Daria Pašalić
Department of Medical Chemistry, Biochemistry and Clinical Chemistry
Zagreb University School of Medicine
Šalata ul 2.
10 000 Zagreb, Croatia
Phone +385 (1) 4590 205; +385 (1) 4566 940
E-mail: dariapasalic [at] gmail [dot] com

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Mandić S1, Nestić M2, Mandić D3, Horvat V1, Debeljak Ž1, Majetić-Cetina N1. P11-1: Influence of extraction on GC/MS analysis of drugs. Biochemia Medica 2009;19(Suppl 1):S153.
1Department for Clinical Laboratory Diagnostics, Osijek University Hospital, Osijek, Croatia
2Department of Forensic Medicine and Criminology, School of Medicine, University of Zagreb, Zagreb, Croatia
3Institute of Public Health of Osijek-Baranya County, Osijek, Croatia
Corresponding author:mandic [dot] sanja [at] gmail [dot] com
Introduction: In clinical and forensic toxicology there is often need for confirmation of certain types of drugs. Their concentrations can vary, from very low to very high levels. Sample preparation, in terms of choice of extraction technique, solvent and chromatographic conditions of analysis can have great influence (qualitative and quantitative) on results.
Materials and methods: We have prepared three different concentration levels of commercial serum control Abbott Immunoassay MCC (Bio Rad), which comprises 23 different drugs, with three most common extraction techniques in forensic and clinical toxicology: liquid-liquid extraction with Toxi-Tubes A (Varian), liquid-liquid extraction with Chem Elut (Varian) and solid phase extraction on Amberlite XAD-2 (Sigma Aldrich). All extracts were reconstituted in chloroform and analyzed in GC/MS (Agilent).
Results: Those three extraction methods showed different results, both qualitatively and quantitatively. Best results at low concentrations levels showed Toxi-Tubes A system (18 drugs confirmed). At medium and high concentrations levels best results were obtained with XAD-2 (22 drugs confirmed), but only when we used 5 mL of solvent. With 1 mL of solvent, best results were obtained with Toxi-Tubes A and Chem Elut systems (19 drugs at medium and 20 drugs at high concentration levels confirmed).
Conclusion: Best results amongst displayed methods showed XAD-2, but when we take into consideration other parameters such as time consumed, amount of chemicals and complexity of procedure, best results were obtained with TOXI-TUBES A system.