Chromate in toys – determination by ion chromatography

Children are exposed to intakes of heavy metals from a wide variety of sources. Chromate in particular represents a potential hazard, as it is absorbed from food and drinking water, from the air that is breathed, from textiles, from utensils that contain metal and from toys. The analytical determination of the chromate content in toys for compliance with limit values is described in the European standard DIN EN-71-3-2013 (Safety of toys Part 3 – Migration of certain elements).

The standard differentiates between three categories, depending on the kind of toys:

Category I – migration limit: 0.02 mg/kg of Cr(VI)

• Dry, brittle, powder-like or soft toy materials eg., leads of pencil crayons, chalk, wax crayons

Category II – migration limit: 0.005 mg/kg of Cr(VI)

• Liquid or sticky toy materials, finger paints, liquid ink or soap solutions

Category III – migration limit: 0.2 mg/kg of Cr(VI)

• Scraped-off toy materials: coats of paint, printing inks, decorative paints
• Paper and cardboard, glass, ceramics, metallic materials, uncoloured and coloured materials, eg., wood and leather

Metrohm has developed an ion chromatography method for this application using preconcentration and Inline Matrix Elimination.

A portion of the migration solution produced in accordance with the regulation DIN EN 71-3:2013-07 is placed on a preconcentration column where a rinsing solution is used to elute the matrix from the column. In the second step, chromatographic separation takes place on an anion exchanger. Detection is accomplished using a very specific post-column derivatisation in combination with UV/VIS detection.