Connective Tubing and Fittings

The connective tubing in the HPLC system should be made of material inert to the solvents and constituents of the mobile phase. Often tubing is made of stainless steel or polymer-based materials (e.g. PEEK®, Teflon®, etc.). The connections between the tubings and HPLC components are made with fittings and unions designed to minimize excess volume, or dead volume. Zero dead volume (ZDV) and low dead-volume (LDV) fittings are necessary to reduce band-broadening effects. Also, great care should be used when assembling columns and Rttings so that they match properly. Tubing should be cut flat and fit flush, and all fittings should be zero dead volume. Any extra-column volume compromises separation efficiency. Polymer-based, or PEEK®, tubing and fittings throughout the chromatographic flow path are becoming very popular. PEEK tubing is available in a wide range of sizes, is colour-coded for ease of size selection, is easy to work with, is tolerant to a wide range of buffer and solvent conditions, and is impermeable to oxygen.

The effects of band-broadening are not important prior to injection; therefore, the inner diameter of the tubing from the pump to the injector/autosampler should be as large (i.e. typically 0.030 inch i.d.) as possible (i.e. to reduce system back-pressure) while maintaining high-pressure strength. From the injector to the column to the detector, all tubing should be as short as possible and of the narrowest diameter available to minimize extra-column effects. Post-injector tubing diameters are often 0.01-0.005 inch i.d.

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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