Validation of Methods for Determining Elements in Solid Waste by Microwave Digestion

Abstract

The techniques which are typically used to prepare RCRA wastes for analysis for metals and other elements are generally relatively time consuming, requiring several hours to several days to complete. They also often involve the use of acid digestions and thermal decomposition steps which may result in analyte losses, incomplete recoveries, or sample contamination. These limitations are well known to the analytical community and to the end users of these data in EPA, States, and industry. The resulting inefficiency of these techniques reduces laboratory sample throughput, drives up the cost of analytical testing, and impedes decision making. Given these concerns, the OSW Methods Section is interested in developing cost effective sample preparation techniques for metals and other elements in environmental and process waste samples. Once developed, these techniques can then be written as methods for inclusion in Test Methods for Evaluation of Solid Waste SW-846 and made available to the user community. This paper reports on the evaluation of a microwave assisted sample preparation method for determining elements in solid waste. The Method was evaluated for microwave digestion of sediments, sludges, soils, and oils.

Selenium deficiency risk predicted to increase under future climate change

“…The samples were microwave-digested based on method 3051A ( 64 , 65 ). Aliquots of 100–200 mg samples and a ratio of 4 mL HNO 3 to 1 mL H 2 O 2 and 1 mL H 2 O were added to15-mL polytetrafluoroethylene (PTFE) containers and were digested at high pressure (180 bar) and high temperature (250 °C) in an UltraCLAVE 4 microwave (Milestone Inc.).…”

Autoclave decomposition method for metals in soils and sediments

“…During the depositional process in aquatic environment, oxides and hydroxides of Fe, Mn, and Al often trap trace metals, which are subsequently accumulated as hydroxides. The estimation of metal concentrations in sediments often depends on the type of digestion procedures used for extracting the metals (Binstock et al 1991;Medved et al 1998;Pérez Cid et al 2002;Wanekaya et al 2002;Arslan and Tyson 2008). Normally, for total digestion of metals (e.g., Pb, Cu, Zn, Mn, Cd, Co, Ni, etc.,) HF is often used to extract the complete matrix.…”

Digestion of Titanium Bearing Geologic Materials Involving Microwaves

“…The interference caused by phosphate ions in many of the analytical procedures has somewhat limited their use for dissolving the samples. A number of reports citing microwave energy for the dissolution of geological samples [9][10][11][12][13][14][15] have been a major advance in geochemical analysis. A large number of papers [16][17][18][19][20][21] have studied the dissolution of refractories present in geological matrices but with partial success.…”