Adsorption of Solvents and Molecular Interactions in LSC with a Ternary Mobile Phase

Abstract

A modification of Jaroniec equation [1] is proposed. Adsorption of all solvents is taken into account. A physical meaning of the slope of the equation is analysed. The effects of solvents adsorption, solvent-solvent and solute-solvent molecular interactions on the retention in LSC with ternary mobile phase are discussed.     

Retention Behavior of Purine-Like Compounds on Titania and the Effect of Organic Modifiers Content in the Mobile Phase

The retention behavior of purine and purine-like compounds on titania was investigated in order to elucidate the strong retention of purine on titania. It was verified that, as expected, the strong retention stemmed from the formation of a chelate ring using the two nitrogen atoms N3 and N9 with titania. Purine has two possible tautometric forms because of proton tautomerism between N7 and N9. Hence, the lone pair of either of the two nitrogen atoms could be located immediately in an sp² orbital. Therefore, it was found that the lone pairs of N3 and N9 must be located in an sp² orbital, and the location is essential to forming the chelate with titania. Moreover, the effect of the presence of methanol and acetonitrile in the mobile phase on retention was also investigated. The retention strength increased with their content, but the tendency of this increase was different for the two organic solvents. It was concluded that the difference stems from the differing degrees of strength of the ligands, which includes the analytes and the solvents, as a result of competing with each other. Water and methanol acted as ligands strong enough to compete with the analytes, but acetonitrile did not, probably because it lacks hydroxy groups, which have a strong affinity for titania.     

Development of an FI-ICP Method for On-Line Preconcentration and Determination of Platinum

This paper presents a new simple and rapid procedure for the preconcentration and determination of platinum. It is based on the adsorption of the metal ion and preconcentration on a micro-column (3cm×3mm) placed in the injection valve of a flow injection (FI) manifold and packed with 1,5-bis[(2-pyridyl)-3-sulphophenyl-methylene]thiocarbonohydrazide (PSTH) immobilised on an anion-exchange resin (Dowex 1X8-200). The metal was eluted from the column using a solution of 2M HNO₃. Various parameters and chemical variables affecting the preconcentration and determination of this metal by ICP-AES were evaluated. Five variables (sample flow rate, eluent flow rate, nebulizer flow rate, buffer concentration and mixing coil length) were considered as factors in the optimisation process. Interactions between analytical factors, and their optimal levels were investigated using two level factorial and central matrix designs. The optimum conditions established were applied to the determination of platinum by flow injection inductively coupled plasma atomic emission spectrometry (FI-ICP-AES). The method has a linear calibration range of 25 to at least 200ngmL^–1 with a detection limit of 7.4ngmL^–1 (S/N=3) and a throughput of 10 samples h^–1 using 5min. preconcentration time. The precision of the method (RSD) was 3.06% ngmL^–1 at the 50ngmL^–1 level of Pt(IV) and 2.93% at the 150ngmL^–1 level. The accuracy of the method was examined by determining the analyte content in spiked waters and by analysing an automobile catalyst standard reference material. The results show good agreement with the certified value and sufficiently high recoveries.     

两种三唑类杀菌剂的拆分研究

将纤维素-三（3,5-二甲基苯基氨基甲酸酯）（CDMPC）涂敷于自制的球形氨丙基硅胶上,制备了手性固定相.正相条件下,在该固定相上直接拆分了两种三唑类杀菌剂三唑酮与戊唑醇外消旋体,并且系统地选用了多种流动相体系对样品拆分的流动相条件进行了优化,筛选出了适合三唑酮与戊唑醇拆分的流动相体系.     

Development of Microdroplet Generation Method for Organic Solvents Used in Chemical Synthesis

Recently, chemical operations with microfluidic devices, especially droplet-based operations, have attracted considerable attention because they can provide an isolated small-volume reaction field. However, analysis of these operations has been limited mostly to aqueous-phase reactions in water droplets due to device material restrictions. In this study, we have successfully demonstrated droplet formation of five common organic solvents frequently used in chemical synthesis by using a simple silicon/glass-based microfluidic device. When an immiscible liquid with surfactant was used as the continuous phase, the organic solvent formed droplets similar to water-in-oil droplets in the device. In contrast to conventional microfluidic devices composed of resins, which are susceptible to swelling in organic solvents, the developed microfluidic device did not undergo swelling owing to the high chemical resistance of the constituent materials. Therefore, the device has potential applications for various chemical reactions involving organic solvents. Furthermore, this droplet generation device enabled control of droplet size by adjusting the liquid flow rate. The droplet generation method proposed in this work will contribute to the study of organic reactions in microdroplets and will be useful for evaluating scaling effects in various chemical reactions.     

