0.5 mL of water was added to the residue, vortexed for 1 min, filtered through a filter membrane, and determined by liquid chromatography-tandem mass spectrometry. 8.3 Preparation of matrix-matched standard curve Take the extracted and purified blank sample solution, add an appropriate amount of mixed standard working solution and 10 μL of 1 μg/mL mixed internal standard working solution, Blow dry with nitrogen in a water bath at 35°C, add 0.5 mL of water and vortex for 1 min to prepare the concentration of 2 μg/L, 4 μg/L, 20 μg/L, 40 μg/L,.200 μg/L Matched standard solution with 400 μg/L matrix, filtered and used for liquid chromatography-tandem mass spectrometry determination. The measured nitroimidazoles were compared with the corresponding The ratio of the characteristic ion peak area of the internal standard is the ordinate, and the concentration of the standard solution is the abscissa, draw the standard curve, and find the regression equation and correlation coefficient. 8.4 Determination 8.4.1 Reference conditions for liquid chromatography a) Chromatographic column. C18 chromatographic column (50mm×2.1mm, 1.7μm) or equivalent; b) Mobile phase. A is 0.1% formic acid aqueous solution, B is 0.1% formic acid acetonitrile solution, the gradient elution program is shown in Table 1; c) Flow rate. 0.3mL/min; d) Column temperature. 30°C; e) Injection volume. 10 μL. 8.4.2 Reference conditions for mass spectrometry a) Ion source. Electrospray (ESI) ion source; b) Scanning mode. positive ion scanning; c) Detection method. multiple reaction monitoring; d) Spray voltage. 3000V; e) Atomization temperature. 350°C; f) Source temperature. 100°C; g) Cone gas flow rate. 30L/h; h) Atomized gas flow rate. 600L/h; i) Refer to Table 2 for the reference values of the qualitative ion pair, quantitative ion pair, cone voltage and collision energy of the drug to be tested. 8.4.3 Assay 8.4.3.1 Qualitative determination Under the same test conditions, the retention time of nitroimidazoles in the sample solution matches that of the nitroimidazoles in the standard working solution. The ratio of the retention time of the substance, the deviation is within ±2.5%, and the relative ion abundance detected should match the standard solution of the matrix with the same concentration. The relative abundance of ions is consistent. The allowable deviation should meet the requirements of Table 3. 8.4.3.2 Quantitative determination Take the sample solution and matrix matching standard working solution for single-point or multi-point calibration, and quantify according to the internal standard method. Matrix matching standard working solution and sample The response values of the target substances in the solution should be within the linear range of instrument detection. Under the above conditions of chromatography-mass spectrometry, the characteristic ion mass of the standard solution For chromatograms see Appendix B. 8.5 Blank test Take the blank sample, except that no drug is added, the same measurement steps are used for parallel operation.

9 Calculation and presentation of results

The residual amount of nitroimidazoles in the sample was calculated according to the standard curve or formula (1). 10 Method sensitivity, accuracy and precision 10.1 Sensitivity The detection limit of this method was 0.5 μg/kg, and the limit of quantification was 1 μg/kg. 10.2 Accuracy The recovery rate of this method was 60%-120% at the spiked concentration level of 1 μg/kg-10 μg/kg. 10.3 Precision In this method, the relative standard deviation within the batch was ≤20%, and the relative standard deviation between batches was ≤20%. ......

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