固相微萃取气相色谱法测定饮料中山梨酸和苯甲酸

采用溶胶凝胶聚甲基苯基乙烯基硅氧烷萃取头萃取饮料中山梨酸和苯甲酸,用直接固相微萃取与气相色谱联用进行测定,通过试验确定了萃取时间、酸度等萃取条件。山梨酸和苯甲酸的浓度在0.2～40μg/mL范围内与色谱峰面积呈良好的线性关系,相关系数分别为0.9988,0.9989,检出限分别为0.0332,0.00320μg/mL,饮料样品和加标样品测定结果的相对标准偏差为4.18%～7.03%(n=3),两个添加水平的加标回收率为80.5%～96.5%。该方法灵敏度比传统的液–液萃取气相色谱法高。

Determination of Sorbic and Benzoic Acid in Beverages by Solid-Phase Microextraction and Gas Chromatography

Sorbic and benzoic acid in beverages were extracted by using sol-gel polymethyl phenyl vinyl siloxane （PMPVS） coated fiber and determined by immediacy solid-phase microextraction （ID-SPME） and gas chromatography（GC）. Extraction time and acidity were defined. Concentration of orbic acid or benzoic acid was linear with peak area in the range of 0.2-40μg/mL with the correlation coefficients of 0.998 8 and 0.998 9 respectively. The detection limits were 0.033 2μg/mL for sorbic and 0.003 20 μg/mL for benzoic acids. Relative standard deviations of dectection results of real samples and added samples were 4.18%-7.03%（n=3）. Recoveries for the two analytes in the samples at two added levels ranged from 80.5% to 96.5%. The sensitivity of the method is higher than that of liquid-liquid extraction gas chromatography.