Analysis of MCPA and TCP in water by liquid chromatography-ion trap-electrospray tandem mass spectrometry

An HPLC-IT-MS technique with SPE preconcentration was used to determine 2-methyl-4-chlorophenoxy acetic acid (MCPA) and 2,4,6-thrichlorophenol (TCP) in water. The extraction procedure involved sieving 1 L water samples through a 0.5g graphitised carbon black (GCB) extraction cartridge and elution of the analytes using methylene chloride/methanol (80:20v/v) with 10mmolL(-1) formic acid. Under optimised LC-MS/MS and SPE conditions, recoveries of 85-96% were achieved when three water samples were spiked with each acidic compound at concentrations between 50 and 200ngL(-1). RSDs between 2% and 10% were obtained. Excellent linear relationships were observed within 0.02-1 mu g L-1 (solvent calibration) and 0.05-2.5 mu g L-1 (matrix-matching calibration) with linear correlation coefficients greater than 0.99. Detection limits between 3 and 14ngL(-1) were obtained. The method was successfully used to determine MCPA and TCP in water and applied to real samples.