Closed-system, solid-phase extraction cleanup method for removal of normal paraffin hydrocarbon from samples prior to purge-and-trap volatile analysis

Abstract

A novel approach has been developed to separate potential semivolatile interferences from volatile analytes prior to purge-and-trap analysis. This technique involves a closed system with solid-phase extraction which provides a simple, inexpensive method with minimal loss of volatile components. In addition, the separation method minimizes the potential adsorption of unwanted volatile species from the surrounding air during the cleanup procedure and reduces the radioactive level in actual tank waste samples. This cleanup method has been applied to radioactive, hazardous mixed waste samples containing normal paraffin hydrocarbon (NPH) from a Hanford single-shell tank. NPH, present at the percent level in actual tank wastes either as a native component or introduced as a hydrostatic fluid, interferes with the purge-and-trap gas chromatography/mass spectrometry (GC/MS) analysis of volatile components. Validation of the procedure was performed by analyzing blank spikes and actual, spiked single-shell tank waste samples. The NPH removal from actual waste samples and blank samples was better than 99%. This methodology could be easily extended to a sample matrix, such as water, sorbents, or soils, that contains excessive quantities of normal paraffin hydrocarbons. 9 refs., 8 figs., 4 tabs.