The role of alternative specimens in toxicological analysis.

The use of alternative specimens in the field of toxicology was first described in 1979, when hair analysis was used to document chronic drug exposure. Since then, the use of these 'alternative' samples has gained tremendous importance in forensic toxicology, as well as in clinic toxicology, doping control and workplace drug testing. It is not surprising, therefore, that a large number of papers dealing with the determination of several classes of drugs in saliva, sweat, meconium and hair have been published ever since, owing to the fact that chromatographic equipment is becoming more and more sensitive, mass spectrometry (and tandem mass spectrometry) being the most widely used analytical tool, combined with gas or liquid chromatography. 'Alternative' specimens present a number of advantages over the 'traditional' samples normally used in toxicology (e.g. blood, urine and tissues), namely the fact that their collection is not invasive, their adulteration is difficult, and they may allow increased windows of detection for certain drugs. The main disadvantage of this kind of samples is that drugs are present in very low concentrations, and therefore high-sensitivity techniques are required to accomplish the analysis. This paper reviews a series of publications on the use of alternative specimens, with special focus on the main analytical and chromatographic problems that these samples present, as well on their advantages and disadvantages over traditional samples in documenting drug exposure.