ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Application of capillary zone electrophoresis for analysis of thyreostatics (1996)
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1959-1963 
    Details
    ISSN: 0173-0835
    Keywords: Capillary zone electrophoresis ; Thyreostatics ; Methylthiouracil ; Urine ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Capillary zone electrophoresis was optimized for the separation of thiouracil, methylthiouracil and propylthiouracil. Methylthiouracil could be determined in various types of urine (human, bovine, horse), either without any pretreatment or in ethyl acetate extracts, within 15 min. For identification, the simultaneous detection at three UV wavelengths (216, 245 and 278 nm) was advantageously used while for quantification the wavelength of the absorbance maximum at 278 nm was preferred. Under optimized conditions a linear response of the detector in the concentration range 0.1-100 ppm was obtained. On analysis of untreated urine, a detection limit of 0.5 ppm was found; for urine extracts the detection limit was 0.1 ppm. Univocal peak identification, based on absorption at three wavelength, was only possible above 2 ppm. Relative standard deviation for standard solutions of methylthiouracil, diluted in the background electrolyte, was 1%; for methylthiouracil in extracts dissolved in the background electrolyte it was 4.5%, and for methylthiouracil in untreated urine, 12.7%.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150171226
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Recent application and developments of capillary isotachophoresis (1997)
    Weinheim : Wiley-Blackwell
    Electrophoresis 18 (1997), S. 2154-2161 
    Details
    ISSN: 0173-0835
    Keywords: Isotachophoresis ; Capillary zone electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Capillary isotachophoresis is a powerful electromigration separation method with a pronounced capability to concentrate trace components in diluted samples. At present, capillary isotachophoresis is utilized predominantly as the first step in on-line combination with capillary zone electrophoresis. This article is a continuation of previous reviews and summarizes the results published during 1993-1996.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150181206
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Analysis of heparin-like pharmaceuticals by capillary zone electrophoresis and isotachophoresis (1996)
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 125-129 
    Details
    ISSN: 0173-0835
    Keywords: Capillary zone electrophoresis ; Isotachophoresis ; Heparinlike pharmaceuticals ; Aprosulate ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Synthetic sulfated bis-lactobionic acid amides are important heparin-like pharmaceuticals. The synthesis of these compounds yields molecules differing in the number of sulfate groups, and during the isolation procedure, the required species may partially decompose or take in some impurities. This article shows that capillary zone electrophoresis may serve well as an expedient method for the analysis of the above-mentioned pharmaceuticals. Complex-forming equilibria between the analytes and bivalent cations present in the background electrolyte bring selectivity necessary for the separation, and the detection at various wavelengths serves as an aid in the characterization of admixtures, decomposition products, and impurities. Capillary isotachophoresis may also be used for the analysis of these species, bringing about the potential of micropreparation of individual compounds and opening the chance for continuous free-flow electrophoresis.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150170121
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    A comparison of resolution of DNA fragments between agarose gel and capillary zone electrophoresis in agarose solutions (1995)
    Weinheim : Wiley-Blackwell
    Electrophoresis 16 (1995), S. 1345-1353 
    Details
    ISSN: 0173-0835
    Keywords: Resolution ; DNA ; Capillary zone electrophoresis ; Gel electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The resolving power of capillary zone electrophoresis (CZE) is compared to that of gel electrophoresis (GE) under similar conditions (agarose, similar length of DNA fragments, identical buffer) but with differences in temperature and field strength. The comparison is based on the time required to reach a desired degree of resolution by each of the two methods. A resolution parameter is developed which is equally applicable to CZE, with relatively diffuse initial conditions in the absence of stacking and measurements expressed in terms of time, and to GE, in which measurements are expressed in terms of spatial parameters. The resolution time in CZE using agarose solutions at 40°C was found to be greater by at least one order of magnitude than that in GE using agarose gels. Thus, the increased migration velocity due to high field strength in CZE substantially outweights the lower dispersion in GE.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.11501601222
