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 λ em 350 nm after excitation at λ ex 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 ( r 2  > 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.