Enantiomeric Separation of Epinephrine and Salbutamol by Micellar Electrokinetic Chromatography Using β-Cyclodextrin as Chiral Additive

Enantiomeric separation of epinephrine and salbutamol was investigated by micellar electrokinetic chromatography employing β-cyclodextrin as chiral additive in ammonium chloride-ammonia solution. The analytes were detected by electrochemistry using gold microelectrode at +0.65 V versus SCE reference electrode. The effects of detection potential, concentration of β-cyclodextrin, concentration of sodium dodecyl sulfate, pH value of electrolyte and applied voltage were discussed.

Simultaneous determination of ten nucleosides and bases in Ganoderma by micellar electrokinetic chromatography

Ganoderma(lingzhi)is a famous herbal medicine and edible supplement in oriental countries for a long history.In this study,a simple micellar electrokinetic chromatography(MEKC)method was established for the analysis of nucleosides and bases,the major bioactive components in Ganoderma for the first time.By optimizing the borate concentration,the sodium dodecyl sulfate(SDS)concentration and the pH value of running buffer,10 nucleosides and bases achieved an ideal separation.In real sample analysis,the developed method was successfully used to determine the 10 target analytes in 23 batches of Ganoderma samples from different regions.Results indicated that contents of 10 investigated analytes in each sample showed obvious variation.The principal components analysis(PCA)and hierarchical cluster analysis(HCA)analysis classified the samples into three groups,and the HCA tree visualized the relationships which was mainly contributed by geographical partition.The results indicated geographical origin to be an important factor that affect the accumulation of nucleosides and bases in Ganoderma.In summary,this study provides a simple and practical strategy for quality assessment and cultivation reference of Ganoderma.

Quantitative analysis of two analgesic formulations by micellar electrokinetic chromatography

A micellar electrokinetic chromatographic (MECC) method with sodium cholate as pseudostationary phase was proposed for the separation and quantitation of two analgesic formulations containing acetaminophen, dextro-methorphan hydrobromide, phenylpropanolamine hydrochloride, and chlorpheniramine maleate. The internal standard method was proved to be able to yield satisfactory results even with a modular CE instrument with RSD between 0.6 similar to 2.1%, and recoveries ranging from 98.1 similar to 99.9%.

Study of Tea Digitized Chromatographic Fingerprint Spectra Using Micellar Electrokinetic Chromatography

This paper described the principle of digitized chromatographic fingerprint spectrum and established digitized chromatographic fingerprint spectra of ten brands of Chinese famous tea by the micellar electrokinetic chromatography. This work was done using a 25 mmol·L -1 sodium dodecylsulfate in a 20 mmol·L -1 borate (pH 7 0) solution as running buffer, 20 kV applied potential and detection at 280 nm. The chromatographic fingerprint spectra were digitized by the relative retention value ( α ) and the relative area ( S r), and were analyzed to identify the tea samples. In the absence of the standard samples, the present method was easy setup and inexpensive, and provided the applicable information for the quality assessment of teas.

Effect of organic modifiers on the capacity factor in micellar electrokinetic chromatography

Organic modifiers were effective both to extend the migration time window and to improve the separation of very hydrophobic compounds in MEKC. An iteration method was used to determine the migration time of micelles. The quantitative relationship between the capacity factor k' and the concentration of organic modifiers was derived, which was investigated experimentally. The linear solvation energy relationships (LSER) methodology was applied to MEKC, and good linear relationships between lnk' and solvatochromic parameters of 15 solutes were obtained in the presence of organic modifier in different concentrations, which indicated a new access in MEKC to predict k' from the structural parameters of solutes. The effect of column temperature T on k' was also investigated.

Enantiomeric Separation of Epinephrine and Salbutamol by Micellar Electrokinetic Chromatography Using β-Cyclodextrin as Chiral Additive

Enantiomeric separations of epinephrine and salbutamol, by means of micellar electrokinetic chromatography (MEKC) employing β-cyclodextrin as chiral additive in ammonium chloride-ammonia solution were investigated. In this system, the analytes migrated with the micellar phase towards the anode and were detected by electrochem- istry using gold microelectrode at +0.65 V vs. SCE. The success of the chiral separations is strongly dependent on the concentration of β-CD and SDS, and the optimal concentration is 8 mmol?L-1 and 15 mmol?L-1 respectively. The effects of detection potential, pH value of electrolyte and applied voltage were discussed also. Using the pro- posed method, baseline separation of the enantiomers could be accomplished in 6 min. Further, an attempt was made to elucidate the plausible mechanism of the chiral recognition.

