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GB 5009.31-2025: National food safety standard - Determination of p-hydroxybenzoic acid esters in foods Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedure Status: Valid GB 5009.31: Historical versions
Similar standardsGB 5009.31-2025: National food safety standard - Determination of p-hydroxybenzoic acid esters in foods---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GB5009.31-2025 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA National Food Safety Standard - Determination of P- hydroxybenzoic Acid Esters in Foods Issued on: MARCH 16, 2025 Implemented on: SEPTEMBER 16, 2025 Issued by. National Health Commission of the People’s Republic of China; State Administration for Market Regulation. Table of ContentsForeword... 3 1 Scope... 4 Method I - Gas Chromatography... 4 2 Principle... 4 3 Reagents and Materials... 4 4 Instruments and Equipment... 6 5 Analytical Steps... 6 6 Expression of Analysis Results... 8 7 Precision... 9 8 Others... 9 Method II - High Performance Liquid Chromatography... 10 9 Principle... 10 10 Reagents and Materials... 10 11 Instruments and Equipment... 11 12 Analytical Steps... 11 13 Expression of Analysis Results... 13 14 Precision... 14 15 Others... 14 Method III - Liquid Chromatography-tandem Mass Spectrometry... 15 16 Principle... 15 17 Reagents and Materials... 15 18 Instruments and Equipment... 16 19 Analytical Steps... 16 20 Expression of Analytical Results... 20 21 Precision... 21 22 Others... 21 Appendix A Gas Chromatogram of Standard Solution of P-hydroxybenzoic Acid Esters ... 22 Appendix B Liquid Chromatogram of Standard Solution of P-hydroxybenzoic Acid Esters... 23 Appendix C Liquid Chromatography-mass Spectrometry Multiple Reaction Monitoring (MRM) Diagram of Standard Solution of P-hydroxybenzoic Acid Esters ... 24 National Food Safety Standard - Determination of P- hydroxybenzoic Acid Esters in Foods1 ScopeThis Standard specifies the determination method for p-hydroxybenzoic acid esters (methyl paraben, ethyl paraben, propyl paraben, isopropyl paraben, butyl paraben, isobutyl paraben and heptyl 4-hydroxybenzoate) in foods. The first method of this Standard, gas chromatography, is applicable to the determination of p- hydroxybenzoic acid esters in foods (except heat-coagulated egg products, brewed sauce and seasoning sauce). The second method of this Standard, high performance liquid chromatography, and the third method, liquid chromatography-tandem mass spectrometry, are applicable to the determination of p-hydroxybenzoic acid esters in foods. Method I - Gas Chromatography2 PrincipleThe specimen is extracted with methanol-water, purified and enriched by a mixed strong anion exchange solid phase extraction column, and concentrated and then, determined by a gas chromatograph equipped with a hydrogen flame ionization detector, and quantified by the external standard method.3 Reagents and MaterialsUnless otherwise specified, all reagents used in this Method are analytically pure, and the water is Grade-1 water specified in GB/T 6682. 3.1 Reagents 3.1.1 Methanol (CH3OH). 3.1.2 Formic acid (HCOOH). 3.1.3 Concentrated ammonia water (NH3 H2O). 25% ~ 28%. 3.2 Preparation of Reagents 3.2.1 Methanol-water solution (2 + 8). measure-take 100 mL of methanol and 400 mL of water, solutions is 2.0 g/mL, 5.0 g/mL, 10 g/mL, 20 g/mL, 50 g/mL and 100 g/mL. 3.5 Materials 3.5.1 Organic phase microporous filter membrane. with a pore size of 0.22 m. 3.5.2 Mixed strong anion exchange solid phase extraction column. 500 mg/6 mL, or other columns with equivalent performance.4 Instruments and Equipment4.1 Gas chromatograph. equipped with a hydrogen flame ionization detector (FID). 4.2 Electronic balance. respectively with a division value of 0.001 g and 0.0001 g. 4.3 Vortex mixer. 4.4 High-speed centrifuge. maximum speed is not less than 6,000 r/min. 4.5 Ultrasonic oscillator. 4.6 Nitrogen blowing instrument. 4.7 Homogenizer. 4.8 Grinder.5 Analytical Steps5.1 Preparation of Specimens Liquid samples are mixed, semi-solid samples are homogenized with a homogenizer, and solid samples are thoroughly grinded with a grinder and evenly stirred. The prepared specimens are placed in a clean specimen container, sealed and labeled. Liquid specimens are stored at 4 C, and other specimens are stored at 18 C. 5.2 Processing of Specimens 5.2.1 Extraction 5.2.1.1 Fresh fruits, fresh vegetables, baked food fillings and surface batter, vinegar, soy sauce, liquid compound seasoning, etc. Weigh-take 5 g (accurate to 0.01 g) of sample into a 50 mL graduated centrifuge tube, add 5 mL of water, conduct vortex for 3 min, add 10 mL of methanol, conduct vortex for 3 min, conduct ultrasound for 20 min, and at 6,000 r/min, centrifuge it for 3 min. Take all the supernatant into another 50 mL graduated centrifuge tube, add 10 mL of methanol-water solution (2 + 8) to the residue, repeat the extraction once, combine the two extracting solutions, add water to 40 mL, at 6,000 r/min, centrifuge it for 3 min, take all the supernatant for purification. 