Objective:The self contrast and correction factor method was established to determine the content of the related substances in Compound Omeprazole Chewable Tablet.Method: Chromatography was carried out by reversed-phase technique on an Agilent XDB C8 column（4.6 mm×150 mm

5 μm） with a mobile phase composed of 0.01 mol · L-1 disodium hydrogen phosphate（adjusted to pH 7.6 with phosphate acid） and acetonitrile in the ratio of（75∶25） pumped at a flow-rate of 1.0 mL · min-1.The detection was carried out at 280 nm and a column temperature of 35 ℃.The injection volume was 20 μL.The slope of linear equation was used to determine the correction factor between impurity A

B

C

D

E and omeprazole.The relative retention time was used to determine the position of impurities.Result: The relative retention time between impurity A

B

C

D

E and Omeprazole was 0.3

0.9

3.4

0.8 and 0.4

respectively.The correction factor of impurity A

B

C

D

E was 1.45

0.66

1.21

1.39 and 0.80

respectively.The content of impurity D was 0.023% in three batches of samples.Other impurities weren’t detected.Conclusion: The method was simple

efficient and accurate for analyzing the related substances in Compound Omeprazole Chewable Tablet.