Development of salting out assisted liquid-liquid extraction method followed by high performance liquid chromatography for the determination of caffeine and nicotinic acid in raw and roasted coffee

Abstract

In this study, salting out assisted liquid-liquid extraction (SALLE) method coupled with high performance liquid chromatography (HPLC) has been proposed for determination of caffeine and nicotinic acid from raw and roasted coffee samples. In the study, various parameters affecting chromatographic separations including mobile phase composition, injection volume, flow rate, wavelength, and column temperature as well as experimental parameters affecting the extraction efficiency of SALLE method such as type and volume of organic solvent, type and amount of salt, pH, concentration of ion pair reagent tetrabutylammonium hydrogen sulfate (TBAHS) were studied and optimum conditions were established. The calibration curves which were constructed by spiking ultrapure water at five different concentration levels and extracting with the optimum SALLE conditions exhibited wide linearity, with coefficient of determination R 2 , 0.9953 and 0.9999 for nicotinic acid and caffeine respectively. The limits of detection (LODs) of the developed method were 0.2 and 0.8 mgkg-1 for nicotinic acid and caffeine respectively. Intra- and inter-day precision studies were also performed at two concentration levels and demonstrated satisfactory precision, which is less than 10% RSD in both studies. Relative recovery studies were also ranging from 82-122% for both raw and roasted coffee samples. Hence, from the observed results the developed method is effective and could be utilized as attractive alternative for the determination of caffeine and nicotinic acid in raw and roasted coffee samples