Application of GC-HRMS and GC×GC-TOFMS to aid in the understanding of a dioxin assay's performance for soil and sediment samples.

There have been numerous attempts to correlate results obtained by gas chromatography-mass spectrometry (GC-MS) to alternative techniques such as immunoassays and bioassays for the analysis of dioxins in environmental samples. In spite of these efforts, uncertainties about the performance of these methods remain. Following a series of performance studies of various dioxin assays, an in-depth evaluation of sample extracts from the Procept Rapid Dioxin Assay was conducted to provide users with a clearer understanding of the differences in the assay's results compared to traditional mass spectrometry. Two powerful analytical techniques [high-resolution mass spectrometry (HRMS) and two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS)] were used to provide a unique perspective about the assay's underlying analytical performance. HRMS analyses demonstrated that the target dioxin and furans were consistently captured in the assay's extracts. TOFMS analyses revealed that interferents in the sample extracts resulting from inconsistencies in the sample preparation process appear to be the primary factor contributing to the assay's imprecision. The conclusion of this research was the assay results cannot be expected to correlate directly with HRMS and should only be utilized as a screening technique (e.g., to identify the relative ranking of contamination, to determine if samples are above/below threshold levels, or to monitor a cleanup) for environmental matrices such as soil and sediment.