Skip to product information
1 of 6

PayPal, credit cards. Download editable-PDF and invoice in 1 second!

GB/T 22807-2008 English PDF (GBT22807-2008)

GB/T 22807-2008 English PDF (GBT22807-2008)

Regular price $70.00 USD
Regular price Sale price $70.00 USD
Sale Sold out
Shipping calculated at checkout.
Quotation: 24-hr self-service. Click GB/T 22807-2008
See Chinese contents: GB/T 22807-2008

GB/T 22807-2008: Leather and fur -- Chemical tests -- Determination of chromium VI content

This Standard specifies the methods of determining chromium VI content in leather and fur. This Standard is applicable to various types of leather, fur and their products.
GB/T 22807-2008
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 59.140.30
Y 46
Leather and Fur - Chemical Tests -
Determination of Chromium VI Content
ISSUED ON: DECEMBER 30, 2008
IMPLEMENTED ON: SEPTEMBER 1, 2009
Issued by: General Administration of Quality Supervision, Inspection and Quarantine;
Standardization Administration of the PEOPLE Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Principle ... 4
4 Reagents and Materials ... 5
5 Devices ... 6
6 Sample Preparation ... 6
7 Procedure ... 7
8 Result Expression ... 9
9 Test Report ... 11
Appendix A (Informative) Decolorizer ... 12
Leather and Fur - Chemical Tests -
Determination of Chromium VI Content
1 Scope
This Standard specifies the methods of determining chromium VI content in leather and fur.
This Standard is applicable to various types of leather, fur and their products. 2 Normative References
Through the reference in this Standard, clauses in the following documents become clauses of this Standard. In terms of references with a specific date, all the subsequent modification lists (excluding corrected content) or revised editions are not applicable to this Standard. However, all parties that reach an agreement in accordance with this Standard are encouraged to explore the possibility of adopting the latest version of these documents. In terms of references without a specific date, the latest version is applicable to this Standard.
QB/T 1267 Fur - Chemical Physical and Mechanical and Fastness Tests - Sampling Location
QB/T 1272 Fur - Preparation of Chemical Test Samples
QB/T 2706 Leather - Chemical, Physical and Mechanical and Fastness Tests - Sampling Location (QB/T 2706-2005, ISO 2418: 2002, MOD)
QB/T 2716 Leather - Preparation of Chemical Test Samples (QB/T 2716-2005, ISO 4044: 1977, MOD)
QB/T 2717 Leather - Chemical Tests - Determination of Volatile
3 Principle
Use phosphate buffer, of which the pH value is between 7.5 ~ 8.0 to extract soluble chromium VI in the sample. When needed, decolorizer may be used to remove substances that might interfere the tests. Under acidic condition, chromium VI in the filtrate reacts with 1,5-diphenylcarbazide, and generates purplish red complex. Use spectrophotometry to determine at 540 nm.
5 Devices
5.1 Mechanical oscillator: conduct horizontal loop oscillation, frequency: 50 times/min ~ 150 times/min.
5.2 Conical flask: 250 mL, equipped with a grinding plug.
5.3 Air duct and flow meter.
5.4 pH meter, equipped with glass electrode; reading shall be accurate to 0.1 unit. 5.5 Volumetric flask: 25 mL, 100 mL, 1,000 mL.
5.6 Transfer pipette: 0.5 mL, 1.0 mL, 2.0 mL, 5.0 mL, 10.0 mL, 20.0 mL, 25.0 mL. 5.7 Spectrophotometer or filter photometer, wavelength: 540 nm.
5.8 Quartz cuvette, thickness: 2 cm, or other cuvettes with suitable thickness. 5.9 Decolorizing column: glass or polypropylene column; internal diameter: around 3 cm; equipped with suitable decolorizer, for example, PA decolorizer (around 4 g). Please refer to Appendix A for the selection of decolorizers.
6 Sample Preparation
6.1 Sampling
6.1.1 Standard part sampling
a) Leather: comply with the stipulations in QB/T 2706.
b) Fur: comply with the stipulations in QB/T 1267.
6.1.2 Non-standard part sampling
Adopt random sampling method. Sample shall be representative. The sampling shall be recorded in detail in test report.
6.2 Sample Preparation
6.2.1 Leather: comply with the stipulations in QB/T 2716.
6.2.2 Fur: comply with the stipulations in QB/T 1272. During the shearing process, avoid damaging the fur; maintain intactness of the fur.
