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Critical evaluation of a seaFAST system for the analysis of trace metals in marine samples

Citation

Wuttig, K and Townsend, AT and van der Merwe, P and Gault-Ringold, M and Holmes, T and Schallenberg, C and Latour, P and Tonnard, M and Rijkenberg, MJA and Lannuzel, D and Bowie, AR, Critical evaluation of a seaFAST system for the analysis of trace metals in marine samples, Talanta, 197 pp. 653-668. ISSN 0039-9140 (2019) [Refereed Article]

Copyright Statement

Copyright 2019 Elsevier B.V.

DOI: doi:10.1016/j.talanta.2019.01.047

Abstract

A seawater preconcentration system (seaFAST) with offline sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) detection was critically evaluated for ultra-low trace elemental analysis of Southern Ocean samples over a four-year period (20152018). The commercially available system employs two Nobias PA1 resin columns for buffer cleaning and sample preconcentration, allowing salt matrix removal with simultaneous extraction of a range of trace elements. With a primary focus on method simplicity and practicality, a range of experimental parameters relevant to oceanographic analysis were considered, including reduction of blank levels (over weeks and years), instrument conditioning, extraction efficiencies over different pH ranges (5.86.4), and preconcentration factors (~1070 times). Conditions were optimised for the analysis of ten important trace elements (Cd, Co, Cu, Fe, Ga, Mn, Ni, Pb, Ti and Zn) in open ocean seawater samples, and included initial pre-cleaning and conditioning of the seaFAST unit for one week before each separate analytical sequence; a controlled narrow buffer pH of 6.20  0.02 used for extraction; and a sample preconcentration factor of 10 for (relatively) concentrated rainwater or sea ice, 40 for typical seawater samples, and up to 67 times for seawater samples collected in the remote open ocean such as the Southern Ocean.

Method accuracy (both short days to weeks - and long term months to years) were evaluated through extensive analysis of a range of oceanographic standard reference samples including SAFe D1 (n = 20), D2 (n = 3), S (n = 15), GEOTRACES GD (n = 6), GSC (n = 42) and GSP (n = 42), as well as NASS-6 (n = 6). Measured values for oceanographic samples were found to agree with consensus values to within  6% for Cd, Cu, Fe, Ni, Pb and Zn. Offsets were noted for Co (labile fraction only; no UV oxidation), Mn (difference also noted in other recent studies) and Ti (limited reference values). No consensus values currently exist for Ga. Iron and Mn in Southern Ocean samples were also independently verified via flow injection analysis methods (R2 = 0.95, n = 244 (Fe) and 0.92, n = 85 (Mn), paired t-test, p ≪0.05). Precisions over four years were evaluated through analysis of community seawater samples as well as a range of bulk in-house seawaters (3 sources, each n~100) and acid blanks (n = 250), and were typically found to be within 58%, depending on analyte and concentration.

Values presented here represent one of the largest independent data sets for these reference samples, as well as the most documented comprehensive suite of GSP and GSC values currently available (consensus values have not yet been released). Samples covering a range of salinities (060) were investigated to demonstrate method versatility, with excellent recoveries noted using the seaFAST Nobias PA1 column (>98% for most elements, with 7080% for Ga and Ti). By way of example, data is presented showing the application of the method to samples collected on the Kerguelen plateau in the Indian sector of the Southern Ocean (HEOBI voyage, January-February 2016) and in land-fast ice and brine collected near Davis station, Antarctica, in austral summer 2015 (with a salinity range from 0 to 73 g kg−1). Finally, a range of recommendations for successful implementation of a seaFAST system are provided, along with considerations for future investigation.

Item Details

Item Type:Refereed Article
Keywords:trace metals, seawater, seaFAST preconcentration system, sea ice and brines, SF-ICP-MS, GEOTRACES
Research Division:Chemical Sciences
Research Group:Analytical Chemistry
Research Field:Instrumental Methods (excl. Immunological and Bioassay Methods)
Objective Division:Environment
Objective Group:Physical and Chemical Conditions of Water
Objective Field:Physical and Chemical Conditions of Water in Marine Environments
UTAS Author:Wuttig, K (Dr Kathrin Wuttig)
UTAS Author:Townsend, AT (Associate Professor Ashley Townsend)
UTAS Author:van der Merwe, P (Dr Pier van der Merwe)
UTAS Author:Gault-Ringold, M (Dr Melanie East)
UTAS Author:Holmes, T (Mr Thomas Holmes)
UTAS Author:Schallenberg, C (Dr Christina Schallenberg)
UTAS Author:Latour, P (Miss Pauline Latour)
UTAS Author:Tonnard, M (Miss Manon Tonnard)
UTAS Author:Lannuzel, D (Associate Professor Delphine Lannuzel)
UTAS Author:Bowie, AR (Professor Andrew Bowie)
ID Code:130970
Year Published:2019
Web of Science® Times Cited:6
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2019-02-23
Last Modified:2019-06-13
Downloads:0

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