Translated English of Chinese Standard: GB7917.2-1987 (GB/T7917.2-87) www.chinesestandard.net Sales@ChineseStandard.net NATIONAL STANDARD OF THE GB UDC 668.58:543.062 C 51 PEOPLE S REPUBLIC OF CHINA GB 7917.2-87 (GB/T 7917.2-87) Standard Methods of Hygienic Test for Cosmetics Arsenic 化妆品卫生化学标准检验方法砷 Issued on: May 28, 1987 Implemented on: October 1, 1987 Issued by: Ministry of Health of PRC www.chinesestandard.net Page 1 of 10
Table of Contents 1 Silver Diethyldithiocarbamate Spectrophotometric Method... 3 2 Arsenic Stain Method... 7 Additional Information:... 10 www.chinesestandard.net Page 2 of 10
Standard Methods of Hygienic Test for Cosmetics Arsenic This Standard is applicable to the determination of total arsenic in cosmetics. The minimum detectable limit of the two specified methods is 0.5µg arsenic; if take 1g of sample to determine, minimum detectable concentration is 0.5ppm. 1 Silver Diethyldithiocarbamate Spectrophotometric Method 1.1 Method summary After ashing or digesting of sample, by the action of potassium iodide and stannous chloride, the pentavalent arsenic in the sample solution is reduced into trivalent. The trivalent arsenic and nascent hydrogen generates hydrogen arsenide gas. Remove the interference of hydrogen sulfide by the cotton dipped into the lead acetate solution, then react with silver diethyldithiocarbamate soluble into triethanolamine-chloroform, and generate brown red colloidal silver, then perform colorimetric analysis. The following elements may interfere the generation of hydrogen arsenide, such as cobalt, nickel, mercury, silver, platinum, chromium and molybdenum; but under normal circumstances, their content in the cosmetics shall not generate the interference. Antimony has significant interference with the determination. 1.2 Collection of sample See Chapter 2 in GB 7917.1-87 Standard Methods of Hygienic Test for Cosmetics Mercury. 1.3 Reagents 1.3.1 The deionized water or water with the same purity: pure the primary distilled water through ion-exchange water purifier, and store in the full glass bottle or polyethylene bottle. NOTE: such water is used during the preparation, purification and analysis of the reagent. 1.3.2 Nitric acid (density 1.42g/ml), analytically pure. www.chinesestandard.net Page 3 of 10
glass balls. Then add 5ml of water and 10~15ml of nitric acid (1.3.2), stand for a moment; slowly heating; after the beginning of reaction, remove the heat source; cooling off, add 5ml of sulfuric acid (1.3.3), continue heating. If during the digesting period, the solution turns to brown, add a little of nitric acid to digest; repeat for several times till the solution is clear or light-yellow. After standing and cooling off, add 20ml of water, continue heating and boiling till white smoke is produced. Treat for twice in such a way, move quantitative digestive solution into the 50ml volumetric flask; add water to make constant volume, and store for backup. Every 10ml of such solution contains sulfuric acid (1+1) of 2ml. 1.5.1.2 Dry ashing method Weigh 1.00~2.00g of specimen mixed thoroughly, place it into 50ml porcelain evaporating dish, meanwhile do the reagent blank; add 10ml of 10% magnesium nitrate solution (1.3.9)1, 1g of magnesium oxide (1.3.8) powder; mix the specimen and ashing aid thoroughly; evaporate moisture on the water bath; then charring on the small fire till there is no smoke, move into the box-shaped electric furnace; ashing for 4h at 600 C, cool off and take out; add a little water to ash, make it wet; then add 20ml of hydrochloric acid (1+1) (1.3.10) for several times to dissolve ash and clean evaporating dish. Add water to make constant volume 50ml, store for backup. Every 10ml of such solution contains 2.0ml of hydrochloric acid (1+1) (excluding the neutralized consumption). 1.5.2 Determination Take 0, 0.50, 1.00, 2.00, 4.00, 6.00, 8.00, 10.0ml of standard arsenic solution (1.3.20), appropriate amount of sample solution (1.5.1.1 or 1.5.1.2) and blank solution; place them into the hydrogen arsenide generating bottle, respectively. If the sample is treated by wet digestion method (1.5.1.1), add sulfuric acid to make the total amount of acid equivalent to 10ml of sulfuric acid (1+1); if the sample is treated by dry ashing method (1.5.1.2), add hydrochloric acid (1+1) to make the total amount of acid equivalent to 10ml. Then add water till the total volume is 50ml. Add 2.5ml of 15% potassium iodide solution (1.3.11) and 2.0ml of 40% stannous chloride solution (1.3.12), respectively, shake evenly. After standing for 10min, add 3~5g zinc particles (1.3.13); immediately connect to the air duct with lead acetate cotton plug; and insert it into the absorption tube added 5.0ml of silver diethyldithiocarbamate solution (1.3.12). React for 1h at the room temperature (25 C). 1 After the completion of reaction, if the volume of absorption liquid is reduced, supplement with chloroform to 5.0ml. Move partial absorption liquid into 1cm cuvette, 1 The sample contains a lot oil and wax shall be modified into 1g magnesium nitrate solid. www.chinesestandard.net Page 6 of 10
amount of sample solution (2.5.1.1 or 2.5.1.2) and blank solution; place them into hydrogen arsenide generating bottles, respectively; separately add 10ml of hydrochloric acid (1+1) (2.3.10) (the sample and blank bottle shall minus the added acid content of the added sample solution and blank solution); add water till the total volume is 50ml. Add 2.5ml of 15% potassium iodide (1.3.11) and 2.0ml of 40% stannous chloride solution (2.3.12), shake evenly, stand for about 10min. Put the lead acetate cotton and lead acetate filter paper into the arsenic-measuring tube, hold the mercury bromide test paper between the upper grounds of arsenicmeasuring tube. Pay attention that the test paper must be held tightly, and align the aperture position. Add 3~5g zinc particles (2.3.13) to the hydrogen arsenide generating bottle, quickly install the arsenic-measuring tube, and plug tightly. React for 1h at the room temperature (25 C), take off the mercury bromide test paper. Compare the arsenic stain sample and standard arsenic stain, and quantify it. 2.6 Calculation of analytical results Calculate the arsenic concentration as per Formula (2): Where: m 0 arsenic content in blank solution obtained through compared with standard arsenic stain, in µg; m 1 arsenic content in test solution obtained through compared with standard arsenic stain, in µg; m sample mass, in g; V 1 sampling volume of sample solution during test, in ml; V total volume of sample solution, in ml. www.chinesestandard.net Page 9 of 10