Preliminary Studies of Philippine Vodka as an HPLC Organic Modifier

Abstract

In the United States, attempts have already been made to use distilled spirits as an organic modifier. However, the chromatograms produced were inferior in terms of number of theoretical plates (NTP) and noise compared with chromatograms produced using HPLC grade ethanol. This study aimed at finding a locally available vodka that produces chromatograms comparable with ACS HPLC grade ethanol in terms of NTP and noise. Three brands of locally produced vodka (Cossack, Antonov and Tosca) were tested and the brand that passed the ACS set limits for absorbance and residue on evaporation was selected. The brand that passed specifications was then used for isocratic and gradient HPLC separation. All experimental runs were carried out in triplicates. It was found out that Antonov Vodka passed the said set limits, which was then used in separating caffeine and benzoic acid under isocratic and gradient modes. Results revealed that the resulting chromatograms had NTP and baseline noise that were comparable to the ACS HPLC grade ethanol. In the case of caffeine, the NTP under isocratic conditions were 6006.67±36.35 and 5943.33±12.74 for ACS HPLC grade ethanol and Antonov Vodka, respectively. Using Antonov Vodka, good separation of caffeine and benzoic acid from other matrix components in three brands of energy drinks (Cobra, Lipovitan and Red Bull) was likewise observed. Hence, with the proper validation procedures in place like testing the robustness of the analytical method, Antonov Vodka may replace HPLC grade ethanol in the analysis of some samples.