Abstract: In order to improve the stability of the test solution extracted from mainstream cigarette smoke for determining ammonia by ion chromatography(IC), the partial correlation of ammonia to some carbonyl compounds(formaldehyde, acetaldehyde, acetone, acrolein, propaldehyde, crotonaldehyde and 2-butanone) in mainstream smoke of 57 cigarette samples was analyzed. On the basis of partial correlation analysis results, the extraction solution specified in standard YC/T 377-2010 was replaced by formaldehyde-HCl solution(15% formaldehyde and100 mmol/L HCl), and the stability of test solution was investigated with 5 cigarette samples.The results showed that: 1) There was a significantly negative correlation between the deliveries of ammonia and formaldehyde in mainstream cigarette smoke, the two increased coordinately in the test solution. 2) The test solutions of the 5 samples were quite stable in 24 hours. 3) The limit of detection of the improved method was 0.30 μg/cig and the recoveries ranged from 97.05% to 102.40% with the inter-day relative standard deviation(RSD) of 1.28%. Theimproved method resolved the problem that the concentration of ammonia in test solution increased with the proceeding of time, and it was suitable for analyzing the delivery of ammonia in mainstream cigarette smoke.