Spectrofluorometric determination of clonazepam in dosage forms: Application to content uniformity testing and human plasma.

The present paper describes a developed and validated simple, highly sensitive and cost-effective spectrofluorometric method for determination of clonazepam (CNP). The proposed method depends on forming a highly fluorescent product through the reduction of CNP with Zn/HCl. The produced fluorophore exhibits a strong fluorescence at λem 350 nm after excitation at λex 250 nm. The use of carboxymethylcellulose (CMC) greatly enhanced the fluorescence intensity of the produced fluorophore to the extent of about 100%. Calibration curve showed good linear regression (r2  > 0.9998) within test ranges of 20-400 ng ml-1 with a lower detection limit of 0.67 ng ml-1 and lower quantification limit of 2.22 ng ml-1 upon using CMC. The method was successfully applied to the analysis of CNP in its pharmaceutical formulations and the results were in agreement with those obtained using a reference method. Furthermore, the content uniformity testing of the tablets was also performed. The application of the proposed method was extended to determine CNP in spiked human plasma sample as a preliminary investigation and the results were satisfactory.