固相萃取-固相光谱联用仪的构建及其应用于食品中罗丹明B的测定

设计并制造了以膜材料为分离富集介质的固相萃取装置和以漫反射光谱法为测定手段的测定装置相结合的自动化分析仪并应用于测定食品中罗丹明B的含量。该仪器由固相萃取装置、固相光谱测定装置和软件等3个部分组成。样品溶液(调节pH至2.00)负压自动进样,调节真空度在合适的速率下通过滤膜,待测物质富集于滤膜上。滤膜经热风干燥后由积分球在滤膜固相介质表面采集被测物质的漫反射光谱,仪器控制、光谱采集和数据处理直至报告的发出均由软件完成。在分析辣椒样品时,取样品0.500g,用水50.0mL超声提取10.0min,离心后取上清液测定罗丹明B的含量。测定时用混合纤维素膜进行富集,并选择测定波长为546.7nm。罗丹明B的线性范围为5.0~15.0μg·L^-1。分析红茶样品时,将样品用水稀释10倍后进行分析。在红茶的基质下,罗丹明B的线性范围为10.0~30.0μg·L^-1。上述2种样品的回收率为88.0%~108%,测定值的相对标准偏差(n=5)为4.6%~9.3%。     

HPLC/APCI Mass Spectrometry of Saturated and Unsaturated Hydrocarbons by Using Hydrocarbon Solvents as the APCI Reagent and HPLC Mobile Phase

Saturated and unsaturated, linear, branched, and cyclic hydrocarbons, as well as polyaromatic and heteroaromatic hydrocarbons, were successfully ionized by atmospheric pressure chemical ionization (APCI) using small hydrocarbons as reagents in a linear quadrupole ion trap (LQIT) mass spectrometer. Pentane was proved to be the best reagent among the hydrocarbon reagents studied. This ionization method generated different types of abundant ions (i.e., [M + H]⁺, M^+•, [M – H]⁺ and [M – 2H]^{+ •}), with little or no fragmentation. The radical cations can be differentiated from the even-electron ions by using dimethyl disulfide, thus facilitating molecular weight (MW) determination. While some steroids and lignin monomer model compounds, such as androsterone and 4-hydroxy-3-methoxybenzaldehyde, also formed abundant M^+• and [M + H]⁺ ions, this was not true for all of them. Analysis of two known mixtures as well as a base oil sample demonstrated that each component of the known mixtures could be observed and that a correct MW distribution was obtained for the base oil. The feasibility of using this ionization method on the chromatographic time scale was demonstrated by using high-performance liquid chromatography (HPLC) with hexane as the mobile phase (and APCI reagent) to separate an artificial mixture prior to mass spectrometric analysis.     

反相液相色谱二元流动相组成的计算机统计试验全局最佳化

本文用一类非线性规划形式表述的分离模型作为最优化标准,用统计试验全局最佳化方法寻求二元流动相的最佳组成。实验证明:至多5个试验和10分钟左右的计算时间即可找到全局最佳点。     

反相高效液相三元流动相台阶梯度分离条件的快速优化方法

 根据溶质在柱内的迁移规律 ,建立了一种利用线性梯度实验快速获得溶质保留值方程系数 ,然后以串行响应函数为优化指标进行多台阶梯度分离条件优化的方法。与利用等度实验获得保留值方程的方法相比 ,该法可以大大缩短优化时间。通过该方法对芳香胺和衍生化氨基酸样品进行了分离 ,获得了满意的分离度 ,表明该方法的预测精度很好。     

Supramolecular Micellization of Diblock Copolymer Mixtures Mediated by Hydrogen Bonding for the Observation of Separated Coil and Chain Aggregation in Common Solvents

This paper describes a new approach towards preparing self‐assembled hydrogen‐bonded complexes that have vesicle and patched spherical structures from two species of block copolymer in non‐selective solvents. The assembly of vesicles from the intermolecular complex formed after mixing polystyrene‐block‐poly(4‐vinyl phenol) (PS‐b‐PVPh) with poly(methyl methacrylate)‐block‐poly(4‐vinylpyridine) (PMMA‐b‐P4VP) in tetrahydrofuran (THF) is driven by strong hydrogen bonding between the complementary binding sites on the PVPh and P4VP blocks. In contrast, well‐defined patched spherical micelles form after blending PS‐b‐PVPh with PMMA‐b‐P4VP in N,N‐dimethylformamide (DMF): weaker hydrogen bonds form between the PVPh and P4VP blocks in DMF, relative to those in THF, which results in the formation of spherical micelles that have compartmentalized coronas that consist of PS and PMMA blocks.

     

Development and Validation of LC Method for Simultaneous Determination of Two Binary Mixtures Containing Indapamide

A new sensitive, simple, rapid, and precise RP LC method with hydrochlorothiazide as internal standard has been developed for resolving two binary mixtures, perindopril with indapamide and captopril with indapamide, in pharmaceutical formulations. The drugs were separated at room temperature on a 250 mm × 4.6 mm, 5-μm particle, cyanopropyl column with 10 mm KH₂PO₄, pH 6.0-methanol 55:45 (v/v) as mobile phase at a flow rate of 1 mL min^?1. Detection was at 210 nm. Factors affecting the separation process were studied and optimized. The linearity, accuracy, and precision of the method were good, and the method was successfully applied to the determination of the two binary combinations in synthetic mixtures and commercial pharmaceutical products.     

