将药物试样溶解于水中,定容为100 mL后经0.22 μm滤膜过滤,离子色谱法测定滤液中游离硫酸根含量。采用AS11-HC型阴离子色谱柱进行分离,用22 mmol·L-1氢氧化钾溶液等度淋洗,流量1.0 mL·min-1,抑制电流55 mA。在此检测条件下,游离硫酸根质量浓度在0.50~10.0 mg·L-1范围内与对应的峰面积呈线性关系,方法的检出限(3s/k)为0.003 μg·g-1。在3个浓度水平上进行精密度试验,测得相对标准偏差(n=7)均小于2%。以3个药物试样作基体加入标准溶液作回收试验,测得平均回收率在102.0%~106.0%之间。

The drug sample was dissolved in water and diluted to 100 mL in a volumetric flask. The solution was filtered with filtering membrane of 0.22 μm and the filtrate was used for IC determination of free sulfate ion. The Dionex AS11-HC column was used for separation with 22 mmol·L-1 KOH solution as mobile phase with a flow-rate of 1.0 mL·min-1. Conductivity detector with depression current of 55 mA was used in the determination. Linear relationship between values of peak area and mass concentration of SO2-4 ion was obtained in the range from 0.50 to 10.0 mg·L-1, and detection limit (3s/k) found was 0.003 μg·g-1. Precision was tested at 3 concentration levels and values of RSD′s (n=7) found were less than 2%. Test for recovery was made by standard addition method using 3 drug samples as matrixes. Values of average recovery found were from 102.0% to 106.0%.