Pseudo Peak Phenomena in Micellar Electrokinetic Capillary Chromatography by Using Ionic Surfactant

The origin of pseudo peak was studied by means of micellar electrokinetic capillary chromatography with cetyltrimethylaminium bromide as the pseudo stationary phase. It has been pointed that two peaks may appear for one component under certain conditions. Experiments showed that the relative areas of the two peaks of analyte depended on the time and the temperature of reaction between analyte and surfactant, and the concentration of surfactant in the sample solution. It means that the interaction between the analyte and the surfactant is a slow process, and a stable substance can be produced from the interaction. It is the substance and the analyte that may lead to the formation of two peaks. The fast interaction mechanism between the solute and the micellar should be queried from the experiment result.

Separation of Six Pyridoncarboylxic Acid Derivatives by Micellar and Microemulsion Electrokinetic Chromatography

Micellar and microemulsion electrokinetic chromatography (MEKC & MEEKC) separation of six closely structural pyridoncarboylxic acid derivatives were studied and compared Both anionic surfactant sodium dodecyl sulfate (SDS) and cationic surfactant hexadecyl-trimethyl ammonium bromide: (CTAB) were used to form micellar and microemulsion as pseudostation phases, respectively. The effects of the separation conditions on retention time and selectivity were studied. Good resolutions were obtained in selected systems. indicating that there is markably different selectivity between SDS and CTAB systems.

Extraction of catechins and caffeine from different tealeaves and comparison with micellar electrokinetic chromatography

This work describes the simultaneous deter- mination of catechins and caffeine in green, black tealeaves and canned tea-drink using micellar electrokinetic chromatography. The catechins analyzed include (+)-catechin, (-)- epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate and (-)-epigallocatechin gallate. Using UV absorption method at 280 nm, the limits of detections of catechins and caffeine are 10-6 mol/L, which is suitable for the real sample determination. Using this analytical method, the extraction of these compounds from the tealeaves with hot water is compared under different temperatures. The effects of temperature on the amount of catechins and caffeine extracted are evident, showing that (-)-epigallocatechin gallate is the most easiest to be extracted at 100℃. The stability of catechins and caffeine in stocking solution of tea-drink at 4℃ is also compared on five consecutive days. The contents of catechins and caffeine in green and black teas are discussed and the difference of the content between different tealeaves can provide a reference for the assessment of tea quality.

Separation of Aniline Derivatives by Micellar Electrokinetic Capillary Chromatography

A micellar electrokinetic capillary chromatography (MECC) was developed for the determination of aniline and 6 substituted anilines. The seven components were separated within 25 min in the buffer solution of 40 mmol/L sodium borate and 100 mmol/L SDS. It was found that the separation was dependent on operating voltage, pH value, borate and SDS concentrations. The analytical performance was examined in terms of linear response and reproducibility. Wastewater was determined by the established method.

Separation of Biphenyl Nitrile Compounds by Microemulsion Electrokinetic Chromatography with Mixed Surfactants

A mixture of nine biphenyl nitrile compounds with high hydrophobicity and similar structures was successfully separated by microemulsion electrokinetic chromatography (MEEKC) within 30 min. The buffer system contained 100 mmol/L sodium dodecyl sulfate (SDS), 80 mmol/L sodium cholate (SC), 0.81% heptane, 7.5% n-butanol, 10% acetonitrile and 10 mmol/L borate. The addition of SC, organic modifiers, sample preparation and temperature all showed remarkable effect on the separation. Meanwhile, the MEEKC method was briefly compared with micellar electrokinetic chromatography (MEKC) method.

Optimized Separation of Nine Xanthones by Microemulsion Electrokinetic Chromatography

A microemulsion electrokinetic chromatography method has been firstly used for the separation of the therapeutically important xanthones from Securidaca inappendiculata. The separation of the nine xanthones was systematically optimized with respect to pH, composition of microemulsion, addition of cyclodextrins, applied voltage and column temperature. Baseline separation was successfully achieved for the nine xanthones, which was also compared with that by micellar electrokinetic chromatography.

