Peak compression technique based on the difference of the solute migration velocity in two different mobile phases was described theoretically and confirmed using benzaldehyde and 4-hydroxyquinoline (4-HQ) as model compounds. After peak compression, the peak compression factors (the ratio of peak width at half-height under non-compression and that under compression condition) of benzaldehyde and 4-HQ were 0.19 and 0.13, respectively. By this application of the peak compression technique to the mixture, both enhanced peak height and good separation were obtained in one run cycle. This peak compression technique was introduced to determine benzaldehyde from semicarbazide-sensitive amine oxidase-catalyzed enzymetic reaction in order to illustrate the applicability of this technique to the real sample. As a result, the peak was compressed effectively, and 4.94-fold, 19.3-fold and 5.74-fold enhancement in peak height, plate number and signal to noise ratio were also achieved, respectively. Peak compression technique based on the difference of the solute migration velocity in two different mobile phases was described theoretically and confirmed using benzaldehyde and 4-hydroxyquinoline (4-HQ) as model compounds. After peak compression, the peak compression factors (the ratio of peak width at half-height under non-compression and that under compression conditions) of benzaldehyde and 4-HQ were 0.19 and 0.13, respectively. By this application of the peak compression technique to the mixture, both enhanced peak height and good separation were obtained in one run cycle. This peak compression technique was introduced to determine benzaldehyde from semicarbazide-sensitive amine oxidase-catalyzed enzymetic reaction in order to illustrate the applicability of this technique to the real sample. As a result, the peak was compressed effectively, and 4.94- fold, 19.3-fold and 5.74-fold enhancement in peak height, plate number and signal to noise ratio were also achieved, respectively.