ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
    Springer
    Monatshefte für Chemie 131 (2000), S. 1031-1038 
    ISSN: 1434-4475
    Keywords: Keywords. Potentiometry; Glycine; Cephalosporins; Complexes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  The interaction of Ca(II), Cu(II), Zn(II), Pb(II), and La(III) ions with the antibiotics cephalexin, cefadroxil, cephaloridine, and cefoperazone as secondary ligands was investigated potentiometrically. The formation constants were determined for a ligand-to-metal ratio of 1:1 at 25°C and KNO3. The protonation constants of the complexes were evaluated for the system . The order of stability of the binary and ternary complexes were examined. It was found that glycine adds preferably [M(II)-cephalosporin] rather than to the aqueous complexes of M(II). In all cases 1:1:1 complexes were formed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1434-4475
    Keywords: Complexes ; Tetracycline ; Oxytetracycline ; Potentiometric studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Wechselwirkungen von Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II), Hg(II), Pb(II), Al(III) und UO2(II) Ionen mit Tetracyclin (TC) wurden mittels potentiometrischerpH-Titrationen untersucht. Die Komplexbildungskonstanten wurden bei 25±0.1°C und μ=0.1 mol/1(NaNO3) bestimmt. Unter den gleichen Bedingungen wurden die Komplexierung von Cu(II), Cd(II), Pb(II) und UO2(II) mit Oxytetracyclin (OTC) mittel potentiometrischerpH Gleichgewichtsmessungen untersucht. Aus den potentiometrischenpH-Titrationskurven ergab sich die Bildung von (1:1) binären Komplexen. Die Protonierungskonstanten vonTC undOTC wurden ebenfalls bestimmt und rechnerisch verfeinert (ESAB2M Computer Programm). Die Stabilitätskonstanten für die Übergangsmetalle stimmen mit der Irving-Williams Reihe überein.
    Notes: Summary The interaction of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II), Hg(II), Pb(II), Al(III), and UO2(II) ions with tetracycline (TC) were studied by potentiometricpH titrations. The formation constants of the different binary complexes formed in such systems have been determined at 25±0.1°C and μ=0.1 moll−1 (NaNO3). PotentiometricpH equilibrium measurements have been made under the same conditions for the interaction of oxytetracycline (OTC) and Cu(II), Cd(II), Pb(II), and UO2(II). The formation of (1:1) binary complexes are inferred from the potentiometricpH tritration curves. The protonation constants ofTC andOTC were also determined under the same conditions and refined (ESAB2M computer program). The transition metal stability constants are consistent with the Irving-Williams series.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Differential pulse polarography and cyclic voltammetry have been used to elucidate the complexation reaction between folic acid (vitamin B9) and cadmium(II) in unbuffered solutions. In order to follow this mechanism, the interaction of compounds related to folic acid (pterin, pterin-6-carboxylic acid, pteroic acid, and glutamic acid) with cadmium ions has been investigated using the same conditions. It appears that no complexation occurs between cadmium(II) and glutamic acid and that the complexation is very weak with pterin. One complex is formed with pterin-6-carboxylic acid with log β1 = 6.72, two complexes are formed with pteroic acid with log β1 = 5.0 and log β2 = 10.88, and three complexes appear with folic acid with log β1 = 5.56, log β2 = 10.40, and log β3 = 16.63. The mechanism of complexation is also considered.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Both differential pulse polarography (DPP) and differential pulse anodic stripping voltammetry (DPASV) have been applied to the determination of the conditional stability constants of copper(II)-folic acid complexes. The polarographic technique does not allow the investigation of these reactions in neutral media due to the interference of a hydroxy copper complex. DPASV exhibits two complexes with 1:1 and 1:3 stoichiometry at pH 7.4. The addition of 2 mM phosphate buffer affects the complexation mechanism; three different species are formed. In a weakly acidic medium (pH 4.5), only one complex is evidenced, but, due to the protonation of the pterin moiety of folic acid, which is the active site for complexation, an increase of the proton concentration inhibits the complex formation. Copper(II) ions are shown to be more strongly complexed than lead and cadmium ions under the same conditions. Using d.p.a.s.v. Copper(II) can be determined over the 4 × 10-6 to 2 × 10-5 M concentration range in the presence of 5 × 10-6 M folic acid.