A novel method for the spectrophotometric determination of L-arginine and tryptophan in different pharmaceutical formulations and pure form via homemade continuous flow injection analysis - Merging Zones Technique


An accurate and simple CFIA-Merging zones method for determination of two different amino acids ( L-arginine & tryptophan ) by using two different reactions .The procedure for the estimation of arginine is based on the oxidation condensation reaction of arginine with α-naphthol in the presence of sodium hypobromite as an oxidizing agent in alkaline medium to produce a red colored product measured at λmax 501nm . While tryptophan procedure based on azo-coupling reaction of tryptophan with an azotized product which produced by treated of diphenyl amine sulphonate with sodium nitrate in acidic medium to yield a pink colored product measured at λmax 522 nm . The ideal condition for the formation of the complexes was investigated and it was observed that the calibration curves were obeys with Beer's low at the range 3-1400µg.ml-1and 5-100 µg.ml-1 with detection limit 1 µg.ml-1& 1 µg.ml-1 for L-arginine and tryptophan respectively . CFIA –Merging zones system was able to estimate L-arginine and tryptophan with sampling rate 45&52 sample /h respectively . The novel method was found to be appropriate for the estimation of L-arginine and tryptophan in pharmaceutical formulations and in it's pure form .