Elemental determination for clinical diagnosis and prognosis: Challenges and trends in sample preparation

Abstract

The concentration of chemical elements in biological samples (e.g. blood, hair, serum, plasma, saliva, and nail) has been used as biomarker in diagnosis and/or prognosis for several diseases. Among them, Parkinson's disease, diabetes mellitus, autism spectrum, cancers, neurological diseases, schizophrenia, thyroid diseases, periodontal diseases, stroke, fibrotic and cirrhotic hepatic can be cited. Inductively coupled plasma-mass spectrometry (ICP-MS) can be considered as one of the most important analytical techniques for elemental determination in low concentration. In general, most of applications of ICP-MS requires liquid or dissolved sample in a suitable solution. Several analytical methods employing ICP-MS have been proposed, but challenges during sample preparation and determination steps have been reported. One of the reasons is the high complexity of many biological matrices that makes difficult a proper sample preparation and the removal of interferences. Solutions obtained after sample preparation must be suitable to be introduced in the ICP-MS equipment to avoid interferences or instrument damage, and to guarantee the quality of results. Several strategies have been applied for preparation of biological samples. Wet digestion methods in open or closed vessels, using conventional or microwave heating have been extensively carried out. Combustion methods, such as the microwave-induced combustion, and extraction methods (assisted by microwaves or ultrasound) have been also used. Additionally, several works reported the use of simple dilution for the elemental determination in biological samples by ICP-MS. Thus, this chapter will present the main preparation methods of biological samples used for diagnosis and/or prognosis for further elemental determination by ICP-MS.