Dietrich Saur

Anodic stripping voltammetric determination of heavy metals in solutions containing humic acids

SummaryVarious simultaneous effects of humic acids on the current and potential of differential pulse anodic stripping peaks of copper, lead, cadmium and zinc in weakly alkaline and acidic (pH 2) solutions have been investigated and interpreted with regard to metal complexation and the adsorption of humic acid on the mercury electrode. The applicability of the standard additions method for metal quantitation and the experimental conditions for UV-photolysis with a high-pressure mercury lamp have been examined in model as well as real water samples.

Studies on the UV-photolytic decomposition of some tensides and complexones inhibiting the inverse-voltammetric determination of metal ions

SummaryThe UV-photolytic decomposition of some tensides and complexones has been investigated using the DPASV peak of indium as an indicator. The results show that UV-irradiation alone can completely decompose these compounds at lower concentrations within a short time. Higher concentrations need an additional oxidising agent.

Differential Faradaic rectification polarography (DFRP)

ZusammenfassungEs wird ein neues polarographisches Verfahren beschrieben, das auf der Messung des Faradayschen Gleichrichtungseffektes beruht. Es ist von Interesse für analytische Zwecke sowie für Untersuchungen der Elektrodenkinetik.SummaryA new polarographic technique is described which is based on the determination of the Faradaic rectification effect. It will be of interest for analytical investigations and for electrode kinetics.

Flow-through voltammetry (FTV) with the hanging mercury drop electrode (HMDE)

A flow-through cell with integrated hanging mercury drop electrode for voltammetric, inverse voltammetric, adsorptive voltammetric, and chronoamperometric methods is described. HMDE droplets are automatically formed and renewed. By optimizing the flow-channel the sensitivity could be increased approximately five times in comparison with batch methods using the same deposition conditions.

Polarographische Bestimmung des Nickels im ppb-Bereich nach Extraktion als Dioxim

SummaryThe analysis of aqueous solutions of nickel in the ppb-region is possible by extracting Niheptoxime-chelate and subsequent differential pulse polarographic determination of the extracted compound in a supporting electrolyte of toluene/methanol/ LiCl. Working conditions for the determination of Ni in presence of a large amount of Co, Fe and inert salts are given. The limit of determination is in the range of 1–2ppb Ni.ZusammenfassungZur Bestimmung des Nickels in wäßrigen Lösungen im ppb-Bereich wird das NiHeptoxim ausgeschüttelt und die extrahierte Verbindung in einer Grundlösung aus Toluol/Methanol/LiCl mit der differentiellen Pulse-Polarographie bestimmt. Arbeitsbedingungen für die Bestimmung des Nickels neben einem großen Überschuß an Co, Fe und Neutralsalzen werden angegeben. Die Bestimmungsgrenze liegt im Bereich von 1–2 ppb Ni.

Grundlagen der nichtlinearen wechselstrompolarographischen Analysenverfahren

SummaryWith the aid of a simple mathematical model the influence of the AC amplitude on the shape of current/voltage-curves as obtained in higher harmonics polarography is investigated. The theoretical considerations are confirmed by experiments.ZusammenfassungAnhand eines einfachen mathematischen Modells wird der Einflu\ der Wechselspannungsamplitude auf die Ausbildung oberwellenpolarographischer Strom/Spannungskurven untersucht. Die theoretischen überlegungen werden experimentell bestÄtigt.

Effect of ethylenediamine on the anodic stripping voltammetric determination of heavy metals in the presence of humic acid

Ligand competition coupled with differential pulse anodic stripping voltammetry has been investigated for the determination of copper, lead and cadmium. Ethylenediamine displaces humic acid in its metal complexes forming kinetically labile compounds. It also eliminates interferences associated with the oxidation of copper. This enhances the sensitivity of the determination of the metals over a wide range of humic acid concentration (up to 30 mg/l). The procedure has been applied to the determination of heavy metals in a real water sample.

Eine programmgesteuerte Anordnung zur inversen Voltammetrie

SummaryA device for inverse voltammetry is described. Formation of the electrode, deaeration, electrolysis, and registration of the stripping process are directed by a programming unit.ZusammenfassungEs wird eine Anordnung zur inversen Voltammetrie beschrieben, bei der sämtliche Arbeitsgänge (Elektrodenformierung, Entlüftung, Elektrolyse und Aufnahme der Stromspannungskurve) programmgesteuert durchgeführt werden.

Instrumentation und Nachweisvermögen oberwellenpolarographischer Analysenverfahren

SummaryThe influence of the different units of a higher harmonics polarograph on detection sensitivity is investigated. The complete construction of such a polarograph is described.ZusammenfassungDer Einfluß der Instrumentation der einzelnen Baugruppen eines Oberwellenpolarographen auf das Nachweisvermögen der Gesamtmeßeinrichtung wird untersucht. Der Gesamtaufbau eines solchen Polarographen wird beschrieben.

Zur Registriergeschwindigkeit polarographischer Strom/Spannungskurven

SummaryThe dependence of the registration speed of DC-, AC-, and higher harmonics polarograms on signal processing is investigated.ZusammenfassungDie AbhÄngigkeit der Registriergeschwindigkeit von der Me\signalverarbeitung bei Gleichstrom-, Wechselstrom- und Oberwellenpolarogrammen wird untersucht.