Indirect photometric assay determination of gabapentin in bulk drug and capsules by capillary electrophoresis.

A capillary electrophoresis (CE) method was developed for the assay determination of gabapentin (GBP) in bulk drug and capsules. Separation was carried out on 74cm (62.5cm effective length) x 75microm i.d. fused silica capillary by applying a potential of -20kV at ambient temperature. Background electrolyte (BGE) consisting of 5mM 5-sulphosalicylic acid and 0.5mM cetyltrimethylammonium bromide (CTAB), pH 11.0 was employed for the separation. Indirect method of UV detection was performed at a wavelength of 215nm using sulphosalicylate ion as a chromophore. A linear calibration curve was obtained over a concentration range 20-200microg/ml of GBP in deionized water with a correlation coefficient (r) of 0.9998. Recoveries were shown to be >/=98% both in bulk drug and capsules with standard deviation (S.D.) </=2.3%. No placebo (matrix) peaks were observed at the migration times of GBP and L-glutamic acid (internal standard, I.S.).