GAS-PHASE MOLECULAR ABSORPTION SPECTROMETRY - DETERMINATION OF SULFITE WITH DIODE-ARRAY DETECTION

A method is described for determining sulphite by SO2 generation and U V-visible molecular absorption spectrometry with diode-array detection . The molecular absorption maximum of SO2 appears at 198 nm. The param eters affecting generation (particularly those relating to the kinetic s of the process) and determination are optimized; under the optimum c onditions found, only a 30 s preconcentration time is necessary. The l inear response range is between 10 and 1000 mu g ml(-1) of SO32-, the RSD is 3.5% and the detection limit is 3.2 mu g ml(-1). The effect of different species on the SO2 signal is also studied. The method is app lied to the determination of SO2 in air samples.