Heavy metals in powder-based cosmetics quantified by ICP-MS: an approach for estimating measurement uncertainty

Abstract

A method based on microwave digestion and high resolution mass spectrometry was developed for the determination of Cd, Co, Cr, Ni and Pb in powder cosmetic samples. The procedure was validated in-house at the native concentration found in the cosmetic and at three fortification levels. Measurement uncertainties were calculated using data generated from repeatability, recovery and calibration linearity studies. The mean repeatability estimates were ≤11% for Cd, Co, Ni and Pb and ≤25% for Cr. The average recoveries ranged between 70% (Cr) and 112% (Pb). The expanded uncertainties (k = 2) of the method were between 34% (Cd) and 63% (Cr) at the native concentration and from 14% (Cd and Pb) to 34% (Cr) at the highest fortification level. The results accompanied by their uncertainty statements in the powder cosmetic were as follows (in mg kg⁻¹): Cd, 0.026 ± 0.009; Co, 1.61 ± 0.60; Cr, 3.00 ± 1.88; Ni, 6.87 ± 2.53; Pb, 0.25 ± 0.09.