Sensitive spectrophotometric determination of lamotrigine in bulk drug and pharmaceutical formulations using bromocresol green

Abstract

Two new, simple, rapid and reproducible spectrophotometric methods have been developed for the determination of lamotrigine (LMT) both in pure form and in its tablets. The first method (method A) is based on the formation of a colored ion-pair complex (1:1 drug/dye) of LMT with bromocresol green (BCG) at pH 5.02±0.01 and extraction of the complex into dichloromethane followed by the measurement of the yellow ion-pair complex at 410 nm. In the second (method B), the drug-dye ion-pair complex was dissolved in ethanolic potassium hydroxide and the resulting base form of the dye was measured at 620 nm. Beer's law was obeyed in the concentration range of 1.5-15 µg mL-1 and 0.5-5.0 µg mL-1 for method A and method B, respectively, and the corresponding molar absorptivity values are 1.6932 x 10 4 and 3.748 x 10 4 L mol-1 cm-1. The Sandell sensitivity values are 0.0151 and 0.0068 µg cm-2 for method A and method B, respectively. The stoichiometry of the ion-pair complex formed between the dug and dye (1:1) was determined by Job's continuous variations method and the stability constant of the complex was also calculated. The proposed methods were applied successfully for the determination of drug in commercial tablets.

Spectrophotometric Determination and Cloud Point Extraction of Lamotrigine Drug in Pure Form and Pharmaceutical Preparation

“…The reaction first formed diazoniume salt in acidic medium and the excess of nitrite is removed by using sulfamic acid, then coupling diazonium salt with LMT to produce azo dye orange color in basic medium as shown in scheme. [1] The UV-Vis spectrum of 100µg.ml -1 LMT with 100µg.ml -1 AOB showed band peak at424nm.This illustrated in figure (2). Which it was adopted in subsequent studies which indicate to form the product, while the blank solution did not give absorbance in this wavelength.…”

“…It is sparingly soluble in ethanol freely soluble in water and in methanol [1] . Several HPLC methods were reported in the literature for the determination (LMT) [2] & Gas chromatography (GC) [3] .…”

Spectrophotometric Studies of Lamotrigine Charge Transfer Complexes:Synthesis and Characterization

“…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].…”

Potentiometric Sensing of Lamotrigine Based on Molecularly Imprinted Polymers

“…The immunoassay techniques [39,40] have been developed for the determination of the drug in biological samples. UV-spectrophotometric method [41] was used to determination of LTG in tablets. Though the method is claimed to be selective, any N-containing basic moiety would definitely interfere with the assay.…”