Liquid chromatographic determination of aliphatic amines in water using solid support assisted derivatization with 9-fluorenylmethyl chloroformate

A simple and sensitive method has been developed for the liquid chromatographic determination of short-chain aliphatic amines in water. Analytes are retained in solid-phase extraction (SPE) cartridges, and then derivatized by drawing an aliquot of the fluorogeneic reagent 9-fluorenylmethyl chloroformate (FMOC) through the cartridges. After a certain reaction time the derivatives formed are desorbed with acetonitrile. The collected extracts are then chromotographed on a LiChrospher 100 RP18 125 mm x 4 mm i.d., 5 mum, column using an acetonitrile-water gradient. The influence of experimental conditions (SPE material, volume of sample, concentration of FMOC, time of reaction and pH) has been investigated. Optimal results have been obtained with C-18 SPE cartridges using a sample volume of 5.0 mL. For derivatization, 0,25 mL aliquots of 25 mM FMOC have been used, the reaction time being only 2 min. The method has been applied to the quantification of several aliphatic amines: methylamine, ethylamine, dimethylamine, n-butylamine, n-pentylamine and n-hexylamine. Under the proposed conditions the percentages of analytes retained plus derivatized were of about 54-107% compared to those obtained with direct solution derivatization. The method provided good reproducibility, linearity and accuracy within the 0.050-1.0 mg L-1 concentration range. The limits of detection were in the 0.25 - 5.0 mug L-1 range. The utility of the described approach has been tested by analysing tap water, river water and industrial waste water.