Physicochemical Properties

In choosing an electrophoretic system it is important to consider both matrix and the structural features of the analytes. Whereas 18 amino acids are found after the hydrolysis of proteins, more than 50 derivatives are present in physiological fluids.

Amino acids are small, highly polar species. The individual species only differ in the residues R. Except for glycine this situation induces a chiral centre at the a-C-atom where two enantiomers (R-, S-) can be distinguished. Classifying these residues R by their impact on electrophoretic behaviour means a differentiation by their polarity or the generation of charge. Due to their zwitterionic nature, amino acids possess isoelectric points (pI); pH values equal to pI yield molecules without net charge and therefore no migration occurs in an electrical field. At pH values above the pI the molecules are negatively charged and migrate against the electroosmotic flow (EOF) towards the anode, whereas lower pH values induce cations which migrate with the EOF towards the cathode.

Most amino acids lack suitable physical characteristics that can be exploited for detection. Only few species possess aromatic groups with high absorptivity, e.g. try, phe and tyr. In order to analyse native amino acids three strategies can be pursued. UV detection can be used at low wavelengths. A second approach is the application of indirect detection techniques. Detection concepts involving derivatization technology, especially fluorescence labelling, can also improve detection sensitivity.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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