【摘要】 采用在柱阴离子选择性耗尽进样(ASEI)-碱堆积(BS)双重富集毛细管电泳法测定了卷烟样品中无机阴离子。毛细管先充满含0.4 mmol/L十四烷基三甲基溴化铵(TTAB)的三羟甲基氨基甲烷(Tris)缓冲液抑制电渗流;再以高差法引入水塞,吸附于毛细管壁的TTAB溶解到水中,使该段毛细管的zeta电势变负;电泳电源用负高压,电动进样时样品池中阴离子快速迁移并堆积在毛细管内缓冲液和水塞界面上,同时流向进样端的电渗流将水塞排出毛细管;接着电动注入NaOH溶液,快速迁移的OH-与来自缓冲液的Tris+形成低电导样品区,可进一步堆积样品带,还可使电动进样的时间延长。同常规电动进样相比,该双重富集法可达到(0.8~1.3)×105的富集倍数。用本方法测定了卷烟中6种无机阴离子,检出限低于6.2 ng/L。更多还原

【Abstract】 An on-column dual-preconcentration method combining anion-selective exhaustive injection with base stacking and capillary electrophoresis was proposed for preconcentration and determination of inorganic anions in cigarette samples.In the first place,the separation capillary was filled with tris（hydroxymethyl） aminomethane（Tris） buffer solution containing 0.4 mmol/L trimethyl（tetradecyl） ammonium bromide（TTAB） to suppress electroosmotic flow（EOF）.Water plug was introduced and TTAB on the capillary inner wall could be dissolved into the water plug,which enhanced negative zeta potential of the capillary section.Then sample solution was（injected） electrokinetically.The anions in sample cell migrated quickly into the capillary and were stacked at the boundary between the buffer solution and water plug,meanwhile,the water plug moved back to the capillary inlet by EOF.Sequencially,the soluiton of NaOH zone was injected electrokinetically.The fast migrating hydroxide（ions） reacted with Tris⁺ from buffer solution to form a low conductive（sample） zone, and made the zone be condensed further.The preconcentration method achieved an enhancement factor of（0.8¹.3）×10⁵ compared with the normally electrokinetic sample injection.The proposed method has been applied successfully to determine six anions(Cl^-,NO^-₂,NO^-₃,SO^2-₄,F^-,HPO^2-₄) in cigarette samples with the detection limits lower than 6.2 ng/L.更多还原