Taste masking of roxithromycin by spray drying technique.

The spray drying technique was used to obtain the roxithromycin containing microcapsules with high taste masking efficiency. Eudragit L30D-55 was chosen as a barrier coating. The taste was evaluated by an electronic tongue, and taste-masking effect in water lasted at least several dozen hours.

Electrochemical studies of self-assembled monolayers composed of various phenylboronic acid derivatives.

Gold electrodes were functionalized with thiolated phenylboronic acids or by sequential immobilization of alkanethiols with terminal carboxylic groups and conjugation with aminophenylboronic acids. The stepwise assembly of organic molecules was characterized by several voltammetric techniques with systematic monitoring of surface coverage of organic molecules anchored to the gold electrodes. The receptor properties and applicability of the obtained monomolecular layers for the voltammetric detection of fructose and fluoride ions in solution were evaluated. The MPBA and APBA modified electrodes can be applied for the voltammetric determination of chosen non-electroactive analytes on the basis of the changes in peak currents of ferricyanide/ferrocyanide couple in the presence of the detected species.

Organoboron compounds as Lewis acid receptors of fluoride ions in polymeric membranes.

Newly synthesized organoboron compounds - 4-octyloxyphenylboronic acid (OPBA) and pinacol ester of 2,4,6-trifluorophenylboronic acid (PE-PBA) - were applied as Lewis acid receptors of fluoride anions. Despite enhanced selectivity, the polymer membrane electrodes containing the lipophilic receptor OPBA exhibited non-Nernstian slopes of the responses toward fluoride ions in acidic conditions. Such behavior was explained by the lability of the B-O bond in the boronic acids, and the OH(-)/F(-) exchange at higher fluoride content in the sample solution. In consequence, the stoichiometry of the OPBA-fluoride complexes in the membrane could vary during the calibration, changing the equilibrium concentration of the primary anion in membrane and providing super-Nernstian responses. The proposed mechanism was supported by (19)F NMR studies, which indicated that the fluoride complexation proceeds more effectively in acidic solution leading mainly to PhBF(3)(-) species. Finally, the performances of the membranes based on the phenylboronic acid pinacol ester, with a more stable B-O bond, were tested. As it was expected, Nernstian fluoride responses were recorded for such membranes with worsened fluoride selectivity.

Classification of amino acids and oligopeptides with the use of multi-mode chemical images obtained with ion selective electrode array.

The analysis of amino acids and oligopeptides as important bioanalytes is a significant task in medical diagnostics and proteomic research and currently it is based on chromatographic and electrophoretic methods. In this paper, an approach based on sensor array coupled with titration is proposed for effective recognition of 5 amino acids and 4 oligopeptides. It is shown, that the increase of information gained during measurements of sensors' signals in various pH allows for capturing more data on interaction of amino acids and oligopeptides with various polymeric membranes of potentiometric electrodes used in the array, and that leads to the lowering of classification errors in partial least squares analysis.

Electronic tongue for the detection of taste-masking microencapsulation of active pharmaceutical substances.

Electronic tongues can produce chemical images of samples, whose changes can be correlated with general properties, e.g. taste sensations. In this work, a sensor array equipped with eight types of ion-selective electrodes was coupled with Principal Components Analysis in order to detect microencapsulation effect of two Active Pharmaceutical Ingredients (APIs), which influences their taste properties. The character of change of sensor array responses in samples modified by microencapsulation was the same in two investigated APIs (Ibuprofen and Rixithromycin), proving, that the "sensed taste" becomes similar in both formulations after Eudragit modification. The obtained results show, that the presented electronic tongue can be used for analysis of masking effects in drugs and detection of microencapsulation effect.