Contamination with explosives in analytical laboratory procedure.

The philosophy underlying the procedure with the trace from the moment of the securing of the evidence up to its ultimate inspection is of significance for the result achieved. Hands of the people who conduct investigative action or of the experts involved in examinations contaminated with explosives may adversely affect results of the analyses. The contamination effect is one of the most dangerous consequences of non-observance of the strict rules in handling the traces secured on the crime scene. The aim of this research work was to examine whether at all, and if so, with what an ease and at which stage of the analytical procedure there occurs a likely contamination of the evidence material with explosives such as TNT, RDX, PETN, NG. The analytical procedure employed consisted of the sampling stage, extraction from gauze swab, transfer of the extract and execution of an instrumental analysis based on gas chromatography with electron capture detector (ECD). The most significant contamination effect was observed during the analytical procedure for TNT, followed by a similar, yet less pronounced, for RDX and PETN. Contaminating the research material with nitroglycerin, known to be liquid under normal conditions, proved unsuccessful.