对氨基苯胂酸及其氧化物的色谱研究

用紫外分光光度计分析了对氨基苯胂酸（PABAA）及其氧化物的光谱特征后,在十八烷基键合相硅胶柱上,以甲醇-缓冲液作流动相,研究了二者的容量因子随流动相离子强度、柱温、甲醇含量变化的规律。用季铵盐作离子对试剂,反相离子对色谱法分离PABAA时,分离机理符合高子对机理,在适当条件下,所试验的化合物都可有所保留。对保留值作出贡献的有固定相排阻作用、分配作用以及居次要地位的PABAA与固定相表面剩余硅醇基的相互作用。排阻作用及分配作用的相对重要性与流动相中甲醇和离子对试剂的浓度有关。     

色谱法研究杂多酸 II.杂多酸在反相高效液相色谱中的保留行为

在十八烷基键合硅胶柱上,以甲醇-缓冲液作流动相,研究了杂多酸的容量因子随流动相离子强度、柱温、甲醇含量变化的规律,这些规律与我们导出的关系式相一致.对保留值作出贡献的有固定相排阻作用、分配作用以及居次要地位的杂多酸与固定相表面剩余硅醇基的相互作用.排阻作用与分配作用的相对重要性与流动相中甲醇含量有关.杂多酸可能形成了离子缔合物,其保留行为与一般的有机分子相似,但离子强度有影响.而影响最大的是杂多酸阴离子电荷数与甲醇含量.用季铵盐作离子对试剂,反相离子对色谱法分离杂多酸时,分离机理与“动态离子交换模型”差异较大,可能接近“离子对机理”.在适当的条件下,所试验的六种杂多酸都可有所保留.     

反相离子对色谱中的死时间测定（Ⅱ）

前文用NaNO_3和NH_4NO_3两种硝酸盐作为探头所测定的反相离子对色谱的死时间,在柱温、流速一定的情况下,并非一常数,而是随着流动相的有机溶剂的含量、离子对试剂的浓度而变化的。前文认为其可能的原因是离子对试剂在固定相上的吸附作用。本文对此将作进一步的探讨。 本文研究了用四丁基碘化铵(TBAI)和十二烷基硫酸钠(SLS)作离子对试剂,以重水(D_2O)作探头时,离子对试剂浓度、甲醇含量、进样量对D_2O保留值的影响,并与以NaNO_3作探头时以上因素对保留值的相     

手性离子对色谱法

阐述了手性离子对色谱分离药物对映体的基本原理。在ＨＰＬＣ流动相中加入光学纯反离子可与流动相中的对映体生成非对映体复合物（离子对）,离子对复合物之间具有不同的稳定性和分配性质,并可与固定相发生不同的静电、疏水和氢键作用,进而差速迁移得以分离。影响方法立体选择性的主要因素有：反离子的性质（酸碱性、亲脂性、光学纯度）、反离子的浓度、流动相的组分、流动相的流速、固定相的性质和色谱柱的温度等。     

反相离子对高效液相色谱法快速分离和定量测定食品中的甜蜜素

采用反相离子对高效液相色谱法快速分离和测定食品中的甜蜜素。在ODS柱上,以V（甲醇）：V（水,含离子对试剂）=30：70的溶液为流动相进行分离,分别考察了流动相中离子对试剂和甲醇浓度对甜蜜素保留行为的影响。检测波长为205nm;采用外标法定量,测得甜蜜素在0．5～2．5g／L范围内具有良好的线性关系;回收率在96．9％～101．7％之间;检测限为0．05g／L。     

用离子对色谱分离氨基酸衍生物的对映体

通过在由（Ｓ）－（Ｎ）－（２萘基）丙氨酸衍生而成的“刷型”手性固定相上采用离子对色谱分离氨基酸的３,５－二硝基苯甲酰衍生物,探讨了非手性离子对试剂的浓度对溶质保留和选择性的影响。使用甲醇与磷酸盐缓冲溶液组成的溶剂为流动相,考察了甲醇含量对手性分离的影响,另外,通过在不同构型的和性固定相上做对照实验,证明在结构相同、构型相反的手性固定相上,对映体的出峰顺序是相反的。     

金属有机化合物的分析（Ⅷ）：氢硼酸金属有机络合物的反相色谱机理

本文研究了具有特殊结构的氢硼酸金属有机络合物的反相色谱及机理。在MicropakC_(18)柱上,加入含离子试剂的甲醇-水作为流动相,通过用电导法测定流动相电性能,Break-through法测定离子试剂在固定相上的吸附量及制备色谱法研究各流分组成,认为此类化合物的保留机理为动态离子交换过程。     

