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GB/T 38287-2019: Determination of hexavalent chromium in plastic materials 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/T 38287-2019: Determination of hexavalent chromium in plastic materials---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/GBT38287-2019NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 83.080.01 G 31 Determination of hexavalent chromium in plastic materials ISSUED ON: DECEMBER 10, 2019 IMPLEMENTED ON: NOVEMBER 01, 2020 Issued by: State Administration for Market Regulation; Standardization Administration of the People's Republic of China. Table of ContentsForeword ... 3 1 Scope ... 4 2 Normative references ... 4 3 Methods ... 5 4 Precision ... 13 Annex A (informative) Reference spectrums ... 14 Determination of hexavalent chromium in plastic materials WARNING - Persons who uses this Standard shall have practical experience in formal laboratory work. This Standard does not point out all possible security issues. It is user’s responsibility to take appropriate safety and health measures and to ensure compliance with the conditions stipulated by relevant national regulations.1 ScopeThis Standard specifies the method to determine the content of hexavalent chromium [Cr(VI)] in plastic materials by diphenyl carbazide spectrophotometry and liquid chromatography-inductively coupled plasma mass spectrometry. This Standard is applicable to determination of hexavalent chromium in various plastic raw materials and products. NOTE: Diphenyl carbazide spectrophotometry: determination of yellow interference when iron content is about 50 times that of hexavalent chromium; color interference is generated when vanadium content is about 10 times that of hexavalent chromium but the color developed by vanadium and reagent shall disappear after 10min; molybdenum and mercury above 200mg/L interfere with the determination of hexavalent chromium.2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB/T 602, Chemical reagent - Preparations of stock standard solutions GB/T 6682, Water for analytical laboratory use - Specification and test methods GB/T 8170, Rules of rounding off for numerical values & expression and judgement of limiting values 3.1.2.13 Diphenyl carbazide acetone solution (color developer): Weigh 0.5g of diphenyl carbazide to dissolve in 100mL of acetone. Store in a brown bottle. It can be stored in a 4°C refrigerator for half a month. It cannot be used when the solution becomes deep. 3.1.2.14 Hexavalent chromium standard stock solution (100mg/L or other concentration): Use single-element or multi-element standard stock solution of a certain concentration that is certified by the country and awarded with a reference material certificate. It can also prepare the standard solution required according to GB/T 602. Accurately weigh 0.1414g of potassium dichromate that has been dried at 120°C for 2h. Use water to dissolve and move into a 1000mL volumetric flask. Use water to dilute to the scale. Shale well. The hexavalent chromium concentration of this solution is 100mg/L. 3.1.3 Instruments and equipment 3.1.3.1 Ultraviolet-visible spectrophotometer. 3.1.3.2 Constant temperature shaking water bath: Temperature control accuracy is ±1°C. 3.1.3.3 Microwave extraction instrument: equipped with Teflon extraction tank or other suitable extraction tank. 3.1.3.4 pH meter: resolution is 0.01pH. 3.1.3.5 Analytical balance: accuracy is 0.0001g. 3.1.3.6 Coarse grinder or cutter for stainless steel bottom screen. 3.1.3.7 Centrifugal grinder or ball mill. 3.1.3.8 Colorimetric tube or beaker. 3.1.3.9 All utensils and extraction tanks cannot use chromic acid washing liquid to soak. When necessary, the glassware and extraction tank used can be soaked in dilute nitric acid for more than 12h. Then use water to rinse before using. 3.1.4 Analysis steps 3.1.4.1 Sample crushing Crush a sample to obtain plastic sample powders of which particle size is less than 250μm. The difference in plastic material shall result in different minimum powder particle size. Minimize the particle size of plastic materials to accelerate sample leaching or extraction. The sample of which the particle size is still large after crushing can extend the leaching time or extraction time to promote the According to the sensitivity, linear range of the instrument and the actual content of hexavalent chromium in the sample solution, determine the concentration and scope of standard use solution. Usually use at least 5 concentration points (except blank). Standard solutions shall be stored in chromium-free plastic containers. Hexavalent chromium standard use solution shall be prepared when needed. 3.1.4.3.2 Establishment of standard curve Take zero point of hexavalent chromium standard series solution as reference. In ascending order of concentration, measure the absorbance of standard series solutions at 540nm. Use the concentration as the abscissa and the absorbance value as the ordinate to make a standard curve. Correlation coefficient (R2) is not less than 0.998. 3.1.4.3.3 Sample determination Perform two parallel experiments for each sample, while conducting a sample blank experiment. The color reaction of the extraction solution and the hexavalent chromium standard series solution shall be carried out simultaneously. The color- developed solution shall be measured within 15min after the color-developing agent is added. Calculate the content of hexavalent chromium in the extraction solution from the standard curve. If the measurement result exceeds the standard curve range, it shall be diluted before measuring or re-establishing a suitable standard curve. 3.1.5 Result calculation The content of hexavalent chromium in the sample is expressed by X and calculated according to formula (1): Where, X - Content of hexavalent chromium in test sample, in milligrams per kilogram (mg/kg); ρ1 - Content of hexavalent chromium in test solution, in micrograms per liter (μg/L); ρ0 - Content of hexavalent chromium in blank solution, in micrograms per liter (μg/L); Hexavalent chromium mass number: 52,53. Analysis mode: collision reaction cell. NOTE: The above instrument parameters and working conditions are for reference only. Different types of instruments can be optimized and set according to the manufacturer's recommended values. Use the tuning fluid recommended by the manufacturer for tuning. 3.2.4.3.2 Preparation of calibration solution Hexavalent chromium standard intermediate solution (1.00mg/L): Pipette 1.00mL of hexavalent chromium standard stock solution into a 100mL volumetric flask. Add water to dilute to the scale. Mix well. Hexavalent chromium standard series solutions: Respectively pipette 0.0mL, 1.25mL, 2.5mL, 5.0mL, 7.5mL, 10.0mL, 12.5mL of hexavalent chromium standard intermediate solution (1.0mg/L) into 25mL volumetric flasks. Use water to dilute and set volume to the scale. Mix well. The mass concentrations of this hexavalent chromium standard series solution are 0.00mg/L, 0.05mg/L, 0.10mg/L, 0.20mg/L, 0.30mg/L, 0.40mg/L, 0.50mg/L, respectively. It shall, according to the sensitivity, linear range of the instrument and the actual content of hexavalent chromium in the sample solution, determine the concentration and range of standard use solution. Usually use at least 5 concentration points (except blank). Standard solutions shall be stored in chromium-free plastic containers. Hexavalent chromium standard use solution shall be prepared when used. Instrument tuning fluid: According to the instrument operating instructions, take appropriate instrument tuning stock solution. Use nitric acid solution (5+95) to prepare into the right concentration of tuning solution. 3.2.4.3.3 Qualitative determination Conduct qualitative comparison of peak retention time with standards (see Annex A). Use the result of mass number 53 to assist in characterization. The natural abundance ratio of chromium is 52Cr / 53Cr = 8.8. When the ratio of 52Cr and 53Cr peak areas in the sample is between 7.2~9.7, it shall determine that the sample contains hexavalent chromium. 3.2.4.3.4 Quantitative determination Perform two parallel experiments for each sample, while conducting a sample blank experiment. After measuring the mass spectrum signal intensity of the reagent blank, determine the peak area of the hexavalent chromium mass 52 in the mixed standard solution series from low concentration to high concentration in order. ......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/T 38287-2019 be delivered?Answer: The full copy PDF of English version of GB/T 38287-2019 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/T 38287-2019_English with my colleagues?Answer: Yes. 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