On-line determination of aliphatic amines in water using in-tube solid-phase microextraction-assisted derivatisation in in-valve mode for processing large sample volumes in LC

This paper describes a cost-effective procedure for the analysis of short-chain aliphatic amines in water samples using a solid-phase microextraction device. Analyte preconcentration and derivatisation were effected into a capillary column coated with 95% polydimethylsiloxane 5% polydiphenylsiloxane, which was used as the injection loop of a Rheodyne injection valve. The coating was previously loaded with the derivatisation reagent, 9-fluorenylmethyl chloroformate. A volume of 1 mL of samples was then drawn into the capillary column, and the extracted analytes were left to react on the capillary coating for 5 min. Next, the capillary column was cleaned by passing water. Finally, the injection valve was rotated, and the derivatives formed were dynamically desorbed and transferred to the analytical column into the mobile phase. Methylamine, ethylamine, propylamine, n-butylamine and n-pentylamine were selected as model compounds. Excellent sensitivity was achieved, being the limits of detection of 15-200 mu g/L when using UV detection and of 0.1-0.4 mu g/L by fluorescence.