Quantitative Determination of Diazepam in Pharmaceutical Preparation by Using a New Extractive-Spectrophotometric Method

Abstract

A simple and sensitive extraction-spectrophotometric method in the visible region is described for the determination of diazepam in bulk sample and pharmaceutical formulations. The method is based on 1 : 1 ion-association complex formation with the acidic dye, bromocresol green at pH 3.5, which is extractable into chloroform from the aqueous phase. Spectrophotometric measurement was done at 410 nm. Different variable affecting the reaction were studied and optimized. Beer's law is obeyed in a general concentration ANALYTICAL LETTERS range of 2-60 mgÁmL À1 for the investigated complex. Sandell sensitivity for 0.001-absorbance unit is 57 ngÁcm À2 . The proposed method could be applied successfully to the determination of diazepam in tablets and injections with good accuracy and precision. The results were compared with the official method. By using the method, diazepam was recovered from a blood serum sample.

Quality control Fourier transform infrared determination of diazepam in pharmaceuticals

“…Additionally, diazepam has been determined in the visible region based on the formation of an ion-association complex with bromocresol green [12] and by flow injection fluorimetry [13]. However, in our knowledge only a precedent exists on the use of vibrational spectroscopy to solve this problem based on the quotient between the absorbance at two wavenumbers in the infrared region [14].…”

Metal Complexes as Self-Indicating Titrants for Acid–Base Reactions in Chloroform

“…Also, extractive spectrophotometric methods based on the formation of 1:1 ion-association complexes of benzodiazepines with acidic dyes have been carried out. 47 Finally, the capability of benzotiazepines to form intensely colored metal complexes has been exploited for their spectrophotometric determination. 48 We have purchased from local suppliers the dosage forms of the following benzodiazepines: olanzapine (3; Teva, 20 mg), flurazepam hydrochloride (4; flunox, 30 mg, Teofarma), triazolam (5; halcion, Pfizer, 0.25 mg tablets), diazepam (6; valium, Roche, 5 mg tablets), and bromazepam (7; lexotan, Roche, 6 mg tablets) (Figure 6).…”

“…Since the spectral region explored for the determination is affected by too many interferences from other absorbing substances, improved results have been obtained with difference or derivative spectrophotometry. Also, extractive spectrophotometric methods based on the formation of 1:1 ion-association complexes of benzodiazepines with acidic dyes have been carried out …”

RP-HPLC estimation of imipramine hydrochloride and diazepam in tablets

“…Diazepam has been studied separately, in combination with other benzodiazepines and other drugs [14][15][16][17][18][19][20] and its metabolites [21] . It was studied in whole blood [16] , plasma [17,18] , urine, hair and oral fluids [19,22] and in pharmaceutical form [23][24][25][26] . These studies were carried out using analytical methods such as secondderivative spectrophotometry [5] , chromatography [15] , HPLC [16][17][18]26] , LC-MS/MS [18,19] , HPLC electrospray tandem mass spectrometry [20] , capillary electrophoresis…”

“…and HPLC-electrospray ionization mass spectrometry (HPLC-ESI-MS/MS) [21] , gas chromatography-negative ion chemical ionization mass spectrometry [22] , spectrophotometry [23] fluorimetry [24] , differential pulse polarographic determination [25] and capillary electrophoresis [26] .…”