Determination of Sub-ppb Cadmium in Urine by Solid-Phase Extraction and Inductively Coupled Plasma-Mass Spectrometry

In order to determine low levels of Cd in urine samples, we tried to remove Mo interference using ICP-MS with a dynamic reaction-cell technique, but failed due to the low sensitivity and the variance with the standards. We then performed solid-phase extraction (SPE) before the ICP-MS measurement. A commercially available chelating resin, NOBIAS PA-1, was used for SPE, and could effectively remove Mo from urine samples, permitting the accurate determination of Cd by ICP-MS. This SPE-ICP-MS method gave 0.012 µg Cd L-1 as the method limit of quantification, and the mean recovery of Cd spiked with 0.0505 and 5.05 µg L-1 was 93.1 and 97.6%, respectively.