Determination of the esterification degree of hawthorn pectin by headspace solid-phase microexrtaction and gas chromatography

Headspace solid- phase microextraction and gas chromatography( HS- SPME- GC) were used for the qualitative determination of the esterification degree( methyl esterification and ethyl esterification) of haw pectin samples.HS- SPME experimental conditions,such as the type of fibers,extraction temperature,balance time,extraction time,salt concentrations,desorption temperature,desorption time were optimized.The best HS- SPMEGC performance was achieved under the following conditions: 5 m L pectin solution in headspace glass vial with addition of 48.8% Na2SO4,20 min balance time and 30 min extraction time at 40 ℃ using 75 μm CAR-PDMS fiber and 60 s desorption time in the GC inlet at 280 ℃.The correlation coefficient r was greater than 0.9983,the detection limits of the method were 10~15 mg / L,the recovery rates were 95.6% ~116.2%.The proposed method is simple,fast and accurate with high reproducibility.