Development of matrix-matching hydroxyapatite calibration standards for quantitative multi-element LA-ICP-MS analysis: application to the dorsal spine of fish

Abstract

A series of hydroxyapatite pellets were produced to use as matrix-matched standards for LA-ICP-MS analysis of trace metals in the first dorsal spine of tuna fish species (albacore tuna, Thunnus alalunga, and Atlantic bluefin tuna, Thunnus thynnus). These structures are interesting because they present growth rings and therefore could potentially be used as indicators of environmental pollution. The produced standards containing twelve analytes (Mg, Al, V, Mn, Zn, As, Sr, Rb, Cd, Ba, Hg and Pb) were prepared by co-precipitation of hydroxyapatite from calcium nitrate tetrahydrate and ammonium dihydrogen phosphate. Once synthesized, the concentration of the analytes in the standards was carefully determined in the laboratory and recoveries for the analytes were calculated. The hydroxyapatite enriched standards were found to be homogeneous and provided a linear calibration (correlation coefficients were better than 0.991 for most of the analytes). The methodology was applied to the determination of trace element concentration profiles in cross-sections of tuna fish dorsal spines. Limits of detection were estimated between 1.4 ng g⁻¹ for cadmium and 751 ng g⁻¹ for aluminium. The measured values for Mg, Zn, Sr and Pb in pelletized SRM 1486 Bone Meal were in good agreement with certified reference values.