This review provides an overview and discusses different analytical strategies that minimize or eliminate the preparation of samples for speciation of organic and inorganic species of As, Cr and Se in samples of biological interest. These metals are important for the human body and the presence of various chemical forms of metals determines its essentiality and toxicity, thus speciation comes as an important tool for the study of biological samples. However, speciation requires a reduction in the steps of sample preparation, allowing a sample investigation in its most native form in order to reduce the changes in chemical species. The strategies proposed for speciation of these metals include: solid phase extraction, point cloud extraction, suspension and direct analysis. Selected methods proposed for the speciation of organic and inorganic species of As, Cr and Se were reviewed including their main figures of merit, advantages and disadvantages
 Duffus J.H., Glossary for chemists of terms used in toxicology, Pure Appl. Chem., 1993, 65, 2003-2122.
 Buchet J.P., Arsenic speciation in human tissues, in: Cornelis R., Caruso J., Crews H., Heumman K., Handbook of Elemental Speciation II - Species in the Environment, Food, Medicine and Occupational Health, John Wiley & Sons, Inc., England, 2005, 86.
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