Application of green methodology to pharmaceutical analysis using eco-friendly ethanol-water mobile phases

Green analysis techniques based on solvent consumption and substitution are two major applications in greening chromatographic analysis. Decreasing the toxicity of solvents used in mobile phases by substituting them with less or non-hazardous ones or revealing the consumed amounts by using lower diameter columns or miniaturizing instruments are some examples that can be implemented to an analysis. Environmentally friendly water and ethanol based mobile phases reduce the use of toxic solvents such as methanol and acetonitrile, and consequently the necessary cleaning of waste is reduced. In the presented study, ethanol having less toxic and hazardous effects has been selected as organic modifier. Famotidin, Paracetamol and Thiocolchicoside were selected molecules for demonstration of the applicability of green HPLC in pharmaceutical analysis. Experiments were carried out using an LC system connected to a Diode Array Detection (DAD) at 254 nm. C8 (150 x 4.6 mm, 5 mu m) analytical column was tested as stationary phases. In the mobile phase optimization, ethanol and sodium dihydrogen phosphate buffer contents were adjusted to the desired concentrations for the elution of selected analytes both in isocratic and gradient elution modes. Initial flow rate of the mobile phase was set to 1.0 mL/min and the injection volume was 20 mu L. Developed mobile phase consisted of sodium dihydrogen phosphate (pH 4.6; 50 mM), and ethanol in gradient elution mode. All three active pharmaceutical ingredients were well separated both form baseline and each other with the capacity factors of 2.14, 2.53 and 4.26, respectively. Caffeine was selected as internal standard. The developed EtOH based mobile phase method in RP-HPLC was validated in terms of ICH requirements and found to be selective, linear, sensitive, accurate, precise, repeatable, rugged and robust. Developed method was also successful in pharmaceutical analysis of famotidin, paracetamol and thiocolchicoside from Turkish drug market. The findings of the presented study suggested that environmentally friendly ethanol and water based mobile phases could successfully apply in the pharmaceutical analysis.