Determination of enantiomeric impurity of etomidate by high performance liquid chromatography

Objective To determine enantiomeric impurity of etomidate using high performance liquid chromatography. Methods (R)-etomidate and (S)-etomidate were separated on a CHIRALPAK AD-H column. The mobile phase consisted of 20∶80(v/v) isopropanol-n-hexane. The flow rate of the mobile phase was 0.5mL/min. The detected wavelength was 242nm. Results (R)-etomidate and (S)-etomidate could be separated completely under these conditions. The precision of (R)-etomidate was 1.57% (n=3). The limit of detection of (R)-etomidate was 4.25ng/mL. The average percentage content of (S)-etomidate was 0.09% in the samples. Conclusion The method was repeatable and sufficiently sensitive to determine the enantiomeric impurity of etomidate. It allows the quantitation of the impurities at the 0.085% (w/w) level relative to etomidate at a concentration of the test solution of 5mg/mL.

Enantiomeric separation of phenylsuccinic acid by cyclodextrin-modified reversed phase high-performance liquid chromatography

The chiral separation of phenylsuccinic acid(PSA)was studied by reversed phase high-performance liquid chromatography(RP-HPLC)with cyclodextrins(CDs)as chiral mobile phase additives.The effects of types of CDs,concentration of hydroxypropyl-β-cyclodextrin(HP-β-CD),percentage of organic modifier,pH value and column temperature on enantioselective separation were investigated.The quantification property of the developed RP-HPLC method was examined.The chiral recognition mechanism of PSA was also discussed.The results show that a baseline separation of PSA enantiomers is achieved on a Lichrospher C18 column(4.6 mm(inner diameter)×250 mm,5μm)with HP-β-CD as chiral mobile phase additive.The capacity factors of R-PSA and S-PSA are 3.94 and 4.80,respectively.The separation factor and resolution are respectively 1.22 and 8.03.The mobile phase is a mixture of acetonitrile and deionized water(20-80,volume ratio)containing 10 mmol/L HP-β-CD and 0.05% trifluoroacetic acid(pH 2.5,adjusted with triethylamine)with a flow rate of 1.0 mL/min.The ultraviolet(UV)detector is set at 254 nm.The likely roles are inclusion interaction,induction and hydrogen bonding between HP-β-CD and PSA enantiomers.

Chiral separation of triazole pesticide enantiomers by high performance liquid chromatography

Four triazole enantiomers of diclobutrazol (erythro form) (1), paclobutrazol (erythro form) (2), diniconazole (3) and uniconazole (4) have been separated by high performance liquid chromatography (HPLC) on chiral stationary phase (CSP) OA-4700. Chromatographic data, and a chiral recongnition model are presented for the separation of these pesticide enantiomers. The influence of column temperature and composition of mobile phase have been described.

Investigation of retention and chiral recognition mechanism using quantitative structure-enantioselectivity retention relationship in high performance liquid chromatography

The enantiomers of a series of fourteen O-ethyl O-(substituted) phenyl N-isopropyl-phosphoroamidothioates have been separated by high performance liquid chromatography (HPLC) on the Pirkle-type chiral stationary phase. Seven molecular descriptors were calculated and four significant descriptors were chosen to correlate against the experimental lnk' values in order to form the quantitative structure-enantioselectivity retention relationships (QSERRs). Through the QSERRs, the retention and enantioselectivity mechanism were examined.

Comparison of the performance of chiral stationary phase for separation of fluoxetine enantiomers

Separation of fluoxetine enantiomers on five chiral stationary phases （chiralcel OD-H, chiralcel OJ-H, chiralpak AD-H, cyclobond 1 2000 DM and kromasil CHI-TBB） was investigated. The optimal mobile phase compositions of fluoxetine separation on each column were hexane/isopropanol/diethyl amine （98/2/0.2, v/v/v）, hexane/isopropanol/diethyl amine （99/1/0. l, v/v/v）, hexane/isopropanol/diethyl amine （98/2/0.2, v/v/v）, methanol/0.2% triethylamine acetic acid （TEAA） （25/75, v/v; pH 3.8） and hexane/isopropanol/diethyl amine （98/2/0.2, v/v/v）, respectively. Experimental results demonstrated that baseline separation （Rs〉1.5） of fluoxetine enantiomers was obtained on chiralcel OD-H, chiralpak AD-H, and cyclobond I 2000 DM while the best separation was obtained on the last one. The eluate orders of fluoxetine enantiomers on the columns were determined. The first eluate by chiralcel OJ-H and kromasil CHI-TBB is the S-enantiomer, while by chiralpak AD-H and cyclobond 12000 DM is the R-enantiomer.

