Anovel approach for the spectrophotometric determination of tryptophan in drug samples of different origins using homemade FIA/ merging zones techniquesAuthor(s): BushraB.Qassim, Sarah F.Hameed
A new, rapid and sensitive batch and flow injection Â merging zones spectrophotometric methods for the determination of Tryptophan in pure material and pharmaceutical preparations were proposed. These methods based on oxidation of the reagent Diphenyl amine sulphonate (DASA) to diphenyl benzidine sulphonic acid after reaction with sodium nitrite in the sulphuric acid medium. The unstable oxidation product react quickly with sodiumnitrite to produce a diazotized intermediate. The diazotized intermediate is coupled with Trp., a pink color product was developed which is stable for 1 h in 300C. The colored product measured at 522nm. Optimum concentration of chemical reactants and physical instrumental conditions have been investigated. A linear graph of peak high versus concentration indicate that BeerÂs low is obeyed over the concentration range of 3-40 and 5.100µg. ml-1 of Tryptophanwith detection limits of 0.2325 and 0.188 µg.ml- 1 of Tryptophan for batch and FIA methods, respectively. The optimized FIA system was able to determine Trp. with a through put 52 samples.h-1. The proposed methods were applied successfully for the determination of Tryptophan in pharmaceutical preparations and statistical analysis of the results were compared with results by the British pharmacopeia were also reported.