Study of mass transfer in oil-water-oil multiple emulsions by differential scanning calorimetry

A multiple emulsion of the type O1/W/O2 is studied experimentally by means of differential scanning calorimetry (DSC). The aim of this work is to characterize and measure the time-dependent changes within the emulsion. In particular, interest is focused to quantify the concentration changes in the internal and external phases of the O1/W/O2 multiple emulsion. In order to accomplish the objective, the measurement and analysis carried out by DSC are based on the crystallization behavior of the emulsion. A volume of a few mm3 is periodically removed from the O1/W/O2 multiple emulsion. The sample is submitted to steady cooling and the crystallization thermogram is recorded. The experimental data provided by the crystallization thermogram makes it possible to quantify the crystallized mass for both phases, the internal and the external. In addition, the composition in each phase can also be deduced from the thermogram. To deduce the composition, a diagram of crystallization temperatures is elaborated, employing several mixtures of known composition. In addition to the main objective previously mentioned, the influence of formulation parameters such as surfactant concentration in the aqueous phase and the mass ratio of the internal and external phases are also analyzed. The experimental results made it possible to conclude that a mass transfer took place from the internal phase toward the external phase; this transfer is caused by the composition difference on both sides of the aqueous membrane. In this work we analyzed the mass transfer in the multiple emulsion carried out by a composition gradient through the aqueous membrane. The most likely mechanism of mass transfer through the aqueous membrane is a solution-diffusion of tetradecane enhanced by the micelles of the surfactant Tween 20. The model of mass transfer confirms that the osmotic pressure difference controls the kinetics of tetradecane transfer. It is also confirmed that an increment of surfactant concentration in the aqueous phase allows a faster kinetics of the tetradecane transfer.     

高效液相色谱法测定胭脂红酸的研究

研究了以反相C18柱,V(甲醇)∶V(乙腈)∶V(pH 2.8 H3PO4)=12∶8∶80混合溶液为流动相,对胭脂红酸进行高效液相色谱分析的方法。胭脂红酸在2.5~40μg/mL范围内的吸光度线性相关系数达0.9998,方法回收率在98.2%~101.1%,相对标准偏差为0.78%~1.2%,已用于样品中胭脂红酸的测定。     

Characterisation of dirithromycin and spiramycin using high performance liquid chromatography and direct infusion mass spectrometry

Two different high performance liquid chromatography procedures and two detection modes (spectrophotometric and electrochemical) and direct infusion mass spectrometry were used for the characterisation of two macrolide antibiotics, spiramycin and dirithromycin, showing multisignal response in liquid chromatography. In the spiramycin standard three forms were determined qualitatively and quantitatively. The degradation metabolite of dirithromycin, erythromycylamine, was also identified.     

啤酒中单糖的衍生化HPLC-ESI-MS测定方法研究

单糖类样品在溶液中非常稳定,难于离子化,不适合于进行ESI-MS检测。采用1-苯基-3-甲基-5-吡唑啉酮(PMP)将糖类物质衍生化,HPLC-ESI-MS在线联用,选择性离子扫描方式对几种啤酒样品中的5种单糖进行了分离检测。检出限可达到80pg。     

扑草净、乙草胺混配除草剂的HPLC 分析方法

建立了正相高效液相色谱法定量分析二元混配除草剂"昆明6号"中扑草净和乙草胺的方法。采用ShimPackCLC CN(150mm×6.0mm)5μm柱,流动相为正己烷/氯仿(87∶13,V/V),λ=264nm,线性相关系数为0 9997～0 9999。扑草净和乙草胺的加料回收率分别为99 0%和101 0%,RSD分别为0 52%和0 60%。     

Direct separation and quantitative determination of glimepiride isomers by high performance liquid chromatography

A simple and sensitive high‐performance liquid chromatographic procedure for the determination of the trans isomer of glimepiride is reported. Chromatography accomplished direct separation of the cis and trans isomers of glimepiride on a Dikmonsil C18 (250×4.6 mm, 5 μm) column with a mobile phase consisting of methanol‐acetonitrile‐NH₄Ac buffer solution (1.5 mol L^–1, pH = 4.5) (1.1 : 1.3 : 1.0, v/v) at a flow rate 0.5 mL min^–1. The resolution (R_S) was 1.73 with a retention time of 24.885 and 23.018 min for the cis and the trans isomer, respectively. A standard linear calibration curve was established for the trans isomer of glimepiride over the range of 4.95–198.00 μg mL^–1 with a correlation coefficient of 0.99997. This method has been successfully used to analyze four different kinds of glimepiride product.     

