Controlled EOF™ capillaries are used when you want to suppress the EOF partially or completely and you want to use IEF (iso-electro focusing). Since separation takes place strictly due to electrophoretic mobility in coated capillaries, neutral compounds and anions may not enter or pass through the capillary unless you reverse the flow, then cations and neutrals will not be detected. Coated capillaries have a rather limited lifetime as the coating is removed at low pH which is very commonly used in CE.

Coated capillaries are not as precise as dynamic coatings and used mostly for IEF of proteins.  

Dynamic coatings are ideal when migration times are critical and must be precise. Using the CElixir™ products, you get a very robust EOF and it is extremely precise run to run. CE with CElixir dynamic coating is as precise and often more precise than HPLC can be. The downside of using any CE is that you compounds must be ionizable to load onto the capillary or move through it. If they are not, then you must use MEKC which uses buffer additives such as Cyclodextrins or micelles with the CElixir. In this case, with dynamic coatings, the runs are still very precise and the separations can be very good and chiral separation is reproducible if you use the exact same CD each time. Making CD with the same degree of substitution is difficult so it can be hard to obtain similar batches. Within the same batch of CD, the reproducibility is excellent. Chiral separation depends on the cyclodextrin used and your compounds.

Capillaries for CE

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