Application of Micellar Mobile Phase for Quantification of Sulfonamides in Medicated Feeds by HPLC-DAD

Rapid chromatographic procedure for quantification of five sulfonamides in medicated feeds are proposed. Satisfactory separation of sulfonamides from medicated feeds was achieved using a Zorbax Eclipse XDB C18 column (4.6 × 150 mm, 5 µm particle size) with a micellar mobile phase consisting of 0.05 M sodium dodecyl sulphate, 0.02 M phosphate buffer, and 6% propan-2-ol (pH 3). UV quantitation was set at 260 nm. The proposed procedure allows the determination of sulfaguanidine, sulfadiazine, sulfamerazine, sulfamethazine, and sulfamethoxazole in medicated feeds for pigs and poultry. Application of the proposed method to the analysis of five pharmaceuticals gave recoveries between 72.7% to 94.7% and coefficients of variations for repeatability and reproducibility between 2.9% to 9.8% respectively, in the range of 200 to 2000 mg/kg sulfonamides in feeds. Limit of detection and limit of quantification were 32.7–56.3 and 54.8–98.4 mg/kg, respectively, depending on the analyte. The proposed procedure for the quantification of sulfonamides is simple, rapid, sensitive, free from interferences and suitable for the routine control of feeds. In the world literature, we did not find the described method of quantitative determination of sulfonamides in medicated feeds with the use of micellar liquid chromatography.     

高效液相色谱法分离药物对映体中手性流动相添加剂的应用

综述了近年来手性流动相添加剂在高效液相色谱拆分对映体中的应用,阐述了各类手性流动相添加剂的拆分机理及其在药物分析中的应用,引用文献52篇.     

反相液相色谱中固定相和流动相对柱相比的贡献

依据柱相比的热力学定义和反相液相色谱中溶质的计量置换保留理论(the stoichiometric dispheement heory of solute for retention，SDT-R)，对反相液相色谱中固定相和流动相性质、温度对柱相比的影响进行了研究。结果表明：固定相的种类和配基的疏水性对柱相比影响较大，而流动相中有机溶剂的种类，特别是脂肪酸作为置换剂时，对柱相比的影响更大，而柱相比受温度的影响较小。此外，通过用27种小分子溶质对柱相比的测定，其logI和Z良好的线性关系，进一步证明柱相比是一个与溶质性质无关的常数。     

流动相离子色谱法测定杂多酸中氯与磷酸根离子

探讨了用流动相离子色谱法测定杂多酸中C l-与PO43-的分析条件。通过在淋洗液中加入两性离子3-(N-吗啉)-1-丙磺酸(3-(N-morpholino)propanesu lfon ic ac id,MOPS),调节流动相pH值,找到一种pH 6.98的流动相,同时优化离子对试剂的配比,并加入无机添加剂和有机改进剂,能有效的抑制杂多酸的分解,较精确地测定其中所含阴离子。     

采用易挥发溶剂,静置、自然干燥法涂渍气相色谱固定液

在涂渍气相色谱固定液时,选用易挥发,低粘度溶剂(如正己烷,丙酮等)．担体与溶剂按一定比例混合,溶剂恰好湿润担体,无多余溶剂,涂渍过程不需搅拌、加热等程序,不需旋转蒸发器、水浴、红外灯等设备．此方法具有操作简单,涂渍快速,操作人员中毒少,担体破碎少等优点,而且保证固定液涂渍均匀．本文给出了常用固定液所用易挥发溶剂及常用担体在用本方法涂渍时固定液与溶剂的比例．     

用于蛋白同时复性及纯化的制备型装置中流动相用量的优化研究

 在生物大分子的高效液相色谱分离中 ,由计量置换保留模型可得出生物大分子在色谱柱上的保留行为取决于流动相中置换剂的浓度的结论。据此提出了用于蛋白同时复性及纯化的制备型装置 (USRPP)中最小流动相用量的估算公式 ,并进一步得出在保持最小流动相用量不变的条件下 ,改变流动相流速和线性梯度时间几乎不影响制备型USRPP分离蛋白的分离度和复性效率的结论。该结论与实验结果一致。     

正负离子表面活性剂与高聚物混合双水相体系的相行为及蛋白质的分配

报道了由正负离子表面活性剂与高聚物混合溶液形成的一种可用于蛋白质的分离及分析的新型双水相萃取体系.研究了正负离子表面活性剂(溴化十二烷基三乙铵/十二烷基硫酸钠)分别与葡聚糖和聚乙二醇混合双水相体系的形成规律、相行为及牛血清蛋白和溶菌酶在双水相体系中的分配.通过在高聚物分子中接上亲和配基,研究蛋白质在双水相体系中的亲和分配.结果表明,在该体系中,表面活性剂与高聚物分别富集于不同相中.升高温度及加入无机盐均可促进双水相体系的形成,不同蛋白质可分配于不同的相中.亲和配基的引入极大地增强了蛋白质分配的选择性.