A rapid HPLC determination of C-2-C-7 aliphatic diamines by precolumn derivatization with acetylacetone in methanol-water

A rapid reversed-phase high performance liquid chromatographic analysis for the determination of seven aliphatic diamines in water is described. Preco lumn derivatization with acetylacetone is used for traces of aliphatic diam ines in water-methanol (10:1 v/v) medium, The acetylacetone derivatives obt ained after 15 min were extracted with an octadecylsilane functionalized si lica cartridge, and then injected into the HPLC system, The HPLC system con sisted of a reversed-phase column, and a spectrophotometric detector adjust ed to 310nm as elution solvent a methanol-tetrahydrofuran-water (55:3:42 v/ V) mixture was used. The acetylacetone derivatives of the C-2-C-7 diamines were separated with a good resolution in 23 min. The detection limits achie ved for each diamine were between 0.18-0.72 ng/ml for a 100 ml water sample . The recovery of diamine derivatives from river and seawater was 88-101%, with relative standard deviations of 2.2-4.0%, and 82-93%, with relative st andard deviations of 2.8-4.6%, respectively, Aliphatic diamines are widely used as chemical reagents, occur as metabolic in biomedical studies and are used as chelating agents in analytical chemi stry. As they are soluble in water, their use results in their ultimate rel ease to the environment. The need for a sensitive, selective and rapid dete rmination of aliphatic diamines in environmental samples thus has become im portant. Dobberpuhl et al. [1] have described a highly sensitive pulsed ele ctrochemical detection for aliphatic monoamines and diamines following thei r chromatographic separation. Although, it is a sensitive method the determ ination has to be carried out in alkaline conditions. The most common metho d for the determination of aliphatic amines is high performance liquid chro matography (HPLC), using different derivatives with either fluorescence [2- 5] or UV-visible detection [6-11]. The fluorescence detection method most o ften relies on post-column derivatization, which requires a second pump to deliver the reagent. Acetylacetone is soluble to some degree in water, and has been used as a pr e-column derivatization reagent [12]. The reaction only is effective with d iamines, and results in UV-active acetylacetone derivatives known as Schiff bases. But acetylacetone requires a long reaction time in water, which mak es it rather unsuitable for routine analysis. In this paper an optimized re versed-phase HPLC determination procedure for C2-C7 aliphatic diamines at l ow ng/ml levels in water is described.