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lipid-modified carbon paste electrodes were electrochemically characterized and their potential for drug analysis was compared with conventional carbon paste electrodes. The presence of lipids (phospholipids, fatty acids) in the paste matrix provided enhanced current responses with improved reproducibility. With 5 minutes of accumulation, phenothiazines exhibit a 40-fold enhancement of the response compared to that obtained without accumulation. As a result, a detection limit of 1 × 10-9 M was attained. The response was characterized with respect to pH, preconcentration potential, accumulation time, paste composition, possible interferences, and other variables. The determination of the tranquilizer in serum and urine required no preliminary treatment other than dilution with phosphate buffer and medium exchange. Detection limits are 5 × 10-8 M in urine and 2 × 10-7 M in serum.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electroanalysis 5 (1993), S. 85-89 
    ISSN: 1040-0397
    Keywords: Cefobid ; Adsorptive stripping voltammetry ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A sensitive voltammetric method has been developed for the cephalosporin antibiotic, cefoperazone monosodium salt (cefobid). The method is based on controlled adsorptive preconcentration of cefobid on the hanging mercury drop electrode (HMDE), followed by voltammetric determination of the surface species by cathodic stripping voltammetry. Cyclic voltammetry was used to examine the interfacial behavior of the drug. The electroanalytical techniques used were direct current stripping voltammetry (DCSV) and differential pulse stripping voltammetry (DPSV). The adsorptive stripping response was evaluated with respect to preconcentration dependence, possible interferences, and other variables. The drug is strongly adsorbed in acidic media, with maximum adsorption at pH2. The detection limit found by DPSV was 2 × 10-9 M (1.33 ppb), with 240 second preconcentration. The relative standard deviation at the 1 × 10-7 M level was 3.2%. The interference of uric and ascorbic acids and copper and calcium ions has been studied. The method was applied to the determination of cefobid in urine.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1040-0397
    Keywords: Cephalosporin ; Ceftriaxone ; Cefoperazone voltammetry ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two cephalosporin antibiotic derivatives, ceftriaxone (CFRX) and cefoperazone (CFPZ), have been studied by direct current, differential pulse polarography (DPP), and cyclic voltammetry. Both give rise to two irreversible two-electron reduction steps. The characteristics of the corresponding electrode reactions are discussed. The electrooxidation of both drugs was also studied at the carbon paste electrode (CPE). Both drugs give rise to one oxidation peak at about +1.05 V vs. SCE (pH 1.6, phosphate buffer solution). Optimum pH ranges for the determination of these drugs at the CPE are also given. Linear calibration plots were obtained over the concentration ranges 0.49 to 99 μg/mL and 0.66 to 534 μg/mL for CFRX and CFPZ, respectively. Detection limits of 2.5 ng/mL and 0.13 μg/mL for CFRX and CFPZ, respectively, were readily achieved.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
  • 10
    Publication Date: 2021-10-28
    Description: This study investigated seasonal variation, spatial distribution, sources, composition and potential ecological risks of 16 polycyclic aromatic hydrocarbons (PAHs) in Red Sea coastal water. Surface seawater samples were collected at fourteen different locations. The sum of 16 PAHs concentrations in Red Sea showed clear variation between seasons, ranged from 1.08–6.10, 0.79–50.86, 1.37–54.47 and 0.21–7.18 μg/L in summer, autumn, winter, and spring respectively. PAHs levels in Red Sea coastal waters were relatively high at certain sites during autumn and winter seasons. They could be classified as highly polluted by PAHs contaminants (〉10 μg/L). According to the diagnostic ratios measured, the majority of PAHs in this study originated from pyrogenic sources, while minor amounts originated from petrogenic sources. Four rings PAHs accounted for more than 64% of the total PAHs studied. PAHs pose a high ecological risk along the period of study, according to the ecological risk assessment by Risk quotients (RQNCs and RQMPCs).
    Electronic ISSN: 2071-1050
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...