5.2.1.2 Fruit and vegetable juice, carbonated beverages, flavored beverages, etc. Weigh-take 5 g (accurate to 0.01 g) of specimen into a 50 mL graduated centrifuge tube (carbonated beverages need to be ultrasonically degassed in an ultrasonic cleaner for 10 minutes before weighing), add 30 mL of methanol-water solution (3 + 7), conduct vortex for 3 minutes, and conduct ultrasound for 20 minutes. Then, add methanol-water solution (3 + 7) and reach 40 mL, at 6,000 r/min, centrifuge it for 3 minutes, filter the supernatant, take the filtrate for purification. 5.2.1.3 Jams, etc. Weigh-take 5 g (accurate to 0.01 g) of sample into a 50 mL graduated centrifuge tube, add 5 mL of concentrated ammonia water, conduct vortex for 3 min, let it stand for 1 h; add 10 mL of methanol, conduct vortex for 3 min, conduct ultrasound for 20 min, and at 6,000 r/min, centrifuge it for 3 min. Take all the supernatant into another 50 mL graduated centrifuge tube. Add 10 mL of methanol-water solution (2 + 8) to the residue, conduct vortex for 3 min, conduct ultrasound for 20 min, and at 6,000 r/min, centrifuge it for 3 min. Combine the two extracting solutions, add water to 40 mL, at 6,000 r/min, centrifuge it for 3 min, and take all the supernatant for purification. 5.2.2 Purification Respectively use 5 mL of methanol and 5 mL of water to activate the solid phase extraction column, transfer the solution to be purified into the activated solid phase extraction column, successively use 5 mL of water and 5 mL of methanol-water solution (3 + 7) to rinse it and use 6 mL of methanol to elute it. Use 6 mL of 2% formic acid methanol solution to elute the jam samples, collect the eluate, in a 40 C water bath, use nitrogen to blow it dry. Use 1.0 mL of methanol to re-dissolve it and filter the membrane for the determination by gas chromatograph. 5.3 Reference Conditions of Instruments 5.3.1 Chromatographic column. weak polar quartz capillary column, column stationary liquid is (5%) phenyl-(95%) methyl polysiloxane, 30 m 0.25 mm (inner diameter), 0.25 m (film thickness), or equivalent column. 5.3.2 Inlet temperature. 280 C. 5.3.3 Carrier gas. nitrogen, purity 99.999%; flow rate 1 mL/min, tail blowing 30 mL/min (the flow rate of carrier gas can be adjusted in accordance with the instrument conditions). 5.3.4 Injection volume. 1 L. 5.3.5 Injection mode. split (split ratio can be adjusted in accordance with chromatographic conditions) or splitless injection. 5.3.6 Temperature programming. initial temperature 70 C, hold for 2 min; at 20 C/min, raise to 300 C; hold for 2 min. 5.3.7 Detector. hydrogen flame ionization detector (FID), temperature 300 C. 5.3.8 Gas. hydrogen 35 mL/min; air 400 mL/min (the flow rate of hydrogen and air can be adjusted in accordance with the instrument conditions). 5.4 Drawing of Standard Curve Inject the mixed standard working solution of p-hydroxybenzoic acid esters into the gas chromatograph in order of concentration from low to high. With the mass concentration of the standard solution as the horizontal axis and the peak area as the vertical axis to draw the standard curve. See Figure A.1 of Appendix A for the gas chromatogram of p-hydroxybenzoic acid esters. 5.5 Determination of Specimen Solution 5.5.1 Qualitative determination In accordance with the conditions described in 5.3, respectively inject the mixed standard working solution of p-hydroxybenzoic acid esters and the specimen solution into the gas chromatograph and use the retention time for qualitative determination. Compare the retention time of the chromatographic peak in the specimen solution with the retention time of p- hydroxybenzoic acid esters in the mixed standard working solution, and the allowable deviation shall be less than 0.5%. 5.5.2 Quantitative determination In accordance with the conditions described in 5.3, inject the specimen solution into the gas chromatograph to obtain the peak area of the compound under test. In accordance with the standard curve, obtain the mass concentration of the compound under test in the specimen solution. The response value of the compound under test in the specimen solution shall be within the linear range of the standard curve. If the response value exceeds the linear range of the standard curve, it shall be diluted and re-analyzed. 