Metals in Hair

Hair analysis has mainly been applied to expose drugs of abuse, pharmaceuticals, chemicals, poisons, and mineral elements. For metals, hair analysis is useful to document exposure to these elements in addition to the standard use of biological fluids such as urine and blood. Nevertheless, hair mineral analysis is hindered by the difficulty of distinguishing between endogenous and exogenous sources, so exogenous contamination has greatly limited its application. In this chapter, metal incorporation, hair washing procedures, and sample preparation are developed and it is shown that the data obtained for the elements are highly dependent on hair washing and preparation procedures, as well as on the specific analytical method used. With regard to analytical methods, definitive progress for the determination of minerals in hair has been achieved in recent years with inductively coupled plasma (ICP) techniques such as ICP-mass spectrometry (ICP-MS), ICP-optical emission spectrometry (ICP-OES) and the new bioimaging techniques including laser ablation (LA-ICP-MS). The applications of metal analysis in hair are assessed regarding their use in many fields: medical such as therapeutic monitoring and clinical toxicology, forensic toxicology, environmental monitoring, workplace exposure, and the geochemical and archaeological domains.