Stir bar sorptive extraction-liquid desorption (SBSE-LD) has been applied as an efficient sample preparation method for the analysis of beer bitter acids. Extracts free of almost all interfering compounds were obtained, allowing simultaneous analysis of iso-alpha-acids and reduced iso-alpha-acids. A robust micellar electrokinetic chromatography (MEKC) method was developed that enables fast separation of iso-alpha-acids and reduced iso-alpha-acids. Quantitative data are in good agreement with results obtained by high-performance liquid chromatography (HPLC) using direct beer injection.