Isotope dilution mass spectroscopy (IDMS)/ICP-MS combined with microchip solvent extraction was successfully for the online determination of copper in an aluminum alloy. The microchip solvent
extraction was developed for the separation of Cu from major element, and optimal pH range was wider
than that of the batch wise extraction method. The dimensions of the microchip were 30mm×70mm
and that of micro-channel on the microchip was 180_mwide and 40_mdeep. The copper complex with
8-hydroxyquinoline was extracted into o-xylene at pH 5.5 and back extracted with 0.1 mol l−1 nitric acid
at flow rate of 20_l min−1. The total extraction efficiency (water/organic solvent/nitric acid) was around
40%. IDMS/ICP-MS was coupled with solvent extraction for precise determination of Cu. The extraction
and back-extraction on the microchip took about 1 s and the total measurement time for the IDMS/ICP-MS was about 40 s/sample. The blank value of this method was 0.1 ng g−1. The proposed method was used for the determination of Cu in Al standard materials (JSAC 0121-C, The Japan Society for Analytical Chemistry and 7074 Al alloy, Nippon Light Metal Co. Ltd.). The obtained analytical results are in good agreement with the certified values.