固相萃取和样品堆积耦联MEKC富集分离BPA

采用固相萃取和改进的样品堆积方法,建立了固相萃取和样品堆积耦联胶束电动色谱富集检测分析方法。采用此方法进一步改善了胶束电动色谱对双酚A的浓度检出限,实现了约300倍的富集效果。在优化的实验条件下,BPA的质量浓度在0.005~0.08 mg/L范围内与色谱峰面积成良好的线性关系,相关系数为0.9964,方法检出限为2μg/L。样品平均加标回收率为88%,测定结果的相对标准偏差为10%(n=6)。显示出固相萃取和样品堆积耦联MEKC方法不但可以起到对BPA进行富集的目的还可以实现对分析样品进行净化的作用。

胶束电动色谱法分离和测定双酚A、辛基酚和壬基酚

用胶束电动色谱法分离了双酚A、辛基酚和壬基酚。以含 1 0 %乙腈和 2 5mmol/L十二烷基硫酸钠、pH 9.0、浓度为 1 2 .5mmol/L的硼砂溶液为缓冲溶液 ,在 2 5kV的分离电压下 ,三物质获得了基线分离。用该法对自来水、水库水等水样中 3种物质的加入回收进行了研究 ,测定的回收率在 90 .5 %～ 1 0 8.1 %之间。

胶束电动毛细管色谱法测定全血环孢霉素A

建立了用于临床测定全血环孢霉素A的毛细管电泳分析方法。采用未涂渍熔融石英毛细管(50μm×58.5 cm,有效长度50.0 cm),以含20 mmol/L磷酸氢二钠、50 mmol/L十二烷基硫酸钠的乙腈-水(1∶1)体系为电泳介质体系,采用乙醚萃取的前处理方法,有效去除了全血中内源性物质的干扰。通过柱上富集浓缩技术,提高检测灵敏度,检出限达70μg/L,实现了环孢霉素A的低浓度检测。

胶束毛细管电动色谱法用于DNA碱基腺嘌呤和嘌呤类抗癌药物的研究

The adenine, 8-hypoxanthine, 6-thioguanine and 8-azaguanine were separated and determined with the method of micellar electrokinetic capillary chromatography. The optimal conditions of electrophoresis were studied. At 25 ℃ and 20 kV applied voltage, the four components were baseline separated within 16 min in 25 mmol/L phosphate-borate buffer（pH=7.0） including 30 mmol/L SDS at the detection wavelength of 210 nm. The peek area versus concentration was linear over the concentration range of （12200）×10{-6} mol/L for 8-hypoxanthine and 8-azaguanine, and （6.5100）×10{-6} mol/L for adenine and 6-thioguanine. The detection limits of all analytes mentioned above attained to 10{-6} mol/L grade. And the correlationg coefficients of four analytes were over 0.998 5. In the real sample of the mean absolute recoveries of 8-hypoxanthine, adenine, 6-thioguanine and 8-azaguanine were 97.2%{102.1%}, and the relative standard deviations for the four components were less than 3.41%（n=5）. The method is rapid, simple with a good solution for the analysis of 8-hypoxanthine, adenine, 6-thioguanine and 8-azaguanine, and satisfactory results were obtained.

环孢素A三联用药的胶束电动毛细管色谱分离与方法耐用性评价

建立了适合环孢素A、硫唑嘌呤、强的松三联用药系统分离的胶束电动毛细管色谱（MECC）方法,考察了运行缓冲液体系中SDS浓度、乙腈含量及电渗流促进剂牛磺酸（FX）比例对电泳分离方法耐用性的影响。MECC优化分离系统为：毛细管50cm×50μm×50μmuncoated（Bio-Rad）,缓冲液组成：45mmol／LSDS的背景电解质溶液（50mmol／L磷酸二氯钠,12.5mmol／L硼砂,PH8.25）-乙腈-FX（50：50：25）,操作电压18kV（＋）→（-）,进样量10psi×s,柱上检测UV200nm,毛细管柱温25℃。器官移植手术常用的环孢素A、硫唑嘌呤和强的松三联用药在10min之内获得了理想的分离。

