DEVELOPMENT AND VALIDATION OF THE METHOD FOR ANALYSIS OF ARSENIC IN POST-MORTEM BLOOD BY GRAPHITE FURNACE ATOMIC ABSORPTION SPECTROMETRY

Arsenic (As) is the chemical element that, according to the United State Agency for Toxic Substances and Disease Registry (ATSDR), offers more risk to human health due to its high toxicity and high occurrence in the environment. The As often is involved in situations of accidental or intentional poisoning in humans or the environment that require chemical analysis for its detection and quantification. Forensic Toxicology Section (STF) is the official laboratory responsible for dead bodies forensic toxicological analysis samples in the state of Rio de Janeiro, Brazil and must be able to identify and quantify any potentially toxic substance. The objective of this work was to develop and validate an appropriate and feasible method As analysis by Graphite Furnace Atomic Absorption Spectrometry (GF-AAS) in postmortem blood for forensic applications, ensuring reliability and traceability of measurements according to the practices of chemical metrology. The crucial stage of the work was the sample preparation for its complexity and the interference caused by the organic matrix. Two procedures for opening the samples were assessed: acid digestion in a closed system assisted by microwave and open system with heating in a water bath. The determination of residual carbon by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) was used to assess and compare the efficiency of the digestion processes. The initial analysis by GF-AAS showed a marked matrix effect and the necessity to obtain the calibration curve in the matrix. The Inductively coupled plasma mass spectrometry (ICP-MS) was used as an independent technique to compare the results obtained by GF-AAS. The validation step has evaluated of four methods (GF-AAS and ICP-MS with samples digested by microwave and water bath). The results of the validation tests were satisfactory for the evaluated performance parameters and evaluation criteria (Selectivity, Linearity, Limit of Detection and Quantification, Precision and Accuracy) demonstrating the suitability for the intended use. The values of expanded uncertainty relating to all the methods studied was less than 10% for all samples. The methods studied are suitable to apply for forensic analysis with reliable and traceable results.