Abstract: An optimized flow injection analysis method was described for the determination of lanatoside A, B and C, digoxin, digitoxin, acetyldigitoxin and ouabain, based on their reaction with picric acid in alkaline media and spectrophotometric detection at 486 nm. The flow injection manifold (diagram given) consisted of a FIA 20 Analyser linked to a Zeiss Spekol 10 photometer; the flow rate was 0.6 mL min-1 through the PTFE reaction coil (200 cm) with a sample volume of 100 µL. The calibration graph was rectilinear for 0.025 to 0.5 g L-1 for the cited glycosides (except ouabain) and from 0.01 to 0.2 g L-1 for ouabain; coefficient of variation (n = 6) were 0.6 to 2.2%. Sample throughput was 60 h-1. An optimized flow injection method for the determination of various cardiac glycosides (lanatoside A, B and C, digoxin, digitoxin, acetyldigitoxin, and ouabain) was based on their reaction with picric acid in alkaline media with spectrophotometric detection at 486 nm. The calibration graph was linear for 0.025-0.5 g L-1 cardiac glycosides (except ouabain) and 0.01-0.2 g L-1 ouabain, with relative standard deviation between 0.62 and 2.16% and a sample throughput of 60 h-1. This method was utilized for the determination of digoxin in tablets and lanatoside C, and ouabain in injections.

Abstract: A flow injection binding assay for glucosides and mannosides is described. The sample was mixed with enzyme label (horseradish peroxidase) and passed through a column of immobilized concanavalin A. Bound activity was measured by passing substrate (to peroxidase) and chromogenic reagent through the column and monitoring the effluent spectrophotometrically. To speed up the assay, the sample was applied in pulses and the substrate was included in the column regeneration buffer. Calibration graphs for glucosides and mannosides were rectilinear for 0.02 to 2 mM.