A versatile solid-phase extraction method using InertSep ME-2 for simultaneous analysis of covering medium to heavy mass trace elements in diverse water matrices.

Simultaneous analysis of trace elements within one running time of preconcentration allows accurate assessment of their transport and distribution, as these elements serve as critical geochemical tracers in natural water systems. In this study, a solid-phase extraction method using InertSep ME-2 resin coupled with ICP-MS was developed for the preconcentration and analysis of trace metals and rare earth elements (REEs). Adapting and optimizing calibration strategies: internal standard and bracketing standard (BS) methods were applied to compensate for matrix effects across a wide range of salinity and ionic strength. Notably, the BS-method enables simultaneous analysis within one running time of preconcentration using only 50 mL of sample, covering medium to heavy-mass elements across the periodic table and allowing evaluation of possible element fractionation behavior during the analytical process. Major ions (Mg, Ca, Na, and K) were effectively removed by InertSep ME-2 resin, with removal approaching 100%, minimizing matrix interference during ICP-MS analysis. The BS-method demonstrated good analytical performance, with repeatability and intermediate precision below 3-5 % relative standard deviation. Recoveries were close to quantitative (∼95-105%), and method accuracy was validated using certified reference materials (NASS-7 and NMIJ 7204-a), showing good agreement with reported values. The method was successfully applied to natural waters along a river-groundwater-submarine groundwater discharge-seawater continuum in Toyama Bay, revealing clear variations in trace element distributions across hydrologically connected environments. This approach provides a robust and efficient strategy for simultaneous multi-element analysis across diverse water matrices.