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The spectrofluorimetric determination of vitamin K3 (menadione) using a flow injection (FI) assembly provided with a solid-phase reactor with immobilized zinc is described. The naphthohydroquinone was produced by means of two coupled steps in the FI system: hydrolysis of the sodium sulfite derivative of the menadione in a basic medium and reduction of the generated menadione in the zinc reactor in an acidic medium. The fluorescent product was monitored spectrofluorimetrically (lambda ex 325 nm; lambda em 425 nm). The calibration graph was linear over the range 0.1-18 micrograms ml-1 with a reproducibility of 1.6%; the limit of detection was 0.005 microgram ml-1 and the sample throughput was 70 h-1. The influence of foreign compounds was studied and the procedure was applied to the determination of vitamin K3 in three different pharmaceutical formulations.

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A determinação indiretade aminoácidos é realizada em um sistema de injeção de fluxo utilizando-se um reator de fase sólida que contém sais cúpricos, imobilizados em esferas de resina de poliéster. Uma substância farmacêutica é forçada através do reator e os íons cúpricos liberados (complexados pela substância farmacêutica) agem como catalisadores da reação subseqüente en tre Fe(III) e tiosulfato de sódio. A curva de calibração é lin ear no intervalo de concentrações 0,1-0,3 µg L -1 para glicina, com um desvio padrão relativo de 2,3% e uma velocidade de passagem de 28 amostras por hora. Foi analisada a influência de substâncias estranhas e o método foi aplicado à determinação de glicina em duas formulações farmacêuticas diferentes.The in di rect de ter mi na tion of amino ac ids is car ried out in a flow-injection as sem bly by means of a solid-phase re ac tor con tain ing cu pric salts, im mo bi lized in poly es ter resin be ads. A phar ma ceu ti cal sub stance is forced through the re ac tor and the re leased cu pric ions (compl exed by the phar ma ceu ti cal sub stance) act as a cat a lyst for the sub se quent re ac tion be tween Fe(III) and so dium thiosulfate. The cal i bra tion graph is lin ear over the range 0.1-3.0 µg mL -1 glycine, the RSD was 2.3%, and the sam ple through put was 28 h -1 . The in flu ence of for eign sub stances was stud ied and the method was ap plied to the de ter mi na tion of glycine in two dif fer ent pha rma ceu ti cal for mu la tions.