A continuous two‐phase reaction system coupled on‐line with capillary chromatography for the determination of polar solutes in water

Abstract

SummaryGas chromatographic procedures are described for the determination of carboxylic acids and chlorinated anilines in water samples.Propionic acid and 2,&difluorobenzoic acid in aqueous solution have been simultaneously alkylated and extracted by means of a continuous two-phase reaction system, and then quantitated by on-line coupled capillary gas chromatography; tetrahexylammonium hydrogen sulfate was used as phase transfer catalyst and pentafluorobenzyl bromide as reagent.A factorial design approach was used to optimize on-line derivatization of aqueous propionic acid with regard to pH and concentration of phase transfer catalyst. Alkylation and extraction, under optimized conditions, followed by quantitation of the pentafluorobenzyl ester by flame ionization detection furnished a linear calibration for concentrations between 0.1 and 10 pg/ml.The relative standard deviation was 9-15 %.The continuous two-phase reaction system was also used to determine (chlorinated) anilines present in water at concentrations of 0.1-1 pg/ml; pentafluorobenzoyl chloride was used as reagent and analysis was performed by capillary gas chromatography with flame ionization or electron capture detection. The on-line acylation of p-chloroaniline was optimized with regard to pH, reagent concentration, and reaction time.The on-line reaction system worked satisfactorily for both applications, although excess reagent caused some problems with the chromatography.

Fast field analysis of short‐chain aliphatic amines in water using solid‐phase microextraction and a portable gas chromatograph

“…1) is compatible with GC. The reaction can be performed in very mild conditions, and provided relatively high sensitivity and good chromatographic resolution [40].…”

Coupled High Performance Liquid Chromatography with High Resolution Gas Chromatography

“…Brinkman and co-workers, for example, have presented a complete automated on-line system that allows both the LLE and alkylation of organic acids (38). More recently, this same group have reported the coupling of such a system with an atomic emission detector (AED) for the analysis of nitrogenchlorine-and sulfur-containing pesticides in aqueous samples (39), as shown in Figure 2.19.…”

On-line sample treatment—capillary gas chromatography

“…In order to determine more polar compounds, a derivatization step was included in the on-line LLE-GC approach by adding reagents to the liquid streams [74]. Propionic acid and 2,6-difluorobenzoic acid were derivatized by extractive alkylation using tetrahexylammonium hydrogen sulphate as the phase transfer catalyst and pentafluorobenzylbromide as the alkylating reagent.…”