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NEGATIVE ION ELECTROSPRAY OF BROMO- AND CHLORACETIC ACIDS AND AN EVALUATION OF EXACT MASS MEASUREMENTS WITH A BENCH-TOP TIME-OF-FLIGHT MASS SPECTROMETER
Citation:
Debre, O., W L. Budde, AND X. Song. NEGATIVE ION ELECTROSPRAY OF BROMO- AND CHLORACETIC ACIDS AND AN EVALUATION OF EXACT MASS MEASUREMENTS WITH A BENCH-TOP TIME-OF-FLIGHT MASS SPECTROMETER. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 11(9):809-821, (2000).
Description:
The negative ion electrospray mass spectra of six bromo- and chloroacetic acids were measured using two different electrospray interfaces and single quadrupole and bench-top time-of-flight mass spectrometers. With each acid at 50 ug/mL in aqueous methanol at pH 10, the anions observed included deprotonated molecules, adducts, and fragment ions. With each acid at 100 ng/mL in aqueous acetronitrile at pH 10, mainly deprotonated molecules are observed. The exact m/z measuring capbility of the time-of-flight mass spectrometer was evaluated to assess the potential for determination of the individual acids in mixtures without an on-line separation. Mean measurement errors were nearly always less than + or - 9 ppm and the majority were less than + or - 5 ppm. Potential interferences by substances having similar exact masses and the ability to form anions in aqueous solutions were evaluated. The estimated detection limits of the five regulated haloacetic acids in drinking water, without a sample preconcentration step, are in the range of 24-86 ng/mL, which is within about a factor of 10 of the levels required for routine monitoring of the acids. Actual drinking water samples were not analyzed pending the development of slightly more sensitive techniques and quantitative analytical procedures.