Comparison of Direct (X-Ray Diffraction and Infrared Spectrophotometry) and Indirect (Infrared Spectrophotometry) Methods for the Analysis of α-Quartz in Airborne Dusts

In this study, the α-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 α-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