MECC-DAD和HPLC-FLD测定牛乳中5种黄曲霉毒素的方法比较研究

建立高效胶束电动毛细管色谱耦合二极管阵列检测器(micellar electrokinetic capillary chromatographydiodearraydetector,MECC-DAD)检测牛乳中痕量黄曲霉毒素的新方法,采用高效液相色谱-荧光检测器(high performance liquid chromatography-fluorescence detector,HPLC-FLD)法及MECC-DAD法检测牛乳样品中5种黄曲霉毒素的残留量,考察2种检测技术的特异性。牛乳样品经免疫亲和柱净化后,MECC-DAD法采用未涂层熔融石英毛细管柱进行分离,以7.5 mmol/L四硼酸钠、30 mmol/L十二烷基磺酸钠及体积分数5%乙腈体积比1∶1∶1的混合液(pH 8.5)为缓冲液,检测波长为214 nm;HPLC-FLD法采用C18柱(150 mm×4.6 mm,5μm)进行分离,乙腈-水为流动相进行梯度洗脱,荧光检测器激发波长360 nm、发射波长440 nm。结果表明:MECC-DAD法的色谱图峰形更对称、平滑、尖锐,无拖尾现象;MECC-DAD和HPLC-FLD法的检出限分别为0.182~1.669、0.014~0.058μg/L,MECC-DAD法的检出限虽高于HPLC-FLD法,但也能满足牛乳中黄曲霉毒素的测定要求;HPLC-FLD法的精密度稍高于MECC-DAD法;MECC-DAD法的加标回收率为80.3%~137.0%,HPLC-FLD法的加标回收率为79.6%~134.0%,二者相当;2种方法对市售牛乳样品的定量检测结果偏差为P=0.900>0.05,没有显著性差异。MECC-DAD法分离快速、高效、经济,更适合牛乳样品中黄曲霉毒素残留量的检测。

Chiral Recognition of Binaphthyl Derivatives with L-Undecyl Leucine Surfactants in the Presence of Sodium and Lysine Counterions

This study investigates the effect of counterions on the chiral recognition of 1,1'-Binaphthyl-2,2'-diamine (BNA) and 1,1'-Binaphthyl-2,2'-diyl hydrogenphosphate (BNP) enantiomers when using an amino acid-based surfactant undecanoyl L-leucine (und-Leu) as the chiral pseudostationary phase in capillary electrophoresis. The effects of using two different counterions (sodium and lysine) on the chiral recognition of binaphthyl derivatives were compared at varying pH conditions. The enantiomeric separation of BNA and BNP enantiomers via capillary electrophoresis, using und-Leu as the chiral recognition medium, significantly improved the enantiomeric resolution in capillary electrophoresis at pH 7 when using Lysine counterions as compared to using sodium as the counterion. More specifically, at a surfactant concentration of 45 mM, at pH 7, a significant increase in chiral selectivity was observed when lysine was used as the counterion compared to sodium. The enantiomeric resolution of BNA and BNP increased by 6-fold and 1.1-fold, respectively, in capillary electrophoresis experiments when lysine was utilized as the counterion compared to using sodium. Furthermore, the retention factor of BNA and BNP enantiomers also increased approximately 3.5-fold and 4-fold, respectively, in the presence of lysine counterions as compared to using sodium counterions. When running buffer in capillary electrophoresis was increased to pH 11, the resolution and retention factors were nearly identical when comparing the effects of the sodium and lysine counterions. This signifies the important role of lysine’s positive net charge on chiral recognition. This study provides insight into the potential advantages of using cationic, pH-dependent counterions such as lysine to significantly improve the chiral recognition of binaphthyl derivatives when using chiral anionic surfactants as the pseudostationary phase in capillary electrophoresis.

高效毛细管电泳法检测血中环孢素A浓度

目的建立定量检测全血环孢素A的毛细管胶束电动电泳技术,排除环孢素A代谢物对测定的干扰,为临床提供一种有效的检测方法。方法运用高效毛细管胶束电泳法对30例临床服用环孢素A患者进行环孢素A测定,并与免疫方法进行对照。结果建立了定量检测全血环孢素的毛细管胶束电动电泳方法,与免疫方法检测结果对照线性良好,结果差异有显著性(P<0.001)。结论该方法能去除代谢物对环孢素A测定的干扰,可广泛应用于临床。