Chromium speciation in solid matrices and regulation: a review

Abstract

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-Na(2)CO(3) 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.

Study of Cr+6behavior in three agricultural soils

“…As expected, the soil which shown the highest pH (Encín), presented the highest Cr +6 concentrations in the three fractions. This fact indicates that the reduction to Cr +3 process is lesser than in soils from Escorial and Talamanca, both with pH<7 in which thermodynamics lead to the formation of Cr +3 (Unceta et al 2010). This pH effect is clear when Encín and Talamanca soils are compared.…”

Research on chromium and arsenic speciation in atmospheric particulate matter: short review

“…The PM from industrial zone turned out to be almost fivefold richer in Cr(III). The level of Cr(VI) in air over the whole city was similar and the mean concentration of PM-bound Cr(VI) was 6.0 ng/m 3 . In non-polluted areas mean concentration of Cr(VI) was lower than 0.5 ng/m 3 [24].…”

“…Considering the fact of As and Cr toxicity it can be stated that understanding their speciation is more important, than knowing its total contents in the exact elements of the environment [3]. All over the world the quantitative assessment of As and Cr species in all elements of the environment such as water, soil, sediments, wastes, plants, particulate matter etc.…”

Raman microscopic detection of chromium compounds

“…Separation techniques coupled with highly sensitive detection methods are needful for the analysis of the single chromium forms. For the detection of CrVI are recently used methods as [8]:…”