Comparison of three different sample preparation procedures for the determination of traffic-related elements in airborne particulate matter collected on glass fiber filters

Abstract

Three different procedures for sample preparation have been compared for the determination of Cu, Mo and Sb in airborne particulate matter (APM) collected on glass fiber filters using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). Direct solid sample analysis of the ground filters was compared with microwave-assisted acid leaching with aqua regia and ultrasound-assisted extraction also using aqua regia. The main absorption line at 324.754nm or the secondary line at 216.509nm was used for the determination of Cu, depending on the analyte content in the samples. The primary absorption line at 313.259nm was used for Mo and the secondary line at 212.739nm for Sb determination. The limits of detection (LOD, 3σ) found for the direct solid sampling method, based on ten atomizations of an unused filter were 15μgg−1 for all three analytes, corresponding to 40ngm−3 for a typical air volume of 1440m3 collected over a period of 24h. The LOD for the other two methods were less than a factor of two inferior, but the total time required for an analysis was significantly longer. The repeatability of the measurements was between 3 and 9% (n=5), and the results obtained with the three methods did not show any significant difference. The ratio between the three analytes on the filters from areas of intense traffic was found to be around Cu:Mo:Sb≈4:1:1.4, which suggests that the source of all three elements is brake linings, i.e., related to automobile traffic. When the ratio deviated significantly from the above values, the source of contamination was assumed to be of different origin.