Manufacturing and testing flexible microfluidic devices with optical and electrical detection mechanisms

Flexible microfluidic devices made of poly(dimethylsiloxane) (PDMS) were manufactured by soft lithography, and tested in detection of ionic species using optical absorption spectroscopy and electrical measurements. PDMS was chosen due to its flexibility and ease of surface modification by exposure to plasma and UV treatment, its transparency in...

Oxygen sensor for float production lines

The development of a special oxygen sensor for the continuous measurement of equilibrium oxygen pressure and oxygen content in the float bath of a float-glass production line was discussed. The measuring principle is based on an electrochemical cell where the core of the sensor consist of a metal-metal oxide mix in a fully-yttria-stabilized...

Toxicokinetics of the nerve agent (±)-VX in anesthetized and atropinized hairless guinea pigs and marmosets after intravenous and percutaneous administration

In continuation of our investigations on the toxicokinetics of the volatile nerve agents C(±)P(±)-soman and (±)-sarin, we now report on the toxicokinetics of the rather nonvolatile agent (±)-VX. A validated method was developed to determine blood levels of (±)-VX by means of achiral gas chromatography at blood levels ≥10 pg/ml. The ratio of the...

Electrochemical impedance study on the formation of biological iron phosphate layers

Phosphating is the most commonly applied pre-treatment process. However, some disadvantages exist: heavy metals and phosphoric acid are used in the process. Volkland et al. developed a process, in which these compounds can be left out, using bacteria to activate the phosphating process. This paper addresses the analysis of this phosphating...

A comparison of the eco-efficiency of two production routes for methanol

To achieve sustainable development in the chemical industry, there is a need for methodologies to assess the eco-efficiency of alternative and novel technologies. The aim of this project was to use a case study to investigate the application of existing tools to assess eco-efficiency. The case study compared the conventional methanol production...

Techno-economische beoordeling van een foto-elektrochemische reactor

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Gas and vapour detection using polypyrrole

The vapours of organic solvents like toluene, butanon, and ethanol do effect the electrical conductivity of electrochemically synthesised polypyrrole. This property allows the use of polypyrrole in sensors for vapour detection. The conductivity is also a function of temperature and the history of the sensor. When exposed to water vapour, the...

Enantioselective oxidation of secondary alcohols at a quinohaemoprotein alcohol dehydrogenase electrode

Quinohaemoprotein alcohol dehydrogenase from Comamonas testosteroni was co-immobilized with a redox polymer (a poly(vinylpyridine) complex functionalized with osmium bis(bipyridine) chloride) on an electrode. The enzyme electrode readily oxidizes primary alcohols and secondary alcohols with maximum current densities varying between 0.43 and 0.98...

Effect of methylglyoxal on the physico-chemical and biological properties of low-density lipoprotein

In patients with diabetes, non-enzymatic glycation of low-density lipoprotein (LDL) has been suggested to be involved in the development of atherosclerosis. α-Dicarbonyl compounds were identified as intermediates in the non-enzymatic glycation and increased levels were reported in patients with diabetes. We studied the effect of the α-dicarbonyl...

Electron transfer between a quinohemoprotein alcohol dehydrogenase and an electrode via a redox polymer network

A quinohemoprotein alcohol dehydrogenase (QH-EDH) from Comamonas testosteroni was immobilized on an electrode in a redox polymer network consisting of a polyvinylpyridine partially N-complexed with osmiumbis-(bipyridine)chloride. The enzyme effectively transfers electrons to the electrode via the polymer. An average maximum catalytic current of...

The interaction of the anti-cancer drug cisplatin with phospholipids is specific for negatively charged phospholipids and takes place at low chloride ion concentration

The interaction of the anti-cancer drug cis-diamminedichloroplatinum(II) (cisPt) with model membranes was studied, with emphasis on the cisPt and phospholipid species involved. Binding studies using large unilamellar vesicles have revealed that: (i) Interaction involved negatively charged phospholipids only, and (ii) Interaction with negatively...

Detection of salicylate and its hydroxylated adducts 2,3- and 2,5-dihydroxybenzoic acids as possible indices for in vivo hydroxyl radical formation in combination with catechol- and indoleamines and their metabolites in cerebrospinal fluid and brain tissue

It has been suggested that salicylate (SA) hydroxylation can be used to detect hydroxyl radical formation in vivo. Here we describe a rapid and sensitive HPLC method using ultraviolet absorbance (UV) and electrochemical detection (EC) to detect SA (UV), its hydroxylated adducts 2,3- and 2,5- dihydroxybenzoic acids (DHBA) and catechol in...

Electrochemical techniques for delamination studies

Electrochemical impedance spectroscopy (EIS) has been described by several authors as a technique to measure delamination of organic coatings. The interpretation of EIS data can be performed in several ways. In this paper two methods are critically compared. These two methods are the breakpoint frequency method (BF) as described and used by...

Investigations of the negative plate of lead/acid cells 3. Model calculations of the impedance of self-similar porous electrodes

In this paper a model for the calculation of the admittance (reciprocal impedance) of a porous metal electrode is derived, under anodic constant-current conditions, during precipitation of an insoluble salt at the metal/electrolyte interface. An example of the discharge, at low current density, of the negative plate in a lead/sulphuric acid...

High-performance liquid chromatographic determination of urinary free catecholamines with electrochemical detection after prepurification on immobilized boric acid

A reliable high-performance liquid chromatographic method is presented for the determination of the urinary free catecholamines noradrenaline, adrenaline and dopamine. Urine is purified on a column of immobilized boric acid. Catecholamines are separated by ion-pair reversed phase high-performance liquid chromatography and detected...