title: Determination of carboxylic acids in water by gas chromatography-mass spectrometry after continuous extraction and derivatisation.
abstract: 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 ≈ 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 ≈ 10 μL, the analytes were spiked with 60 μL of the derivatising reagent and derivatised in a household microwave oven for 3 min. Among the reagents tested (BF(3)/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.
authors.affiliation: Department of Analytical Chemistry, Campus of Rabanales, University of Córdoba, E-14071 Córdoba, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Jurado-Sánchez
authors.forename: Evaristo
authors.initials: E
authors.lastname: Ballesteros
authors.forename: Mercedes
authors.initials: M
authors.lastname: Gallego
mesh_terms: D053000:Analytic Sample Preparation Methods / Q000379:methods*; D002264:Carboxylic Acids / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D052616:Solid Phase Extraction / Q000379:methods*; D013997:Time Factors; D014867:Water / Q000737:chemistry*
chemical_list: D002264:Carboxylic Acids; D014867:Water