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Determination of carboxylic acids by isotope dilution gas chromatography/Fourier transform infrared spectroscopy

Journal Article · · Anal. Chem.; (United States)
DOI:https://doi.org/10.1021/ac00169a016· OSTI ID:6743320

A method has been developed for determining carboxylic acids by isotope dilution with /sup 18/O-enriched carboxylic acids and measurement of the isotope ratio in methyl esters of the analyte and standard mixture by capillary gas chromatography/Fourier transform infrared (GC/FTIR) spectroscopy. The difference in the carbonyl absorption maxima for the analyte and standard esters allowed separate absorbance chromatograms to be reconstructed by integration over two narrow frequency ranges in each analyte/standard GC/FTIR spectrum. Area ratios obtained from the absorbance reconstructed chromatograms were plotted versus concentration ratios to give a nonlinear calibration plot, which was expressed as a third-order polynomial by least-squares polynomial fitting. The method was more accurate than GC/MS method developed with the same standards, analytes, and range of concentrations. The isotope dilution GC/FTIR method was applied to the quantitative analysis of aqueous mixtures of coal oxidation products.

Research Organization:
Univ. of North Dakota Energy and Mineral Research Center, Grand Forks (USA)
DOE Contract Number:
FC21-86MC10637
OSTI ID:
6743320
Journal Information:
Anal. Chem.; (United States), Journal Name: Anal. Chem.; (United States) Vol. 60:18; ISSN ANCHA
Country of Publication:
United States
Language:
English