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    A practical procedure for the determination of association constants of the analyte-chiral selector equilibria by capilllary zone electrophoresis (1996)
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1921-1924 
    Details
    ISSN: 0173-0835
    Keywords: Capillary zone electrophoresis ; Chiral separations ; Association constants ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A practical procedure is proposed for the determination of association constants and mobility of the associate of a solute with a chiral selector in chiral separations by capillary zone electrophoresis. The procedure is based on the measurement of the effective mobility of a solute at zero and two different nonzero concentrations of the chiral selector. Simple explicit formulas have been derived in order to calculate the required data. The essence of the procedure is that all mobility data are adjusted to the background electrolyte (BGE) without chiral selector, serving as the viscosity reference. A simple procedure is described for measuring the viscosity of the operational electrolytes directly with the commercial capillary electrophoresis instrumentation, and Walden's rule has been utilized for adjusting the experimental mobility data to constant reference viscosity. The use of the procedure is exemplified by a separation of D,L-tryptophan in BGE containing α-cyclodextrin as chiral selector.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150171219
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    System peaks in capillary zone electrophoresis. 3. Practical rules for predicting the existence of system peaks in capillary zone electrophoresis of anions using indirect spectrophotometric detectionFor Parts 1 and 2 of the series, see [6] and [7], respectively. (1997)
    Weinheim : Wiley-Blackwell
    Electrophoresis 18 (1997), S. 1998-2007 
    Details
    ISSN: 0173-0835
    Keywords: System peaks ; Indirect detection ; Capillary zone electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A theoretical and experimental study of the existence and evolution of system peaks in capillary zone electrophoresis (CZE) with indirect spectrophotometric detection is presented with respect to the effect of the number of coions present in the background electrolyte (BGE). It is shown that in BGEs having only one coion (i.e., the UV-absorbing probe anion), the sample produces only negative peaks due to each analyte anion and no system peaks, with the number of sample peaks corresponding to the number of analytes present in the sample injected. In BGEs containing two coions, a sample with one analyte anion produces one negative indirect detection peak and one system peak. The transition between BGEs having one coion and those with two coions has also been studied and it has been shown that an addition of ca. 5% of the second coion to a single coion BGE causes the resulting BGE to behave macroscopically as a regular two-coion BGE. A descriptive model is proposed, based on transient isotachophoresis (transient stacking) of the sample species and of the coion from the BGE which has the closest mobility to the sample ion. This model explains qualitatively the formation and evolution of the sample peak (containing the sample species and being detected by indirect detection due to displacement of the UV-absorbing probe in its zone) and the system peak (containing no sample species and being a vacancy in the continuum of coions of the BGE). It is shown that the system peak may be positive or negative as it corresponds to the situation where the vacancy of one component of the BGE results in an enhanced concentration of the other component. It has been demonstrated that the system peak is created by a vacancy of that component of the BGE which has the greatest difference in mobility relative to that of the sample species. On indirect detection in BGEs containing two coions the sample displaces predominantly the BGE coion which has a mobility closest to that of the analyte anion. In systems with BGEs containing two coions, a sample having n analytes produces n sample peaks and one system peak, the sign and magnitude of which are dependent on the sum of the UV absorbances of the analytes involved. The effect of bicarbonate from atmospheric CO2 has also been studied and it has been shown that weakly alkaline BGEs with a single anionic UV-absorbing coion, such as those currently used for anionic analyses with indirect detection, may suffer from the presence of system peaks due to bicarbonate.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150181120
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Separation of aracytidine and cytidine by capillary electrophoretic techniques (1996)
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1954-1958 
