GB 5009.235-2016 PDF EnglishUS$90.00 · In stock · Download in 9 seconds
GB 5009.235-2016: National food safety standard - Determination of Amino Acid Nitrogen 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
Similar standardsGB 5009.235-2016: National food safety standard - Determination of Amino Acid Nitrogen 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/GB5009.235-2016GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA National Food Safety Standard - Determination of Amino Acid Nitrogen in Foods ISSUED ON: AUGUST 31, 2016 IMPLEMENTED ON: MARCH 01, 2017 Issued by: National Health and Family Planning Commission of the PRC Table of ContentsForeword ...3 1 Scope ...4 2 Principle ...4 3 Reagents and materials ...4 4 Instruments and apparatuses ...6 5 Analysis steps ...6 6 Description of the analysis result ...7 7 Precision ...7 8 Principle ...8 9 Reagents and materials ...8 10 Instruments and apparatuses ...9 11 Analysis steps ...9 12 Description of the analysis result ... 10 13 Precision ... 10 14 Others ... 10 National Food Safety Standard - Determination of Amino Acid Nitrogen in Foods1 ScopeThis Standard specifies the method for determination of amino acid nitrogen in soy sauce, grain paste and soybean paste. Method 1 of this Standard applies to the determination of amino acid nitrogen in soy sauce which is brewed or prepared from grain and its by-products such as bean cake and bran, sauce which is made from grain, AND soybean paste products which are made from soybean and wheat flour. Method 2 applies to the determination of amino acid nitrogen in soy sauce which is brewed or prepared from grain and its by-products such as bean cake and bran. Method 1 - PH meter2 PrincipleUse the amphoteric effect of amino acid; add formaldehyde to fix the basicity of the amino group and to make the carboxyl group acidic; use sodium hydroxide standard solution to titrate and fix-volume; use the pH meter to determine the end.3 Reagents and materialsUnless otherwise specified, all the reagents in this method are analytical reagents, the water is grade-3 water that is specified by GB/T 6682. 3.1 Reagents 3.1.1 Formaldehyde (36%~38%): it shall not contain polymer (no precipitation and no stratification of the solution). 3.1.2 Sodium hydroxide (NaOH). 3.1.3 Phenolphthalein (C20H14O4). 3.1.4 Ethanol (CH3CH2OH). 3.1.5 Potassium hydrogen phthalate (HOOCC6H4COOH): reference material.4 Instruments and apparatuses4.1 PH meter (with magnetic stirrer). 4.2 10 mL micro-basic burette. 4.3 Analytical balance: the sensitivity is 0.1mg.5 Analysis steps5.1 Soy sauce sample Weigh 5.0 g of sample into a 50 mL beaker; use water to wash it into a 100 mL volumetric flask for several times; add water to the scale; mix and take 20.0 mL into a 200 mL beaker; add 60 mL of water; turn on the magnetic stirrer; use sodium hydroxide standard solution [c(NaOH) = 0.050 mol/L] to titrate until the pH meter indicates a pH of 8.2; record the number of milliliters of the sodium hydroxide standard titration solution which is consumed to calculate the total acid content. Add 10.0 mL of formaldehyde solution and mix. Use sodium hydroxide standard titration solution to further titrate until the pH reaches 9.2; record the number of milliliters of the sodium hydroxide standard titration solution which is consumed. At the same time, take 80 mL of water; firstly, use sodium hydroxide standard solution [c(NaOH) = 0.050 mol/L] to adjust to pH 8.2; then add 10.0 mL of formaldehyde solution; use sodium hydroxide standard titration solution to titrate to pH 9.2; do a reagent blank test. 5.2 Grain paste and soybean paste samples Evenly stir the grain paste or soybean paste sample; place it in a mortar, and rapidly ground it to a state that no visible particles are seen in 10 minutes; place it in a grinding bottle for use. Use a weighing bottle of a known weight to weigh 5.0 g of the sample which is evenly stirred; use 50 mL of distilled water at about 80°C to wash it into a 100 mL beaker for several times; cool it, and transfer it to a 100 mL volumetric flask; use a small amount of water to wash the beaker for several times; merge the cleaning mixture into a volumetric flask; add water to the scale; mix and filter. Pipette 10.0 mL of filtrate; place it in a 200 mL beaker; add 60 mL of water; turn on the magnetic stirrer; use sodium hydroxide standard solution [c(NaOH) = 0.050 mol/L] to titrate until the pH meter indicates pH 8.2; record the number of milliliters of sodium hydroxide standard titration solution that is consumed, so as to calculate the total acid content. Add 10.0 mL of formaldehyde solution and mix. Use sodium hydroxide standard titration solution to further titrate until the pH reaches 9.2; record the number of milliliters of the sodium hydroxide standard titration solution which is consumed. At the same time, take 80 mL of water; firstly, use sodium hydroxide standard solution [c(NaOH) = 0.050 mol/L] to adjust to pH 8.2; then add 10.0 mL of formaldehyde solution; use sodium hydroxide standard titration solution to titrate to pH 9.2; do a reagent blank test. Every milliliter of the solution is equivalent to 1.0 mg of ammonia-nitrogen (it can be stably stored in the refrigerator below 10°C for more than 1 year). 