Measurement of trace elements and phosphorus in marine animal and plant tissues by low-volume microwave digestion and ICP-MS

The measurement of trace elements and phosphorus in marine biological tissu es by ICP-MS after low-volume closed-vessel microwave digestion with nitric acid is described. Variations in final nitric acid concentration (0-6%, v/ v) of digests caused a decrease in ICP-MS signal only for Zn and Se. Polyat omic interferences from Ca, Na, K, Mg, P, S, Cl, and C at levels expected i n marine tissues were investigated. Isotopes of Cr, V, Fe, Co, Ni, Cu, Zn, Cd, As, and Se are likely to suffer from interferences. Choosing alternativ e isotopes for most elements can minimize potential interferences. Eleven C RMs were analyzed: BCR CRM 414 Plankton, IAEA 140/TM Fucus, NIES No. 9 Sarg asso Seaweed, IAEA-MA-A-1 Copepods, NIST SRM 1566a Oyster Tissue, AGAL-3 Pr awn, NRCC Tort-1 Lobster Hepatopancreas, AGAL-2 Shark, IAEA MA-A-2 Fish Fle sh, NRCC DOLT-1 Dog Fish Liver, NIST CRM 50 Albacore Tuna. Acceptable conce ntrations were obtained for P, V, Mn, Fe, Cr, Co, Ni, Cu, Zn, As, Se, Ag, C d, and Pb. There was little indication of - interference from CI on As and Se or from Ca on Co. Sb concentrations were in general agreement with certi fied concentrations, but variability in certified concentrations are large, thus not allowing a rigorous comparison to be made. Cr concentrations are also in general agreement with certified concentrations when isotopic mass counts are corrected for carbon and/or chloride interferences. Hg values ar e consistently overestimated and variable as the CRM concentrations are nea r the instrumental limit of detection.