Comparative Optical Separation of Racemic Ibuprofen by Using Chiral Stationary Phase

Ibuprofen is widely used as a non-steroidal anti-inflammatory drug and produced as racemic mixture. Its pharmacological activity resides only in S-(+)-enantiomer, and R-()-enantiomer is not only inactive but also has many side effects. Thus it is necessary to separate R-enantiomer from racemic ibuprofen. We studied optical separation of racemic Ibuprofen with chiral high performance liquid chromatography (HPLC). Out of three different chiral stationary phases, which were selected on the basis of structure and availability, two were found to be ef-fective. There was optimum eluent composition for each stationary phase for good resolution in optical separation. Resolution decreased with increase of eluent flow rate, but effect of injection volume on resolution was insignificant at high eluent flow rate.

左沙丁胺醇在联合雾化吸入中的稳定性研究

目的:建立一种用新型键合纤维素手性固定相拆分沙丁胺醇对映异构体的高效液相色谱法,并研究联合超声雾化过程中左沙丁胺醇(R-沙丁胺醇)的稳定性。方法:使用Chiralpak IC(250 mm×4.6 mm,5μm)手性色谱柱,流动相为正己烷-异丙醇(80∶20,V/V,0.1%二乙胺),流速0.8 mL/min,柱温25℃,检测波长226 nm拆分沙丁胺醇对映体。布地奈德、R-沙丁胺醇联合超声雾化30 min后,制备样品溶液,判断R-沙丁胺醇超声雾化中稳定性。结果:沙丁胺醇在新型键合纤维素手性固定相上能够完全分离,分离度为2.12,先流出物为R-沙丁胺醇。对比联合雾化后和刚拆封R-沙丁胺醇吸入溶液色谱图,峰型及峰面积变化不大,说明联合雾化中R-沙丁胺醇稳定性较好。结论:本方法可方便地实现沙丁胺醇对映体的分离,与布地奈德联合雾化30 min,R-沙丁胺醇稳定性较好。

β-环糊精金属有机骨架材料HPLC手性柱拆分噁唑禾草灵

合成了以β-环糊精和间羧基苯磺酰氯为有机配体、钾离子为配位离子的金属有机骨架材料(MOF)键合在高效液相色谱硅珠上,构建了高效液相色谱(HPLC)手性固定相(β-CD-MOF-P20@SiO_(2))新型材料,以此作为HPLC固定相,在反相色谱模式下,以乙酸铵-三乙胺/乙酸缓冲液和乙腈为流动相,优化流动相配比、缓冲液pH值、浓度和流速等色谱条件,获得了噁唑禾草灵两对映体最佳分离度,可达9.89。两对映体色谱峰响应信号与消旋体浓度在6.20×10^(-6)~2.99×10^(-4) mol/L范围内的线性相关性好(r=0.996 2~0.999 9),该MOF材料为噁唑禾草灵单一对映体定性、定量及制备提供了新方法。

