GB/T 5009.81-2003Method for Analysis of Hygienic Standard of Stainless Steel Food Containers and Table Wares (English PDF)

Foreword

This Standard replaces GB/T 11681-1989 "Method for Analysis of Hygienic Standard of Stainless Steel Food containers and Table Wares".

Compared with GB/T 11681-1989, the major changes of this Standard are as follows.

- According to GB/T 20001.4-2001 "Rules for Drafting Standards - Part 4: Methods for Chemical Analysis", the structure of the previous standard is changed.

This Standard was proposed by and shall be under the jurisdiction of the Ministry of Health of the People's Republic of China.

This Standard was responsibly drafted by Shangxi Province Health and Anti-Epidemic Station, and Liaoning Province Food Hygiene Supervision and Inspection Institute.

1 Scope

This Standard specifies the method for the analysis of the hygienic standard of stainless steel food containers and table wares.

This Standard applies to the determination of all hygienic indicators of all kinds of kitchen wares, table wares, food containers, as well as other containers, wares and devices in contact with foods, which are made of the material of stainless steel.

2 Normative References

The provisions in the following documents become the provisions of this Standard through the reference of this Standard. For the dated reference documents, none of their subsequent amendments (excluding corrigendum) or revisions apply to this Standard.

However, all parties who reach an agreement according to this Standard are encouraged to study whether the latest editions of these documents can be applied. For the undated reference documents, their latest editions apply to this Standard.

GB/T 5009.12 Determination of Lead in Foods GB/T 5009.62 Method for Analysis of Hygienic Standard of Ceramics for Food Containers GB/T 5009.72 Method for Analysis of Hygienic Standard of Aluminum-Wares for Food Use

3 Preparation of Samples

5 ML of c(HNO3) = 6 mol/L nitrate to dissolve; transfer to a 1 000 mL volumetric flask; add

water to dilute to the scale mark. This solution contains 1 mg of lead per milliliter.

4.1.2.4 Nickel standard solution. weigh precisely 1.000 0 g of nickel (Ni, 99.99%); add 5 mL of c(HNO3) = 6 mol/L nitric acid to dissolve; transfer to a 1 000 mL volumetric flask; add water to dilute to the mark. This solution contains 1 mg of nickel per milliliter.

4.1.2.5 Standard solutions of chromium, nickel and lead. before use, dilute gradually the standard solutions of chromium, nickel and lead, respectively, to the metal standard working solutions equivalent to 1 µg per milliliter.

4.1.3 Instruments

4.1.3.1 Graphite furnace atomic absorption spectrophotometer.

4.1.3.2 Pyrolytic graphite tube and high purity argon.

4.1.3.3 Trace pipettor.

4.1.4 Analysis steps

4.1.4.1 Preparation of samples and mixed standard series Draw 0.50 mL ~ 1.00 mL of sample soaking solution to place into a 10 mL volumetric flask;

take another six 10 mL volumetric flasks; draw metal standard working solutions respectively. chromium. 0, 0.20, 0.40, 0.60, 0.80 and 1.00 mL, nickel. 0, 0.50, 1.00, 1.50, 2.00 and 2.50 mL; lead. 0, 0.30, 0.60, 0.90, 1.20 and 1.50 mL. Add 1.0 mL of 50 g/L ammonium dihydrogen phosphate solution to the samples and standard tubes; use water to dilute to the scale mark and mix evenly. The metal contents of the standard series prepared are - chromium. 0, 0.20, 0.40, 0.60, 0.80, 1.00 µg; nickel. 0, 0.50, 1.00, 1.50, 2.00 S -- area of sample in contact with soaking solution, in square centimeter (cm2);

2 -- 2 mL of soaking solution per square centimeter, in milliliter per square centimeter (mL/cm2).

4.2 Diphenylcarbazide colorimetry (determination of chromium)

4.2.1 Principle

Use potassium permanganate oxidate low-valent chromium to high-valent chromium (Cr6+);

add sodium pyrophosphate to hide the residual iron; use diphenylcarbazide to produce red complex with chromium; then quantify by comparing with the standard series.

