Elemental analysis using ICP-AES, ICP-MS, and electrospray MS detection: A comparative study

Speciation is the determination and quantitation of the different chemical forms of an element of interest. It has become an important area of research in the field of elemental analysis since the toxicity of an element depends on its chemical form and/or oxidation state. By coupling the separation power of high-performance liquid chromatography (HPLC) with the low detectability of inductively coupled plasma mass spectrometry (ICP-MS), speciation information at the sub-nanogram to picogram level is obtained. Chapter One gives an overview of HPLC-ICP-MS work done to date.;Chapters Two and Three discuss the speciation of chromium by anion-exchange liquid chromatography with detection by ICP-AES (atomic emission spectroscopy) and ICP-MS, respectively. Much interest has been placed on the toxicity of chromium compounds because of their widespread use in industrial processes such as steel alloying and leather tanning. Speciation of samples containing chromium is necessary since Cr(III) is an essential trace nutrient, while Cr(VI) is known to induce human lung cancer and cause mutations both in vivo and in vitro. Anion-exchange HPLC was used to separate the species with on-line detection by ICP-AES at 2766 A in preliminary studies, and ICP-MS with single-ion monitoring at m/z 52 and m/z 53 for final work. Excellent linearity and %RSD were obtained with absolute detection limits for both species in the sub-nanogram range.;The second part of the dissertation research involved a comparative study of electrospray mass spectrometry (ES-MS) and ICP-MS for elemental analysis. Currently there is renewed interest in electrospray ionization as an atmospheric pressure ionization source for mass spectrometric detection, and Chapter Four provides the reader with an introduction to the technique.;Studies have shown that ES-MS has significant potential to become a generic ion source for elemental mass spectrometry. Chapter Five discusses the construction of an electrospray source for a mass spectrometer normally utilized as an ICP-MS detector. The quantitative comparison of ES-MS and ICP-MS in Chapter Six provides an interesting look at the characteristics of each ionization source using the same mass spectrometer. In conclusion, Chapter Seven summarizes the results of this research. Potential applications of HPLC-ICP-MS and elemental ES-MS are given.