In recent years, the extensive use of chromium in industrial processes has led to the promotion of several directives and
recommendations by the European Union, that try to limit and regulate the presence of Cr(VI) in the environment and to protect
industrial workers using chromium and end-users of manufactured products. As a consequence, new standard methods and analytical
procedures have been published at the EU level for Cr(VI) determination in soil, sludge, sediment, and similar waste materials,
workplace atmospheres, cement, packaging materials, industrially produced samples, and corrosion-protection layers on some
components of vehicles and electrical and electronic equipment. The objective of this article is to summarize the different
directives and recommendations and to critically review the currently existing standard methods and the methods published
in the literature for chromium speciation in the above mentioned solid matrices, putting the emphasis on the different extraction
procedures which have been developed for each matrix. Particular attention has been paid to Cr(III) and Cr(VI) inter-conversions
that can occur during extraction and efforts to minimize these unwanted reactions. Although the use of NaOH-Na2CO3 solutions with hot plate extraction seems to be the more widespread procedure, species transformation can still occur and
several studies suggest that speciated isotope-dilution mass spectrometry (SIDMS) could be a suitable tool for correction
of these interconversions. Besides, recent studies have proved the role of Cr(III) in chromium toxicology. As a consequence,
the authors suggest an update of standard methods in the near future.
Keywords Hexavalent chromium - Cr legislation - Solid matrix - Solid-liquid extraction