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GB 31656.7-2021: National food safety standard - Determination of niclosamide residues in aquatic products by liquid chromatography-tandem mass spectrometry
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| GB 31656.7-2021 | English | 139 |
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National food safety standard - Determination of niclosamide residues in aquatic products by liquid chromatography-tandem mass spectrometry
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GB 31656.7-2021
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Basic data | Standard ID | GB 31656.7-2021 (GB31656.7-2021) | | Description (Translated English) | National food safety standard - Determination of niclosamide residues in aquatic products by liquid chromatography-tandem mass spectrometry | | Sector / Industry | National Standard | | Classification of Chinese Standard | X20 | | Word Count Estimation | 7,786 | | Issuing agency(ies) | National Health Commission of the People's Republic of China, State Administration for Market Regulation | GB 31656.7-2021: National food safety standard - Determination of niclosamide residues in aquatic products by liquid chromatography-tandem mass spectrometry
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National food safety standards
Determination of niclosamide residues in aquatic products
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
This document complies with the provisions of GB/T 1:1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents"
Drafting:
This document is published for the first time:
National food safety standards
Determination of niclosamide residues in aquatic products by liquid chromatography-tandem mass spectrometry
1 Scope
This document specifies the sample preparation and liquid chromatography-tandem mass spectrometry determination methods for the detection of niclosamide residues in aquatic products:
This document is suitable for the detection of niclosamide residues in edible tissues of fish, shrimp, turtle and other aquatic products:
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
GB/T 30891-2014 Sampling specifications for aquatic products
3 Terms and definitions
There are no terms or definitions that need to be defined in this document:
4 Principles
The remaining niclosamide in the sample was extracted with ammoniated acetonitrile, purified with C18 adsorbent, detected by liquid chromatography-tandem mass spectrometer, and quantified by the external standard method:
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:
5Reagents 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 Acetonitrile (C₂H₃N): chromatographically pure:
5:1:2 Ammonia (NHa·H₂O):
5:1:3 Anhydrous magnesium sulfate (MgSO₄):
5:2 Solution preparation
5:2:1 Ammonia solution: Take 5mL of ammonia, add 5mL of water, and mix well:
5:2:2 Ammoniated acetonitrile solution: Take 100 μL of ammonia solution, add acetonitrile to 100mL, and mix well:
5:2:3 70% acetonitrile aqueous solution: Take 70mL of acetonitrile, add 30mL of water, and mix well:
5:3 Standard products
Niclosamide (Niclosamide, C13 H8 Cl2 N2 O4, CAS number: 50G 65G 7), content ≥96:0%:
5:4 Preparation of standard solution
5:4:1 Standard stock solution (0:1 mg/mL): Take 10 mg of niclosamide standard, weigh it accurately, add 10 mL of acetonitrile, dissolve it with ultrasound, and dissolve it with acetonitrile:
Dilute nitrile to a 100mL brown volumetric flask, shake well, and get it: - Store below 18 ℃, valid for 2 months:
5:4:2 Standard working solution (1 μg/mL): Accurately measure 1 mL of the standard stock solution, put it into a 100 mL brown volumetric flask, and dilute it with acetonitrile to
Temperature, shake well, and it is ready: - Store below 18 ℃, valid for 1 month:
5:5 Materials
C18 adsorbent: particle size 40 μm~ 60 μm, or equivalent:
6 Instruments and equipment
6:1 Liquid chromatography-tandem mass spectrometer: equipped with electrospray ion source (ESI):
6:2 Analytical balance: sensitivity 0:01g and sensitivity 0:00001g:
6:3 Centrifuge: 8000r/min or above:
6:4 Vortex mixer:
6:5 Ultrasonic cleaning instrument:
6:6 Nitrogen blower:
6:7 Stoppered polypropylene centrifuge tube: 50mL:
