Determination of low-molecular-weight carboxylic acids in aqueous samples by gas chromatography and nitrogen-selective detection of 2-nitrophenylhydrazides |
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Authors: | Appathurai Vairavamurthy Kenneth Mopper |
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Institution: | Division of Marine and Atmospheric Chemistry, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149-1098 U.S.A. |
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Abstract: | A gas chromatographic method was developed for the determination of low-molecular-weight carboxylic acids in aqueous samples based on a derivatization procedure compatible with aqueous solutions. The technique uses nitrogen-selective detection with a thermionic-specific detector after derivatization of carboxylic acids as 2- nitrophenylhydrazides. The hydrazides were extracted with ethyl acetate prior to injection into the gas chromatograph. The derivatives appear to be stable in ethyl acetate at 0–5° C for long periods and, therefore, can be stored for analysis at a later date. The detection limits of different short-chain acids are in the range 0.8–1.4 pmol per injected sample. The relative standard deviation is less than 10% at the 1 μM level. Examples of the use of the method are given for the determination of carboxylic acids in anoxic marine sediment pore waters, coastal sea water and Black Sea water samples. |
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Keywords: | Carboxylic acids Waters |
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