水溶性维生素制剂的反相离子对色谱分析

考察了反相离子对试剂Ｂ系列（Ｂ５～Ｂ８）对水溶性维生素分离的色谱行为，确定了用国产庚烷磺酸钠作离子对试剂、（甲醇）＝０．２９的水溶液为流动相的最佳色谱条件，在１６ｍｉｎ内达到对六种混合水溶性维生素（烟酸、烟酰胺、Ｖ—Ｂ１、Ｖ—Ｂ２、Ｖ—Ｂ６、叶酸）的一次性良好分离，并用所选定条件测定了多维胶囊、复合维生素Ｂ的含量。该方法线性良好，精密度较高．     

碱基在十二胺-N,N-二亚甲基膦酸改性氧化锆固定相上色谱行为的研究

研究了碱基在十二胺-N,N-二亚甲基膦酸(DDPA)改性氧化锆固定相（DPZ）上的色谱保留行为,考察了流动相中甲醇含量、流动相pH值、缓冲溶液中离子类型和离子强度对碱基保留的影响,对DDPA在氧化锆表面的吸附方式进行了研究。研究结果表明,DDPA仅以一个膦酸基与氧化锆结合,因而DPZ固定相表面上除了有长链的疏水烷基外,还有酸性的膦酸基和碱性的氨基。碱基分子中也存在氨基和酰胺基等极性基团,因此碱基在DPZ固定相上除了有疏水作用外,还具有电荷排斥作用、离子交换作用等多种保留机理。由于多种保留机理的存在,使得碱基在DPZ固定相上具有较好的分离选择性,在酸性条件下对碱基混合样品的分离取得了满意的结果。     

离子对高效液相色谱－TPPS＿4光度法测定痕量锌和铜

本文用ＴＰＰＳ＿４作柱前衍生试剂，研究了试剂与锌（Ⅱ）和铜（Ⅱ）的配位反应，在ＯＤＳ柱上，用乙腈／水体系（２８％，Ｖ／Ｖ）作流动相，苄基三乙基氯化铵作离子对试剂．在４１５ｎｍ处检测，提出了离子对高效液相色谱。光度法快速分离测定痕量锌铜的新方法，检测限：Ｚｎ和Ｃｕ分别为０．１５和０．１０ｎｇ／ｍＬ，本法用于花生样品中痕量Ｚｎ、Ｃｕ的测定，结果与ＡＡＳ一致。     

离子对色谱-间接紫外检测法分析哌啶离子液体阳离子

建立了快速分析无紫外光吸收的哌啶离子液体阳离子的离子对色谱-间接紫外检测法。采用反相C18色谱柱,以背景紫外吸收试剂-离子对试剂水溶液/有机溶剂为流动相分离哌啶离子液体阳离子。研究了背景紫外吸收试剂、检测波长、离子对试剂、有机溶剂、柱温、流速对分离测定哌啶阳离子的影响。最佳色谱条件为：以0.5 mmol/L对氨基苯酚盐酸盐-0.1 mmol/L庚烷磺酸钠水溶液/甲醇（80：20,v/v）为流动相,检测波长210 nm,柱温30 ℃,流速1.0 mL/min。在此条件下,3种哌啶阳离子可在4 min之内基线分离。所测阳离子的检出限（S/N=3）为0.137~0.545 mg/L,峰面积和保留时间的相对标准偏差（n=5）分别不高于0.72%和0.37%。将此方法用于分析实验室合成的哌啶类离子液体,加标回收率为97.0%~98.4%。本方法简便、快速,重现性、线性关系等均能满足哌啶类离子液体阳离子的定量分析要求。     

Ethylammonium formate as an organic solvent replacement for ion-pair reversed-phase liquid chromatography

