Capillary electrophoresis quantitative

Altria, K. D., Clayton, N. G., Harden, R. C., Makwana, J. V., and Portsmouth, M. J. (1995). Intercompany cross-validation exercise on capillary electrophoresis. Quantitative determination of drug counter-ion level. Chromatographia 40, 47—50. 

Katzmann JA, Clark R, Namyst-Goldberg C, Sanders L, Kyle RA, Landers JP. Identification of monoclonal proteins by capillary electrophoresis quantitative comparison with acetate and agarose electrophoresis. Electrophoresis 1997 18 1775-80. 

B Verzola, C Gelfi, PG Righetti. Protein adsorption to the bare silica wall in capillary electrophoresis quantitative study on the chemical composition of the background electrolyte for minimizing the phenomenon. J Chromatogr A 868 85-99, 2000. 

Protein quantitation by MS makes it possible to use in-line liquid-phase separation methods such as multidimensional chromatography and capillary electrophoresis. Quantitation can be carried out by comparing peptide ion currents but this is inherently inaccurate and is biased by instrument design. Instead, quantitation is often based on the use of stable isotopes. The general approach is to label alternative samples with equivalent reagents, one of which contains a heavy isotope and one of which contains a light isotope. The samples are mixed, separated into fractions, and analyzed by MS. The ratio of the two isotopic variants can be determined from the heights... 

We have developed the method for quantitative analysis of urinary albumin with CE. A capillary electrophoresis systems Nanophor 01 (Institute of Analytical Instmmentation, Russian Academy of Sciences, Saint-Petersburg) equipped with a UV-detector was used to determine analyte. Separation was achieved using 45 cmx30 p.m I.D. fused silica capillary column with UV-detection at 214 nm. 

Lechtenberg, M. et al., Quantitative determination of curcuminoids in Curcuma rhizomes and rapid differentiation of Curcuma domestica Val. and Curcuma xanthor-rhiza Roxb. by capillary electrophoresis, Phytochem. Anal, 15, 152, 2004. 

There are many proteins in the human body. A few hundreds of these compounds can be identified in urine. The qualitative determination of one or a series of proteins is performed by one of the electrophoresis techniques. Capillary electrophoresis can be automated and thus more quantified (Oda et al. 1997). Newer techniques also enable quantitative determination of proteins by gel electrophoresis (Wiedeman and Umbreit 1999). For quantitative determinations, the former method of decomposition into the constituent amino acids was followed by an automated spectropho-tometric measurement of the ninhydrin-amino add complex. Currently, a number of methods are available, induding spectrophotometry (Doumas and Peters 1997) and, most frequently, ELISAs. Small proteins can be detected by techniques such as electrophoresis, isoelectric focusing, and chromatography (Waller et al. 1989). These methods have the advantage of low detection limits. Sometimes, these methods have a lack of specifidty (cross-over reactions) and HPLC techniques are increasingly used to assess different proteins. The state-of-the-art of protein determination was mentioned by Walker (1996). 

Shi, H., Zhang, R., Chandrasekher, G., and Ma, Y., Simultaneous detection and quantitation of sodium, potassium, calcium and magnesium in ocular lenses by high-performance capillary electrophoresis with indirect photometric detection, ]. Chromatogr. A, 680, 653 1994. 

Simple etching of the capillary end served to decouple the electrophoretic current from that of amperometric detection, permitting quantitation of attomole levels of catecholamines from brain microdialyzates.24 A postcolumn reactor using bromine generated electrochemically in situ has been used in the detection of peptide thiols, such as glutathione and cysteine, separated by capillary electrophoresis.25... 

Pathogen-suppressing oligosaccharides in human milk were quantitated using capillary Electrophoresis by MEKC with detection by absorption at 205 nm.90 A 24 kDa glycoprotein associated with muscle-wasting cachexia... 

Peng, X., Bowser, M.T., Britz-McKibbin, P., Bebault, G.M., Morris, J.R., and Chen, D.D.Y., Quantitative description of analyte migration behavior based on dyamic complexation in capillary electrophoresis with one or more additives, Electrophoresis, 18, 706, 1997. 

Hurst, W.J. and Martin, R.A. Jr, The quantitative determination of caffeine in beverages using capillary electrophoresis analysis, 21,389-91,1993. 

Lada, M.W., Kennedy, R.T. (1996). Quantitative, in vivo monitoring of primary amines in rat caudate nucleus using microdialysis coupled by a flow-gated interface to capillary electrophoresis with laser-induced fluorescence detection. Anal. Chem. 68, 2790-2797. 

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. 

Valproic acid has been determined in human serum using capillary electrophoresis and indirect laser induced fluorescence detection [26], The extract is injected at 75 mbar for 0.05 min onto a capillary column (74.4 cm x 50 pm i.d., effective length 56.2 cm). The optimized buffer 2.5 mM borate/phosphate of pH 8.4 with 6 pL fluorescein to generate the background signal. Separation was carried out at 30 kV and indirect fluorescence detection was achieved at 488/529 nm. A linear calibration was found in the range 4.5 144 pg/mL (0 = 0.9947) and detection and quantitation limits were 0.9 and 3.0 pg/mL. Polonski et al. [27] described a capillary isotache-phoresis method for sodium valproate in blood. The sample was injected into a column of an EKI 02 instrument for separation. The instrument incorporated a conductimetric detector. The mobile phase was 0.01 M histidine containing 0.1% methylhydroxycellulose at pH 5.5. The detection limit was 2 pg/mL. 

CL reactions can be coupled as a detection technique in chromatography, capillary electrophoresis, or immunoassay, providing qualitative and/or quantitative information of a large variety of species in the gas and liquid phases. 

Qualitative and quantitative characterization of biologically active materials especially useful for clinical and forensic work where small amounts of complex samples may be involved. Nanogram to 3 femtogram scale separations by capillary electrophoresis. 

Biomolecular MS and in particular MALDI-TOF-MS (see Sections 2.1.22 and 2.2.1) permit the routine analysis of oligonucleotides up to 70-mers, intact nucleic acids, and the direct detection of DNA products with no primer labels with an increase in analysis speed and mass accuracy especially in contrast to traditional DNA separation techniques such as slab gels or capillary electrophoresis. Applications focus on the characterization of single nucleotide polymorphisms (SNPs) and short tandem repeats (STRs). Precise and accurate gene expression measurements show relative and absolute numbers of target molecules determined independently of the number of PCR cycles. DNA methylation can be studied quantitatively. 

As the name implies, capillary electrophoresis is electrophoresis that is made to occur inside a piece (50 to 100 cm) of small-diameter capillary tubing, similar to the tubing used for capillary GC columns. The tubing contains the electrolyte medium, and the ends of the tube are dipped into solvent reservoirs, as is the paper in paper electrophoresis. Electrodes in these reservoirs create the potential difference across the capillary tube. An electronic detector, such as those described for HPLC (Chapter 13), is on-line and allows detection and quantitative analysis of mixture components. 

Capillary electrophoresis is an electrophoresis technique in which the mixture components are separated in a capillary tube and detected with an on-line detector after the separation occurs. The advantages include smaller quantity of sample and qualitative and quantitative analysis in a much shorter time. 

Because of their high separation capacity, short analysis time, low reagent consumption and simplicity, various electrophoretic methods have found application in the separation and quantitative determination of anthocyanins in various complex matrices [267].The different techniques used for the measurement of anthocyanins in beverages [268], the application of capillary electrophoresis (CE) for the analysis of natural food pigments [269], the use of CE for the determination of anthocyanins in foods [270] and in medicinal plants [271] have been previously reviewed. 

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