title: Determination of quartz in bulk materials from workplace environments using X-ray diffractometry and the absorption diffraction method.
abstract: A method is described for the determination of crystalline quartz in bulk materials from workplace environments as part of occupational hygiene investigations using X-ray powder diffractometry. The absorption-diffraction model was used for quantification with mass absorption coefficients for samples being experimentally determined using an absorption cell placed in front of the diffracted beam anti-scatter slit. The method was found to be reliable for samples containing from 0.5 to 100 wt.% crystalline quartz, where mass absorption coefficients did not exceed 120 cm(2)g(-1). Repeatability studies found that mass absorption coefficient determinations and crystalline quartz determinations were both generally within 1-2% relative standard deviation. The method was assessed for accuracy and found to be within 2% absolute when a National Institute of Standards and Technology (NIST) quartz certified reference material (SRM1879a) was analysed. The technique was compared to an internal standard procedure and a paired students t test showed that there was no significant statistical difference between the two methods at the 95% confidence level where the t value was found to be 0.40 (p>0.05=0.69) and the t critical value being t(crit,0.05,29)=2.05. The method was suitable for a variety of matrixes including those containing amorphous material and could be routinely applied to most samples of occupational interest.
authors.affiliation: TestSafe Australia - WorkCover NSW, Chemical Analysis Branch, 5A Pioneer Ave., Thornleigh, NSW 2120, Australia. james.hurst@workcover.nsw.gov.au
authors.forename: James A
authors.initials: JA
authors.lastname: Hurst