Determination of piroxicam by solid-phase spectrophotometry in a continuous flow system.

A simple flow injection UV spectrophotometric method was developed for the determination of piroxicam. The method is based on its transient retention and concentration on Sephadex DEAE-A-25 anion-exchange gel beads packed in the flow cell and the continuous monitoring of its native absorbance on the solid phase at 354 nm. The sample was injected into a 0.1 M NaCl carrier stream at pH 9.5 by using a simple monochannel FIA manifold. When the analytical signal reached a maximum value, piroxicam was eluted from the solid support by means of a desorbing solution (0.2 M, pH 4.5). The response of the sensor was linear in the concentration range 0.5-10 microg ml(-1) with a R.S.D. (%) of 1.8, a detection limit (3 sigma criterion) of 0.1 microg ml(-1) and a sampling rate of 13 h(-1). Application to the analysis of pharmaceutical samples testifies to the utility of this sensor. The accuracy of the proposed method was better than 5%.