Determination of Organic Acids in Beer by HPLC method

Kukleva Ekaterina Abstract Optimization and validation of HPLC method with RI or UV detection system for determination of six major organic acids in beer was made. Beer is very complicated matrix, therefore, the samples needs pretreatment using SPE. For solid phase extraction Algient Bond-Elute SAX (SAX) and Supelco ENVI-Carb (CB) cartridges were used and compared. Differences between those two cartridges is in their principle of pretreatment. While on SAX cartridge dissociated organic acid ions will be retained and interfere substances not, on CB cartridge interfering carbohydrates will be retained instead of organic acid ions, which will get through sorbent. Recoveries for organic acids on SAX and CB cartridges were80 - 110 % and 20 - 50 %, respectively. For determination of six organic acids, by name citric, malic, succinic, lactic, acetic and oxalic, Eurokat H (Knauer) HPLC column was used with 0.01 N sulfuric acid as a mobile phase. Time of analysis was 25 minutes per sample. Organic acid ions were detected using Refractive Index (RI) and Ulraviolet (UV) detectors. Peak resolution was 1,2 - 1,8 and 1,1 - 1,6 for RI and UV detection, respectively