ABSTRACT
This chapter discusses two general types of measurement methods for gases and vapors. The first includes methods that remove the material of interest from air, retaining it for subsequent analysis. The second type of measurement determines the analyte directly in the atmosphere. Ultraviolet and visible spectrophotometry (UV-Vis) are the simplest of all the analytical techniques for many industrial hygiene measurements. Methods based upon this approach usually involve the reaction of an analyte to form a chromophore which can be determined spectrophoto-metrically in the UV-Vis range. High-performance liquid chromatography (HPLC) has been applied to measure less volatile organic compounds and thermally labile compounds. Capillary column technology is also being applied to HPLC with the development of micropore-packed capillary columns. In UV-Vis photometry, radiant energy in the ultraviolet or visible region of the electromagnetic spectrum is passed through a solution or gas-air mixture where some of the energy is absorbed by the analyte.
