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  • 1
    Electronic Resource
    Electronic Resource
    Coulometric titration of tetraphenylborate ion with electrogenerated silver ion. Application to determination of potassium, rubidium, and cesium (1967)
    s.l. : American Chemical Society
    Analytical chemistry 39 (1967), S. 168-171 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac60246a016
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  • 2
    Electronic Resource
    Electronic Resource
    Hydrophobic stripping voltammetry using a lipid-modified glassy carbon electrode (1989)
    s.l. : American Chemical Society
    Analytical chemistry 61 (1989), S. 170-173 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00177a018
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  • 3
    Electronic Resource
    Electronic Resource
    Microdetermination ofN-substituted phenothiazine compounds by coulometric techniques (1970)
    Springer
    Microchimica acta 58 (1970), S. 950-954 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Ein coulometrisches Mikroverfahren zur Bestimmung N-substituierter Phenothiazine mit elektrolytisch gebildetem Cer(IV), Brom oder Mangan(III) wurde ausgearbeitet. 0,1 bis 3 mg lassen sich mit einem durchschnittlichen Fehler von ±1% rel. bestimmen.
    Notes: Summary A method has been developed for the coulometric microdetermination ofN-substituted Phenothiazine compounds with electrogenerated cerium(IV), bromine and manganese(III). Quantities of 0.2–3 mg are determined with an average error of less than ±1% relative.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01225723
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  • 4
    Electronic Resource
    Electronic Resource
    Spectrophotometric study of the acid-base equilibria of an imidazobenzodiazepine, midazolam, and its determination in pharmaceutical formulations (1989)
    Springer
    Microchimica acta 97 (1989), S. 181-190 
    Details
    ISSN: 1436-5073
    Keywords: midazolam ; acid-base equilibria ; kinetic analysis ; spectro-photometry ; pharmaceuticals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The acid-base behaviour of midazolam, a psychotropic drug derived from imidazobenzodiazepine family, has been studied spectro-photometrically. This compound hydrolyzes at pH values lower than 4. Reversible cleavage of the azomethine bond takes place and the open-ring compound is in equilibrium with the closed-ring compound (protonated form of the parent drug). Absorbance-time data (measured at 225 nm and for different pH values) have been evaluated by a pseudo-first order logarithmic approach, leading to different apparent kinetic constants, depending on pH and temperature. A simple mechanism of hydrolysis, corresponding to fast protonation and slow hydrolysis with opening of the ring is in good agreement with the kinetic results. From data obtained at pH values greater than 4, the deprotonation constant of the nitrogen atom at position 2 of the imidazole ring has been calculated and a pKa value of 5.50 ± 0.05 obtained. In addition, a Spectrophotometric method has been developed which allows the determination of midazolam at concentrations from 1.23 × 10−6 M to 3.38 × 10−5 M. This method has been applied to a pharmaceutical formulation midazolam; the Dormicum error, in terms of relative standard deviation, was lower than 1.5%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01242464
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  • 5
    Electronic Resource
    Electronic Resource
    Coulometric titration of organic and pharmaceutical compounds with electrogenerated gold(III) (1979)
    Springer
    Microchimica acta 71 (1979), S. 415-421 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung An der Elektrode entwickeltes AuCl4− in 0,02M HCl wurde für die Titration von Hydrochinon, Ascorbinsäure, Phenylhydrazin, Phenelzinsulfat und Phenylsemicarbazid mit biamperometrischer Endpunktanzeige verwendet. Die Ergebnisse wurden mitgeteilt und mit den Resultaten der Coulometrie mit Cersulfatoxydation verglichen. Im Gegensatz dazu können mit weniger als 1 mg Probe in derselben Lösung Folgetitrationen durchgeführt werden. Abweichend von seinem Verhalten gegenüber stärkeren Oxydationsmitteln reagiert Phenelzinsulfat stöchiometrisch.
    Notes: Summary Electrogenerated AuCl4− in 0.02M HCl is used to titrate hydroquinone, ascorbic acid, phenylhydrazine, phenelzine sulphate and phenylsemicarbazide, with biamperometric end-point detection. Titration recoveries are reported and compared with results of coulometry with ceric sulphate oxidation. With less than 1 mg of sample, successive titrations can be performed in the same solution, in contrast to coulometry with ceric sulphate. Phenelzine sulphate reacts stoichiometrically, as opposed to its reactions with stronger oxidizing agents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01197414
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  • 6
    Electronic Resource
    Electronic Resource
    Electrochemical study of cadmium complexes with folic acid and its related compounds (1989)
    Weinheim : Wiley-Blackwell
    Electroanalysis 1 (1989), S. 87-92 
    Details
    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
    URL: http://dx.doi.org/10.1002/elan.1140010114
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of hydrophobic substances in aqueous-organic and micellar media by use of electrochemical techniques (1994)
    Weinheim : Wiley-Blackwell
    Electroanalysis 6 (1994), S. 791-798 
    Details
    ISSN: 1040-0397
    Keywords: Hormones ; Micellar media ; Voltammetry ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new electroanalytical methodology for the determination of hormones in micellar media by use of differential pulse polarography (DPP) and adsorptive stripping voltammetry (ASV) is reported. It was applied to the determination of hydroxyprogesterone in Triton X-100 as micellar medium, with a detection limit of 3.6 × 10-6 M (DPP) and 2.5 × 10-11 M (ASV). A theoretcal explanation for the increased diffusion current of the hormone in the micellar medium is provided and its significance discussed. The electrochemical behavior of this hormone and β-estradiol in aqueous-organic media was also studied by using DPP and ASV. The detection limits thus obtained for the two compounds were 1.2 × 10-5 M β-estradiol and 1.5 × 10-5 M hydroxyprogesterone by the former technique and 8 × 10-9 M hydroxyprogesterone by the latter. The β-estradiol showed no adsorption in any of the assayed media, so the ASV determination of hydroxyprogesterone in its presence was highly selective.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140060914
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  • 8
    Electronic Resource
    Electronic Resource
    Voltammetric determination of the stability constants of copper(II) complexes with folic acid (1989)
    Weinheim : Wiley-Blackwell
    Electroanalysis 1 (1989), S. 341-345 
    Details
    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
    URL: http://dx.doi.org/10.1002/elan.1140010410
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  • 9
    Electronic Resource
    Electronic Resource
    Preconcentration and determination of promethazine at lipid-modified carbon paste electrodes (1989)
    Weinheim : Wiley-Blackwell
    Electroanalysis 1 (1989), S. 501-505 
    Details
    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
    URL: http://dx.doi.org/10.1002/elan.1140010605
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  • 10
    Electronic Resource
    Electronic Resource
    Obtiuary (1992)
    Weinheim : Wiley-Blackwell
    Electroanalysis 4 (1992), S. i 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140040102
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