Three polyamidoamine(PAMAM) dendrimers have been synthesized by divergence method with ethylenediamine as core. The surface tensions of aqueous solution of different generation PAMAM were determined by traditional sur...Three polyamidoamine(PAMAM) dendrimers have been synthesized by divergence method with ethylenediamine as core. The surface tensions of aqueous solution of different generation PAMAM were determined by traditional surfactant method. The results showed that the whole PAMAM doesn′t have surface acti- vity and the half PAMAM have certain surface activity. Their critical micelle concentrations(CMC) were obtained from surface tension curves, and the hydrophile-lipophile balance number(HLB), saturated adsorption capacity, molecular cross section area and molecular diameter were calculated. The results revealed that the molecular diameter of 0.5G, 1.5G and 2.5G PAMAM were 0.743, 0.998 and 1.371 nanometer, respe- ctively. The dendrimer obtained was also proved to be of nanometer order.展开更多
海水中兽药多残留分析时，基质效应会对测定准确度产生较大影响．以反渗透水为空白对照，液相色谱-串联质谱联用（1iquid chromatography-tandem mass spectrometry，LC—MS／Ms）检测，在500倍浓缩条件下，评价了3种常用亲水一亲油平衡...海水中兽药多残留分析时，基质效应会对测定准确度产生较大影响．以反渗透水为空白对照，液相色谱-串联质谱联用（1iquid chromatography-tandem mass spectrometry，LC—MS／Ms）检测，在500倍浓缩条件下，评价了3种常用亲水一亲油平衡（hydrophile-lyophile balance，HLB）固相萃取柱（Waters、Supelco和安谱）对海水中35种兽药的基质效应和保留效果．研究发现：反渗透水实验中3种HLB柱表现出柱填料的外源性基质效应，喹诺酮类和四环素类兽药呈现基质正效应，雌激素类等呈现基质负效应，磺胺类和氯霉素类兽药基质效应不显著．海水基质实验中由于外源性杂质与内源性杂质共同作用，大部分喹诺酮类和四环素类兽药呈现基质正效应，氯霉素类和雌激素类呈现基质负效应，磺胺类兽药基质效应不显著．与外标法相比较，基质匹配标准校正法可有效消除基质效应．在50和200ng／L两个加标质量浓度下，3种HLB柱对海水中35种目标兽药校正后的回收率分别为26．8％～147．8％（Waters）、60．4％～159．3％（Supelco）和52．0％～112．1％（安谱）；两个加标浓度的相对标准偏差（RSD）（n=4）在0．1％～11．1％．结果表明，相同实验条件下，3种HLB柱的基质效应不容忽视，采用基质匹配标准校正法可以有效克服基质效应，为海水样品中兽药多残留分析方法准确度的改善提供了参考数据．展开更多
采用白金板法对Surfactin的表面活性进行研究,并用浊度法和离心法对其乳化性进行研究。结果表明：Surfactin的临界胶束浓度为9.03×10-5 mol/L,可将水的表面张力由73.98 m N/m降至最低27.48 m N/m。在浓度为1×10-3~1.2×10...采用白金板法对Surfactin的表面活性进行研究,并用浊度法和离心法对其乳化性进行研究。结果表明：Surfactin的临界胶束浓度为9.03×10-5 mol/L,可将水的表面张力由73.98 m N/m降至最低27.48 m N/m。在浓度为1×10-3~1.2×10-2 mol/L的NaCl溶液中,Surfactin溶液的表面张力随盐浓度升高逐渐降低并最终稳定在34 m N/m;Surfactin在121℃处理20 min后,其表面张力仍能保持在37.10 m N/m;在pH值为2~12范围内,其表面活性稳定并良好;表明Surfactin具有较强的NaCl浓度、温度、pH值的耐受性。浊度法测得Surfactin亲水亲油平衡（hydrophile lipophilic balance,HLB）值为14,对所需HLB值为12~16的油相乳化性能良好。展开更多
文摘Three polyamidoamine(PAMAM) dendrimers have been synthesized by divergence method with ethylenediamine as core. The surface tensions of aqueous solution of different generation PAMAM were determined by traditional surfactant method. The results showed that the whole PAMAM doesn′t have surface acti- vity and the half PAMAM have certain surface activity. Their critical micelle concentrations(CMC) were obtained from surface tension curves, and the hydrophile-lipophile balance number(HLB), saturated adsorption capacity, molecular cross section area and molecular diameter were calculated. The results revealed that the molecular diameter of 0.5G, 1.5G and 2.5G PAMAM were 0.743, 0.998 and 1.371 nanometer, respe- ctively. The dendrimer obtained was also proved to be of nanometer order.
文摘海水中兽药多残留分析时，基质效应会对测定准确度产生较大影响．以反渗透水为空白对照，液相色谱-串联质谱联用（1iquid chromatography-tandem mass spectrometry，LC—MS／Ms）检测，在500倍浓缩条件下，评价了3种常用亲水一亲油平衡（hydrophile-lyophile balance，HLB）固相萃取柱（Waters、Supelco和安谱）对海水中35种兽药的基质效应和保留效果．研究发现：反渗透水实验中3种HLB柱表现出柱填料的外源性基质效应，喹诺酮类和四环素类兽药呈现基质正效应，雌激素类等呈现基质负效应，磺胺类和氯霉素类兽药基质效应不显著．海水基质实验中由于外源性杂质与内源性杂质共同作用，大部分喹诺酮类和四环素类兽药呈现基质正效应，氯霉素类和雌激素类呈现基质负效应，磺胺类兽药基质效应不显著．与外标法相比较，基质匹配标准校正法可有效消除基质效应．在50和200ng／L两个加标质量浓度下，3种HLB柱对海水中35种目标兽药校正后的回收率分别为26．8％～147．8％（Waters）、60．4％～159．3％（Supelco）和52．0％～112．1％（安谱）；两个加标浓度的相对标准偏差（RSD）（n=4）在0．1％～11．1％．结果表明，相同实验条件下，3种HLB柱的基质效应不容忽视，采用基质匹配标准校正法可以有效克服基质效应，为海水样品中兽药多残留分析方法准确度的改善提供了参考数据．
文摘采用白金板法对Surfactin的表面活性进行研究,并用浊度法和离心法对其乳化性进行研究。结果表明：Surfactin的临界胶束浓度为9.03×10-5 mol/L,可将水的表面张力由73.98 m N/m降至最低27.48 m N/m。在浓度为1×10-3~1.2×10-2 mol/L的NaCl溶液中,Surfactin溶液的表面张力随盐浓度升高逐渐降低并最终稳定在34 m N/m;Surfactin在121℃处理20 min后,其表面张力仍能保持在37.10 m N/m;在pH值为2~12范围内,其表面活性稳定并良好;表明Surfactin具有较强的NaCl浓度、温度、pH值的耐受性。浊度法测得Surfactin亲水亲油平衡（hydrophile lipophilic balance,HLB）值为14,对所需HLB值为12~16的油相乳化性能良好。
