Non-chromatographic methods focused on speciation of arsenic and selenium in food and environmental samples

Speciation is a promising and essential tool inthe evaluation of the contamination of metals in food andenvironmental samples. In this context, information aboutthe species of these elements is important considering thattoxic effects are directly related to their chemical forms. Theenormous progress in combining separation and detectiontechniques has enabled the effective chemical speciation.However, a possible source of error in studies of speciationoccurs during sample preparation. Appropriate treatmentof samples is necessary in order to ensure that interconversionbetween the species does not occur duringthe experimental procedure prior to the final analysis.In this review, methods of sample preparation for thedetermination of arsenic and selenium in food andenvironmental samples are discussed. We decided to focuson these elements since they account for around 50% ofall speciation studies. Procedures including conventionalextraction, microwave-assisted extraction and sonolysisare discussed as simple ways to ensure species selectivity.The main purpose of this review is to provide an update onthe recent literature concerning the strategies for arsenicand selenium speciation and to critically discuss theiradvantages and weaknesses compared with the commonlyaccepted approach of combining non-chromatographicand spectroscopic techniques. The problems focused oninvolve sampling, sample preparation and storage, as wellas changes in ‘species information’ that occur during theuse of various separation technologies. These difficulties are described along with recent developments aimed atovercoming these potential issues