Chromate in toys, leather and drinking water

Chromate is allergenic, carcinogenic and extremely toxic.

Generally speaking, chromate Cr(VI) is classified as allergenic, carcinogenic, and extremely toxic. It is therefore subject to strict monitoring.

It is present in different concentrations in drinking water, toys, textiles, leather and many other materials. Metrohm has developed various methods for ion chromatographic determination of chromium(VI) which, thanks to Inline Sample Preparation, are suitable for a variety of matrices and concentration ranges – from ng/L to mg/L.

Chromate in toys according to DIN EN 71-3

Children are exposed to heavy metals from a wide variety of sources. In par­ticular, Cr(VI) represents a potential hazard, as it is absorbed from food and drinking water, from the air, from textiles, and from toys. Analytical determi­nation of the Cr(VI) content in toys is described in the European Standard DIN EN-71 -3-2013 (Safety of toys Part 3 – Migration of certain elements), as well as in the EU directive 2009/48/EC. The limit values that apply to Cr(VI) accor­ding to the EU directive are listed in Table 1. According to DIN EN 71 Part 3 the user is free to choose whichever analysis method he or she prefers, as long it is validated. Metrohm has developed an ion chromatography method for this application that uses lnline Preconcentration and lnline Matrix Elimination. The method can be almost entirely automated.

Sample digestion using synthetic gastric juice

Chromium(VI) is extracted from the toy material at body temperature using hydrochloric acid. This type of sample digestion simulates how gastric juice dissolves out the harmful substance from swallowed toy material. The sam­ple that is obtained using this method is then manually neutralized and di­luted. Dilution is required because the high ion concentration present in the sample – which is caused by hydrochloric acid extraction and subsequent neutralization – does not permit preconcentration of chromium(VI).

Automation improves convenience and safety

All the remaining steps are automated. To start with, the entire sample flow path is equilibrated using sample. A Dosino then feeds a defined sample vo­lume onto the preconcentration column.

The Dosino allows to control with accuracy the injection volume, and this is what forms the basis of reliable determination, especially when dealing with low analyte concentrations. Equally important for the sensitivity, however, is the post-column reaction of Cr(VI) with 1,5-diphenylcarabazide that results in the formation of VIS active complexes. The method presen­ted accurately determines hexavalent chromium in the single digit ppt range, easily complying with the 10 ppt limit set by the EU directive 2009/48/EC.

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