Characterization of liquid hazardous waste with a field portable energy-dispersive x-ray analyzer

The analysis of liquid hazardous waste poses significant problems due to its very heterogeneous nature as a liquid waste is neither solid nor a solution. Most often it is a mixture of solids suspended in a liquid medium. Solid particles may vary considerably in particle size and composition, while the liquid phase may often be a mixture of immiscible liquids. All these factors make analysis difficult, regardless of the analytical method used. X-ray Fluorescence Analysis is particularly attractive for the analysis of hazardous waste because it is fast, requires almost no sample preparation, and is multielemental; however, it fails if applied directly to liquid waste such as waste fuel or inorganic sludge. Recently, several new ASTM Test Methods have been published which address these problems. These methods apply to the analysis of liquid waste by energy-dispersive XRF. With minimal and simple sample preparation, one can achieve levels of detection limits on the order of about 10 to 20 mg/kg for most metals in liquid waste. The results reported are obtained for liquid waste (organic and inorganic matrix) using a field-portable x-ray analyzer equipped with a Si(Li) detector probe. The analyzer, which can utilize empirical as well as a fundamental parameters based calibration, has in the past been successfully used for soil screening. By adding the capability of a reliable analysis of liquid waste (sludge), a portable x-ray analyzer becomes a truly versatile tool for the analysis of metals in hazardous waste.