Review of Quartz Analytical Methodologies: Present and Future Needs

Abstract

Abstract A review of analytical methods for the qualitative and quantitative determination of crystalline silica is presented. The three prevalent forms of crystalline silica—quartz, cristobalite, and tridymite—are alluded to. Performance and popularity of present quartz analytical methods such as X-ray diffraction (XRD), infrared (IR) spectroscopy, and colorimetry are illustrated using Proficiency Analytical Testing (PAT) Program data. Although substantial improvements in performance have been made since the 1970s, quartz PAT sample results still continue to display high imprecision (>20% coefficient of variation). Past and present analytical methods are detailed in terms of theory and use, and strengths and weaknesses are discussed. Methods include gravimetric, chemical, microscopic, atomic absorption, XRD, IR, and colorimetry. Methods for determining bulk materials such as thermal analysis and nuclear magnetic resonance are briefly discussed. Results of a survey regarding international use of analytical methods for quartz are displayed. Both in the United States and internationally, the most popular methods are XRD and IR. Performance criteria such as detection limits, precision and accuracy, and potential future trends are shown using international data. Future needs for enhancing quartz analysis, such as a comprehensive evaluation of direct-on-filter techniques, an attempt at consensus for tridymite analysis, a consensus for defining analytical performance parameters for quartz in general, and a continued examination of methods for analyzing bulk materials for quartz, are suggested. Madsen, F.A.; Rose, M.C.; Cee, R.: Review of Quartz Analytical Methodologies: Present and Future Needs. Appl. Occup. Environ. Hyg. 10(12):991–1002; 1995.