Development of a Simple and Precise Method to Determine Low Urinary Cadmium Levels by Using Inductively Coupled Plasma-Mass Spectrometry

摘要

Cadmium (Cd), a ubiquitous environmental pollutant, is a carcinogenic substance. Cd in the urine reflects an individual's cumulative exposure and the Cd concentration in the kidney. Inductively coupled plasma-mass spectrometry (ICP-MS) can detect Cd levels at the nanogram per liter level; however, mass spectral interference by molybdenum oxide (MoO) has been observed in biological samples. We developed an analytical method that did not include solid phase extraction ICP-MS (SPE-ICP-MS); rather, it used ICP-MS and octapole collision cell (OCC-ICPMS) technology using helium (He) gas. The measurement mass numbers were ~(111)Cd and ~(98)Mo, and we used ~(103)Rh as an internal standard. Method accuracy was assessed using reference urine (SRM 2670a; National Institute of Standards and Technology, Gaithersburg, MD, USA). The method detection and quantification limits of Cd in the urine were 0.0097 and 0.038 μg/L, respectively. Inter-day accuracy and precision were 100.7-102.4% and 0.9-4.9%, respectively. The analytical values of Cd and Mo in SRM 2670a reference urines obtained by the proposed method were within the allowable errors for the certified values. Significantly correlated Cd concentrations of urine samples from healthy 20 women was found between the present OCC-ICP-MS method and the SPE-ICP-MS method (r = 0.866). ICP-MS analysis using He as a collision gas is useful for determining low urinary Cd levels without requiring pretreatment.