Use of two sulfonthalein dyes in the extraction‐free spectrophotometric assay of tramadol in dosage forms and in spiked human urine based on ion‐pair reaction

Abstract

Tramadol is a centrally acting analgesic used in the prevention and treatment of moderate to severe pain. Two sensitive, selective, and rapid spectrophotometric methods are described for the determination of tramadol in its dosage forms and in spiked human urine. The methods are based on formation of yellow ion-pairs between tramadol and two sulfonthalein dyes; bromocresol purple (BCP) and bromocresol green (BCG) in dichloromethane medium followed by absorbance measurement at 400 and 410 nm, respectively. Under the optimum conditions, tramadol could be assayed in the concentration ranges, 1-15 and 1-16 µg ml(-1) with correlation coefficient greater than 0.999 in both cases. The molar absorptivity values are calculated to be 1.84 × 10(4) and 1.97 × 10(4) l mol(-1) cm(-1) for BCP and BCG methods, respectively; and the corresponding Sandell sensitivity values are 0.0143 and 0.0134 µg cm(-2). The limits of detection (LOD) and quantification (LOQ) have also been reported. The stoichiometry of the reaction was found to be 1:1 in both cases and the conditional stability constant (K(f)) values of the ion pairs have been calculated. The within-day and between-day RSD were 0.9-1.96% and 1.56-3.21%, respectively. The methods were successfully applied to the determination of tramadol in tablets and injections and also in spiked human urine with good recoveries. The procedures are simple, accurate, and suitable for quality control application.

Spectrophotometric Studies of Lamotrigine Charge Transfer Complexes:Synthesis and Characterization

“…A number of articles have been published for its determination in bulk drug, commercial formulations, biological and clinical samples. Recently, different reported spectrophotometric methods have been compared by vinay et al [8] with their reported methods. Almost all of the previously reported methods are relatively less sensitive, time consuming or require the expensive reagents.…”

“…Literature survey revealed a number of spectrophotometric methods for the determination of LAM [7] in acidic medium [8], in basic medium [9], through CT and ion pair complexes with bromophenol blue [10], bromocresol green [11], bromocresol purple [12], chlorophenol red [13], p-chloranilic acid [14], through oxidation of LAM [15].…”

Analytical methods for determination of terbinafine hydrochloride in pharmaceuticals and biological materials

“…The reviewed extractive spectrophotometric methods based on ion-association reactions were plagued by several disadvantages. In recent years, there has been a surge in the use of spectrophotometry without liquid-liquid extraction step as a sensitive tool in pharmaceutical analysis [63] , [64] , [65] , [66] , [67] , [68] , [69] , [70] , [71] , [72] , [73] , [74] , [75] , [76] , [77] , [78] , [79] . This new approach can be used in place of extractive spectrophotometry for terbinafine.…”

Ion-Pair Spectrophotometry in Pharmaceutical and Biomedical Analysis: Challenges and Perspectives

“…Ion-pair-based assay methods are proficient in both isolation, identification and quantification of certain substances of biomedical interest [14]. Over time, titrimetric [15,16], gravimetric [17,18], electrometric [19,20], spectrophotometric [21,22] and chromatographic [23,24] methods based on the ion-pair formation were developed.…”