    Details
    ISSN: 0173-0835
    Keywords: Capillary zone electrophoresis ; Aracytidine ; Cytidine ; Serum analysis ; Micellar electrokinetic chromatography ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Aracytidine (cytarabine, 1-β-D-arabinofuranosylcytosine) is a synthetic analog of cytidine in which ribose is substituted by arabinose; it is used as a drug for the treatment of leukemia. A fast and reliable capillary electrophoretic method for the analysis of cytarabine and cytidine is described. The procedure utilizes the interactions with sodium dodecyl sulfate (SDS) micelles and borate, present in the background electrolyte, for the mobilization and selective separation of the analytes. The detection is carried out by UV absorbance at 275 nm. The method was applied both to pharmaceutical preparations and human serum. Analysis of an untreated serum requires 15 min; the detection limit is 0.8 μg/mL and the relative standard deviation (RSD) is 5.3%.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150171225
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Methods for determination of electrophoretic mobility and stability of complexes originating in solutions during the chiral discrimination process (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 276-281 
    Details
    ISSN: 0173-0835
    Keywords: Capillary zone electrophoresis ; Chiral separation ; Stability constants ; Complex mobility ; Cyclodextrins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: An equation for the calculation of electrophoretic mobility of kinetically labile complexes originating in solutions during the chiral discrimination process is derived. The mobility of the complex is calculated from that of a fully ionized racemic compound, measured in absence of the chiral selector, and from the effective mobilities of its enantiomers, corresponding to the concentration of the chiral selector causing their maximum difference. Correct values of stoichiometric stability constants of both enantiomers may be calculated from the mobility of the complex obtained in this way. Both the mobility and the stability values hold only for the experimental conditions used and the selected background electrolyte. The proposed method is demonstrated for the separation of the fully ionized N-t-BOC-DL-tryptophan with β-cyclodextrin in 20 mM aqueous solution of α-hydroxyisobutyric acid, adjusted with NaOH to pH 4.5. Mobility of the complex is 8.4 × 10-9 m2V-1s-1 at 25°C. The stability constants of D- and L-enantiomers of N-t-BOC-DL-tryptophan with β-cyclodextrin, KD and KL, obtained from migration data using this mobility of the complex, are 374 ± 37 M-1 and 336 ± 31 M-1, respectively. The geometrical mean value of calculated stability constants, 355 M-1, agrees perfectly with the value of 350 M-1, calculated from the same experimental data by another procedure recently.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190222
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Highly sensitive chiral analysis in on-line combined chiral and achiral media by capillary zone electrophoresis (1995)
    Weinheim : Wiley-Blackwell
    Electrophoresis 16 (1995), S. 968-973 
    Details
    ISSN: 0173-0835
    Keywords: Capillary zone electrophoresis ; Chiral separations ; Column-coupling system ; α-Hydroxycarboxylic acids ; Sensitivity of optical detection ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A new approach is described for highly sensitive chiral analyses by capillary zone electrophoresis, based on using an on-line combination of two capillaries filled with either chiral selective or achiral background electrolytes (BGE). Thus, the BGEs are selected in such a way that the first capillary provides optimum chiral selectivity and the second one optimum detection sensitivity. Direct chiral separations of enantiomers of mandelic, m-methoxymandelic, 3-phenyllactic and 3-indolelactic acids served as a model example for testing the approach proposed. The analyses were performed in a BGE containing acetate as a coion and L-OH-proline or aspartame as a chiral selector. For high sensitive analyses, an arrangement containing on-line combined chiral and achiral media were tested in one or two capillaries coupled via a bifurcation block. A detection limit as low as 10-18 moles was reached in the column-coupling system when the direct chiral separation was performed in the first capillary, filled with 20 mM acetate buffer, pH 4.4, containing 8 mM Cu (II) and 16 mM aspartame (L-aspartyl-L-phenylalanine methylester) and separated enantiomers were detected in the second capillary, filled with 20 mM acetate buffer, pH 3.1. The principle described is of general use in cases where the separation and detection of analytes in question require mutually different BGEs to reach the optimum selectivity and sensitivity, respectively.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.11501601162
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...