6:8 Stoppered centrifuge tubes: 10mL, 25mL:
7: Preparation and preservation of samples
7:1 Preparation of samples
Prepare samples according to the requirements of Appendix B in GB/T 30891-2014:
a) Take a homogeneous test sample as a test material;
b) Take a homogeneous blank sample as a blank sample;
c) Take a homogeneous blank sample, add 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
Take 5g of the sample (accurate to ±0:02g), put it into a 50mL centrifuge tube with a stopper, add 10mL of ammoniated acetonitrile solution, vortex and mix for 1 minute, and supernatate:
Sonicate for 10 minutes, add 3g of anhydrous magnesium sulfate, vortex and mix for 1 minute, centrifuge at 5000r/min for 5 minutes, take the supernatant and transfer it to a 25mL volumetric flask, repeat the extraction of the residue with 10mL of ammoniated acetonitrile, combine the supernatants, and dilute with acetonitrile Dilute to volume, mix, and set aside:
8:2 Purification
Accurately measure 5 mL of the above reserve solution into a 10 mL centrifuge tube, blow dry with nitrogen at 45°C, and dissolve with 1:0 mL of 70% acetonitrile aqueous solution:
The residue was then added with 50 mg of C18 adsorbent, vortexed for 30 s, centrifuged at 8000 r/min for 6 min, and the supernatant was passed through a 0:22 μm organic filter membrane for LC-MS/MS measurement:
8:3 Preparation of matrix matching standard curve
Take 6 blank samples, extract according to step 7:1, and accurately measure 5 μL, 10 μL, 25 μL, 50 μL, niclosamide standard working solution:
Add 100 μL and:200 μL to 6 blank sample extracts respectively, purify according to step 8:2, take the supernatant, and prepare niclosamide concentrations of 0:5ng/mL, 1ng/mL, 2:5ng/mL, A series of matrix-matched standard solutions of 5ng/mL, 10ng/mL, and 20ng/mL were filtered and used for LC-MS/MS determination: Using the measured niclosamide quantitative ion peak area as the ordinate and the corresponding concentration as the abscissa, draw Matrix standard curve: Find regression equation and correlation coefficient:
8:4 Determination
8:4:1 Liquid chromatography reference conditions
a) Chromatographic column: C18 (150mm × 2:1mm, 5μm), or equivalent;
b) Column temperature: 35℃;
c) Flow rate: 0:2mL/min;
d) Injection volume: 10μL;
e) Mobile phase: A is acetonitrile, B is water, and the gradient elution procedure is shown in Table 1:
8:4:2 Mass spectrometry reference conditions
a) Ionization mode: electrospray ion source (ESI), negative ion mode;
b) Spray voltage: 2500V;
c) Sheath gas pressure: 40L/min;
d) Auxiliary air pressure: 5L/min;
e) Ion transfer tube temperature: 330℃;
f) Scan mode: Selected Reaction Monitoring (SRM): Selected reaction monitoring precursor ions, product ions and collision energies are shown in Table 2;
8:4:3 Determination method
Take the sample solution and the matrix-matched standard solution, conduct single-point or multi-point calibration, quantify the chromatographic peak area, and calculate by the external standard method: The sample solution and
The characteristic ion mass chromatographic peak areas of niclosamide in the matrix-matched standard solution should be within the linear range of instrument detection: Chlorine in the sample solution
The ratio of the retention time of nitlosamide to the retention time of niclosamide in the matrix-matched standard working solution is within ±2:5%: In the sample solution
Compared with the relative ion abundance in the matrix-matched standard solution, the relative ion abundance meets the requirements of Table 3: The characteristic ion mass of the standard solution
See Appendix A for the chromatogram:
8:4:4 Blank test
Take a blank sample and perform parallel operations using the same measurement steps except that no standard solution is added:
9 Calculation and presentation of results
The residual amount of niclosamide 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 this method is 0:2μg/kg, and the quantitation limit is 0:5μg/kg:
10:2 Accuracy
The recovery rate of this method at the added concentration level of 0:5μg/kg~20μg/kg is 70%~110%:
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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