Determination of parabens in human urine by liquid chromatography coupled with electrospray ionization tandem mass spectrometry
A simple and sensitive method was developed for the simultaneous determination of methyl, ethyl, n-propyl, n-butyl, and benzyl parabens in human urine by liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Enzymatic hydrolysis conditions were optimized to deconjugate the urinary parabens, glucuronide and sulfate conjugates. Solid phase extraction (SPE) was then used for sample clean-up. LC-ESI-MS/MS conditions for sample analysis were also optimized to achieve the maximal sensitivity and accuracy. Parabens were finally separated on a C8 reversed phase column. Correlation coefficients (R2) and recoveries ranged from 0.998 to 0.999 and 80.6% to 95.6%, respectively, and intra-day and inter-day precisions (relative standard deviation, RSD) were within 1.2–4.5% and 2.2–7.1%, respectively. Limits of detection (LODs) for methyl, ethyl, n-propyl, n-butyl, and benzyl parabens were 3, 3, 3, 3, and 1 pg, respectively. The optimized method was successfully used to determine parabens in urine samples from school students in Southern China.