Comparison of Microwave-Assisted and Conventional Leaching Using EPA Method 3050B

A microwave-heated EPA method 3050B for the leaching of key elements (cadmium, chromium, copper, lead, nickel, zinc) of environmental importance was tested and compared to conventional hot plate-heated EPA method 3050B. All commercially available temperature and power-controlled atmospheric pressure microwave systems were used for the adaptation of EPA method 3050B. Three temperature feedback control systems were evaluated for regulating the temperature of the leachate including outside (IR sensors) and inside the sample flask (gas bulb thermometer). Results, which show the efficiency and effectiveness of the microwave sample preparation method, are discussed for the leaching of three NIST Standard Reference Materials: 2704, 2710, and 2711. The elements were determined either using ICPMS, ET-AAS, or F-AAS. This study demonstrates that microwave heating with enhanced reaction control leads to improved precision compared to conventional heating sources.