HIGHLY SELECTIVE DETERMINATION OF MACROMOLECULAR CHLOROLIGNOSULFONIC ACIDS IN RIVER AND DRINKING-WATER USING CURIE-POINT PYROLYSIS-GAS CHROMATOGRAPHY TANDEM MASS-SPECTROMETRY

A highly selective pyrolysis-gas chromatography-tandem mass spectromet ry (Py-GC-MS-MS) procedure for the quantitative determination of high molecular weight (MW > 1000) chlorolignosulfonic acids in river and dr inking water is presented. The use of MS-MS considerably enhanced the selectivity toward 2-methoxy-5-chlorophenol (5-chloroguaiacol; a highl y characteristic pyrolysis product of chlorolignosulfonic acids) as co mpared to SIM conditions. The dissociation of the parent ion at m/z 14 3 (C6H4ClO2+) into the daughter ion at m/z 115 (C5H4ClO+, loss of CO) was monitored due to its high selectivity in the complex pyrolysates. Standard addition quantification appeared to be mandatory due to a str ong matrix dependency of the pyrolysis efficiency of 5-chloroguaiacol from the chlorolignosulfonic acids. A repeatability of 5% RSD (n = 5) was obtained for a prepurified drinking water sample. The detection li mit of the procedure is 0.5 mu g/L (S/N = 3) of chlorolignosulfonic ac ids in drinking water and has been decreased by a factor of 60 as comp ared to the former Py-GC-MS-SIM procedure. The CLSA concentrations in the river Rhine have decreased strongly during the past 5 years, leadi ng to CLSA concentrations of ca. 26 mu g/L at present. It was found th at the waterworks WRK [which produces prepurified drinking water using coagulation with Fe(III)Cl-3 and rapid sand filtration] showed an ave rage water purification efficiency of CLSA of 51%; S-x = 27%. The wate rworks GWA (which produces finished drinking water using among others ozonization combined with biological active carbon filtration) showed a purification efficiency of 92-93% for CLSA, which resulted in low (0 .6-0.8 ug/L) concentrations of CLSA in drinking water of the city of A msterdam. The analytical strategy for the selective and quantitative d etermination of CLSA can possibly be applied to other synthetic polyme r classes in water.