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Needle trap extraction for GC analysis of formic and acetic acids in aqueous solution
Author(s) -
Lee Xinqing,
Huang Daikuan,
Lou Dawei,
Pawliszyn Janusz
Publication year - 2012
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.201101082
Subject(s) - chemistry , formic acid , mass spectrometry , chromatography , extraction (chemistry) , detection limit , aqueous solution , flame ionization detector , gas chromatography , analyte , acetic acid , analytical chemistry (journal) , organic chemistry
Formic and acetic acids are ubiquitous in the environment, food, and most of the natural products. Extraction of the acids from aqueous solution is required for their isotope analysis by the gas chromatography‐isotope ratio mass spectrometry. To this objective, we have previously developed a purge‐and‐trap technique using the dynamic solid‐phase microextraction technology, the N eedl EX . The extraction efficiency, however, remains unexamined. Here, we address this question using the flame ionization detector and isotope ratio mass spectrometer while comparing it with that of the CAR / PDMS fiber. The results show that the N eedl EX is applicable at a wide range of concentration through coordination of purge volume given the minimum amount 3.7 ng and 1.8 ng of formic and acetic, respectively, is extracted. The efficiency of N eedl EX was 6–7 times lower than the fiber at 1000 μg/mL depending on the analyte. It is, however, superior to the latter at 10 μg/mL or less owing to its lower detection limit. The extraction efficiency of both acids is equivalent in molar amount. This is, however, disguised by the different response of the flame ionization detector. The isotope ratio mass spectrometor overcomes this problem but is compromised by relatively large errors. These results are particularly useful for isotopic analysis of carboxylic acids.