Simultaneous monitoring of aspirin, phenacetin and caffeine in compound aspirin tablets using a sequential injection drug-dissolution testing system with partial least squares calibration

An automatic system for drug-dissolution studies based on the sequential-in jection (SI) technique is described and used for simultaneous monitoring of dissolution profiles of aspirin, phenacetin and caffeine in compound aspir in tablets. The partial least squares calibration technique was used for si multaneous determination of the three components. 300 mu l test solution in dissolution vessel was aspirated into a PTFE holding coil via on-line filt ers by a syringe pump. After delivering an aliquot (10 mu l) of each aspira ted solution into the transferring line connected to the detector, the resi dual dissolution solution in the holding coil was fed back to the dissoluti on vessel to clear the filter and decrease sample consumption. The sampled aliquot was carried and stopped in the spectrophotometric detector and scan ned within 220 and 310 nm. Fifteen samples run in triple-replicates were pr ocessed per hour with a total of 45 measurements. (C) 1999 Elsevier Science B.V. All rights reserved.