5.6 Blank Test Except for not adding specimen, handle it at the same time as the specimen in accordance with the steps in 5.2.6 Expression of Analysis ResultsThe content of p-hydroxybenzoic acid esters in the specimen (in terms of 4-hydroxybenzoic acid) is calculated in accordance with Formula (1). Where, Xi---the content of p-hydroxybenzoic acid esters in the specimen (in terms of 4-hydroxybenzoic acid), expressed in (mg/kg); ρ---the mass concentration of p-hydroxybenzoic acid esters in the injection solution calculated from the standard curve, expressed in (g/mL); ρ0---the mass concentration of p-hydroxybenzoic acid esters in the blank test solution calculated from the standard curve, expressed in (g/mL); V---the final constant volume of the test solution, expressed in (mL); m---the mass of the specimen weighed, expressed in (g); 1,000---the unit conversion factor; fi---the conversion factor of p-hydroxybenzoic acid esters to 4-hydroxybenzoic acid. Illustration. 0.9078---the conversion factor of methyl paraben to 4-hydroxybenzoic acid; 0.8312---the conversion factor of ethyl paraben to 4-hydroxybenzoic acid; 0.7665---the conversion factor of propyl paraben and isopropyl paraben to 4-hydroxybenzoic acid; 0.7111---the conversion factor of butyl paraben and isobutyl paraben to 4-hydroxybenzoic acid; 0.5845---the conversion factor of heptyl 4-hydroxybenzoate to 4-hydroxybenzoic acid. The calculation result shall retain 3 significant figures.7 PrecisionThe absolute difference between two independent determination results obtained under repeatability conditions must not exceed 10% of the arithmetic mean.8 OthersWhen the sample weight is 5 g and the constant volume is 1.0 mL, the detection limits of the seven p-hydroxybenzoic acid esters are all 0.6 mg/kg and the quantification limits are all 2 mg/kg. Method II - High Performance Liquid Chromatography9 PrincipleThe specimen is extracted with methanol-water, purified and enriched by a mixed strong anion exchange solid phase extraction column, and determined by a high performance liquid chromatograph equipped with a photodiode array detector or a UV detector, and quantified by the external standard method.10 Reagents and MaterialsUnless otherwise specified, all reagents used in this Method are analytically pure, and the water is Grade-1 water specified in GB/T 6682. 10.1 Reagents 10.1.1 Methanol (CH3OH). chromatographically pure. 10.1.2 Phosphoric acid (H3PO4). 10.1.3 Formic acid (HCOOH). 10.1.4 Concentrated ammonia water (NH3 H2O). 25% ~ 28%. 10.1.5 Acetonitrile (CH3CN). chromatographically pure. 10.2 Preparation of Reagents 10.2.1 Methanol-water solution (3 + 7). same as 3.2.2. 10.2.2 Methanol-water solution (2 + 8). same as 3.2.1. 10.2.3 0.1% phosphoric acid aqueous solution. measure-take 1.0 mL of phosphoric acid, add water to reach a constant volume of 1,000 mL, mix it well and reserve for later use. 10.2.4 2% formic acid methanol solution. same as 3.2.3. 10.3 Standard Substances Same as 3.3. 10.4 Preparation of Standard Solutions 10.4.1 Standard stock solution of p-hydroxybenzoic acid esters (1.00 mg/mL). same as 3.4.1. 10.4.2 Mixed standard intermediate solution of p-hydroxybenzoic acid esters (100 g/mL). same as 3.4.2. 10.4.3 Mixed standard working solution of p-hydroxybenzoic acid esters. respectively pipette 0.02 mL, 0.05 mL, 0.10 mL, 0.20 mL, 0.50 mL, 1.0 mL, 2.0 mL and 5.0 mL of the mixed standard intermediate solution of p-hydroxybenzoic acid esters into a 10 mL volumetric flask, and use methanol-water solution (3 + 7) reach a constant volume to obtain mixed standard working solution respectively with a mass concentration of 0.2 g/mL, 0.5 g/mL, 1.0 g/mL, 2.0 g/mL, 5.0 g/mL, 10 g/mL, 20 g/mL and 50 g/mL. Prepare it immediately before use. 10.5 Materials Same as 3.5.11 Instruments and Equipment11.1 High performance liquid chromatography analyzer. equipped with a photodiode array detector or a UV detector. 11.2 Electronic balance. respectively with a division value of 0.001 g and 0.0001 g. 11.3 Vortex mixer. 11.4 High-speed centrifuge. maximum speed is not less than 6,000 r/min. 11.5 Ultrasonic oscillator. 11.6 Homogenizer. 11.7 Grinder.12 Analytical Steps12.1 Preparation of Specimens Process in accordance with 5.1. 12.2 Processing of Specimens 12.2.1 Extraction 12.2.1.1 Fresh fruits, fresh vegetables, baked food fillings and surface batter, vinegar, soy sauce, brewed sauce, seasoning sauce and liquid compound seasoning, etc. Process in accordance with 5.2.1.1. 12.2.1.2 Fruit and vegetable juice, carbonated beverages and flavored beverages, etc. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. |
