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

作者：Jurado Sanchez Beatriz; Ballesteros Evaristo^*; Gallego Mercedes

来源：Talanta, 2012, 93: 224-232.

DOI：10.1016/j.talanta.2012.02.022

• Carboxylic acids
• Water
• Solid-phase extraction
• Microwave assisted derivatisation
• Gas chromatography-mass spectrometry

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 similar to 1.3), 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 similar to 10 mu L, the analytes were spiked with 60 mu 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-1, 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.

• 出版日期2012-5-15