Summary
Minimum capillary lengths on commercial instruments are fixed and cannot be decreased further. To effectively reduce the capillary length used for separation the sample can be injected from the end of the capillary nearest the detector. This procedure is known as a ‘short-end’ injection and can reduces analysis times by at least two-thirds compared to conventional injections. The time reduction benefits are shown in rapid separations of basic drugs, drug-related impurities and chiral compounds. Short-end injections, in combination with both increased electrolyte strength and reduced voltage are an effective approach to reducing the detrimental impact of high sample solution ionic strength. They can also lead to improved resolution by increasing stacking effects and reducing peak tailing. Peak area and migration time precision obtained are shown to be equivalent to those obtained for conventional injection procedures. It is concluded that short-end injections should be considered for routine operation as they are a useful means of reducing analysis time, increasing sensitivity, decreasing buffer depletion effects. They also allow use of higher electrolyte strengths which can improve resolution and reduce peak tailing, and can overcome significant problems which occur when analysing samples containing high salt contents.
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Altria, K.D., Kelly, M.A. & Clark, B.J. The use of a short-end injection procedure to achieve improved performance in capillary electrophoresis. Chromatographia 43, 153–158 (1996). https://doi.org/10.1007/BF02292944
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DOI: https://doi.org/10.1007/BF02292944