6.2.3 Remove glue and attachments on the sample as thoroughly as possible. Mix up the sample; place it in a clean sample bottle to be tested.
the calibration solution, chromium content shall cover the range of test. The calibration solution shall be prepared in 25 mL volumetric flask.
Within the range of 0.5 mL ~ 15 mL standard solution (4.6), at least prepare 6 calibration solutions. Draw a suitable calibration curve. Use transfer pipette to respectively transfer a certain amount of standard solution (4.6) into several 25 mL volumetric flasks. Add 0.5 mL of phosphoric acid solution (4.3) and 0.5 mL of diphenylcarbazide solution (4.2) to each volumetric flask. Use the buffer (4.1) to dilute to the volume, then, mix it up. Place it still for (15 ??? 5) min.
Use the same cuvette used in the sample test to test the calibration solution?€?s absorbance at 540 nm relative to the blank solution (7.5).
Use chromium VI concentration (??g/mL) to draw a calibration curve of the absorbance. Take chromium VI concentration as the X-axis; take the absorbance as the Y-axis. NOTE: it is suggested by many laboratory tests that 2 cm cuvette is the most suitable. The above-mentioned standard solution is for the 2 cm cuvette test. Under certain circumstances, cuvettes which have a longer or a shorter optical path might be suitable. At this moment, please make sure that the range of the calibration curve is within the linear measurement range of the photometer.
7.7 Determination of Recovery Rate
7.7.1 Influence of matrix
The importance of recovery rate determination lies in the supply of information regarding matrix effect that influences the test result.
Weigh-take 10 mL of the solution obtained through 7.3. Add an appropriate volume of chromium VI standard solution, so that the content of chromium VI approaches twice (??? 25%) as much as the chromium VI content in the original extract. The method of selecting the concentration of chromium VI standard solution being added: after adding chromium VI standard solution, the ultimate volume of the solution shall not exceed 11 mL. After adding chromium VI standard solution, the solution shall be processed through the same method as the sample (record the absorbance as E1s and E2s) (please refer to 7.4).
The absorbance shall be within the range of the calibration curve, otherwise, reduce the volume being weighed and taken; re-determine it. The recovery rate shall be more than 80%.
7.7.2 Influence of decolorizer
Weigh-take a certain volume of chromium VI standard solution (4.6) to a 100 mL volumetric flask. Thus, chromium VI content in this solution is equivalent to the Chromium IV content shall indicate its benchmark: the practical mass of sample or the calculation by the dry mass of sample. It shall be expressed in (mg/kg); round off to 0.1 mg/kg. When there is a dispute or arbitration test, the dry mass shall prevail. The volatile shall be expressed in (%); round off to 0.1 %.
The arithmetic mean value two parallel test results shall be considered as the result. The ratio between the difference and the mean value of two parallel test results shall be smaller than 10%.
The detection limit of this method is 3 mg/kg.
If the detected chromium VI content exceeds 3 mg/kg, compare the UV spectrum of the test solution and the standard solution (4.6), so as to determine whether the positive result is caused by interfering substance.
9 Test Report
Test report shall include the following content:
a) Serial number of this Standard;
b) Sample name, category and detailed information of sampling;
c) Category of decolorizer;
d) If 2 cm cuvette is not used, explain the thickness of the cuvette;
e) Chromium VI content (mg/kg) in the sample shall indicate the benchmark: the practical mass of sample or the calculation by the dry mass of sample. If the calculation by the dry mass of sample is taken as the benchmark, then, the volatile content in the sample shall be indicated and expressed in (%); f) The result of test report shall retain 1 decimal place;
g) If recovery rate is less than 80% or more than 105%, recovery rate shall be indicated in detail;
h) Abnormal phenomena during the tests;
i) Differences between the practical determination methods and this Standard; j) Tester and date.

View full details