Run buffer

Conradi, S. Vogt, C. Rohde, E. Separation of Enatiomeric Barbiturates by Capillary Electrophoresis Using a Cyclodextrin-Containing Run Buffer, /. Chem. Educ. 1997, 74, 1122-1125. 

McKillop and associates have examined the electrophoretic separation of alkylpyridines by CZE. Separations were carried out using either 50-pm or 75-pm inner diameter capillaries, with a total length of 57 cm and a length of 50 cm from the point of injection to the detector. The run buffer was a pH 2.5 lithium phosphate buffer. Separations were achieved using an applied voltage of 15 kV. The electroosmotic flow velocity, as measured using a neutral marker, was found to be 6.398 X 10 cm s k The diffusion coefficient,... 

Electrophoretic condition 60 cm (effective length of 50 cm)x75 p.m I.D. fused capillary column, run buffer borate buffer pH 9,0, P-cyclodextrin, electrophoresis voltage 20 kV, detection at 254 nm. 

A stereoselective determination of enantiomers of 5, its A -oxide and N-desmethyl metabolites in human urine was developed by capillary electrophoresis using laser-induced fluorescence detection and sulfonated /1-cyclodextrin in the running buffer (01JC(B)169). 

Fig. 3-3. Comparison of the values of enantiomeric resolution of different DNP-D,L-amino acids at different deconvolution stages of a cyclic hexapeptide sublibrary. Resolution values in a cyclo(Arg-Lys-X-X-X-P-Ala) sublibrary, in the first line, are compared to those obtained in sublibraries with a progressively increasing number of defined positions. All the sublibraries were 30 mM in the running buffer while the completely defined cyclo(Arg-Lys-Tyr-P-Tyr-P-Ala) peptide is used at 10 mM concentration. Conditions cyclopeptide sublibrary in 20 mM sodium phosphate buffer, pH 7.0 capillary, 50 pm i.d., 65 cm total length, 57 cm to the window V = -20 kV, I = 40 electrokinetic injection, -10 kV, 3 s detection at 340 nm. (Reprinted with permission from ref. [75]. Copyright 1998, American Chemical Society.)...

About 15 anthocyanins in bilberries (Vaccinium myrtillus L.) were reported by Ichiyanagi et al. using CZE separation and MS-NMR identification.Anthocyanin analysis of strawberry and elderberry extracts was performed by reverse HPLC at pH 1.8 and CZE using a standard silica capillary and pH 8.0 running buffer. Under these conditions, HPLC had more advantages than CZE in terms of anthocyanin separation in these extracts." ... 

Capillary electrophoresis (CE) or capillary zone electrophoresis (CZE) is the technique most often employed in pesticide residue analysis. In its most basic form, free zone electrophoresis, a fused-silica capillary is filled with electrolyte (running buffer or background electrolyte). A potential is applied across the capillary and the cations... 

The combination of CE and MS enables high-efficiency separations of a wide range of solutes. As with any CE technique the running buffer determines the quality of the separation. In practice, therefore, most CE-MS separations have been performed in an acidic buffer. Unfortunately, these conditions severely constrain the range of samples that can be successfully analysed by CE-MS. CE-MS requires a small volume of a concentrated sample (ICC3 moleL-1). Sensitivity is reported as <1 pmol for SIM and lOpmol for full mass spectra. Very little quantitative work has been performed with CE-MS techniques. 

Lin et al. [95] used capillary electrophoresis with dual cyclodextrin systems for the enantiomer separation of miconazole. A cyclodextrin-modified micellar capillary electrophoretic method was developed using mixture of /i-cyclodextrins and mono-3-0-phenylcarbamoyl-/j-cyclodextrin as chiral additives for the chiral separation of miconazole with the dual cyclodextrins systems. The enantiomers were resolved using a running buffer of 50 mmol/L borate pH 9.5 containing 15 mmol/L jS-cyclodextrin and 15 mmol/L mono-3-<9-phcnylcarbamoyl-/j-cyclodextrin containing 50 mmol/L sodium dodecyl sulfate and 1 mol/L urea. A study of the respective influence of the /i-cyclodcxtrin and the mono-3-(9-phenylcarbamoyl-/i-cyclodextrin concentration was performed to determine the optical conditions with respect to the resolution. Good repeatability of the method was obtained. 

