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

An automatic system for drug-dissolution studies based on the sequential-injection (SI) technique is described and used for simultaneous monitoring of dissolution profiles of aspirin, phenacetin and caffeine in compound aspirin tablets. The partial least squares calibration technique was used for simultaneous determination of the three components. 300 μl test solution in dissolution vessel was aspirated into a PTFE holding coil via on-line filters by a syringe pump. After delivering an aliquot (10 μl) of each aspirated solution into the transferring line connected to the detector, the residual dissolution solution in the holding coil was fed back to the dissolution vessel to clear the filter and decrease sample consumption. The sampled aliquot was carried and stopped in the spectrophotometric detector and scanned within 220 and 310 nm. Fifteen samples run in triple-replicates were processed per hour with a total of 45 measurements.