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GB 31656.17-2022: (National Food Safety Standard - Determination of Dithiocyanomethane Residues in Aquatic Products by Gas Chromatography)
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(National Food Safety Standard - Determination of Dithiocyanomethane Residues in Aquatic Products by Gas Chromatography)
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GB 31656.17-2022
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Basic data | Standard ID | GB 31656.17-2022 (GB31656.17-2022) | | Description (Translated English) | (National Food Safety Standard - Determination of Dithiocyanomethane Residues in Aquatic Products by Gas Chromatography) | | Sector / Industry | National Standard | | Classification of Chinese Standard | X04 | | Word Count Estimation | 8,863 | | 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 31656.17-2022: (National Food Safety Standard - Determination of Dithiocyanomethane Residues in Aquatic Products by Gas Chromatography)
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National Health Commission of the People's Republic of China
National Food Safety Standards
Determination of residues of dithiocyanomethane in aquatic products
gas chromatography
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 Dithiocyanomethane Residues in Aquatic Products by Gas Chromatography
1 Scope
This document specifies the sample preparation and gas chromatography determination methods for the determination of dithiocyanomethane residues in aquatic products.
This document is applicable to the determination of dithiocyanomethane residues in edible tissues of fish, shrimp, crab, turtle and other aquatic products.
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
GB/T 30891-2014 Sampling Specifications for Aquatic Products
3 Terms and Definitions
This document does not have terms and definitions that need to be defined.
4 principles
The remaining dithiocyanomethane in the sample was extracted with a mixture of dichloromethane and n-hexane, degreased, purified by a neutral alumina solid-phase extraction column, and gas
Determined by phase chromatography and quantified by external standard method.
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 Acetonitrile (CH3CN). chromatographically pure.
5.1.2 Methanol (CH3OH). chromatographically pure.
5.1.3 n-Hexane (C6H14). chromatographically pure.
5.1.4 Dichloromethane (CH2Cl2). chromatographically pure.
5.1.5 Acetone (CH3COCH3). chromatographically pure.
5.1.6 Anhydrous sodium sulfate (Na2SO4).
5.2 Solution preparation
Dichloromethane-n-hexane (1.1, V/V). take 250mL of dichloromethane and n-hexane respectively, and mix well.
5.3 Standards
Methylenebisthiocyanate (Methylenebisthiocyanate, C3H2N2S2, CAS number. 6317-18-6), content ≥99%.
5.4 Preparation of standard solution
5.4.1 Standard stock solution. Accurately weigh 10mg of dithiocyanomethane standard substance, dissolve it with an appropriate amount of acetonitrile and dilute to 50mL brown
The volumetric flask was prepared into a standard stock solution with a concentration of.200 μg/mL. Stored below -18°C, the validity period was 3 months.
5.4.2 Standard working solution. Accurately measure an appropriate amount of dithiocyanomethane standard stock solution, dilute it with dichloromethane, and prepare a concentration of
0.05μg/mL, 0.1μg/mL, 0.5μg/mL, 1.0μg/mL, 2.0μg/mL, 5.0μg/mL and 10.0μg/mL series standards
Working fluid. Ready to use.
5.5 Materials
Neutral alumina solid phase extraction column, packing 60mg/3mL, or equivalent.
6 Instruments and equipment
6.1 Gas chromatograph equipped with pulsed flame photometric (PFPD) detector.
6.2 Homogenizer.
6.3 Rotary evaporator.
6.4 Centrifuge.
6.5 Vortex mixer.
6.6 Analytical balance. Sensitivity 0.00001g and 0.01g.
6.7 Nitrogen blowing instrument.
7 Preparation and storage of samples
7.1 Preparation of samples
Prepare samples according to the requirements of Appendix B of GB/T 30891-2014.
a) Take the homogenized test sample as the test material;
b) Take the homogenized blank sample as the blank sample;
c) Take the homogenized blank sample, add the standard working solution of appropriate concentration, and add the sample as the blank.
7.2 Storage of samples
Store frozen below -18°C.
8 Measurement steps
8.1 Extraction
Take 5g of the sample (accurate to ±0.05g), put it in a 50mL stoppered glass centrifuge tube, add dichloromethane-n-hexane (1.1, V/V)
15 mL, immediately vortexed for 1 min, ultrasonically extracted for 10 min, centrifuged at 4000 r/min for 5 min, and the supernatant was taken into a chicken heart bottle with a glass dropper.
Repeat the extraction once, combine the supernatants of the two times, mix well, and blow nitrogen at 40°C to 0.5mL-1.0mL, and set aside.
8.2 Purification and concentration
Take a neutral alumina solid-phase extraction column, add 1.0 g of anhydrous sodium sulfate to the upper layer, pass the spare liquid through the column and collect it, and use dichloromethane-n-hexane
(1.1, V/V) 2.0 mL washes 8.1 chicken heart bottles containing the extract, passes through the column, and collects them in 15 mL glass test tubes, and then washes them with dichloromethane.
8mL eluted small column, and collected in the same glass test tube, dried with nitrogen at 40°C, added dichloromethane-n-hexane (1.1, V/V) 1.0mL, vortexed
1 min to make it completely dissolved, and then used for gas chromatograph determination.
8.3 Preparation of standard curve
Precisely measure the appropriate amount of standard working solution for gas chromatography determination. Take the measured peak area as the ordinate, and the corresponding standard solution concentration as the abscissa
Coordinates, draw a standard curve. Find the regression equation and correlation coefficient.
8.4 Determination
8.4.1 Chromatographic conditions
a) Chromatographic column. HP-5MS quartz capillary column (30m×0.32mm, particle size 0.25μm), or equivalent;
b) Injection method. splitless injection;
c) Carrier gas. nitrogen, purity 99.999%;
d) Column flow rate. 1.0mL/min;
e) The inlet temperature is 230°C, and the detector temperature is 310°C;
f) Column temperature program. the initial column temperature is 50°C, keep for 1min, raise the temperature to 180°C at 25°C/min, and keep for 2min;
g) Injection volume. 1.0 μL.
8.4.2 Determination method
Take the sample solution and the corresponding standard solution for single-point or multi-point calibration, and calculate the peak area according to the external standard method. The standard solution and the sample solution
The response value of dithiocyanatomethane in the liquid should be within the linear range of the instrument detection. Under the above chromatographic conditions, the gas chromatogram of the standard solution is shown in the attached
Record A.
8.4.3 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 the analyte 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 5 μg/kg, and the quantification limit was 10 μg/kg.
10.2 Accuracy
The recovery rate of this method was 60%-110% at the spiked concentration level of 10 μg/kg-500 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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