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EVALUATION OF GAS CHROMATOGRAPHY/MATRIX ISOLATION INFRARED SPECTROMETRY FOR THE DETERMINATION OF SEMIVOLATILE ORGANIC COMPOUNDS IN AIR SAMPLE EXTRACTS
Citation:
Childers, J., N. Wilson, AND R. Barbour. EVALUATION OF GAS CHROMATOGRAPHY/MATRIX ISOLATION INFRARED SPECTROMETRY FOR THE DETERMINATION OF SEMIVOLATILE ORGANIC COMPOUNDS IN AIR SAMPLE EXTRACTS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-92/130.
Description:
The capabilities of gas chromatography/matrix isolation-infrared (GC/MI-IR) spectrometry for determination of semivolatile organic compounds (SVOCs) in air sample extracts were evaluated. ystematic experiment, using xylene isomers as test compounds, were conducted to determine the repeatability of the steps involved in GC/MI-IR measurements and to identify parameters that affect the precision in quantitation. he repeatability of MI-IR net absorbance measurements for single and replicate depositions was determined. n single depositions if was better than 2%, whereas for daily replicate depositions the relative standard deviations were less than 4%. he effect of parameters, such as deposition tip position and cryogenic disk time resolution on precision is illustrated. etection limits and range of linear response for o, m, and p-xylene were determined by analyzing standards. he MI-IR net absorbance was nonlinear at concentrations higher than 52.1 ng/uL, probably due to an increase in the sample spot size relative to the IR beam focus or a decrease in the matrix-to-solute ratio to less than acceptable matrix isolation conditions. he method detection limit for xylene isomers was between 1 and 2 ng/uL injected on-column for routine measurements. xtensive signal averaging was required to obtain spectra at concentrations less than 1ng/uL. he method was tested by determining target SVOCs in ambient air sample extracts. he MI-IR quantitative results were compared to those from the system's flame ionization detector(FID). he FID response exhibited a high bias when unknown compounds coeluted with target analytes. he ability of GC/MI-IR to quantify target compounds in the presence of interferents and to discriminate between coeluting isomers is demonstrated.