Simultaneous determination of cyanogen chloride and cyanogen bromide in treated water at sub-mu g/L levels by a new solid-phase microextraction-gas chromatographic-electron-capture detection method

A headspace solid-phase microextraction (HS-SPME) procedure has been develo ped and applied for the determination of cyanogen halides in treated water samples at mug/L concentrations. Several SPME coatings were tested, the div inylbenzene-Carboxen-polydimethylsiloxane fiber being the most appropriate coating. GC-electron-capture detection was used for separation and quantita tion. Experimental parameters such as sample volume, addition of a salt, ex traction time and desorption conditions were studied. The optimized method has an acceptable linearity, good precision, with RSD values <10% for both compounds, and it is sufficiently sensitive to detect ng/L levels. HS-SPME was compared with liquid-liquid microextraction (US Environmental Protectio n Agency Method 551.1) for the analysis of spiked ultrapure and granular ac tivated carbon filtered water samples. There was good agreement between the results from both methods. Finally, the optimized procedure was applied to determine both compounds at the Barcelona water treatment plant (N.E. Spai n). Cyanogen chloride in treated water was <1.0 mug/L and cyanogen bromide ranged from 3.2 to 6.4 mug/L. (C) 2000 Elsevier Science B.V. All rights res erved.