Problems of Forensic Sciences 2000 Vol. 42 (XLII) 47-58

OPTIMISATION OF SOLID PHASE MICROEXTRACTION (SPME) CONDITIONS FOR HEADSPACE ANALYSIS OF ORGANOPHOSPHATE PESTICIDES IN WHOLE BLOOD

Kamarruddin ASRI1, Robert A. ANDERSON2
1Department of Chemistry, Jalan Sultan, Petaling Jaya, Selangor, Malaysia
2Department of Forensic Medicine and Science, University of Glasgow, Glasgow, United Kingdom

Streszczenie
Organophosphate (OP) pesticides are a significant cause of fatal poisoning in many countries. Problems exist in detecting the parent substances in autopsy blood when putrefaction has occurred. This study evaluated the use of SPME as an extraction technique for the analysis of OP pesticides in whole blood. Malathion and Diazinon were used as model compounds, added to whole blank blood. Parameters affecting the adsorption of analyte on the SPME fibre were sampling time, temperature, agitation, and modification of the ionic strength and pH. The best conditions for extraction were at 90°C, with a conditioning time of 10 minutes, exposure time of 30 minutes and desorption time of 5 minutes. All samples were agitated during the extraction process. The primary detection and quantification technique was GC-NPD but GC/MS was also used as a confirmatory identification technique. The minimum detectable level by GC-NPD was 100 ng per 0.5 ml whole blood and the linear quantifiable range was from 200-1000 ng per 0.5 ml whole blood (correlation coefficient 0.993). Recoveries were approximately 0.39% with a coefficient of variation of 6.8%. The rates of in vitro change of Malathion concentrations in blood during storage at ambient temperatures in the range 20-25°C and at 4°C were also measured. The time limit of detection at 20-25°C was 4 h but at 4°C was more than 11 days. No interferences from the putrefying blood were observed. From the results it was concluded that headspace-SPME could be used as an alternative technique for sample preparation which is simpler and more rapid than liquid-liquid extraction or conventional solid phase extraction.

Słowa kluczowe
Solid phase microextraction; Organophosphates pesticides; GC/MS.

Pobierz PDF