ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 55, Number 1
JKCSEZ 55(1)
February 20, 2011 

A highly sensitive and selective extraction-spectrophotometric method has been developed for determination of trace amounts of cimetidine. This method is based on the extraction of cimetidine as an ion pair with bromothymol blue (BTB) into chloroform and measuring its absorbance at 417 nm. The effect of different variables such as pH, concentration of BTB, volume of chloroform and shaking time was investigated. The effect of interfering ions on the extraction was also studied. The calibration curve was linear in the range of 0.25-8 μg mL^-1 with correlation coefficient of 0.9997. The detection limit based on 3Sb was 0.14 μg mL^-1 and relative standard deviation for 10 replicated measurements of 1.0 and 4.0 μg mL^-1 of cimetidine was 3.2 and 1.49%, respectively. The proposed method was applied to the determination of cimetidine in pharmaceutical samples with good recoveries.