Optimization of the RP-HPLC method for multicomponent analgetic drug determination.

The optimization of RP-HPLC method defined the simultaneous influence of some important conditions, such as the mobile phase composition, pH of the mobile phase and temperature, on the separation and determination. The RP-HPLC method was done for the determination of paracetamol, caffeine and propyphenazone in a multicomponent pharmaceutical dosage form. The separation factor values define the optimal conditions, which were confirmed by analysing the appropriate mathematical models. The chromatographic system Hewlett Packard 1100 consisted of a HP 1100 pump, HP 1100 UV-VIS detector and HP integrator. Separations were performed on a Beckman Ultrasphere ODS 4.6 x 150 mm, 5 microns particle size column. Samples were introduced through a Rheodyne injector valve with a 20 microL sample loop. UV detection was performed at 265 nm and phenobarottons was used as an internal standard. The optimization was performed within the pH range from 2.5 to 6.0; temperature range from 20 degrees C to 55 degrees C and composition of the mobile phase methanol-water from (30:70 V/V) to (65:35 V/V). The three-D graphs, constructed with sixty-four experimental points, confirmed the optimal conditions for the determination of the investigated analgetic drugs.