高效液相色谱法同时测定反应液中的巯基乙酸和巯基乙酸异辛酯

建立了同时测定反应液中的巯基乙酸(TGA)和巯基乙酸异辛酯(TGB)的高效液相色谱分析方法.实验采用Shimpack C18色谱柱,紫外检测器,检测波长210 nm,以V(乙腈)∶V(水)=70∶30作为流动相(用H3PO4调节流动相pH为3),流速1.0 mL/min,柱温30 ℃.结果表明,TGA和TGB在上述色谱条件下可实现较好分离,测定结果的最大相对标准偏差分别为0.53%和0.46%,检出限分别为2.03×10-3 g/L和6.11×10-3 g/L,加标回收率分别在99.0%～100.8%和99.1%～100.7%.     

反相高效液相色谱法同时测定水样中辛硫磷和氯菊酯

采用AgilentSBC8(5μm,4.6mmi.d.×150mm)色谱柱,以V(乙腈)∶V(水)=70∶30为流动相进行分离,二极管阵列检测器(PDA)在210nm波长处检测,建立了反相高效液相色谱法同时测定辛硫磷和氯菊酯的分析方法。辛硫磷和氯菊酯的线性范围分别为0.1～10μg mL和0.02～10μg mL,检出限分别为0 05和0.01μg mL,实际水样的加标回收率为90.3%和95.3%,相对标准偏差为1.3%和3.2%(n=7)。     

高效液相色谱法快速测定大黄中大黄素,大黄酸和芦荟大黄素的研究

研究了高效液相色谱法测定大黄中大黄素、大黄酸和芦荟大黄素。大黄中大黄素、大黄酸和芦荟大黄素用氯仿加热回流提取,提取液蒸干溶剂,以甲醇溶解定容待测。以安捷仑ZORBAX Stable Bound(4.6 mm×50 mm,1.8μm)色谱柱为固定相,质量分数0.1%的H3PO4和甲醇为流动相,梯度洗脱(0 min:VH3PO4∶V甲醇=27∶73;1 min:100%甲醇);在该色谱条件下,大黄素、大黄酸和芦荟大黄素在2.0 min内可达到基线分离;用紫外二极管矩阵检测器检测。方法标准回收率为99.4%~102%,相对标准偏差为1.5%~1.8%。可用于大黄中大黄素、大黄酸和芦荟大黄素的快速分析检测。     

高效液相色谱法分离和测定白菜黑斑病菌中的腐败菌素B

建立了一种高效液相色谱分离和测定白菜黑斑病菌腐败菌素B的新方法。被真菌毒素感染的白菜病叶用乙酸乙酯萃取，用Nove-Pak C18柱进行分离，流动相为乙腈－水（1＋1），pH3.42，流速1．0mL/min，紫外检测波长206nm，腐败菌素B的分离时间是11．49min，检出限达到2．3ng，线性动态范围至少是3个数量级。本方法应用于白菜黑斑病叶样品的测定，并进行了回收率试验，腐败菌素B的5次测定值RSD≤1．2％，平均回收率≥97．1％。     

固相萃取-高效液相色谱法同时测定水中的对二氯苯与六氯苯

采用国产新型D4020 大孔吸附树脂作固定相,用自制的玻璃富集柱研究了柱长、上样速度、样品溶液的pH、盐度等因素对对二氯苯与六氯苯吸附率的影响,确定了最佳固相萃取条件,建立了固相萃取-高效液相色谱同时测定水中痕量对二氯苯与六氯苯的分析方法;不同加标水平的对二氯苯与六氯苯的回收率为86.4%～93.9%,RSD≤4.2%,检出限分别为0.85和0.10 ng/mL;方法已用于实际水样分析.     

水环境中酚、二元酚和三元酚的高效液相色谱分析

采用固相萃取法富集水样，研究了水环境中苯酚、二元酚和三元酚类化合物的反相高效液相色谱分析法。     

微柱高效液相色谱法测定丹参中的几种有效成分

研究了用微柱高效液相色谱法测定丹参中的4种有效成分(丹参素,原儿茶酸,原儿茶醛,丹酚酸B)的方法。丹参样品中的几种有效成分用体积分数40%的甲醇超声振荡提取,然后以WatersXterraTMRP18(1.0×50mm,2.5μm)微柱为固定相,甲醇和体积分数1%的HAc溶液梯度洗脱为流动相分离,在该色谱条件下,丹参中的4种有效成分在4.0min内可达到基线分离;用紫外二极管矩阵检测器检测。方法标准回收率为97%~102%,相对标准偏差为1.6%~2.3%。用此方法可测定几种丹参样品中的有效成分。     

