Annals of Occupational Hygiene Advance Access originally published online on June 22, 2005
Annals of Occupational Hygiene 2005 49(8):661-671; doi:10.1093/annhyg/mei024
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© 2005 British Occupational Hygiene Society Published by Oxford University Press
Original Article |
Comparison of Direct (X-Ray Diffraction and Infrared Spectrophotometry) and Indirect (Infrared Spectrophotometry) Methods for the Analysis of 
-Quartz in Airborne Dusts
Institut National de Recherche et de Sécurité (INRS), Avenue de Bourgogne, BP27, 54500 Vand
uvre lès Nancy, France
* Author to whom correspondence should be addressed. Tel: +33 (0)3 83502023; fax: +33 (0)3 83502060; e-mail: edmond.kauffer{at}inrs.fr
In this study, the 
-quartz contents measured by different analytical techniques (X-ray diffraction, direct method; and infrared spectrophotometry, direct and indirect methods) were compared. The analyses were carried out on filters sampled in an industrial setting by means of a Dorr-Oliver cyclone. To verify the methodology used, filters loaded with pure -quartz were also analysed. By and large, the agreement between the two direct methods was close on average, but on the basis of a comparison of the individual results, considerable differences exist. In absolute value, the mean relative deviation between the two techniques was <25% in only 47.8% of the cases. The results obtained by the indirect method (infrared) were on average 13% lower than the results obtained by the two direct methods with a more important difference (23%) for samples where calcite was identified by X-ray diffraction in comparison with those where it was not (8%). This underestimation, which was not owing to dust losses during preparation, is probably explained by the elimination of organic compounds during dust calcinations or by the transformation of mineral compounds. The indirect method introduces additional sample handling operations with more risk of material loss. When the quantity of calcined material was <0.4 mg, the weighing operations necessary to correct any losses of material resulted in considerable variability. In terms of overall uncertainty, it would be better in this case not to carry out correction and to employ an operating mode favouring the recovery of a maximum of material while accepting a bias of about 5–7%.
Keywords: direct and indirect methods • infrared • quartz • X-ray diffraction
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