Abstract: X-ray contrast media containing iohexol, iopentol or iodixanol was mixed with HCl and the individual drugs were dissolved in water and HCl. Samples were then injected into a carrier stream (2 ml/min) of 7% NaCl in HCl, reagent streams (0.8 ml/min) of 1 M HCl and 0.6 mM NaNO2 merged and mixed in a knotted reaction coil (40 cm x 0.8 mm i.d.) and the reagent and carrier streams merged. After passing through a knotted reaction coil (200 cm x 0.8 mm i.d.), a reagent stream (0.8 ml/min) 0.1% N-(1-naphthyl)ethylenediamine-dihydrochloride merged and the resultant stream passed through a knotted reaction coil (50 cm x 0.8 mm i.d.) to a spectrophotometer for measurements at 511 nm. Calibration graphs were linear for the primary aromatic amine Cpd 5400 [5-amino-NN'-bis-(2,3-dihydroxypropyl)-2,4,6-tri-iodo-1,3- benzenedicarboxamide] for 4-40 µg/ml with recoveries of 81.3-101.2% and RSD (n = 12) of 2.3-17.5%.

Abstract: Biological fluids were deproteinized and I was adjusted before centrifugal filtration (Amicon Centrifree filter; 20 min). The filtrate was analyzed for amino-acids by HPLC on a column (15 cm x 3 mm) of cation-exchange resin (7 µm; Li+ form) at 45°C with Li citrate buffers (pH 2.75 and 7.5) as gradient eluents (0.3 mL min-1), post-column derivatization with phthalaldehyde and fluorescence detection at 425 nm (excitation at 334 nm). Iohexol and trometamol were eluted near or on the tyrosine peak, phenylpropanolamine was co-eluted with tyramine in the following chromatogram and amikacin gave a post-arginine peak which carried over on to the subsequent 2 to 3 chromatograms.