Determination of trace metal (Mn, fe, ni, cu, zn, co, cd and pb) concentrations in seawater using single quadrupole icp‐ms: A comparison between offline and online preconcentration setups

Abstract

The quantification of dissolved metals in seawater requires pre‐treatment before the measurement can be done, posing a risk of contamination, and requiring a time‐consuming procedure. Despite the development of automated preconcentration units and sophisticated instruments, the entire process often introduces inaccuracies in quantification, especially for low‐metal seawaters. This study presents a robust method for measuring dissolved metals from seawater accurately and precisely using a seaFAST and quadrupole Inductively Coupled Plasma Mass Spectrometer (ICPMS), employed in both offline (2016–2018) and online (2020–2021) setups. The proposed method shows data processing, including the re‐calculation of metals after eliminating the instrumental signals caused by polyatomic interferences. Here, we report the blank concentration of Fe below 0.02 nmol kg−1, somewhat lower values than that have been previously reported using high-resolution and triple‐quad ICPMS. The method allows for the accurate determination of Cd and Fe concentrations in low‐metal seawaters, such as GEOTRACES GSP, using a cost‐effective quadru-pole ICPMS (Cdconsensus: 2 ± 2 pmol kg−1, Cdmeasured: 0.99 ± 0.35 pmol kg−1; Feconsensus: 0.16 ± 0.05 nmol kg−1, Femeasured: 0.21 ± 0.03 nmol kg−1). Between two setups, online yields marginally lower blank values for metals based on short‐term analysis. However, the limit of detection is comparable between the two, supporting optimal instrumental sensitivity of the ICPMS over 4+ years of analysis.