According to the developed model based on Shockley equation and the Lambert-Beer law, PEDD-based photometric devices generate a potentiometric analytical signal that is directly proportional to the analyte concentration.

Disaccharides are determined mainly for dietetic purposes, hence the most analyses are carried out for food and drink samples. Its content can also be used to profile groceries in order to identify the origin and quality of the products. They also can be an indicator of the rate of metabolism as well as for the control of some technological and biotechnological processes. Unfortunately most of technological analysis are performed with nonselective polarimetry methods. Sugars due to specific physicochemical properties of compounds are difficult to determine with classical analytical techniques. The most common disaccharides are composed of several types of monomers connected by a different configuration of the glycosidic bond, therefore, there are subject of the same characteristic reactions. This often enforces the need for pre-separation of sample components. Therefore, nowadays the most popular analytical methodologies for disaccharides determination are based on chromatographic and electrophoretic techniques. An alternative is enzymes application that allow both selective recognition of target analyte and its conversion to easy detected product, allowing detection by relatively simple conventional analytical methods. Another approach is the use of advanced chemometric methodologies for computing of data obtained from some spectroscopic techniques. This article is a review of the recent analytical literature devoted to non-selective and selective methods for disaccharide determination in real samples.

No abstract

No abstract

No abstract

No abstract

Integration of two light emitting diodes allows construction of a fluorometric paired emitter detector diode (FPEDD)--a compact optoelectronic device useful as a complete flow-through fluorescence detector.

A cost-effective, highly compact, and versatile optoelectronic device constructed of two ordinary light emitting diodes compatible with optosensing films has been developed. This fibreless device containing chemoreceptor, semiconductor light source, and detector integrated in a miniaturized flow-through cell of low microliter internal volume works as a complete photometric chemical sensor suitable for detection in flow analysis. The operation of the developed device under nonstationary programmable-flow conditions offered by sequential injection analysis has been demonstrated using Prussian Blue film as a model optical chemoreceptor. The unique spectroelectrochemical properties of the sensing material enable its use for optical sensing of redox species, whereby ascorbic acid and hydrogen peroxide have been chosen as model analytes. The reported SI-sensor system features fast and reproducible determination of both analytes in the submillimolar range of concentrations. The construction concept demonstrated in this work can be easily applied to other kinds of optical sensors based on absorbance sensing films.Electronic supplementary materialThe online version of this article (doi:10.1007/s00216-010-4384-2) contains supplementary material, which is available to authorized users.