糖诱导相分离/超高效液相色谱-高分辨质谱法测定牛奶中高氯酸盐含量

目的建立基于糖诱导相分离技术结合超高效液相色谱-高分辨质谱法(ultra performance liquid chromatography-high resolution mass spectrometry,UPLC-HRMS)测定牛奶中高氯酸盐含量的分析方法。方法样品制备采用乙腈为提取溶剂,木糖为相分离诱导剂。分析物经Poroshell 120(50 mm×2.1 mm,1.9μm)色谱柱分离,以甲醇-1%乙酸水溶液为流动相进行梯度洗脱。采用电喷雾负离子模式与单一离子监测(targeted single ion monitoring,tSIM)扫描模式,结合同位素内标法进行定量。结果在0.1~20.0μg/L的范围内,高氯酸盐线性关系良好(r^(2)=0.9988)。方法检出限(limits of detection,LODs)和定量限(limits of quantification,LOQs)分别为0.1μg/L和0.3μg/L;3个加标水平下,回收率为88.7%~116.8%,相对标准偏差为2.3%~8.1%。在30份牛奶样品的检测分析中,高氯酸盐的检出率达100%。结论该方法操作简便,对样品净化效果良好,具有低成本、高灵敏度的优点,适用于牛奶中高氯酸盐检测。

四氢嘧啶的分离纯化及分析方法的研究进展

在高盐度的环境中,嗜盐微生物通过合成具有特殊作用的化合物来维持细胞内外渗透压平衡,保持其正常的生命活动。四氢嘧啶作为一种独特的相容性物质,可以帮助微生物在盐度较高的不利条件下生存,其在生物保护、化妆品、临床医学、环境修复和新能源应用等领域都具有广阔的应用前景。介绍了目前国内外对四氢嘧啶的制备、分离纯化过程、分析方法等方面的最新研究进展,并对各种方法的优缺点进行总结,以期对四氢嘧啶的进一步研究与应用提供一定的参考资料。

枸杞提取物中玉米黄质和叶黄素含量的高效液相测定方法

选用色谱柱Innoval ODS-2(4.6 mm×250 mm,5µm),以0.05%三乙胺-乙腈为流动相,流速为0.8 mL/min,柱温为28℃,在450 nm波长处测定样品。结果显示:玉米黄质在0.207~20.7µg/mL范围内线性关系良好,判定系数r^(2)=1.0000,平均回收率为113.72%(n=6),RSD为1.50%,检出限为0.027µg/mL;叶黄素在0.216~21.6µg/mL范围内线性关系良好,判定系数r^(2)=1.0000,平均回收率为105.96%(n=6),RSD为3.78%,检出限为0.056µg/mL。该方法快速、简单稳定、结果准确,适用于同时测定枸杞提取物中叶黄素和玉米黄质。

流动相对百树菊酯高效液相色谱手性分离的影响

在一种由N－3，5二硝基苯甲酸苯基甘氨酸衍生而成的Pirkle1-A型手性固定相上分离百树菊酯的8个立体异构体，通过选用不同的醇作为流动相的强溶剂，研究二元体系中流动相组分对保留值和选择性的影响。结果表明：对同一种组分的流动相，增加流动相的强度会缩短溶质的保留时间，且对非对映体的选择性影响比较大，而对对映体的选择性影响却不大，作为强溶剂的醇的结构不同会对异构体的分高度及峰形产生影响，二级醇或三级醇作强溶剂时的分高度好于一级醇，小分子醇作强溶剂时的峰形好于较大分子醇。

HPLC同时分析金银花中绿原酸和黄酮类成分的方法建立及其应用

目的建立应用反相高效液相色谱法同时测定金银花中绿原酸和4种黄酮类成分——芦丁、木犀草素7-O-β-D-半乳糖苷、忍冬苷、槲皮素含量的方法。方法色谱柱为AglientZorbax80A(4.6mm×250mm,5μm);流动相为乙腈-0.5%磷酸,梯度洗脱;流速1.0mL·min-1,检测波长为355nm。结果绿原酸、芦丁、木犀草素7-O-β-D-半乳糖苷、忍冬苷、槲皮素的线性范围分别为0.275-22μg(r=0.9998),7.725-772.5ng(r=0.9997),8.025-802.5ng(r=0.9999),7.725-772.5ng(r=0.9999),3.338-333.8ng(r=0.9999),平均回收率(n=9)分别为99.42%,99.11%,101.46%,98.61%,100.65%。结论本法准确、快速、重现性好,适合于同时测定各种金银花中绿原酸和黄酮类成分的含量。

