[Determination of perchlorate in human urine by cold-induced liquid-liquid extraction coupled with ultra-performance...

To develop a rapid analytical method based on cold-induced liquid-liquid extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry (CI-LLE-UPLC-MS/MS) for the determination of perchlorate in human urine.

After spiking urine samples with stable isotope-labeled internal standards, the samples were centrifuged with a mixture of acetonitrile and water (60∶40, V/V) and then kept at -40 ℃ for 30 min. The supernatant was diluted tenfold with acetonitrile and separated on a Poroshell 120 PFP column (50 mm×2.1 mm, 1.9 μm) with a gradient elution of methanol and 1% acetic acid aqueous solution. Perchlorate was quantified by UPLC-MS/MS using the internal standard method.

The method exhibited good linearity (coefficient of determination R2>0.999), with a detection limit of 0.3 μg/L and a quantification limit of 1.0 μg/L. The average recoveries at low, medium, and high spiked levels were 101.2%-106.7%, and the intra-day and inter-day relative standard deviations were both less than 5%(n=6). The determination result of perchlorate in the human urine standard reference material (SRM 3668) were (2.75±0.11) and (13.67±0.34) μg/L, both within the reference ranges. Analysis of 243 real urine samples from China revealed a 100% detection rate for perchlorate, with concentrations ranging from 1.91 to 87.41 μg/L and a median value of 18.74 μg/L.

The method features simple pretreatment, rapid detection, and high sensitivity, precision, and accuracy, making it suitable for large-scale detection of perchlorate in human urine.