An Environmentally Friendly Method for As, Cd, Cr, Cu, Ni, and Pb Determination in Terrestrial Moss Samples Using Ultrasonic Slurry Sampling Combined with Electrothermal Atomic Absorption Spectrometry

Abstract

Novel ultrasonic slurry sampling methods combined with the ETAAS determination of As, Cd, Cr, Cu, Ni, and Pb in terrestrial moss samples were developed without using corrosive acids. A pulverized moss sample between 1 to 50 mg (depending on element concentration) was placed into a 2.5 mL autosampler cup with 2 mL of HNO3 (0.2 M), containing 0.01% of Triton X-100 reagent. The sample was then sonicated directly into the autosampler cup, using an ultrasonic probe at 85% power setting of 7 W for 25 seconds before injection. Chemical modifiers were introduced directly into the graphite tube after sample introduction. An amount of 3 mu g of Mg(NO3)(2) and 5 mu g of Pd was used as the chemical modifier for the As and Cu determination; 70 mu g of NH4H2PO4 and 4 mu g of Mg(NO3)(2) for Cd and Pb determination; and 20 mu g of Mg(NO3)(2) for Cr. Nickel (Ni) was determined without the addition of a chemical modifier. The methods were sensitive and precise, resulting in LODs of 51.3, 4.2, 94.4, 57.0, 124.7, 50.5 ng g(-1) for As, Cd, Cr, Cu, Ni and Pb, respectively, and RSDs of <10%. The accuracy was evaluated using certified reference materials GBW 07604 Poplar Leaves and Pseudoscleropodium purum (M2 and M3), and the results obtained were in good agreement with the certified values for all the elements studied. The developed method was applied for element determination in real moss samples and to the best of our knowledge, no studies have previously reported trace element determination in moss samples using this methodology.