高效液相色谱手性固定相法拆分克伦特罗对映体

以正己烷、异丙醇为流动相 ,用Whelk O1手性固定相成功拆分了药物克伦特罗对映体。出峰时间在 5min左右 ,峰形对称性好 ,完全达到基线分离 ,分离因子大于 1 .4 ,可用于该对映体药物的分析与制备分离。讨论了二元流动相中异丙醇含量及温度的变化对分离的影响 。

利用二硝基苯甲酰苯基甘氨酸型手性固定相直接拆分丙卡特罗药物对映体

用手性源(R) 苯基甘氨酸,采用非对称合成方法制备了3,5 二硝基苯甲酰 (R) 苯基甘氨酸手性固定相(DNB PGCPS),利用它直接拆分了丙卡特罗药物的部分对映体,取得了良好的拆分效果。以不同比例的异丙醇 正己烷(体积比分别为20∶80,10∶90,5∶95,2∶98)为流动相,对丙卡特罗进行了拆分,其分离因子α的范围为1 54～1 67。此外,还测试了不同流动相组成对分离效果的影响,考察了液固吸附色谱保留值方程lnk=a+cCb+blnCb中保留因子k和分离因子α与强极性洗脱剂组分b的浓度Cb的关系,对拆分机理进行了讨论。

植物激素的反相高效液相色谱法分离和测定

探讨了分离和测定８种植物生长激素的反相高效液相色谱法。结果表明：以含有０．８％醋酸的甲醇和水作为流动相，采用梯度洗脱，可在１６ｍｉｎ内将８种物质完全分离并可进行定量测定，线性关系良好。方法具有快速、简便、准确的特点。

高效液相色谱法测定甜叶菊糖中的甜菊苷和莱鲍迪苷A

建立甜叶菊糖中甜菊苷（简称为XT）和莱鲍迪苷A（简称为RA）的HPLC定量分析方法。色谱分离采用Kromasil NH2柱（250mm×4．6mm i．d．，5μm），以V（乙腈）：V（水）=75：25为流动相，采用质谱检测器鉴定甜叶菊糖中主要的成分。sT和RA质量浓度分别为9．0～287．6mg／L和3．9—126．1mg／L时线性关系良好，两者平均回收率分别为98．61％和97．40％，RSD分别为2．3％和1．3％（n=5）。本实验还利用经典的Eschweiler-clark甲基化反应将氨基柱的伯胺转变为叔胺，发现上述溶质保留减小，同时分离选择性减小，说明氨基与糖苷类化合物的氢键作用和偶极-偶极作用对分离有重要贡献。

直链淀粉手性固定相分离马来酸曲美布汀和昂丹司琼对映体

建立了马来酸曲美布汀和昂丹司琼对映体的高效液相色谱拆分方法。使用Chiralpak AD-H手性色谱柱,采用正相洗脱方式,考察了流动相中有机改性剂的种类和浓度、酸碱比(冰乙酸-三乙胺)、柱温及流速等因素对对映体拆分的影响。确定了最佳拆分条件:分离马来酸曲美布汀的流动相为正己烷-异丙醇-冰乙酸-三乙胺(97∶3∶0.1∶0.3),流速为0.6mL/min;分离昂丹司琼的流动相为正己烷-异丙醇-冰乙酸-三乙胺(70∶30∶0.2∶0.4),流速为0.4mL/min,柱温均为20℃。在上述色谱条件下,两种手性药物对映体达到基线分离。

敌草胺对映体的高效液相色谱分离及手性拆分热力学研究

利用直链淀粉三-（3，5-二甲基苯基氨基甲酸酯）手性固定相（AD-RH柱）和纤维素三-（3，5-二甲基苯基氨基甲酸酯）手性固定相（OD-RH柱），以乙腈-水为流动相，对敌草胺对映体进行了直接手性拆分研究。考察了流动相组成、流速、柱温等对敌草胺对映体的色谱保留和分离的影响，并对敌草胺对映体与固定相之间的色谱保留和分离的热力学机理进行了讨论。结果表明，在流速为0．5mL／min、乙腈-水为50：50（体积比）、柱温在10～35℃条件下，AD-RH和OD-RH柱的△△H^0值分别为-1160．79和-673．40J／mol，即AD-RH柱的拆分能力优于OD-RH柱，二者都能实现基线分离。