顶空气相色谱法测定羧甲基壳聚糖中氯乙酸残留量

采用顶空气相色谱法间接测定了羧甲基壳聚糖中氯乙酸的残留量。样品(0.2g)于顶空瓶中超声溶解在水3mL中,加入甲醇2.5mL,硫酸1.5mL,在70℃水浴反应40min使之酯化。按顶空条件进样,用HP-INNOWAX毛细管色谱柱分离,氢火焰离子化检测器测定。分别选择15min和85℃作为样品在顶空瓶中的平衡时间和平衡温度。氯乙酸的质量在0.2～20mg范围内与其峰面积呈线性关系,方法的检出限(3S/N)为5.6mg·L-1。方法用于实样中氯乙酸的测定,用标准加入法做回收试验,测得回收率在90.0%～92.0%之间,测定值的相对标准偏差(n=5)在0.7%～0.9%之间。

Head-Space GC Determination of Residual Amount of Chloroacetic Acid in Carboxymethyl Chitosan

Residual chloroacetic acid was indirectly determined by head-space GC.The sample(0.2 g) was dissolved ultrasonically with 3 mL of H2O in a head-space flask,and the solution was esterified at 70 ℃ in a water bath for 40 min by reacting with 2.5 mL of methanol and 1.5 mL of sulfuric acid.The sample was introduced under the head-space condition.The gaseous analyte was separated on HP-INNOWAX capillary chromatographic column,and determined by hydrogen FID.The time and temperature chosen for equilibration of the sample in head-space flask were 15 min and 85 ℃ respectively.Linear relationship between values of peak area and mass of chloroacetic acid was obtained in the range of 0.2-20 mg,with detection limit(3S/N) of 5.6 mg·L-1.The proposed method was applied to the determination of chloroacetic acid in substantial samples.Recovery was tested by standard addition method,giving values of recovery and RSD′s(n=5) in the ranges of 90.0%-92.0% and 0.7%-0.9%.