ISO 17072-1:2019 pdf free download – Leather – – . Chemical determination of metal content – Part 1: Extractable metals.
7.3 Determine the volatile matter content in accordance with ISO 4684. The same sample of leather can be used for the extraction in 8.2.
8 Procedure
8.1 Preparation of acid artificial-perspiration solution
Preparation of acid artificial-perspiration solution, shall be in accordance with ISO 105-E04. The solution shall be freshly prepared each day, containing, per litre:
— 0,5 g of L-histidine monohydrochloride monohydrate (5.3);
— 5 g of sodium chloride (5.4);
— 2,2 gof sodium dihydrogen phosphate dihydrate(5.5).
The solution is brought to pH (5,5 ± 0,1) with 0,1 mol/l sodium hydroxide solution.
8.2 Extraction of leather sample
Weigh accurately 2 g of the prepared leather to the nearest 0,001 g using an analytical balance (5.3) and place in a 250 ml Erlenmeyer flask (5.8).
Add 100 ml of the acid artificial-perspiration solution (8.1) by pipette and, at (37 ± 2) °C, shake (6.10) in a water bath (6.10) for 4 h ± 5 mm.
In case of insufficient sample, it is possible to sample 1 g of leather, but in this case the extraction shall be performed with 50 ml of the acid artificial-perspiration in a 150 ml Erlenmeyer flask.
Filter the extract with a filter paper (6.6), then filter with a membrane filter (6.5).
In the case of Sn, Sb, Pb determination, check that the filtration doesn’t cause a partial loss of these elements.
For the direct measurement of the elements, take a suitable amount of extract for analysis and add 5 % (by volume) of nitric acid (5.2). Consider this addition in the dilution factor.
To control the contaminants, it will be necessary to carry out a blank procedure. An aliquot of acid perspiration is placed in a sample container and treated as a sample, in all respects, including all analytical procedures.
The above extraction conditions shall be followed exactly. Any deviation would lead to the wrong results.
In the case of mercury (Hg) determination, add 10 i.tl of gold solution (5.10) at the same time as the acid artificial-perspiration solution.
8.3 Analysis by ICP, AAS and SFA
8.3.1 General
The solution obtained in 8.2 can be analysed directly, provided it contains a concentration of analysed metals within calibration limits. Otherwise, the solution should be diluted as appropriate.
Prepare standard reference solutions of the required metals in accordance with ISO 11885, using perspiration solution (8.1), water or acidified water.
If required, the results can be given based on the dry, degreased mass of the leather sample. Details
shall be noted in the test report.
10 Test report
The test report shall include at least the following information:
a) name of the laboratory;
b) a reference to this document, i.e. ISO 17072-1;
c) a specification of the applied analytical system used;
d) a description of the leather sample tested;
e) results of the dry matter determination;
f) results obtained for the amount of extracted metal, expressed in milligrams per kilogram of dry leather (mg/kg);
g) details of any deviations from this standard test method.