4.2.2 Reagents

4.2.2.1 Sulfuric acid. c (H2SO4) = 2.5 mol/L. Take 70 mL of guaranteed reagent sulfuric acid to add to water while stirring; add water to 500 mL after placing aside for cooling.

4.2.2.2 3 g/L potassium permanganate solution. weigh 0.3 g of potassium permanganate and add water to dissolve to 100 mL.

4.2.2.3 200 g/L urea solution. weigh 20 g of urea and add water to dissolve to 100 mL.

4.2.2.4 100 g/L sodium nitrite solution. weigh 10 g of sodium nitrite and add water to dissolve to 100 mL.

4.2.2.5 Saturated sodium hydroxide solution.

4.2.2.6 50 g/L sodium pyrophosphate solution. weigh 5 g of sodium pyrophosphate (Na4P 2O7 - 10H2O) and add water to dissolve to 100 mL.

4.2.2.7 Diphenylcarbazide solution. weigh 0.5 g of diphenylcarbazide to dissolve in 50 mL of acetone; add 50 mL of water; prepare immediately prior to use; store in a brown bottle.

If the color of the solution becomes dark, it shall not be used.

4.2.2.8 Chromium standard solution. the preparation method is the same as 4.1.2.2; the concentration of the working solution is 10 µg of chromium per milliliter.

4.2.3 Instruments

4.2.3.1 Spectrophotometer and 3 cm cuvettes.

4.2.3.2 25 mL stoppered cuvettes.

4.2.4 Analysis steps

4.2.4.1 Draw standard curves Draw 0, 0.25, 0.50, 1.00, 1.50, 2.00, 2.50 and 3.00mL of chromium standard working 4.3.2.1 100 g/L ammonium citrate dibasic solution. weigh 10 g of ammonium citrate dibasic [(NH4)2HC6H5O7] to dissolve in water to 100 mL.

4.3.2.2 10 g/L dimethylglyoxime-ethanol solution. weigh 1 g of dimethylglyoxime [(CH3)2C2 (NOH) 2] to dissolve in ethanol [95% (volume fraction)] to 100 mL; filter if any insoluble matter; prepare the filtrate for use.

4.3.2.3 10 g/L alkaline dimethylglyoxime solution. weigh 1 g of dimethylglyoxime to dissolve in c (NaOH) = 0.2 mol/L sodium hydroxide solution to 100 mL.

4.3.2.4 Hydrochloric acid. c (HCI) = 0.5 mol/L.

4.3.2.5 4% (volume fraction) acetic acid.

4.3.2.6 Ammonia. c (NH4OH) = 5 mol/L.

4.3.2.7 Ammonia. c (NH4OH) = 2 mol/L.

4.3.2.8 Ammonia. c (NH4OH) = 0.3 mol/L.

4.3.2.9 20% (volume fraction) sodium hydroxide solution.

4.3.2.10 Nickel standard solution. the preparation method is the same as 4.1.2.4; the concentration of the working solution is equivalent to 10 µg of nickel per milliliter.

4.3.3 Instruments

4.3.3.1 Spectrophotometer and 1 cm cuvettes.

4.3.3.2 25 mL stoppered cuvettes.

4.3.3.3 125 mL and 60 mL separating funnels.

4.3.4 Analysis steps

4.3.4.1 Draw standard curves Draw 0, 0.25, 0.50, 1.00, 2.00, 3.00, 4.00 and 5.00 mL of nickel standard working solution;

add 4% acetic acid to 100 mL; transfer to 125 mL separating funnels; operate hereunder same as the operation of the samples; draw standard curves by taking the absorbance as ordinate and the standard concentration as abscissa.

4.3.4.2 Determination Take 100 mL of sample soaking solution; add 20% sodium hydroxide solution to adjust to neutral or weak alkalinity; place aside for 2 h; filter then transfer the filtrate to a 125 mL separating funnel; add 2 mL of ammonium citrate dibasic; add several drops of 2 mol/L ammonia to adjust the pH value of the solution to 8~9.Add 2 mL of dimethylglyoxime ethanol solution; add 10 mL of chloroform; shake vigorously for 1 min; stand then separate ......