QuEChERS-高效液相色谱检测土壤中的吡虫啉

建立了测定土壤中吡虫啉的方法。土壤样品以乙酸-乙腈(体积比为0.1∶100)溶液提取,分散固相萃取净化,乙腈-水为流动相(体积比为7∶13),流速0.9 mL/min,270 nm检测,外标法定量。方法的线性范围为0.1~50μg/mL,线性相关系数为0.9994。平均加标回收率为90.1%~94.5%,RSD为0.7%~4.9%(n=6)。方法检测限为0.001 mg/kg(以信噪比为3计),定量限为0.004 mg/kg(以信噪比为10计)。该方法可用于新建房屋白蚁预防土壤化学屏障中吡虫啉的检测。     

固相萃取-高效液相色谱法测定枸杞中的类胡萝卜素

研究了固相萃取富集和预分离,高效液相色谱测定枸杞中的类胡萝卜素的方法;枸杞中的类胡萝卜素用WatersXterraTMRP18固相萃取小柱预分离,以WatersXterraTMRP18(3.9×150mm,5μm)液相色谱柱为固定相,甲醇 四氢呋喃(4 1)为流动相分离,用二极管矩阵检测器检测,检测波长为450nm。方法标准回收率为95%～103%。用该方法测定了几种枸杞样品中的类胡萝卜素。     

高效液相色谱法测定化妆品中氯噻酮和吩噻嗪

建立了反相高效液相色谱法测定化妆品中氯噻酮和吩噻嗪的分析方法。化妆品中氯噻酮和吩噻嗪用丙酮超声提取,采用Kromasil C18色谱柱(5μm,250 mm×4.6 mm i.d.),以30 mmol/L NaH2PO4缓冲液(pH 5.6)和甲醇为流动相进行梯度洗脱,得到了理想的分离效果。氯噻酮和吩噻嗪在0.2~100 mg/L范围内,质量浓度与其峰面积呈良好的线性关系。在低、中、高3个添加水平下,氯噻酮的平均回收率为94.8%~104.1%,RSD为0.7%~4.4%,吩噻嗪的平均回收率为92.5%~103.1%,RSD为1.0%~6.9%。方法可用于化妆品中氯噻酮和吩噻嗪的检测。     

Measurement of adsorption energy between a solid adsorbent and a liquid adsorbate using differential scanning calorimetry

We report on a novel method involving the use of differential scanning calorimetry (DSC) in evaluation of adsorption energy between a liquid adsorbate and a solid adsorbent. The proof of concept is demonstrated by measuring the exothermic heat release due to the adsorption of automotive transmission fluid (ATF), the adsorbate, to a paper-based friction material used in automotive torque converters, the adsorbent. The novelty of the measurement technique involves initial freezing of the liquid adsorbate so that the initiation of the adsorption process can be identified. Our experimental results and theoretical calculations reveal that the adsorption energy of the friction paper and the summation of adsorption energies of each friction paper ingredient are in good agreement.     

烟草各部位中茄尼醇含量分布研究

采用Kromsil ODS-1色谱柱,V(甲醇)∶V(乙醇)=55∶45混合液为流动相,在紫外检测波长设定为211 nm的高效液相色谱条件下测定了烟草中各部位提取物中的茄尼醇,其中烟叶中茄尼醇的质量分数为0.45%,其他部位茄尼醇的质量分数为:烟梗0.037%,烟茎0.0037%,烟根0.0037%,其中烟叶中的茄尼醇量最高,具有提取价值.     

化妆品中8种呋喃香豆素的高效液相色谱法检测及质谱确证

建立了同时测定化妆品中8种呋喃香豆素类化合物(8-羟基补骨脂素、补骨脂素、异补骨脂素、8-甲氧基补骨脂素、5-甲氧基补骨脂素、三甲沙林、欧前胡素和异欧前胡素)的高效液相色谱分析方法及液相色谱-串联质谱确证方法。膏霜类、水剂类、香波类、散粉类、唇膏类等不同类型的化妆品样品分别经适宜的提取溶液进行超声提取,提取液以离心处理后,取上清液经微孔滤膜过滤后测定。采用Agilent Zorbax SB-Phenyl色谱柱(250 mm×4.6 mm, 5 μm)分离,以甲醇-乙腈-水三元流动相梯度洗脱,流速1.0 mL/min,柱温30 ℃,检测波长250 nm。8-羟基补骨脂素的定量限为0.25 mg/kg,补骨脂素、异补骨脂素、8-甲氧基补骨脂素、5-甲氧基补骨脂素、三甲沙林、欧前胡素、异欧前胡素的定量限为0.5 mg/kg。在低、中、高3种加标水平下,8种待测组分的平均回收率为85.0%～105.8%,相对标准偏差为0.41%～7.90%。采用本方法在一日内不同时间点(6个时间点,每隔1 h测定一次)和不同日期(6 d内)测定混合标准溶液,得到8个目标物峰面积的日内精密度均小于1%,日间精密度均小于2%。该方法准确、简便、快速,适用于不同类型化妆品中8种呋喃香豆素类化合物的测定。