Abstract
The analysis of samples contaminated by organic compounds is an important aspect of environmental monitoring. Because of the complex nature of these samples, isolating target organic compounds from their matrices is a major challenge. A new isolation technique, solid phase microextraction, or SPME, has recently been developed in our laboratory. This technique combines the extraction and concentration processes into one 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 solventβfree, and easily automated. To minimize matrix interferences in environmental samples, SPME can be used to extract analytes from the headspace above the sample. The combination of headspace sampling with SPME separates volatile and semiβvolatile analytes from nonβvolatile compounds, thus greatly reducing the interferences from nonβtarget compounds.
This 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, ethylβbenzene, 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 water samples, water to soil samples, or by heating. Headspace SPME can also be used to sample semiβvolatile compounds, such as PAHs, from complex matrices.