Capillary zone electrophoresis conductivity

Huang, X., Luckey, J. A., Gordon, M. J., and Zare, R. N. Quantitative analysis of low molecular weight carboxyhc acids by capillary zone electrophoresis/conductivity detection. Anal. Chem., 61, 766, 1989. 

CZE = capillary zone electrophoresis EC = electrochemical detector GC = gas chromatography HCD = Hall conductivity detector HPLC = high performance liquid chromatography IDMS = isotope dilution mass spectrometry MS = mass spectrometry RSD = relative standard deviation SEE = supercritical fluid extraction SPE = solid phase extraction UV = ultraviolet absorbance detection... 

Aussenac et al. (1998) used capillary zone electrophoresis with UV detection at 260 nm to analyze isoflavones in soybean seeds of various varieties grown in various locations. Methanol was used for extraction. Total extraction was not affected by temperature but was affected by the composition of the solvent. Electrophoresis was conducted at pH 10.5, at which the isoflavones were weak acids and were ionized. Boric acid was added to form a negatively charged borate-isoflavone complex. A fast capillary electrophoresis method was also developed by Vanttinen and Moravcova (1999) to determine daidzein and genistein after enzyme hydrolysis in soy products. Photodiode array was used to detect the isoflavones at 254 and 268 nm, respectively. Minimum detection was 0.4 mg/L. p-Nitrophenol was used as an internal standard. 

Capillary zone electrophoresis (CZE), with direct or indirect photometry and conductivity has become popular in wine analysis. Very little, or sometimes no sample preparation is needed and short analysis times are also apparent advantages of CE and CZE in the analysis of wine. Capillary isotachophoresis (ITP), with conductivity, thermometric, and UV absorption detection, is suitable for the separation of various anionic constituents (organic acids and inorganic anions), currently occurring in wines (Masar et al., 2001). 

HA, heterocyclic amine AA, aromatic amine PA, polyamine Al, aliphatic amine N, nitrosamine CZE, capillary zone electrophoresis MEKC, micellar electrokinetic capillary chromatography LIE, laser induced huorescence ED, electrochemical detection CD, conductivity detection AD, amperometric detection PD, potentiometric detection ALA, alkylamines AQA, alkyl and aUcylbenzyl quaternary ammonium compound A, air H, water S, soil W, waste. 

There is also the important issue of data consistency. Many drugs and excipients have had their pK values measured by different methods with very good agreement, provided that all experimental conditions were maintained constant. Examples included atenolol [9.60 0.04 potentiometric, partitioning, and capillary electrophoresis (CE) studies in different laboratories], barbital (5,5-diethylbar-bituric acid) (7.98 0.01 electrometric, potentiometric, and spectrophotometric studies in different laboratories), benzoic acid (4.205 0.015 electrometric, potentiometric, spectrophotometric, and conductance measurements in many separate studies), ephedrine (9.63 0.05 five potentiometric or spectrophotometric studies in different laboratories), isonicotinic acid (pKi = 1.77 0.07, pK2 = 4.90 0.06 five potentiometric or spectrophotometric studies in different laboratories), nicotinic acid (pfCi = 2.07 0.07, pK2 = 4.79 0.04 six potentiometric, spectrophotometric, or capillary zone electrophoresis studies in different laboratories), phenobarbital (5-ethyl-5-phenylbarbituric acid) (7.48 0.02 potentiometric and spectrophotometric studies from several workers in multiple laboratories), nime-sulide (6.51 0.05 potentiometric and spectrophotometric studies in multiple laboratories), and chlorthalidone (9.35, potentiometric 9.36, spectrophotometric/ solubility-pH). The recent comparative studies of Takacs-Novak, Avdeef, and... 

Foret, R, Demi, M., Kahle, V., and Bocek, R, Onhne fiber optic UV detection cell and conductivity cell for capillary zone electrophoresis. Electrophoresis, 1, 430,1986. 

Coufal, P., Zuska, J., van de Goor, T., Smith, V., and GaS, B., Separation of twenty underiva-tized essential amino acids by capillary zone electrophoresis with contactless conductivity detection. 

Vincristine (VC) and vinblastine (VB) are dimeric catharanthus alkaloids isolated from the plant Catharanthus roseus. A capillary zone electrophoresis (CZE) was conducted for systematic and comprehensive study of the separation and quantification of two dimeric catharanthus alkaloids. Various separation parameters such as buffer concentration and pH, column internal diameter, and applied voltage were studied column, 72 cm (57 cm effective length) x 75 pm I.D. buffer, 0.2 M ammonium acetate solution, pH 6.2 and an applied voltage of 10 kV. Although the separation of VB and VC was the primary focus, the separation parameters determined in this study can be applied to the separation of other alkaloids as well. Separation of other alkaloids in the plant samples was observed under conditions presented in this work. A secondary objective of this study was to develop a method with experimental conditions which could be applied to electrophoresis-mass spectrometry. For this purpose, ammonium acetate buffers, which are more compatible with mass spectrometry than the widely used phosphate buffers, were used exclusively. Also, methanol-water-acetic acid was used as external buffer for the same reason [16]. 

Kaniansky, D. et al.. Determination of chloride, nitrate, sulphate, nitrite, fluoride, and phosphate by on line coupled capillary isotachophoresis-capillary zone electrophoresis with conductivity detection. Analytical Chemistry 66, 4258,1994. 

Klampfl, C.W. and Katzmayr, M.U. (1998) Determination of low-molecular-mass anionic compounds in beverage samples using capillary zone electrophoresis with simultaneous indirect ultraviolet and conductivity detection. J. Chromatogr. A, 822, 117-123. 

Masar, M., Bodor, R. and Kaniansky, D. (1999) Separations of inorganic anions based on their complexations with a-cyclodextrin by capillary zone electrophoresis with contactless conductivity detection. J. Chromatogr. A, 834,179-188. 

Kaniansky et al. [35] have also reported on a method for the determination of nitrate, sulphate, nitrite, fluoride and phosphate by capillary zone electrophoresis coupled with capillary isotachoelectrophoresis in the column coupling configuration. Such distributions of these anions are typical for many environmental matrices, and it is shown that capillary isotachophoresis-capillary zone electrophoresis tandem enables the capillary isotachoelectrophoresis determination of the macroconstituents, while capillary isotachophoresis-preconcentrated microconstituents cleaned up from the macroconstituents can be determined by capillary zone electrophoresis with a conductivity detector. This approach was effective when the concentration ratio of macro-microconstituents was less than (2-3) x 10. The limits of detection... 

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