Sequential injection chromatographic determination of paracetamol, caffeine, and acetylsalicylic acid in pharmaceutical tablets

Abstract

In this contribution, a new separation method for simultaneous determination of paracetamol, caffeine, acetylsalicylic acid, and internal standard benzoic acid was developed based on a novel reversed-phase sequential injection chromatography (SIC) technique with UV detection. A Chromolith® Flash RP-18e, 25-4.6 mm column (Merck, Germany) and a FIAlab® 3000 system (USA) with an 8-port selection valve and a 5 mL syringe were used for sequential injection chromatographic separations in our study. The mobile phase used was acetonitrile-(0.01 M) phosphate buffer (10 : 90, v/v) pH 4.05, flow rate 0.6 mL min^–1. UV detection was at 210 and 230 nm. The validation parameters showed good results: linearity (r >0.999) for all compounds, detection limits in the range 0.3–0.8 μg mL^–1, repeatability (RSD) of peak heights between runs in the range 1.10–4.30% at three concentration levels and intra-day repeatability of the retention times in the range 0.28–0.43%. The analysis time was < 6 min. The method was found to be applicable for the routine analysis of the active compounds paracetamol, caffeine, and acetylsalicylic acid in pharmaceutical tablets.