Emerging procedures and solvents in biological sample pre-treatment

The treatment of biological samples, especially from complex matrices, has consistently challenged analytical operators. The classic problems to be faced for any analysis, regardless of the origin of the sample, such as for example contamination and loss of analyte, in biological samples, are particularly emphasized. In particular, the main cause of the error is due to the degradation of the analyte which in several cases due to biological interaction. Many factors can influence the stability of drugs, chief among them the physicochemical properties of the drug, characteristics of the matrix, the tendency to conjugation/deconjugation, sample collection procedure, container characteristics (e.g., oxidation, adsorption), and the use of preservatives or other additives. The problem is severe in the toxicological and forensic fields, especially for analyzes considered "non-repeatable." In this review, we will explore all the major problems in the pre-extraction phase for the chemical-analytical aspect in the pharmacotoxicological and forensic fields.