Emerging Technologies for Identification of Disinfection Byproducts:  GC/FT−ICR MS Characterization of Solvent Artifacts

Abstract

Water samples from a local water treatment plant were analyzed, using gas chromatography Fourier transform ion cyclotron resonance mass spectrometry (GC/FT-ICR MS), to identify potential disinfection byproducts (DBPs). Both liquid-liquid extraction (LLE) and solid-phase microextraction (SPME) techniques were used for sample preparation prior to GC/MS analyses. Based on the averaged mass measurement accuracy (MMA) of better than five parts-per-million (<5 ppm), multiple solvent artifacts were identified. It is shown that solventless SPME can be utilized to reduce potential interferences from solvent stabilizers. Six DBPs were detected and their molecular compositions were assigned at a high level of confidence. At the ppb concentration ranges and in the broadband mass spectral detection mode, internally calibrated mass spectra provided concurrent high resolution (resolving power M/deltaM50% > 30,000 at m/z values -110) and MMA of better than one part-per-million (MMA < 1 ppm). The use of thermochemical data, such as proton affinities, as a complementary tool to enhance analytical resolution is also demonstrated.

Proton transfer reactions of halogenated compounds: Using gas chromatography/Fourier transform ion cyclotron resonance mass spectrometry (GC/FT-ICR MS) and ab initio calculations

“…Various analytes such as bromodichloromethane, dichloromethane, dichloroacetonitrile, ethanol, mercaptans, and trichloropropanone were present at low concentrations in a local town's treated water samples and accurate mass measurement (MMA) analysis allowed their confident characterization [19]. However, the most abundant GC peak (RT range of 19.5-21.5 min) displayed a wider peak width and was originally assigned to two co-eluting compounds (viz., chloroform and tentatively dichloromethanol) [19].…”

“…The SRI model 8610C GC and an in-house configured cryofocuser were interfaced with FT-ICR MS (based on Jacoby and co-workers' design [25]). A 105-m (0.25-mm i.d., 1-m crossbonded 100% dimethyl polysiloxane stationary phase coating) MXT-1 capillary column (Restek Corp., Bellefonte, PA) was used for all solid phase microextraction (SPME) GC experiments [19]. The vacuum chamber surrounding the ICR cell was maintained at ∼87 ± 5 • C (360 ± 5 K) by a set of DC heating elements [26].…”

“…Previously, we used GC/FT-ICR MS to detect potential DBPs using electron impact ionization (EI); identifications were confirmed by comparisons of MS patterns using authentic chemical standards [19]. However, the EI technique leads to extensive fragmentation of DBPs and can yield mass spectra with very little or no trace of molecular ions.…”

“…In this study, we carried out GC/FT-ICR MS experiments with EI, chemical ionization (CI), and ab initio calculations of PAs and GBs to characterize DBPs in drinking water [19]. Furthermore, we used multiplexed RIM (MRIM) of the CI reagent ions (R i H + ) [21,22] to bracket the gas phase basicities of the neutral analytes eluting from the GC column.…”

Emerging Potable Water Technologies

“…Both liquid−liquid extraction (LLe) and solid-phase microextraction (SPME) techniques were used for sample preparation prior to GC/MS analyses 19 . Quantitative microbial risk assessment (QMRA) is increasingly applied to estimate drinking water safety.…”