9.3.2 Ammonia-nitrogen standard working solution (0.1 g/L): use a pipette to accurately measure 10 mL of ammonia-nitrogen standard stock solution (1.0 mg/mL) in a 100 mL volumetric flask; add water to dilute to the scale; mix. Every milliliter of this solution is equivalent to 100 μg of ammonia-nitrogen (it can be stably stored in the refrigerator below 10°C for 1 month).10 Instruments and apparatuses10.1 Spectrophotometry. 10.2 Electric constant-temperature water bath (100°C ± 0.5°C). 10.3 10 mL glass colorimetric tube with a plug.11 Analysis steps11.1 Sample pretreatment Weigh 1.00 g of sample into a 50 mL volumetric flask; add water to dilute to the scale; mix well. 11.2 Preparation of the standard curve Accurately extract 0 mL, 0.05 mL, 0.1 mL, 0.2 mL, 0.4 mL, 0.6 mL, 0.8 mL, 1.0 mL of ammonia-nitrogen standard working solution (equivalent to 0 μg, 5.0 μg, 10.0 μg, 20.0 μg, 40.0 μg, 60.0 μg, 80.0 μg, 100.0 μg of NH3-N) into a 10 mL colorimetric tube respectively. Add 4 mL of sodium acetate-acetic acid buffer solution (pH 4.8) and 4 mL of color developer to each colorimetric tube; use water to dilute to the scale; mix well. Place it in a water bath at 100°C to heat for 15 min; then take it out; after it is cooled to room temperature in the water bath, transfer it to a 1 cm cuvette; use a zero-tube as the reference; measure the absorbance at a wavelength of 400 nm; draw the standard curve or calculate the linear regression equation. 11.3 Determination of the sample Accurately extract 2 mL of sample dilution solution into a 10 mL colorimetric tube. Add 4 mL of sodium acetate-acetic acid buffer solution (pH 4.8) and 4 mL of color developer; use water to dilute to the scale; mix well. Place it in a water bath at 100°C to heat for 15 min; then take it out; after it is cooled to room temperature in the water bath, transfer it to a 1 cm cuvette; use a zero tube as the reference; measure the absorbance at a wavelength of 400 nm. Compare the sample absorbance with the standard curve quantitatively or substitute it into the linear regression equation to calculate the sample ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of English version of GB 5009.235-2016 be delivered?Answer: The full copy PDF of English version of GB 5009.235-2016 can be downloaded in 9 seconds, and it will also be emailed to you in 9 seconds (double mechanisms to ensure the delivery reliably), with PDF-invoice.Question 2: Can I share the purchased PDF of GB 5009.235-2016_English with my colleagues?Answer: Yes. The purchased PDF of GB 5009.235-2016_English will be deemed to be sold to your employer/organization who actually paid for it, including your colleagues and your employer's intranet.Question 3: Does the price include tax/VAT?Answer: Yes. Our tax invoice, downloaded/delivered in 9 seconds, includes all tax/VAT and complies with 100+ countries' tax regulations (tax exempted in 100+ countries) -- See Avoidance of Double Taxation Agreements (DTAs): List of DTAs signed between Singapore and 100+ countriesQuestion 4: Do you accept my currency other than USD?Answer: Yes. www.ChineseStandard.us -- GB 5009.235-2016 -- Click this link and select your country/currency to pay, the exact amount in your currency will be printed on the invoice. Full PDF will also be downloaded/emailed in 9 seconds.How to buy and download a true PDF of English version of GB 5009.235-2016?A step-by-step guide to download PDF of GB 5009.235-2016_EnglishStep 1: Visit website https://www.ChineseStandard.net (Pay in USD), or https://www.ChineseStandard.us (Pay in any currencies such as Euro, KRW, JPY, AUD).Step 2: Search keyword "GB 5009.235-2016". Step 3: Click "Add to Cart". If multiple PDFs are required, repeat steps 2 and 3 to add up to 12 PDFs to cart. Step 4: Select payment option (Via payment agents Stripe or PayPal). Step 5: Customize Tax Invoice -- Fill up your email etc. Step 6: Click "Checkout". Step 7: Make payment by credit card, PayPal, Google Pay etc. After the payment is completed and in 9 seconds, you will receive 2 emails attached with the purchased PDFs and PDF-invoice, respectively. Step 8: Optional -- Go to download PDF. Step 9: Optional -- Click Open/Download PDF to download PDFs and invoice. See screenshots for above steps: Steps 1~3 Steps 4~6 Step 7 Step 8 Step 9 |
