Determination of ibuprofen and naproxen in tablets

Ibuprofen and naproxen have been quantified in tablets by capillary isotach ophoresis. Hydrochloric acid (10 mmol/l) adjusted with creatinine to pH 5.0 plus 0.1% polyvinylpyrrolidone was used as the leading electrolyte and 10 mmol-l 4-morpholineethanesulfonic acid as the terminating electrolyte. Line arity was observed from 40.0 to 200.0 mg,l of ibuprofen (naproxen), with a coefficient of determination (r(2)) of 0.999. Good quantitation was obtaine d in short analysis time. The isotachophoretic results were compared with t hose obtained by the fluorescence spectrometry. Experimental parameters for ibuprofen were: lambda (EX) = 224 nm and lambda (EM)= 290 nm. Experimental parameters For naproxen were. lambda (EX) = 230 nm and lambda (EM) = 355 n m. The calibration plot was Found to be linear in the range 0.4-2.4 mg,l fo r ibuprofen and 5.0-20.0 mug/l for naproxen. The minimal sample pretreatmen t and relatively low running cost make isotachophoresis a good alternative to existing methods. (C) 2001 Elsevier Science B.V. All rights reserved.