Determination of trace elements in marine plankton by inductively coupled plasma mass spectrometry (ICP-MS)

Abstract

A method has been developed for the determination of 23 elements in marine plankton in which inductively coupled plasma (ICP) source mass spectrometry (MS) was used to quantify the elements in the solution after digestion in a mixture of hydrofluoric and nitric acids in sealed PTFE vessels in a microwave field. The procedure was validated by the analysis of a standard reference soil (SRM 2709 San Joaquin Soil) and a standard reference fresh water plankton (CRM 414). The method was applied to the analysis of several marine plankton samples grown under controlled conditions including several whose growth media had been enriched with selenium. Matrix induced signal suppressions and instrumental drift were corrected by internal standardization. The suitabilities of germanium, indium, rhodium, scandium and yttrium as internal standard elements were evaluated. Neither scandium nor yttrium could be used due to the presence of these elements in the samples, germanium was used for the determination of As, Co, Cu, Fe, Ni, Se, Si and Zn, indium was used for Al, Ba, Ca, Eu, Sr, and Tl, and rhodium was used for Cd, Cr, Hg, Mg, Pb, Sb, Sn, and V. For Al, Ca, Cr, Cu, Fe, Mg, Mn, Ni, Si, Sr, V, and Zn internal standardization did not completely compensate for the suppressive effect of the heavier elements and the solutions were diluted. However, for As, Ba, Cd, Co, Eu, Hg, Pb, Sb, Se, Sn and Tl, it was possible to obtain accurate results despite the 35-40% suppression in the signals. Isobaric overlap was only a problem in the cases of 42 Ca and 78 Se; 44 Ca and 77 Se, respectively, were used. Memory effects were only observed with Hg for which a nitric acid-sodium chloride solution was the most effective wash-out solution. The marine plankton samples were able to tolerate a higher concentration of Hg as the selenium concentration increased.

The trace metal composition of size‐fractionated plankton in the South China Sea: Biotic versus abiotic sources

“…To reduce the matrix effect caused by silicon (Arslan et al 2000), hydrofluoric acid was not applied in the digestion step. After diluting the digested solution to 10 mL with Milli-Q water and removing the filter, the solution was centrifuged to remove any particulate residues.…”

Trace determination of total mercury in rice by conventional inductively coupled plasma mass spectrometry

“…One challenge is the choice of sample dissolution technique in which the various mercury species are to be solubilised as the inorganic mercury 2+ ion. 22,24 It is well known that mercury is easily volatilised, so samples cannot be heated to high temperatures without analyte loss and this complicates the use of microwave-assisted digestion and hotplate digestions.…”

Slurry sampling for determination of lead in marine plankton by electrothermal atomic absorption spectrometry

“…Plankton are mainly composed of organic material, and to some extent contain silicon which is an essential element for planktonic growth [39,40]. Thus, we investigated the performance of dilute HF as a suspension medium for plankton slurries in addition to water and dilute HNO 3 .…”

“…In the analysis of freshwater plankton for method validation, the slurry concentration was not modified and kept constant at 1% m/v since the concentration of Pb was relatively high. For marine plankton samples, ICP-MS analysis [40] revealed that content of Pb was at least an order magnitude lower than in freshwater plankton; therefore, slurries were made in 3% m/v range to achieve accurate determination.…”

“…The marine plankton (3H) samples had been analyzed by inductively coupled plasma mass spectrometry (ICP-MS) for trace element content for which results were discussed elsewhere [40]. Briefly, the 3H plankton samples were digested in concentrated HNO 3 /HF using microwave-assisted digestion.…”