在0.50 g牙膏样品中加入90%(体积分数)甲醇溶液5 mL,涡旋1 min后加水稀释至25.0 mL,超声提取20 min,离心5 min。上清液过Cleanert IC-RP小柱,弃去前4 mL流出液,后续流出液供离子排阻色谱分析。以3 mmol·L^-1甲烷磺酸和60 mmol·L^-1甘露醇的混合溶液为淋洗液,以25 mmol·L^-1四甲基氢氧化铵和15 mmol·L^-1甘露醇的混合溶液为再生液,以IonPac ICE Borate色谱柱分离,用抑制型电导检测器检测。结果显示:硼酸质量浓度在1.0~100.0 mg·L^-1内与其对应的峰面积呈线性关系,检出限(3S/N)为0.002%;方法用于实际样品的分析,测定值的相对标准偏差(n=6)为1.9%,加标回收率为98.3%~105%,检出量均未超过GB 22115-2008规定的限值。

The toothpaste sample (0.50 g) was dispersed with 90% (volume fraction) methnol solution by vortex for 1 min. The mixture was dilluted to 25.0 mL with water, extracted by ultrasound for 20 min and centrifuged for 5 min. The supernatant obtained was purified by Cleanert IC-RP column, and the effuent (the first 4 mL of effluent was discarded) was analyzed by ion exclusion chromatography. Target was seperated by IonPac ICE Borate column with mixed solution of 3 mmol·L^-1 methanesulfonic acid and 60 mmol·L^-1 mannitol as eluant and mixed solution of 25 mmol·L^-1 tetramethylammonium hydroxide and 15 mmol·L^-1 mannitol as regenerant, and detected by suppressed conductance detector. It was shown that linear relationship between values of mass concentration of boric acid and peak area was kept in the range of 1.0-100.0 mg·L^-1, with detection limit (3S/N) of 0.002%. The proposed method was applied to the analysis of actual samples, and RSD (n=6) of the determined values was 1.9%. Results of test for the spiked recovery were found in the range of 98.3%-105%, and the detection amounts were lower than the limit specified by GB 22115-2008.