High performance liquid chromatographic determinations of khellin, phenobarbitone and dipyrone combination in tablets

High performance liquid chromatographic methods for the individual determination of khellin, phenobarbitone and dipyrone in tablets are presented. The methods specify a reverse phase column: methanol + water (68 + 32) as mobile phase at a flow rate of 0.7 ml/min with detection at 254 nm for khellin, visgnagin and dipyrone; water + ammonia + methanol (94.5 + 0.5 + 5) as a mobile phase at a flow rate of 0.7 ml/min with detection at 240 nm for phenobarbitone. At sensitivity of 0.01 AUFS, linearity ranges were found to be 0.5-4 micrograms/ml for khellin, 2.5-12.5 micrograms/ml for dipyrone and 1-7 micrograms/ml for phenobarbitone and with relative standard deviations less than 2%. The mean percentage recoveries +/- SD of khellin, dipyrone and phenobarbitone added to tablets were found to be 101.0 +/- 0.65, 100.0 +/- 0.74 and 99.9 +/- 0.74, respectively. The system can detect 2% w/w visnagin in khellin.