Ethylammonium formate (EAF), an inexpensive and easily synthesized room-temperature ionic liquid, acts like a conventional organic solvent for reversed-phase liquid chromatography (LC). In this report, the use of standard ion-pair reagents with this ionic liquid LC mobile phase and a polystyrene-divinylbenzene PRP-1 column is explored. Starting with the column equilibrated with a methanol mobile phase, the required equilibration time of the column by the EAF ion-pair mobile phase is determined by the plate number profile. Chromatograms of six aromatic carboxylic acids, with either methanol or EAF as the mobile phase, at room temperature (in the absence of an ion-pairing agent) lack resolution with significant peak overlap of nitro-substituted benzoic acids. The addition of 30mM tetrabutylammonium ion to the EAF or methanol mobile phase provides baseline resolution for all peaks in approximately 10 min. Analogous studies using a mixture of four aromatic amines, including protonated tyramine, diphenhydramine, and neutral nitroanilines in the absence or presence of 30mM sodium dodecylsulfate (SDS) in the mobile phase are similar to those for the aromatic acids, indicating baseline resolution with only the ion-pair reagent. Raising the column temperature to 55 degrees C improves the plate count by a factor of approximately 1.2 when using the EAF mobile phase. The retention factor profiles for either the carboxylic acids or the amines, as a function of the organic modifier percentage or ion-pair reagent concentration, are similar for both EAF and methanol. The polymerized acyl monoglycinate surfactant, poly(sodium-N-undecenoyl glycinate), is used for the first time as an LC ion-interaction reagent and is about as effective as SDS for the resolution of organic amines.     

反相离子对色谱-直接电导检测法分析六氟磷酸根离子液体阴离子

建立了反相离子对色谱-直接电导检测六氟磷酸根(PF6-)离子液体阴离子的分析方法。用DiamonsilC18反相色谱柱为分离柱,以离子对试剂-柠檬酸-乙腈混合水溶液为流动相,考察了离子对试剂、乙腈含量、pH值及色谱柱温度对六氟磷酸根保留的影响,并讨论了相关保留机理。在优化的色谱条件下,即流动相为0.05 mmol/L氢氧化四丁铵-0.038 mmol/L柠檬酸-35%乙腈(pH 5.5),流速1.0 mL/min,色谱柱温度40℃时,PF6-与其它常见阴离子(F-、Cl-、Br-、NO3-、SO24-、BF4-)达到基线分离且保留时间在15 min内。方法检出限(S/N=3)为0.25 mg/L,标准曲线的线性范围为0.5～100.0 mg/L,峰面积和保留时间的相对标准偏差(n=5)分别为0.17%和0.15%。该法用于1-丁基-3-甲基咪唑六氟磷酸盐和1-丙基-2,3-二甲基咪唑六氟磷酸盐两种离子液体中PF6-的测定,加标回收率分别为99%和104%。该方法简单、准确、可靠,实用性好。     

整体柱离子对色谱-间接紫外检测法快速测定N-甲基,丙基吗啉阳离子

建立了快速分析无紫外吸收的N-甲基,丙基吗啉阳离子的离子对色谱-间接紫外检测法。采用反相C18硅胶整体柱,以背景紫外吸收试剂-离子对试剂-有机溶剂为流动相。研究了背景紫外吸收试剂、检测波长、离子对试剂、有机溶剂、柱温、流速对吗啉阳离子测定的影响。最佳色谱条件为:(0.5 mmol/L对氨基苯酚盐酸盐-0.1 mmol/L庚烷磺酸钠)溶液-甲醇(9:1, v/v)为流动相,检测波长230 nm,柱温30 ℃,流速1.0 mL/min。在此条件下,N-甲基,丙基吗啉阳离子的保留时间为2.966 min,检出限为0.07 mg/L(S/N=3),峰面积的相对标准偏差为2.1%(n=5),保留时间的相对标准偏差为0.02%(n=5)。将此方法用于分析实验室合成的N-甲基,丙基吗啉离子液体,加标回收率为98.8%。结果表明本方法简便、快速。     

反相高效液相色谱法对八种吡嗪类化合物保留性能的研究

在Ｓｐｈｅｒｉｓｏｒｂ－Ｃ（１８）反相柱上,以甲醇－水为流动相,对八种吡嗪类化合物的保留性能进行了考察。同时用不同浓度下的冲洗剂所得保留值和关系式ｌｎｋ＇＝ａ＋ｃＣｂ中的参数ａ、ｃ作线性关系,得到很好的相关性。流动相中不同的无机盐及微量有机胺类改性剂的加入,可有效地改进分离。当甲醇：０．２ｍｌ／ＬＨＡｃ－ＮａＡｃ缓冲液（ｐＨ４．５）：三乙胺为４０：５９：１（Ｖ／Ｖ）时,除两种同分异构体不能分离外,所有组分在２５ｍｉｎ内可实现较理想的分离。     

Determination of tetraethyl ammonium by ion-pair chromatography with indirect ultraviolet detection using 4-aminophenol hydrochloride as background ultraviolet absorbing reagent

