Fatores condicionantes na análise de etanol, metanol, 2-propanol e acetona em amostras sanguíneas ; Conditioning factores in the analysis of ethanol, methanol, 2-propanol and acetone in blood samples

Dissertação de Mestrado em Química Forense apresentada à Faculdade de Ciências e Tecnologia ; The analysis of volatile organic compounds (VOC) present in biological matrices such as blood is carried out quite frequently in the Chemistry and Forensic Toxicology laboratories of the National Institute of Legal Medicine and Forensic Sciences. Despite being highly relevant analytical determinations, the fact that they are volatile compounds makes their analysis difficult, and it must be ensured that no losses occur, which compromise the analysis and, consequently, the legal process.This study aimed to address different situations such as the collection of different sample volumes, storage temperatures in more than one analysis of the same sample in order to portray the procedure addressed for the daily routine in a forensic laboratory. For this, it was important to study the various factors simultaneously, over a certain period of time, and thus verify how the determination of the different substances studied, ethanol, methanol, 2-propanol and acetone, could be affected.A total of 538,8 mL of white blood was spiked, distributed into 96 tubes with different volumes (3, 6 e 9 mL) to which a mass of 0,1 g NaF was added. The samples were subject to a two temperatures: -20 oC and 5-6 oC, and were stored for a period of 30 days and analyzed on days 0, 15 and 30.To carry out the work, an Agilent 6890N gas chromatograph with a flame ionization detector and an Agilent G1898 fixed volume headspace injector (HS-GC-FID) were used. The results obtained for the four compounds under study were analyzed individually. The difference in concentration obtained in the three periods of analysis, the percentage difference, was calculated and a statistical comparison was made using the Student t-test, with a significance level of 5%.Overall, across all sets of samples, it was found that after a 30-day storage period there were significant differences in the concentration of the four compounds. Acetone was the compound for which the ...