Specific spectrofluorometric quantification of D-penicillamine in bulk anddosage forms after derivatization with 4-fluoro-7-nitrobenzo-2-oxa-1,3-diazole

A specific and sensitive fluorometric method is proposed for the determinat ion of D-penicillamine in pure form and pharmaceuticals. The method is base d on coupling between D-penicillamine and 4-fluoro-7-nitrobenzo-2-oxa-1,3-d izole (NBD-F) to produce the corresponding fluorescent NBD-penicillamine. T he optimum conditions for the reaction were carefully investigated and inco rporated into the procedure. The reaction was proceeded in berate buffer (p H 7.2) containing 20% of ethanol to give intense fluorescence having its ex citation and emission wavelengths at 465 and 530nm, respectively. The fluor escence intensity was a linear function of the drug concentration over the range of 0.6-3 mu g ml(-1). Regression analysis of the concentration fluore scence intensity showed good correlation (r = 0.9975) with a detection limi t of 2 x 10(-3) mu g ml(-1) (1.3 x 10(-8) M). The mean of percentage recove ries of added authentic drug was 100.00 +/- 1.05. The method was applied su ccessfully to the determination of this drug in pharmaceutical dosage form. The mean recovery for the commercial capsules was 98.1 +/- 0.54%. The resu lts were sufficiently accurate, precise and comparable with those obtained from the official method. The method is specific for the intact drug, and c an be adopted in the presence of possible interferences. (C) 2000 Elsevier Science B.V. All rights reserved.