NCJ Number
187169
Journal
Journal of Forensic Sciences Volume: 46 Issue: 1 Dated: January 2001 Pages: 53-56
Date Published
January 2001
Length
4 pages
Annotation
This paper describes the quality assurance testing regime of the Forensic Explosives Laboratory (FEL) near Sevenoaks, Kent in the United Kingdom and summarizes the results from approximately 8 years of tests; lessons learned and improvements made over the period are also discussed.
Abstract
The purpose of FEL's weekly quality assurance testing regime is to prevent the accumulation of explosive traces within the laboratory at levels that could, if other precautions failed, result in the contamination of samples and controls. The first and most important protection is to ensure that samples for trace explosives analysis do not come into direct contact with the laboratory, nor with the analyst, nor with anything else that may contaminate them. This can be regarded as the "inner" protection and is an extension of the precautions that should be applied in all forensic examinations. This paper, however, is primarily concerned with broader prevention procedures known as "outer," because they seek to ensure that explosive traces are minimized in the environment around the "inner" protection. When a forensic sample is processed, a number of procedures are used. First, the operator must have washed and had a complete change of clothes since the last handling of bulk explosives or visiting an explosives store. Second, the operator makes a final clean of the bench work surface immediately before starting work and then covers this cleaned work surface with disposable paper. A further "outer" protection is to control the entry of materials and air into the laboratory so as to minimize ingress of explosive traces from outside. The intention of the overall system is that contamination of samples can only occur if breaches of both "outer" and "inner" contamination prevention procedures occurred. Over a period of 8 years, monitor samples have been taken weekly from surfaces within the laboratory. With few exceptions, they have shown only low levels of contamination, predominantly of RDX. The monitoring regime has also been valuable in a process of continuous improvement, allowing sources of contamination transfer into the laboratory to be identified and eliminated. 6 figures and 8 references