GB/T 28019-2011 PDF English
US$70.00 · In stock · Download in 9 secondsGB/T 28019-2011: Adornment - Determination of Chromium (VI). 1, 5-Diphenylcarbohydrazide spectrophotometric method Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedureStatus: Valid
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivery | Name of Chinese Standard | Status |
| GB/T 28019-2011 | English | 70 |
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Adornment - Determination of Chromium (VI). 1, 5-Diphenylcarbohydrazide spectrophotometric method
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GB/T 28019-2011: Adornment - Determination of Chromium (VI). 1, 5-Diphenylcarbohydrazide spectrophotometric method
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GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 39.060
Y 88
Adornment - Determination of Chromium (VI) - 1,5-
Diphenylcarbohydrazide Spectrophotometric Method
Issued on. OCTOBER 31, 2011
Implemented on. FEBRUARY 1, 2012
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People’s Republic of China
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword... 3
1 Scope... 4
2 Method and Principle... 4
3 Reagents and Materials... 4
4 Apparatus... 5
5 Analysis Steps... 6
6 Representation of the Result... 7
7 Test Report... 8
Foreword
This Standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This Standard was proposed by the China National Light Industry Council.
This Standard shall be under the jurisdiction of the National Technical Committee of
Jewelry Standardization (SAC/TC 256).
Drafting organizations of this Standard. National Jewelry Quality Supervision and
Inspection Center.
Main drafters of this Standard. Li Suqing, Li Yukun, Li Wujun.
Adornment - Determination of Chromium (VI) - 1,5-
Diphenylcarbohydrazide Spectrophotometric Method
1 Scope
This standard specifies the 1,5-Diphenylcarbohydrazide spectrophotometric method
for Chromium (VI).
This Standard applies to the determination of Chromium (VI) in adornment.
2 Method and Principle
Use alkaline leaching solution to leach the water-soluble and water-insoluble
hexavalent chromium compounds from the sample. In acidic solution, the hexavalent
chromium from the leachate reacts with the diphenylcarbazide and the reaction forms
the purple-red complex. At the wavelength of 540 nm, perform spectrophotometric
determination.
3 Reagents and Materials
Unless otherwise stated, in analysis, it can only use the reagents, which are confirmed
as the analytic reagents and distilled water, or deionized water, or the water with the
equal purity.
3.1 Nitric acid - guarantee reagent.
3.2 Sulfuric acid - guarantee reagent.
3.3 Sodium hydroxide.
3.9 Acetone.
3.10 Sulfuric acid solution (1+9).
3.11 Nitric acid solution - c (HNO3) = 5mol/L. Weigh and take 31mL of nitric acid (3.1);
add it into 69mL of water. Nitric acid with brown smoke shall not be used for preparation.
3.15 Standard solution of hexavalent chromium - c [Cr (VI)] = 5.0mg/L. Pipette 5.0mL
of standard stock solution of hexavalent chromium (3.14) in a 100 mL volumetric flask;
dilute it to the mark with water; shake it evenly. Prepare it when it is used.
3.16 Diphenylcarbazide (DPC) solution. Weigh and take 0.5g of diphenylcarbazide
(3.8); dissolve it in 100 mL of acetone (3.9); store it in a brown bottle. When solution's
color fades, it should be reconstituted.
4 Apparatus
Common laboratory apparatus and the following items.
4.1 Spectrophotometer - wavelength 420nm~700nm.
4.2 Oscillating water bath kettle.
5 Analysis Steps
5.1 Sample Preparation
5.1.1 Metal Material
Process the sample into the crumb or strip whose diameter are no more than 1 mm
and whose length are no more than 5 mm.
5.3 Color Rendering
Add 2.0mL of diphenylcarbazide (DPC) solution (3.16) into the filtrate (5.2); mix it
evenly; add sulfuric acid solution (3.10); make filtrate’s pH reach 2±0.5; then transfer
the whole filtrate into a 100mL volumetric flask; use water to dilute it until the mark;
shake it evenly; place it for 0.5h.
5.4 Calibration Solution
Respectively pipette 0.0mL, 2.0mL, 4.0mL, 6.0mL, 8.0mL and 10.0mL of standard
solution of hexavalent chromium (3.15) into the 100mL volumetric flask; add 50mL of
water; add 2.0mL of diphenylcarbazide (DPC) solution (3.16); mix it evenly; add 2
drops of sulfuric acid solution (3.10); make filtrate’s pH reach 2±0.5; use water to dilute
it until the mark; shake it evenly; place it for 0.5h.
5.5 Determination
Adopt 1 cm absorption pool; at the place whose absorption wavelength is 540 nm, use
ultraviolet-visible spectrophotometer (4.1) to measure the absorbance value of the
calibration solution; draw the calibration curve by corresponding the absorbance value
with the concentration value.
6 Representation of the Result
In the sample, the content of hexavalent chromium shall be counted in mass fraction -
w. The numerical value shall be expressed in milligrams per kilogram (mg/kg) and shall
be calculated according to formula (1).
7 Test Report
Test report shall at least include the following information.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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