Selective detection and characterization of chlorine- and bromine-containing compounds in complex mixtures using microwave-induced plasma/chemical reaction interface mass spectrometry

In the environmental and pharmacological sciences, it is important to selectively detect chlorine‐ and bromine‐containing compounds in complex mixtures. Currently, a new technique called microwave‐induced plasma/chemical reaction interface mass spectrometry (MIP/CRIMS) is being used as a selective detector of elements and stable isotopes. This technique, which involves post‐column reactions (a reaction interface), includes a low‐pressure microwave‐induced helium plasma (MIP) to which a reaction gas is added. Effluents of a chromatographic column that enter this reaction interface are converted into small stable neutrals. The mass spectra of these neutrals will identify and quantify the elements and isotopes of interest. Once the retention times of the peaks of interest are obtained, their full mass spectra can be acquired by repeating the experiment with the MIP off. This method combines the sensitivity of a halogen specific detector with the compound identification of mass spectrometry. In this study, SO2 has been found highly effective as a reaction gas for selective detection of chlorine‐ and bromine‐containing compounds using GC/MIP/CRIMS. Detection limits of 10 pg and 1 ng, and dynamic range of at least four and two orders of magnitude, were achieved for chlorine‐ and bromine‐containing compounds, respectively. The selective detection of chlorinated compounds in complex mixtures is demonstrated by using a mixture of non‐chlorinated compounds and polychlorinated biphenyls, and by selective detection of triclopyr (a chlorinated herbicide) in extracts of leaves of garden bean (Phaseolus vulgaris var. Topcrop).