Liquid Electrode Plasma Atomic Emission Spectrometry Combined with Multi-Element Concentration Using Liquid Organic Ion Associate Extraction for Simultaneous Determination of Trace Metals in Water

Liquid electrode plasma atomic emission spectrometry (LEP-AES) is a compact elemental-analysis method, which requires no plasma gas and no high-power source, and is suitable for on-site portable analysis. In this paper, the LEP-AES is combined with the concentration method using liquid organic ion associate extraction, and a concentration/simultaneous determination method for trace metals (Cu, Mn, Pd, Zn, Cd and Pb) in water is developed. Metals were converted into a complex with a chelating reagent in a 40 mL sample solution, and were extracted into a liquid ion associate during phase formation. The volume of the ion associate was mu L-scale. The ion associate was dissolved with 400 mu L of a 50 vol% methanol + 0.1 M HNO(3) solution, followed by detection by LEP-AES using 40 mu L of the sample. As a results, a liquid organic ion associate extraction enabled a 100-fold enrichment of trace metals, and improved the detection limits (3 sigma) by a few mu L L(-1) - sub mg L(-1). Interestingly, for some metal elements, the magnification of the total sensitivity combined with LEP-AES resulted in more than 1000, which is more than the value of 100-fold for the enrichment. This method was applied to the determinations of Cu, Mn, Zn, Cd and Pb in certified reference materials (Enviro MAT EU-H-1 waste water). The values obtained in this method were nearly equal to the certified values.