Determination of several α-amino acids by flow injection and continuous-flow analysis with membrane extraction

Methods for determining several alpha-amino acids in systems of liquid membrane extraction were developed on the basis of flow analysis techniques, namely, flow injection and continuous-flow analysis. Lipophilic alpha-aminophosphonate (O,O-dipentyl-1-(N-benzyl)aminocyclopentylphosphonate) impregnated into a teflon matrix was used as a carrier. Limits of detection of DL-beta-phenyl-alpha-alanine were 4 x 10(-7) M (flow-injection mode) and 7 x 10(-6) M (continuous-flow mode); the value for DL-valine was 9 x 10(-6) M (continuous-flow mode).