Analytical Sciences

Purge-and-Trap Gas Chromatography/Mass Spectrometry forthe Analysis of Carboxylic Acids by Esterification

Yasushi EHARA*,** Ž€Žßnd Kazuhiko SAKAMOTO**

*Criminal Investigation Laboratory, Saitama Prefectural Police Headquarters,15-1, Takasago 3-chome, Urawa, Saitama 336-8533, Japan
**Department of Environmental Science and Human Engineering, Graduate School of Science and Engineering, Saitama University, 255 Simo-okubo, Urawa, Saitama 338-8570, Japan

This report describes the application of purge-and-trap (P&T) gas chromatography/mass spectrometry (GC/MS) to analyze carboxylic acids (CAs) using esterification. The optimum analytical conditions were determined based on the esterification recoveries using 10 mmol L^-1 of a CAs methanol solution. P&T sampling was carried out with a Curie-point head-space sampler. The optimum instrumental conditions were: purging, 150¡Ã for 10 min; trap temperature,-10¡Ã; desorption, 358¡Ã for 20 s. A comparison of pyrolysis (Py)-GC/MS, P&T-GC/MS, and solvent extraction-GC/MS was made based on conversions of the CAs into the corresponding CA methylesters. The merits of the P&T method for the other two methods were validated according to quantitative data, the coefficient of variation, and the lower limit of determination calculated from the standard deviation. As a result, we concluded that the P&T method is more useful than the pyrolysis and solvent extraction methods.

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