An Ultra-sensitive and selective LC-UV method for the simultaneous determination of pravastatin, diltiazem, naproxen sodium and meloxicam in API, pharmaceutical formulations and human serum

The aim of the present work was to develop a sensitive liquid chromatographic method for the quantitation of pravastatin and diltiazem along with naproxen and meloxicam using ultraviolet detector. The separation of components was achieved on Purospher Star, C18 (5 μm, 25 x 0.46 cm) column using methanol-water (80:20 v/v) as mobile phase and pH adjusted 3.4 with 85% o-phosphoric acid. Related parameters that may influence the enrichment efficiency of speration of drugs such as the kind and volume of elute, sample flow rate, sample pH, and volume of the drug samples were investigated. Detection was performed at ambient temperature at 220 nm by pumping the mobile phase at the flow rate 1.0 mL min -1 . The experimental results indicated a good linearity (R 2 > 0.9947) over the concentration range of 0.5-20 μg mL -1 for pravastatin, naproxen and meloxicam and 0.75-24 μg mL -1 for diltiazem. The method was compared by programming the detector adjusting the wavelength with time to match the individual analyte's chromophore which enhanced sensitivity with linear range 0.25-8.0, 0.5-16, 0.4-12 and 0.2-4.0 μg mL -1 for pravastatin, diltiazem, naproxen and meloxicam respectively. The LOD values shifted down from 33, 70, 50 and 80 ng mL -1 to 15, 42, 20 and 10 ng mL -1 for pravastatin, diltiazem, naproxen and meloxicam respectively. Validation of the method showed good precision and accuracy for the proposed method. All the results indicated that this procedure could allow the simultaneous determination of these four compounds in API, pharmaceutical formulations and serum at trace levels. The method can be successfully applied for the determination of these drugs in human serum, clinical laboratories and in pharmaceutical formulations without diode array detector and without interference of excipients or endogenous components of serum.