Review of Methods of Preparing Samples for Chromatographic Analysis for the Presence of Organic Explosive Substances

• NCJ Number: 226839
• Journal: Problems of Forensic Sciences Volume: 69 Dated: 2007 Pages: 5-29
• Author(s): Rafal Borusiewicz
• Date Published: 2007
• Length: 25 pages
• Publication Format: Article
• Publication Type: Literature Review
• Language: English
• Country: Poland

Annotation

This paper reviews the procedures used in various laboratories in preparing samples for the analysis of explosives using chromatographic methods, with attention to solid phase microextraction (SPME) as a popular method.

Abstract

SPME is a simple, quick method that does not require the use of organic solvents. It’s most appealing advantage is the possibility of simultaneous elimination of interfering compounds and concentration of analytes through their selective adsorption. It can be applied to the preparation of samples for analysis by means of either gas chromatography (GC) or high-performance liquid chromatography (HPLC). For aqueous samples, the preparation procedure consists of diluting an appropriate amount of salt in the sample and immersing an SPME fiber in the continuously stirred sample for a defined period of time. Salt is added to the samples, since hydration of ions introduced in this way facilitates adsorption of diluted organic compounds on the fiber phase. Since the majority of explosive compounds are characterized by low pressures of vapors and some of them are thermolabile, this means they cannot be selectively concentrated by adsorption from the headspace, because the pressure of their vapors is too low at room temperature; and increasing the pressure by heating the sample could cause decomposition of the analytes. The first stage of preparation of solid samples, therefore, is usually solvent extraction. Application of SPME as the second stage of sample preparation overcomes the presence of interfering compounds that may be in the sample. A defined volume of organic extract is dissolved in aqueous solution of salt, and analytes are adsorbed with the use of SPME. Over time it is likely that SPME will become even more popular for use in laboratories that analyze explosives. 51 references and an appended glossary of abbreviations and specialist terms used in the text