Automated on-line column-switching HPLC-MS/MS method for the quantification of triclocarban and its oxidative metabolites in human urine and serum.

3,4,4'-Trichlorocarbanilide (triclocarban, TCC) is widely used as an antimicrobial agent in a variety of consumer and personal care products. Because of its widespread use, the potential for human exposure to TCC is high. Human exposure to TCC may be assessed by measuring the concentrations of conjugated or free species of TCC and its two oxidative metabolites, 2'-hydroxy-TCC (2'-OH-TCC) and 3'-hydroxy-TCC (3'-OH-TCC), in urine or serum. To assess human exposure to TCC, we developed a method that uses restricted access materials (RAM) on-line solid phase extraction (SPE) coupled to high performance liquid chromatography-isotope dilution tandem mass spectrometry with peak focusing (HPLC-MS/MS). Sample clean-up by RAM relies on both size exclusion chromatography, to remove the high-molecular matrix components, and reversed phase partition, to extract and pre-concentrate the target analytes. TCC, 2'-OH-TCC and 3'-OH-TCC present in urine or serum were concentrated on the RAM SPE column, back-eluted from the SPE column, diluted through a mixing tee for peak focusing, separated by HPLC, and detected by isotope dilution-MS/MS. The method required a small amount of sample (50 μL) and minimal sample pretreatment. The limits of detection (LOD) ranged from 0.01 to 0.1 ng/mL. The method was applied to measure TCC and its metabolites in 158 urine and 16 serum samples collected from adults with no known exposure to TCC. TCC was detected in 35.4% of the urine samples (range: <LOD to 401 ng/mL). This sensitive method is rugged as well as labor- and cost-effective, and allows for the analysis of a large number of samples for epidemiological studies.