NCJ Number
52625
Journal
Arson Analysis Newsletter Volume: 2 Issue: 6 Dated: (OCTOBER 1978) Pages: 8-12
Date Published
1978
Length
5 pages
Annotation
THE LIMITATIONS AND ADVANTAGES OF THE STEAM DISTILLATION AND SOLVENT EXTRACTION METHODS FOR THE SEPARATION AND CONCENTRATION OF FLAMMABLE LIQUIDS IN ARSON EVIDENCE ARE DISCUSSED.
Abstract
THE GAS-LIQUID CHROMATOGRAPHY METHOD IS PREFERRED FOR THE DETECTION AND IDENTIFICATION OF FLAMMABLE LIQUIDS IN ARSON EVIDENCE; HOWEVER, EFFECTIVE IDENTIFICATION OR COMPARISON OF KNOWN AND QUESTIONED SAMPLES OFTEN REQUIRES PRIOR SEPARATION AND CONCENTRATION. METHODS FOR DOING THIS PRESENT BOTH LIMITATIONS AND ADVANTAGES. IN FORENSIC LABORATORIES, THE MOST WIDELY USED FLAMMABLE LIQUID CONCENTRATION TECHNIQUE IS STEAM DISTILLATION. ALTHOUGH PARTICULARLY SUITABLE FOR SUBSTRATES WHICH ARE NOT READILY EXTRACTABLE (E.G. WOOD), THIS TECHNIQUE IS AWKWARD AND LENGTHY. A PRELIMINARY EVALUATION OF THE DISTILLATION APPROACH IN THE LABORATORY SHOWED THAT IT OFFERS NO SIGNIFICANT ADVANTAGES OVER LESS CUMBERSOME METHODS WHEN A NUMBER OF TYPES OF PHYSICAL EVIDENCE ARE BEING EXAMINED. SOME LESS FREQUENTLY USED DISTILLATION METHODS INCLUDE VACUUM DISTILLATION OF ARSON DEBRIS AND AIR FLUSHING OF THE SAMPLE, THEN COLLECTING THE VAPORS IN A COLD TRAP. THE SECOND MAJOR APPROACH TO THE SEPARATION AND CONCENTRATION OF FLAMMABLE LIQUIDS IN ARSON EVIDENCE IS SOLVENT EXTRACTION. WELL-ESTABLISHED IN THE STUDY OF POLLUTION BY SPILLS AND LEAKAGE OF PETROLEUM PRODUCTS, THIS METHOD HAS EXTRACTED ARSON DEBRIS IN A NUMBER OF FORENSIC LABORATORIES, USING NORMAL HYDROCARBONS SUCH AS N-PENTANE, HEXANE, DODECANE, AND HEXADECANE. HALOGENATED SOLVENTS HAVE ALSO BEEN USED EXTENSIVELY, ALONG WITH OTHER SOLVENTS SUCH AS BENZENE, ETHYL ETHER, AND CARBON DISULFIDE. THE EFFECTS OF USING PARTICULAR SOLVENTS ARE DESCRIBED. ALTHOUGH SOLVENT EXTRACTION TECHNIQUES ARE CONVENIENT FOR USE WITH ARSON EVIDENCE, A CONSIDERABLE AMOUNT OF ADDITIONAL EVALUATION IS NEEDED; AN INDEPTH STUDY SHOULD BE MADE WITH A RANGE OF FLAMMABLE LIQUIDS OF THE TYPES COMMONLY ENCOUNTERED IN ARSON CASES. A MAJOR LIMITATION OF SOLVENT EXTRACTION IS THE ASSOCIATED SEPARATION OF SUBSTRATE MATERIALS AND DEGRADATION PRODUCTS WHICH COMPLICATE THE INTERPRETATION OF THE CHROMATOGRAPHIC PATTERN OBTAINED. REFERENCES ARE PROVIDED. (RCB)