Russell and Rabenstein [43] described a speciation and quantitation method for underivatized and derivatized penicillamine, and its disulfide, by capillary electrophoresis. Penicillamine and penicillamine disulfide were determined by capillary electrophoresis on a capillary (24 cm x 25 pm i.d. or 50 cm x 50 pm i.d. for underivatized thiols) with detection at 357 nm (200 nm for underivatized thiols). The run buffer solution was 0.1 M phosphate (pH 2.3). Detection limits were 20-90 pM without derivatization, and 5-50 pM after derivatization. Calibration graphs were linear from 1 pM to 5 mM thiols. 

Lee et al. [30] described a micellar electrokinetic capillary chromatographic method for the determination of some antiepileptics including valproic acid. They used a fused silica capillary column (72 cm x 50 pm) and SDS as the micellar phase and multiwavelength UV detection. Reaction conditions, such as pH and concentration of running buffer were optimized. Solutes were identified by characterizing the sample peak in terms of retention time and absorption spectra. Recoveries were 93-105%. 

The migration order of wine anthocyanins in CE has been studied in detail and the results have been compared with those obtained by RP-HPLC-MS. Wines were filtered and used for the analyses without any other pretreatment. Wine samples of 10 ml were freeze-dried, redissolved in methanol and applied for semi-preparative fractionation. CZE measurements were carried out in a fused-silica capillary (46 cm effective length, 75 /an i.d.). The capillary was conditioned with 0.1 M NaOH (2 min), water (2 min) and running buffer (5 min). The buffer consisted of 50 mM sodium teraborate (pH = 8.4) containing 15 per cent (v/v)... 

CZE has been employed for the analysis of another set of dyes in foodstuffs. The chemical structures, numbers and names of the dyes included in the investigation are listed in Fig. 3.142. A fused-silica capillary column of 57 cm length (50 cm effective length 75 jum i.d.) was employed for the separations. The capillary was conditioned by 1.0 M NaOH for 20 min followed by 10 min wash with water and 10 min wash with the running buffer. The buffer was prepared by adding NaOH to 10 mM phosphoric acid to reach pH 11.0. The capillary was thermostated at 25°C and the separation voltage was 20 kV. A hydrodynamic injection mode was applied (0.5 psi, 4 s, 21 nl) and spectra of... 

CZE was also employed for the analysis of sulphonated azo dyes in river samples. The chemical structures of dyes are shown in Fig. 3.150. Separations were performed in a fused-silica capillary (total length 57 cm effective length, 50 cm 75 pm i.d.). Activation of the capillary was carried out by washing it with 1.0 M NaOH for 15 min, followed by water (5 min) and the running buffer (5 min). The buffer was prepared from 10 mM... 

Another study employed CE for the determination of the stoichiometry of the conjugation reaction between immonuglobulin and Lissamine rhodamine-B sulphonyl chloride (LRSC). The chemical structure of the dye is shown in Fig. 3.162. Separation of the unconjugated dye from the conjugated end product was performed by CE using an uncoated fused-silica capillary column (60 cm X 75 //m i.d.). The running buffer consisted of 10 rnM borate and 0.5 mM sodium dodecyl sulphate. The separation voltage was 20 kV and analytes were detected by a fluorescence detector. It was concluded from the results that the CE method combined with... 

The synthesis of phtalocyanine dyes was followed by CE and the purity and composition of the end product was investigated by the same method. The chemical structure of the newly synthetized zinc phtalocyanine tetrasulphonic acid is shown in Fig. 3.163. An uncoated fused silica capillary (65cm X 75 /.an i.d.) was employed for the separation of dye components. Running buffers were 10 mM ammonium acetate (pH adjusted to 9.4 with ammonia) and 10 mM potassium dihydrogenphosphate (KH2P04) (pH = 9.0). Samples were injected hydrodynamically (50 mm for 10 s). Separation was realized in the constant current mode at 30 pA, which required about 28 kV separation voltage. Analytes... 

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