A method was developed for the determination of tetraethyl ammonium (TEA) by reversed-phase ionpair chromatography with indirect ultraviolet detection. Chromatographic separation was achieved on a reversed-phase C18 column using background ultraviolet absorbing reagent - ion-pair reagent - organic solvent as mobile phase. The effects of the background ultraviolet absorbing reagents, detection wavelength, ion-pair reagents, organic solvents and column temperature on the determination method were investigated and the retention rules discussed. Results found that TEA could be successfully analyzed by using 0.7 μmol/L 4-aminophenol hydrochloride and 0.15 μmol/L 1-heptanesulfonic acid sodium mixed with 20% (v/v) methanol asmobile phase at a UV detection wavelength of 230 nm. Under these conditions, the retention time of tetraethyl ammonium was 2.85 min. The detection limit (S/N = 3) for TEA was 0.06 mg/L. The relative standard deviations (n = 5) for peak area and retention time were 0.35% and 0.02%, respectively. The method has been successfully applied to the determination of synthesized tetraethyl ammonium bromide. Recovery of tetraethyl ammonium after spiking was 99.1%.     

Rapid and simultaneous determination of piperidinium and pyrrolidinium ionic liquid cations by ion pair chromatography coupled with direct conductivity detection

A method of ion-pair chromatography with direct conductivity detection was developed on a silicabased monolithic column for the fast and simultaneous determination of piperidinium and pyrrolidinium ionic liquid cations. The effects of the mobile phase, column temperature and flow rate on the retention of the cations were investigated. The retention rules were discussed. As an ion-pair reagent, sodium heptanesulfonate is more suitable than sodium pentanesulfonate for the separation and determination of piperidinium and pyrrolidinium cations. The increase of ion-pair reagent concentration led to the increased retention time of the cations. When acetonitrile content and mobile phase flow were increased, the retention time of the cations became shorter. The retention of piperidinium and pyrrolidinium cations is an exothermic process, and the retention of the cations conforms to the carbon number rule. The chromatographic analysis was performed using the Chromolith Speed ROD RP-18e column, 0.5 μmol/L sodium heptanesulfonate-5% acetonitrile as the mobile phase at a flow rate of 3.0 mL/min and column temperature of 30℃. Separation of N-methyl-N-ethyl piperidinium, N-methyl-N-propyl piperidinium, N-methyl-N-butyl piperidinium and N-methyl-N-ethyl pyrrolidinium, N-methyl-N-propyl pyrrolidinium, N-methyl-N-butyl pyrrolidinium cations were achieved within 10 min. The detection limits (S/N=3) were between 0.19 and 3.08 mg/L. Relative standard deviations (n=5) for peak areas were less than 1.2%. The method has been applied to the determination of piperidinium and pyrrolidinium cations in ionic liquid samples. The spiked recoveries of ionic liquid cations were between 96% and 111%. The method is accurate, reliable, rapid, and has a better practicability.     

The use of water structure breakers, urea and guanidium chloride, new mobile phase modifiers in reversed-phase partition high-performance liquid chromatography.

Organic solvent-free mobile-phase systems in ion-pair reversed-phase partition high-performance liquid chromatography (IPRP-HPLC) are demonstrated; using urea at 3.0-7.0 molal (mol kg-1) as a modifier in a mobile phase on an octadecylsilanized silica column, four nitrophenolates and metal 4-(2-pyridilazo)resorcinol (PAR) chelates (in PAR chelates system an aqueous mobile phase with 15 wt% methanol was used) were separated rapidly within 6 min at no sacrifice to the separation efficiency. On the addition of urea in the mobile phase, reduced retention times of nitrophenolates and naphthalenesulfonates and also diminution of the height equivalent to a theoretical plate were observed. The addition of urea and guanidium chloride (GuCl) in the mobile phase gave rise to a decrease in the mobile phase volume; in turn, this meant an increased volume of the stationary phase. As the concentration of urea and GuCl in the mobile phase increased, the volume of the mobile phase in the column decreased within about 70% and 40% at 7.0 molal of urea and GuCl, respectively. A decrease in the mobile phase volume suggests an increase in the extent of solvation of the bonded hydrocarbon chain of the stationary phase. The possible explanations for the LC behavior with the urea and GuCl are turned into reduction of hydrophobic interaction in LC processes, solute partitioning and entangling of alkyl chain brushes, with the addition of urea. The water structure breakers, urea and GuCl, most likely affect the solvation states of both solute molecules and the hydrocarboneous stationary phase by changing the nature of the water solvent, which provides a new technique for fine tuning of the LC resolution of the analytes.