ANALYSIS OF ORGANIC-COMPOUNDS IN ENVIRONMENTAL-SAMPLES BY HEADSPACE SOLID-PHASE MICROEXTRACTION

The analysis of samples contaminated by organic compounds is an import ant aspect of environmental monitoring. Because of the complex nature of these samples, isolating target organic compounds from their matric es is a major challenge. A new isolation technique, solid phase microe xtraction, or SPME, has recently been developed in our laboratory. Thi s technique combines the extraction and concentration processes into o ne step; a fused silica fiber coated with a polymer is used to extract analytes and transfer them into a GC injector for thermal desorption and analysis. It is simple, rapid, inexpensive, completely solvent-fre e, and easily automated. To minimize matrix interferences in environme ntal samples, SPME can be used to extract analytes from the headspace above the sample. The combination of headspace sampling with SPME sepa rates volatile and semi-volatile analytes from non-volatile compounds, thus greatly reducing the interferences from non-target compounds. Th is paper reports the use of headspace SPME to isolate volatile organic compounds from various matrices such as water, sand, clay, and sludge . By use of the technique, benzene, toluene, ethyl-benzene, and xylene isomers (commonly known as BTEX), and volatile chlorinated compounds can be efficiently isolated from various matrices with good precision and low limits of detection. This study has found that the sensitivity of the method can be greatly improved by the addition of salt to wate r samples, water to soil samples, or by heating. Headspace SPME can al so be used to sample semi-volatile compounds, such as PAHs, from compl ex matrices.