OSMIUM (ATOMIC ABSORPTION, DIRECT ASPIRA

2.1 Prior to analysis by Method 7550, samples must be prepared for direct aspiration. The method of sample preparation will vary according to the sample matrix. Aqueous samples are subjected to the acid digestion procedure discussed in this method. Sludge samples are prepared using the procedure described in Method 3050. For samples containing oils, greases, or waxes, the procedure described in Method 3040 may be applicable. Due to the very volatile nature of some osmium compounds, the applicability of a method to a sample must be verified by means of spiked samples or standard reference materials, or both. 2.2 Following the appropriate dissolution of the sample, a representative aliquot is aspirated into a nitrous oxide/acetylene flame. The resulting absorption of hollow cathode radiation will be proportional to the osmium concentration. Background correction must be employed for all analyses. 2.3 The typical detection limit for this method is 0.3 mg/L; typical sensitivity is 1 mg/L.