Automated matrix separation and preconcentration for the trace level determination of metal impurities in ultrapure inorganic salts by high-resolution ICP-MS

A rapid and simple analytical method for the determination of transition me tals and rare earth elements at sub-ng/g levels in alkaline and earth alkal ine salt matrices was developed. Automated solid-phase extraction was utili zed for matrix separation and analyte preconcentration from highly concentr ated brine solutions. The HPLC system used was equipped with a chelation co lumn packed with an iminodiacetate-based resin. Detection was accomplished by means of high-resolution inductively-coupled plasma mass spectrometry (I CP-MS), which allowed quasi-simultaneous multi-element determinations. A mi croconcentric nebulizer was employed for HR-ICP-MS to determine the element s of interest in small volumes of sample extracts. The method was shown to be very sensitive with limits of quantification in the range of 1-40 ng/g f or all investigated elements. The method exhibited excellent precisions, hi gh analyte recoveries, linear responses of least three orders of magnitude, high accuracy and low contamination susceptibility. A comparison of automa ted solid-phase extraction with methodologies utilizing traditional liquid- liquid extraction showed that the former offered similar analytical perform ance but was clearly easier to use and faster to perform, resulting in subs tantial time, labor and cost savings.