GB 31657.1-2021National food safety standard - Determination of Tau-fluvalinate residue in honey and royal jelly by gas chromatography method (English PDF)

Foreword

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:

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National food safety standards

Determination of fluvalinate residues in honey and royal jelly by gas chromatography

1 Scope

This document specifies the sample preparation and gas chromatographic determination methods for the detection of fluvalinate residues in honey and royal jelly:

This document is applicable to the determination of fluvalinate residues in honey and royal jelly:

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 remaining fluvalinate in the sample was dissolved in water, extracted with n-hexane-acetone solution, and purified with a Florisil solid-phase extraction column, using the configuration

Determination by gas chromatography with electron capture detector and quantification by 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:

5:1 Reagents

5:1:1 Acetone (CH3COCH3): chromatographically pure:

5:1:2 n-hexane (C6H14): chromatographically pure:

5:2 Solution preparation

5:2:1 n-hexane-acetone solution (1:1): Take equal volumes of n-hexane and acetone and mix well:

5:2:2 n-hexane-acetone solution (95:5): Take 5mL of acetone and 95mL of n-hexane and mix well:

5:3 Standard products

Fluvalinate (tau-fluvalinate, C26H22ClF3N2O3, CAS number: 102851-06-9): content >= 98:0%:

5:4 Preparation of standard solution

5:4:1 Standard stock solution: Take 10 mg of fluvalinate reference substance, weigh it accurately, dissolve it with n-hexane and dilute it to a volume of 100 mL:

bottle, prepare a standard stock solution with a concentration of 100 µg/mL: Store at 0°C ~ 5°C, and is valid for 6 months:

5:4:2 Standard working solution: Precisely measure an appropriate amount of standard stock solution, dilute it with n-hexane, and prepare a concentration of 10 µg/L, 20 µg/L,

50µg/L, 100µg/L,:200µg/L and 500µg/L series standard working solutions: Ready for use:

5:5 Materials

Florisil solid phase extraction column: 1g/6mL, or equivalent:

6 Instruments and equipment

6:1 Gas chromatograph: equipped with electron capture detector:

6:2 Analytical balance: sensitivity 0:00001g and 0:01g:

6:3 Vortex mixer:

6: Centrifuge:

6:5 Rotary evaporator:

6:6 Solid phase extraction device:

6:7 Nitrogen blower:

7: Preparation and preservation of samples

7:1 Preparation of samples

Honey: Stir the test sample evenly; for crystallized samples, place them in a water bath not exceeding 60°C to dissolve them in a sealed state, and stir

Mix evenly and quickly cool to room temperature: Separate about 150g as a sample, place it in a sample bottle, seal it, and mark it:

Royal jelly: Stir the test sample evenly; for frozen test samples, stir evenly after thawing completely at room temperature: Separate about 150g:

As a test material, place it in a sample bottle, seal it, and mark it:

7:2 Preservation of samples

Honey: Store at room temperature:

Royal jelly: Store below -18 degrees C:

8 Measurement steps

8:1 Extraction

Take 5g of honey (accurate to +/-0:02g) [2g of royal jelly (accurate to +/-0:02g)], put it into a 50mL stoppered polypropylene centrifuge tube, and add water

10 mL, vortex and mix for 1 min to dissolve: Add 20 mL of n-hexane-acetone solution (1:1), vortex for 3 min, and centrifuge at 3000 r/min for 5 min:

Take the upper layer into a 150 mL chicken heart bottle: Repeat the extraction once with 20 mL of n-hexane-acetone solution (1:1), combine the upper layers, and decompress in a 40°C water bath:

Concentrate to nearly dryness, add 3 mL of n-hexane to dissolve, and set aside:

8:2 Purification

The Florisil solid-phase extraction column was activated with n-hexane-acetone solution (95:5) and 5 mL of n-hexane in sequence: Pass the reserve solution through the column, and then use normal hexane:

Wash the chicken heart bottle with 3 mL of hexane, pass the washing liquid through the column, and discard this part of the effluent: Elute with 10 mL of n-hexane-acetone solution (95:5), and collect the washing liquid:

Deliquidate, blow to dryness with nitrogen in a 40°C water bath, redissolve with 1:0 mL of n-hexane, and use for gas chromatography measurement:

8:3 Preparation of standard working curve

Accurately draw an appropriate amount of fluvalinate standard working solution and inject samples respectively: Take the concentration of the standard working solution as the abscissa and the peak area as the vertical axis:

mark and draw the standard working curve:

8: Measurement

8:4:1 Gas Chromatography Reference Conditions

a) Chromatographic column: VFＧ1MS (100% dimethylpolysiloxane) quartz capillary column (30mx0:0:25mmx0:025m), or equivalent

By;

b) Carrier gas: nitrogen, purity >=99:999%;

c) Inlet temperature: 280 degrees C;

d) Detector temperature: 300 degrees C;

e) Column temperature: initial temperature is 80°C, hold for 1 minute, increase temperature to:200°C at 30°C/min, hold for 1 minute, and then increase temperature at 10°C/min:

to 280 degrees C, keep for 6 minutes;

f) Carrier gas flow rate: 1:0mL/min;

g) Injection volume: 1µL;

h) Injection method: Splitless injection, open the split valve after 1 minute:

8:4:2 Measurement method

Take the sample solution and the corresponding standard solution, perform single-point or multi-point calibration, quantify it based on the chromatographic peak area, and calculate it according to the external standard method: The standard solution and

The response value of fluvalinate in the sample solution should be within the linear range of the instrument detection: Under the above chromatographic conditions, the chromatogram of the standard solution is shown in the attachment:

Record A:

8:5 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 the test substance 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 limits of fluvalinate in honey and royal jelly in this standard method are 2 µg/kg and 4 µg/kg respectively:

In this standard method, the quantification limits of fluvalinate in honey and royal jelly are 5 µg/kg and 10 µg/kg respectively:

10:2 Accuracy

The recovery rate of fluvalinate in honey at the addition level of 5 µg/kg~100 µg/kg is 70%~120%:

The recovery rate of fluvalinate in royal jelly at the addition level of 10 µg/kg to 100 µg/kg is 70% to 120%:

10:3 Precision

The intra-batch relative standard deviation of this method is <=20%, and the inter-batch relative standard deviation is <=20%: