BS EN ISO 17075-1:2017 pdf download

11-18-2020 comment

BS EN ISO 17075-1:2017 pdf free download. Leather – Chemical determination of chromium(VI) content in leather – Part 1: Colorimetric method.
BS EN ISO 17075-1:2017 specifies a method for determining chromium(VI) in solutions leached from leather under defined conditions. The method described is suitable to quantify the chromium(VI) content in leathers down to 3 mg/kg.
2 Normative references
ISO 2418, Leather-Chemical, physical and mechanical and fastness tests-Sampling location;
ISO 3696, Water for analytical laboratory use-Specification and test methods;
ISO 4044: 2017, Leather-Chemical tests-Preparation of chemical test samples;
ISO 4684, Leather-Chemical tests-Determination of volatile matter.
4 Principle
Extractable chromium(VI) is leached from the sample in phosphate buffer at pH 7,0 to 8,0 and co-extracted coloured substances which influence the detection are removed by solid phase extraction if necessary. The chromium(VD) in solution oxidizes 1,5-diphenylcarbazide to 1, 5-diphenylcarbazone to give a red /violet complex with chromium which can be quantified photometrically at 540 nm.
5 Chemicals
All reagents used shall have at least analytical grade purity.
5.1 Extraction solution
Dissolve 22.8g dipotassium hydrogenphosphate, K2HP04: 3H20, in 1 000 ml water, adjusted to pH8,0±0,1 with phosphoric acid (5.3).Degas this solution with either argon or nitrogen (5.6)or ultrasonic bath.
Standard practice is to make up a fresh solution each day. However, the solution can be kept for up to one week in a refrigerator at (4+3)°C but shall be warmed to room temperature and degassed prior to use..
5.5 Chromium(VI)standard solution
Pipette 1 ml of solution (5.4)into a 1 000 ml volumetric flask and make up to the mark with extraction solution (5.1 ) One millilitre of this solution contains 1 ug of chromium.
The solution can be kept for up to one week in a refrigerator at (4 +3)°C but shall be warmed to room temperature prior to use.
A stock solution at this concentration evel of hexavalent chromium is an alternative available commercially.
5.6 Argon or nitrogen,oxygen-free
Preference should be given to argon as an inert gas instead of nitrogen because argon has a higher specific mass than air.

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