Influence of the Modifier Type and its Concentration on Electroosmotic Flow of the Mobile Phase in Pressurized Planar Electrochromatography

The aim of this work was to find a relationship between electroosmotic flow (EOF) velocity of the mobile phase in pressurized planar electrochromatography (PPEC) and physicochemical properties like zeta potential, dielectric constant, and viscosity of the mobile phase as well as its composition. The study included different types of organic modifiers (acetonitrile, methanol, ethanol, acetone, formamide, N-methylformamide and N,N-dimethylformamide) in the full concentration range. In all experiments, chromatographic glass plates HPTLC RP-18 W from Merck (Darmstadt) were used as a stationary phase. During the study we found that there is no linear correlation between EOF velocity of the mobile phase and single variables such as zeta potential or dielectric constant or viscosity. However, there is quite strong linear correlation between EOF velocity of the mobile phase and variable obtained by multiplying zeta potential of the stationary phase–mobile phase interface, by dielectric constant of the mobile phase solution and dividing by viscosity of the mobile phase. Therefore, it could be concluded that the PPEC system fulfilled the Helmholtz–Smoluchowski equation

An Innovative Method for Complete Microsensors Fabrication

AbstractA novel low-cost method of amperometric sensors’ fabrication based on thick-film technique on solid support and examples of their analytical applications are presented. The advantages of the fabrication method are flexibility in design and patterning of the deposited area applicable for both rapid prototyping of test samples and mass production. The developed graphite amperometric sensors were applied for quantitative detection of tricyclic antidepressants: imipramine and desipramine as well as DNA hybridization

Microfluidics Based System for Amperometric Determination of CRP

AbstractIn this paper, microfluidic based system for amperometric detection of CRP is described. The amperometric sensors were designed to operate in a microfluidic system for immunoenzymatic test (ELISA). The developed microfluidic system with integrated Pt amperometric sensors is suitable for determination of CRP in the lowest concentration range valuable for clinical diagnosis - 0.1mg/L to 1mg/L

Surface Modification for Microreactor Fabrication

In this paper, methods of surface modification of different supports, i.e. glass and polymeric beads for enzyme immobilisation are described. The developed method of enzyme immobilisation is based on Schiff’s base formation between the amino groups on the enzyme surface and the aldehyde groups on the chemically modified surface of the supports. The surface of silicon modified by APTS and GOPS with immobilised enzyme was characterised by atomic force microscopy (AFM), time-of-flight secondary ion mass spectroscopy (ToF-SIMS) and infrared spectroscopy (FTIR). The supports with immobilised enzyme (urease) were also tested in combination with microreactors fabricated in silicon and Perspex, operating in a flow-through system. For microreactors filled with urease immobilised on glass beads (Sigma) and on polymeric beads (PAN), a very high and stable signal (pH change) was obtained. The developed method of urease immobilisation can be stated to be very effective