Wall-jet Cell Research Articles

Electrochemical detection for liquid chromatography using the wall-jet cell/ultramicroelectrode detector

A carbon fibre array and a platinum thin ring ultramicroelectrode were constructed and used in conjunction with a large volume wall-jet cell as an amperometric detector in liquid chromatography. Electrode characterization studies were performed in 5.00 m M K 3Fe(CN) 6 + 1 M KCl aqueous solution. It was found that the wall-jet cell/ultramicroelectrode combination has much reduced flow rate dependence compared to the wall-jet cell/conventional electrode system. LC application in the absence of supporting electrolyte was found to be possible and have good sensitivity using the ultramicroelectrode. Detection limits were 100 pg and 10 ng for the platinum thin ring and the carbon fibre array electrodes respectively.

Swept-potential oxidative detection in flow streams

A swept-potential electrochemical detector, operated in the oxidative staircase voltammetric metric mode, is demonstrated for the high-performance liquid chromatography of a mixture of catecholamines. Voltammetric limits of detection are approximately 30 pg or 1 nM and chromatographic limits of detection are approximately 250 pg. The use of a platinum working electrode in a wall-jet cell configuration, with potential pulses for cleaning and activation between each sweep, results in a cell that has maintained a constant response for over a year without mechanical refinishing of the electrode surface.

Kinetics of colloidal deposition studied by a wall-jet cell

A new technique for studying the kinetics of colloidal deposition has been developed. Controlled mass transfer to the surface is achieved using a wall-jet. The accumulation of colloidal particles is followed in situ by depositing the particles on a microscope slide, through which light is passed under conditions of total internal reflection. The deposited particles scatter the light which is viewed through a microscope fitted with a photomultiplier. If the rate of particle deposition is mass transfer controlled, then as a consequence of the wall-jet hydrodynamics, the number of deposited particles will vary with r − 5 4 where r is the radial distance from the center of the jet. On the other hand, a uniform deposit will be observed if the rate-limiting step takes place at the surface. Experimental results for the deposition of carbon black on clean and surface-treated glass exhibit kinetic and mass transfer control, respectively. For both cases theory and experiment are shown to be in good agreement.

Determination of oestriol in pregnancy urine by normal-phase high-performance liquid chromatography with electrochemical detection

A method for the determination of oestriol in pregnancy urine by normal-phase high-performance liquid chromatography with electrochemical detection is described. A large-volume wall-jet cell with an AgAg + reference electrode was used as the detector system. The limit of detection obtained is comparable to that of electrochemical detection following reversed-phase liquid chromatography. One of the advantages of electrochemical detection with normal-phase systems is that adsorption problems are minimized.

Amperometric detection in normal-phase high-performance liquid chromatography with a large volume wall jet cell and silver/silver(1+) reference system

L'utilisation d'une cellule a jet de paroi de grand volume permet une detection amperometre en chromatographie en phase liquide a haute performance meme si l'on n'ajoute pas d'electrolyte support a l'eluant et meme si l'eluant est un solvant faiblement dielectrique. On utilise une electrode classique de reference Ag/Ag +

Large-volume wall-jet cells as electrochemical detectors for high-performance liquid chromatography

The wall-jet electrode is an attractive configuration for electrochemical detectors for high-performance liquid chromatography (h.p.l.c.) on account of its high convective mass-transfer characteristics. Another important, though less recognized, feature is its small effective cell volume, which is shown to be almost independent of the geometric cell volume. The effective volume is less than the volume of the hydrodynamic boundary layer, or only a few microlitres. The practical use of the wall-jet detector in both normal-phase and reverse-phase h.p.l.c. is discussed with particular reference to the distance between the jet and the electrode. A new cell design is proposed.

Modifications of the wall-jet electrochemical detector for liquid chromatography and flow analysis

Two modifications are suggested for the construction of electrochemical detectors for liquid chromatography and flow analysis. A convenient, large-volume wall-jet cell has a low-dead volume and performs like cells with microlitre volumes. A new electrode material, silicone rubber-impregnated carbon, is also conveniently prepared and used, and behaves much like carbon paste or glassy carbon.

Electrochemical detector with a 20 nl volume for micro-columns liquid chromatography

A flow-through two electrode wall-jet cell with a platinum measuring electrode and a cell volume of 20 nl has been designed and evaluated. It has been used to detect phenols by reversed phase liquid chromatography using short micro bore columns. The linear dynamic range between the measured current and the concentration is greater than 103 (1.5×10−7−5×10−4 mol/l) and the minimum analyzable amount was found to be 10 pg for pyrocatechol. A negligible broadening in the detector permits the use of micro columns down to 0.5 mm internal diameter, packed with 5 μm particles, without any substantial distortion of eluted zones.