Determination of aromatic compounds in water by solid phase microextraction and ultraviolet absorption spectroscopy .1. Methodology

A simple method is described for determining aromatic compounds (i.e., benzene, toluene, ethylbenzene, etc.) in water that combines solid phase microextraction (SPME) and ultraviolet (UV) absorption spectroscopy, The extraction medium consists of a small ''chip'' of poly(dimethylsiloxane) (total volume of similar to 80 mu L) that is immersed in a water sample contaminated with an aromatic compound, Equilibrium is first allowed to establish between the analyte in the water and the extraction medium, and the concentration of the aromatic compound is then determined directly in the sorbent chip by UV spectroscopy, Calibration information on this new method was obtained for 11 aromatic compounds commonly found in unleaded gasoline (e.g., benzene, toluene, naphthalene, etc), It was found that equilibrium is established in the range of 30-50 min, with the exception of 1-methylnaphthalene and naphthalene, which equilibrated within 100 min, Detection limits for the aromatic compounds at their equilibration times range from 0.40 to 12 ppb except for benzene (97 ppb), Relative standard deviations of the SPME-UV measurements are 3-12%.