Laser-enhanced ionisation spectrometry following matrix modification by automated chelation chromatography for the analysis of biological and environmental reference materials

Abstract

Trace metal analysis of biological and environmental materials by laser-enhanced ionisation (LEI) spectrometry is hampered by measurement interferences caused by high levels of alkali and alkaline earth elements. The use of chelation chromatography to remove the interfering elements from samples prior to analysis is demonstrated, and results from the use of an automated chelation chromatography system are presented. Using this procedure, LEI spectrometry has been utilised for the determination of trace metals in biological and environmental samples. The performance of LEI for the certification analysis of six National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs) is described. The reference materials analysed and the elements determined include: Cd, Co, Cu, Mn, Ni and Pb in Trace Metals in Water (SRM 1643b); Mn and Ni in Inorganic Constituents in Bovine Serum (SRM 1598); Ni and Pb in Buffalo River Sediment (SRM 2704); Cu, Mn and Ni in Total Diet (Proposed SRM 1548); Mn and Ni in Apple Leaves (Proposed SRM 1515); and Mn and Ni in Peach Leaves (Proposed SRM 1547). The concentrations of the elements determined in SRM 1643b ranged from 20 to 47 ng g^–1, in SRM 1598 they were 3.87 and 0.76 ng g^–1, in SRM 2704 45.7 and 154.4 µg g^–1, in proposed SRM 1548 2.43, 5.04 and 0.41 µg g^–1, in proposed SRM 1515 54.9 and 0.97 µg g^–1 and in proposed SRM 1547 98.4 and 0.74 µg g^–1. Precisions ranged from 0.8% relative standard deviation (RSD) for Co in SRM 1643b at a concentration of 26.0 ng g^–1 to 36% RSD for Ni in SRM 1598 at a concentration of 0.76 ng g^–1.