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

Abstract

In the environmental and pharmacological sciences, it is important to selectively detect chlorine-and brominecontaining compounds in complex mixtures. Currently, a new technique called microwave-induced plasma/chemical reaction interface mass speetrometry (MIP/CRIMS) is being used as a selective detector of elements and stable isotopes. This technique, which involves postcolumn 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 OK 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 brominecontaining 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 (Phaseofus vulgaris var. Topcrop).

High-sensitivity elemental ionization for quantitative detection of halogenated compounds

“…Formation of common neutral species prior to ionization for each class of organohalogens is needed to ensure compound-independent response factors. These common species generated by plasma reactions may be (1) molecular fragments (containing C-X bond) and new products (such as HX), 13,[21][22][23][24] and (2) atomic halogens. To evaluate the contribution of these neutral precursors, we consider the relative response factors for F and Cl under similar plasma and MS detection conditions.…”

Activity of Triclopyr Herbicide Enhanced by Combination with Cobalt Chloride or Ammonium Nitrate

“…The second explanation would be through enhanced uptake of the triclopyr (Gerwick et al 1990). To determine the latter, the newly developed technique GC/ MIP/CRIMS (Moini and Abramson, 1991), previously applied to the selective detection of chlorine-containing compounds in complex mixtures, was used (Morré and Moini 1992). With CoCl 2 , the response of the elongation growth of 1-cm stem segments of etiolated seedlings of soybean was similar for both triclopyr and 2,4-D.…”

Continuous-Flow Isotope Ratio Mass Spectrometry Using the Chemical Reaction Interface with Either Gas or Liquid Chromatographic Introduction

“…Its quantitative capability and high selectivity are analogous to those of tracer methods utilizing radioactivity. CRIMS has been successfully coupled to both GC and HPLC separation systems − and has been used on different types of mass spectrometers, including a research quadrupole, a mass-selective detector, and double-focusing magnetic sector instruments. ,, This enables researchers to utilize the various advantages of each mass spectrometer, such as high resolution to separate isobaric interferences. , A possible advantage of the chemical reaction interface is that its chemistry allows both 13 C and 15 N to be quantified under identical experimental conditions just by choosing the appropriate masses. , With conventional chemical combustion interfaces, interference between CO + and N 2 + at m/z 28 requires a CO 2 trap when 15 N detection is desired, while with CRIMS, the NO + that is generated can be monitored without interference from CO 2 .…”