Design and performance of a direct-reading, multichannel spectrometer for the determination of chlorinated purgeable organic compounds by flame infrared-emission spectrometry.

The feasibility of determining chlorinated, purgeable organic compounds (POCs) in aqueous samples by flame infrared-emission (FIRE) spectrometry was evaluated with a specially designed, multichannel, dispersive spectrometer having sufficient resolving power to prevent interference from large amounts of non-halogenated POCs that could also be present in the sample. The polychromator was based on a Czerny-Turner optical mounting with a 0.15-m focal length, a nominal focal ratio of f/3, and a reciprocal linear dispersion of 0.15 mum/mm in the first order. The HCl and CO(2) infrared emission bands (3.77 and 4.42 mum, respectively) were monitored in two analytical channels, while a third reference channel, used for background subtraction, monitored the H(2)O background emission at 2.8 mum. Instrumental performance was evaluated with dichloromethane, trichloromethane, trichloroethylene, 1,1,2,2-tetrachloroethane and monochlorobenzene as test compounds, and parameters such as the linear dynamic range, reproducibility, detection limit and signal-to-noise ratio, and extent of spectral crosstalk between channels were determined. The feasibility of performing a quantitative analysis of a two-component mixture of dichloromethane and trichloromethane at trace levels was demonstrated.