Determination of carboxylic acids in water by gas chromatography-mass spectrometry after continuous extraction and derivatisation

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• 作者：Beatriz Jurado-Sá ; nchez^a ; Evaristo Ballesteros^b ; ^{eballes@ujaen.es} ; Mercedes Gallego^a ; ^{mercedes.gallego@uco.es}
• 关键词：Carboxylic acids ; Water ; Solid-phase extraction ; Microwave assisted derivatisation ; Gas chromatography&ndash ; mass spectrometry
• 刊名：Talanta
• 出版年：2012
• 期刊代码：106_00399140
• 类别：ch
• 出版时间：15 May, 2012
• 卷：93
• 期：Complete
• 页码：224-232
• 文件大小：503 K

摘要

This paper describes a new approach for the determination of monocarboxylic, dicarboxylic and tricarboxylic acids (35 compounds) in water. The analytes, in acid medium (pH 鈭?.3), were sorbed on an 80 mg LiChrolut EN-Supelclean ENVI-18 (1:1) column and subsequently eluted with methanol. After evaporation of the extract to 鈭?0 渭L, the analytes were spiked with 60 渭L of the derivatising reagent and derivatised in a household microwave oven for 3 min. Among the reagents tested (BF₃/1-butanol; acetyl chloride/1-butanol; isobutyl chloroformate/1-butanol; trimethylphenylammonium hydroxide, N,O-bis-(trimethylsilyl)acetamide, N,O-bis-(trimethylsilyl)trifluoroacetamide and trimethylchlorosilane), the best results in terms of reaction yield and stability of the derivatives were obtained with the mixture of 1%trimethylchlorosilane in N,O-bis-(trimethylsilyl)trifluoroacetamide. Microwave assisted derivatisation was used as an alternative heating approach for the rapid silylation of carboxylic acids. The proposed method proved to be a suitable analytical procedure for several types of carboxylic acids in water, with limits of detection within the range 0.6-15 ng L^鈭?, precision values from 4.0 to 6.0%(as within-day relative standard deviation) and recoveries from 93 to 101%for all the target analytes.