The gas chromatographic (GC) and Fourier transform infrared and mass spectroscopic (FT-IR and MS, respectively) properties of (Z)-2-chloro-3-(dichloromethyl)-4-oxobutenoic acid (MX) a highly mutagenic byproduct of drinking water chlorination) and several related compounds were studied. Specifically, MX, the methyl ester of MX (MX-OMe), and three MX-model compounds [mucochloric acid (MCA), mucobromic acid (MBA), and 2,4-(3H,5H)-furandione (24FD)] were analyzed on our GC/FT-IR and GC/MS systems. A concentration study of MX on the GC/FT-IR system reveled a minimum identifiable quantity of approximately 10 ng, with linear response over the range of 10 to 600 ng. MX was stable to approximately 260ÀC. The thermal decomposition product produced above that temperature was tentatively identified by GC/MS as 2-(dichloromethyl)-3-chloro-2-propenal. The GC/FT-IR detector response for 600 ng of MX was compared to that of 600 ng of MX that had been methylated. The ratio of the detector responses indicated that the methylation efficiency was, at best, 40%. Additionally, several extracts of chlorinations of dissolved organic material (DOM) were analyzed by GC/FT-IR nd GC/MS. No MX was detected in any of these extracts. The approximate extraction efficiencies of MX and MCA were determined for several organic solvents, of which ethyl acetate was the most efficient for both compounds. A direct aqueous injection of the water fraction from a DOM chlorination study was made on the GC/FT-IR system. Only simple aliphatic acids were detected. A preliminary alkaline hydrolysis study was undertaken with MCA at a reaction pH of 9.6 at 85ÀC. No MCA was detected after 1 hour.