The choice of any procedure for analysis involves consideration of a number of factors and is best resolved by professional judgment. In general, techniques that require the fewest steps for sample preparation give the best results and instrumentation should be selected with this in mind. In recent times, the most successful determinations of benzene have used nonvisible spectrophotometry and gas chromatography. These techniques provide good sensitivity and require minimal sample preparation. Spectrophotometric methods are best used where there are few interfering compounds and therefore they are adequate for determinations of benzene in air, water, some industrial gases, and simple solvent mixtures. The development of Fourier transform interfacing has greatly improved the sensitivity of spectrophotometers and allows for improved accuracy using small samples. This has been especially realized in the direct analysis of gases by infrared spectrophotometry. The usefulness of gas chromatography lies in its ability to separate components in a mixture before analysis. For this reason, gas chromatography is the technique of choice for determining benzene in complex gaseous or liquid mixtures and biological systems. The development of microcircuitry has improved detector response as well as reduced the costs of most instruments. This, combined with the availability of prepacked columns, has made the gas chromatograph a standard instrument in even small laboratories.
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