SEC Pumps and Flow Rate

Normal isocratic HPLC pumps are used for SEC work but the requirements for good control of the flow-rate are probably more severe. Since in SEC, it is an envelope of a multitude of different molecular weight peaks that is being measured, it is not possible to set an identification window and any small variation in flow rate will produce an error in the molecular weight calculation. Variation in flow-rate can be allowed for by the use of an internal marker. For a typical polystyrene, a deliberate correction of the flowrate by 0.2% produces a variation in the calculated weight average molecular weight from 308 000 to 320000; a variation of approximately 4%.

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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