Fresenius J Anal Chem (1990) 337:721 -728 Fresenius' Joumal of @ Springer-Verlag 1990 Applications of ICP-MS in marine analytical chemistry J. W. McLaren, K. W. M. Siu, J. W. Lam, S. N. Willie, P. S. Maxwell, A. Palepu*, M. Koether**, and S. S. Berman Analytical Chemistry Section, Chemistry Division, National Research Council of Canada, Ottawa, Ontario K1A OR9, Canada Summary. The versatility of ICP-MS in marine analytical chemistry is illustrated with applications to the multielement trace analysis of two recently released marine reference mate- rials, the coastal seawater CASS-2 and the non-defatted lobster hepatopancreas tissue LUTS-I, and to the determina- tion of tributyltin and dibutyltin in the harbour sediment reference material PACS-I by HPLC-ICP-MS. Seawater analyses were performed after separation of the trace elements either by adsorption on immobilized 8-hydroxy- quinoline or by reductive coprecipitation with iron and pal- ladium. Simultaneous determination of seven trace elements in LUTS-1, including mercury, by isotope dilution ICP-MS, was achieved after dissolution by microwave digestion with nitric acid and hydrogen peroxide. Butyltin species in PACS- 1 were separated by cation exchange HPLC of an extract of the sediment; method detection limits for tributyltin and dibutyltin in sediment samples are estimated to be 5 ng Sn/ g and 12 ng Sn/g, respectively. Introduction Since the inception of the National Research Council of Canada (NRCC) Marine Analytical Chemistry Standards Program (MACSP) in 1976, a major portion of the research capacity of our laboratory has been devoted to the develop- ment of methods for the determination of trace elements in marine samples, and the production of a family of marine reference materials including both fresh and saline natural waters, marine sediments, and biological tissues. The addi- tion of inductively coupled plasma mass spectrometry (ICP- MS) to our existing array of techniques for inorganic trace analysis in 1984 has made a considerable impact on MACSP. In some cases, the effect has been the replacement of a formerly used method by virtue of the superior performance of ICP-MS. For example, ICP-MS has largely supplanted inductively coupled plasma atomic emission spectrometry (ICP-AES) for the determination of trace elements in natural water samples because of its much superior detection power. The capability of ICP-MS for isotope ratio determinations has also been heavily exploited in our laboratory in the performance of isotope dilution analyses formerly carried out by spark source mass spectrometry (SSMS). In other cases, ICP-MS has complemented other techniques in Offprint requests to. J. W. McLaren * Summer assistant 1988 ** Summer assistant 1989 enabling the certification of additional elements for which there were previously an insufficient number of independent methods of adequate sensitivity. For example, ICP-MS data have been combined with results obtained by graphite furnace atomic absorption spectrometry to permit the certifi- cation of tin concentrations in a number of marine sediments and biological tissues [1]. Another complementary effect has been the use of ICP-MS as a very sensitive and selective detection technique for high performance liquid chromatog- raphy (HPLC) to address questions of chemical speciation, for selected elements such as arsenic and tin, as, for example, in the determination of arsenic speciation in a dogfish muscle reference material [2]. In this paper the versatility of ICP-MS in marine analyti- cal chemistry is illustrated with three applications carried out in the past year: the determination of 11 trace elements in the coastal seawater reference material CASS-2 after sepa- ration by two preconcentration techniques, the multielement analysis of the non-defatted lobster hepatopancreas tissue LUTS-I, and the quantitation of tributyltin and dibutyltin in the harbour sediment reference material PACS-1 by HPLC- ICP-MS. Experimental Instrumentation A Perkin-Elmer SCIEX (Thornhill, Ont., Canada) in- ductively coupled plasma mass spectrometer was used for all of the work. Samplers and skimmers were either the all- nickel or Pt-tipped nickel type provided by the manufac- turer; sampler and skimmer orifice sizes in either case were 1A4mm and 0.89 ram, respectively. Standard operating conditions for aqueous sample introduction were as follows: plasma Ar, 12 1 rain-l; auxiliary Ar, 2 1 rain-l; nebulizer Ar, 0.9 1 rain-l; R. F. forward power, 1.2 kW; sampling depth, 15 mm from the top of the load coil. Thermal mass flow controllers were used for both the nebulizer and auxili- ary gas flows. The instrument has been fitted with the "organics kit" (offered as an accessory by the manufacturer), which includes a thermostatted nebulizer spray chamber. A glass concentric nebulizer (Model TR-30-C2, J. E. Meinhard Associates, Santa Ana, CA, USA) was used throughout this work. The HPLC system used for the tin speciation work consisted of two dual-piston reciprocating pumps (Waters Model 6000), a gradient controller (Waters Model 680), a valve injector (Rheodyne Model 7125) with either a 100 gl or 200 gl loop, and a 10 ~tm strong cation exchange column