魔芋精粉和虾样品经水蒸气蒸馏除去杂质的干扰,在密闭容器中对样品进行酸化,在氮气流的保护下蒸馏,用甲醛溶液吸收释放出的二氧化硫,提出了离子色谱法测定样品中亚硫酸盐含量的方法。以IonPac AS9-HC色谱柱,以8 mmol·L-1碳酸钠-2.5 mmol·L-1氢氧化钠溶液为淋洗液等度洗脱,用电导检测器测定。亚硫酸盐的质量浓度在6.0 mg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)为4.0 mg·kg-1。方法用于魔芋精粉和虾样品分析,回收率在88.1%~98.3%之间,测定值的相对标准偏差(n=8)在1.4%~6.6%之间。

Samples of konjak refined powder and shrimp were distilled by steam distillation method to eliminate the interference of impurity, and acidified in closed vessel. The SO2 was evolved under nitrogen atmosphere and absorbed in formaldehyde solution. The content of sulfite in absorption solution was determined by IC. IonPac AS9-HC chromatographic column was used as ion exchange column, and a mixture of 8 mmol·L-1 Na2CO3 and 2.5 mmol·L-1 NaOH was used as eluent. Linear relationship between values of peak area and mass concentration of sulfite was obtained in the range within 6.0 mg·L-1, with detection limit (3S/N) of the method of 4.0 mg·kg-1. The proposed method has been used in the analysis of the samples of konjak refined powder and shrimp, giving values of recovery and RSD′s (n=8) in the ranges of 88.1%-98.3% and 1.4%-6.6% respectively.