Multi-element analysis of bread, cheese, fruit and vegetables by double-focusing sector-field inductively coupled plasma mass spectrometry

Abstract

An analytical method using double-focusing sector-field ICP MS was developed for the routine simultaneous multi-element analysis for essential and toxic elements (Ag, Al, As, Cd, Co, Cr, Cu, Fe, Hg, In, Li, Ni, Mn, Mo, Pb, Si, Sb, Se, Sn, V and Zn) in different food samples (bread, cheese, fruit and vegetables). Samples were hot-plate digested with a mixture of concentrated HNO₃ and H₂O₂. Interfering ions involving matrix constituents were detected for several elements at the resolution of 300 (typical for a quadrupole analyzer) and could be separated at the 4000 and 10 000 resolution. The method was validated by the analysis of certified reference materials: wheat flour (NIST 1567a), non-fat milk powder (NIST 1549) and brown bread (BCR-IRMM 191). The method used in our laboratory over the period of one year for the analysis of over 300 samples showed a typical interday precision of 3–5% and intraday precision of 5–10% for virtually all the elements and investigated matrices.