Abstract:
The purpose of this research is'to study the appropriate method to determine P-naphthylaminegroup which is the carcinogenic substance containing in the prohibited azo dyestuffs in textilegarment. The experiment consisted of 4 parts. First, study the condition for the reduction of azodyestuffs to get the optimum quantity of sodium dithionite(N%S,O,) and titanium chloride(TiC1,)and the appropriate quantity of sodium hydroxide(Na0H). It was found that the appropriateconcentration of N%S,O, and TiC1, at 95 OC. were 150 grams per liter and the alkaliconcentration as NaOH is was molar. Second, study the reducing capabilities of N%S,O, andTiC1, to reduce the prohibited azo dyestuffs to get free P-naphthylamine group. Then, theoptimum conditions to determine P-naphthylamine group by HPLC technique with ultravioletand fluorescence detectors were studied. The optimum conditions obtained could be concluded asfollows; the solution of acetonitrile and sodium acetate (0.10 M) of 60 : 40 by the volume ratiowas the best mobile phase when using 100-200 pl sample loop and the C-18 HPLC column. Thereducing capability of sodium dithionite was better than titanium chloride in reducing thedyestuffs since the peak area of P-naphthylamine obtained was higher. Third, study theefficiency of analysis of P-naphthylamine group from reducing step by HPLC technique atoptimum conditions, the accuracy in term of percentage recovery and precision in term of relativestandard deviation for P-naphthylamine determination by ultraviolet detector at 235 nrn were95.73% and 1.73, respectively with detection l i d of 0.144 ppm. In addition, by using thefluorescence detector at the excitation and emission wavelength of 236 nm and 410 nm.,respectively, gave the percentage recovery of 97.32% and the relative standard deviation of 1.74with the detection limit of 0.0029 pprn. Therefore, the HPLC technique with thefluorescence detector is the appropriate method to determine the P-naphthylamine groupbecause of its higher accuracy, precision and lower detection limit. Fourth, study the functionalgroup of P-naphthylamine which characterized by infrared spectrum of FTIR technique, showedthat the spectrum of the standard P-naphthylamine and P-naphthylamine from the reduction ofprohibited Azo dyestuff by sodium dithionite and titanium chloride were identical.