Pre Scanning Considerations

For quantification by reflectance scanning, there is no limitation on the backing used for the chromato-graphic layer, whether it be glass, aluminium or plastic. However, it must be said that quality of the scanned results, reproducibility and quantitative accuracy mainly depend on the quality of the spot or band application of the sample and the choice of developing solvents. The use of automated spot and band application equipment results in a noticeable improvement in relative standard deviation. In practical terms, band application gives even greater accuracy than spot application. This is to be expected since a scanning slit length on the spectroden-sitometer has to be chosen for a spot such that it covers the whole length, as the concentration of the analyte will vary across the spot, with the highest concentration being in the centre. The slit length also has to allow for any variation caused by migration of spots not occurring in a precisely vertical direction (usually due to solvent vapour not being saturated in the developing chamber). For band development, the concentration of the analyte is the same across the length of the band. Hence, there is more latitude on the choice of slit length. Small slit lengths can be chosen which tend to higher sensitivity. Under these conditions with many separations, coefficient of variation (CV) below 1% can be achieved.

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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