J. Saurina et S. Hernandezcassou, FLOW-INJECTION SPECTROPHOTOMETRIC DETERMINATION OF LYSINE IN FEED SAMPLES, Analytica chimica acta, 281(3), 1993, pp. 593-600
A flow-injection spectrophotometric method is described for the determ
ination of lysine, based on the product of the reaction between lysine
and 1,2-naphthoquinone-4-sulphonate in basic medium. The influence of
different physical, chemical and hydrodynamic parameters on absorbanc
e were studied. At 480 nm, the response is linear up to 1.5 X 10(-4) M
, the detection limit is 1.9 x 10(-6) M and the relative standard devi
ation is 0.8%. Sample throughput is 80 h-1. The method was applied to
the determination of free lysine in commercial feed samples, by means
of multivariate calibration techniques, without the need of chromatogr
aphic separation. Good concordance is shown between this method and th
e standard procedure for amino acid analysis.