Determination of polychlorinated dibenzo‐p‐dioxins, dibenzofurans, and biphenyls by gas chromatography/mass spectrometry in the negative chemical ionization mode with different reagent gases

Abstract

Reagent gases that are used in mass spectrometry in the NCI mode for the determination of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) are discussed. Ion-molecule reactions and respective characteristic ions that form while using reagent gases (CH(4), O(2), i-C(4)H(10), NH(3), H(2), He, Ar, Xe, SF(6)) or gas mixtures (CH(4)/O(2), Ar/CH(4), CH(4)/H(2)O, Ar/O(2), i-C(4)H(10)/CH(2)Cl(2)/O(2)) are reviewed. It is shown that only CH(4), O(2), CH(4)/O(2), and CH(4)/N(2)O are widely used and well studied, even though-in the case of these reagent gases-there are contradictions between the publications of various authors. Such reagent gases as NH(3) and He are not well studied, but further investigations of their use for the determination of organochlorine pollutants could be of interest. The possibilities of more sensitive and selective determination of PCDDs, PCDFs, and PCBs are discussed.

Advances in analytical techniques for polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and dioxin-like PCBs

“…Negative ion chemical ionization (NICI or NCI) is also a low-energy ionization technique [103], which produces mass spectra with little fragmentation, resulting in enhanced parent ion signals. NCI analysis of dioxins, furans and PCBs has recently been investigated by Chernestsova using a variety of reagent gases [104]. Detection limits for PCBs are equivalent to or lower than for EI with a trend of increasing signal strength with increasing degree of chlorination.…”

Gas chromatography/mass spectrometry of polychlorinated biphenyls using atmospheric pressure chemical ionization and atmospheric pressure photoionization microchips

“…The most commonly used ionization technique for GC/MS is electron ionization (EI). However, EI lacks the selectivity for high EA compounds, which can conversely be achieved by negative atmospheric pressure ionization or negative chemical ionization 16. The combination of GC and MS with API was first reported decades ago,17 and it has since been applied to the analysis of chlorinated dioxins18–20 and furans 21.…”

Simultaneous profiling of multiple neurochemical pathways from a single cerebrospinal fluid sample using GC/MS/MS with electron capture detection

“…Few investigators have used argon as the reagent gas in negative detection mode. Some found that utilizing argon as the reagent gas resulted in a 30‐fold reduction in sensitivity versus methane 14, 15. Other investigators found a striking enhancement in negative ions when argon pressure was increased in an EI source 16–19.…”