Testing acc. to ISO 5398-2: Leather - Chemical determination of chromic oxide content - Part 2: Quantification by colorimetric determination
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Our test laboratory performs testing according to DIN EN ISO 5398-2 as an accredited test method for the chemical determination of chromic oxide content in leather. The colorimetric method is intended for leather expected to contain more than 0.05 % chromic oxide. It determines total chromium, with the result expressed as chromic oxide (Cr₂O₃) as a percentage by mass based on the dry matter of the leather.
The method is particularly suitable for chrome-tanned leather in the field of leather and leather fibre materials. Leather samples as well as leather taken from finished products, such as footwear or clothing, can be examined. DIN EN ISO 5398-2 is not compound-specific and does not distinguish between different chromium oxidation states.
Testing according to DIN EN ISO 5398-2
The prepared leather specimen is first ashed. The leather ash is then subjected to alkaline fusion, converting the chromium into a form suitable for subsequent colorimetric determination.
After addition of 1,5-diphenylcarbazide, a coloured reaction is produced and its absorbance is measured spectrophotometrically at 540 nm. The chromic oxide content is calculated using a calibration curve. At least two independent determinations are performed for each leather sample.
Applications of the test
Chromic oxide content is an important chemical characteristic of chrome-tanned leather. The test can be used, for example, to compare different leather qualities, tanning processes and production batches and to assess the reproducibility of chrome tanning.
The determination is relevant to leather used in Automotive + Mobility, Shoes + Clothing + Accessories and Furniture + Contract Furnishing. Leather taken from finished products can also be chemically characterized by determining its chromic oxide content.
Distinction from chromium(VI) determination
DIN EN ISO 5398-2 determines the total chromium content of leather and expresses the result mathematically as chromic oxide, Cr₂O₃. The result does not indicate what proportion of chromium is present as chromium(III) or chromium(VI).
For the specific determination of chromium(VI) in leather, FILK offers testing according to DIN EN ISO 17075-1 and DIN EN ISO 17075-2.
Related tests
The ISO 5398 series contains different methods for determining chromic oxide content in leather. An alternative determination is available according to DIN EN ISO 5398-1. Other basic chemical characteristics of leather can also be determined, such as pH according to DIN EN ISO 4045.
Here you will also find an overview of our range of tests according to DIN, CEN and ISO standards.
