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Methods for the reduction of matrix interferences in trace element determinations
Methods for the determination of trace elements in interfering matrices were developed. The methods involve two strategies for the reduction of interferences: the use of new pretreatment methods for use with existing instrumentation, and the development of new instrumentation. A comparison was made of inductively coupled plasma-mass spectrometry (ICP-MS) detection limits and interference reduction for arsenic by hydride generation, flow injection, continuous aspiration, and mixed gas methods. Practical considerations in implementing these common techniques, as well as in the general use and maintenance of an ELAN 5000 ICP-MS instrument are presented for the benefit of new users. Two approaches for the elimination of interferences in the determination of arsenic in gold by ICP-MS. The main challenges in this analysis were the arsenic signal suppression by gold and the polyatomic interference due to chloride. A method was developed for the batch mode reductive precipitation removal of interfering gold matrix from the sample prior to hydride generation and detection of arsenic. This method has great potential value as the basis for other simple methods for the removal of transition metals that interfere with hydride generation. An on-line anion exchange method for the removal of interfering gold prior to hydride generation was subsequently developed to improve the speed of analysis. The batch-mode reduction method for the removal of gold resulted in a better detection limit than the anion exchange method. However, the automated anion exchange gold removal method required less bench chemistry, was faster, consumed less reagents, and created less mess than the off-line method. On-line solid phase extraction methods are a valuable and increasingly popular method for the removal of matrix interferences. The automation of sample pretreatment as well as the small sample size required when the technique is combined with flow injection make it ideal for use in the analysis of hazardous materials. The severe signal suppression of uranium on lithium, beryllium, magnesium, and aluminum was overcome by the on-line flow injection-solid phase extraction removal of uranium using a column packed with Tru-Spec resin. The column was regenerated on-line using ammonium oxalate. The development of an internal combustion engine as a novel source for atomic emission spectrometry was begun. This preliminary stage of development focused on the identification of important experimental parameters to be considered in future work. A one cylinder four stroke engine was modified to allow optical access through the cylinder head. Combustion radiation was monitored with a photomultiplier tube and the signal was stored using LabView software. It is hoped that this work will be the basis for the development of an inexpensive, portable, rugged instrument that will accept a variety of fuels.
Becotte-Haigh, Paul Edward, "Methods for the reduction of matrix interferences in trace element determinations" (1997). Doctoral Dissertations Available from Proquest. AAI9737503.