Stacking in a continuous sample flow interface in capillary electrophoresis.

Using a tee connector in a commercial capillary electrophoresis instrument, the effect of field amplified sample injection from both flowing and static sample volumes was investigated. It is shown that under identical conditions (40min electrokinetic injection at 5kV from a sample volume of 295µL) the limit of detection using the continuous sample flow interface is 4 times lower than from a static vial. The relationship between different flow rates and injection voltages on the injected sample amount was also investigated using a 2D axisymmetric simulation (COMSOL 4.3b) and verified experimentally, confirming conditions under which there is near-quantitative injection of the sample target ions. Using electrokinetic injection at 30kV and a flow rate of 558nL/s the same enhancement from an even smaller volume of 184µL could be achieved in 5.5min than could be achieved from 295µL and a 40min injection. This sensitivity enhancement factor corresponded to four orders of magnitude improvement compared to a hydrodynamic injection. This is the first report showing that a continuous sample flow interface combined with stacking methods under conditions approaching quantitative injection from the entire sample volume has the potential to be more sensitive than a static system.

Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2012-2014).

One of the most cited limitations of capillary (and microchip) electrophoresis is the poor sensitivity. This review continues to update this series of biannual reviews, first published in Electrophoresis in 2007, on developments in the field of on-line/in-line concentration methods, covering the period July 2012-July 2014. It includes developments in the field of stacking, covering all methods from field-amplified sample stacking and large-volume sample stacking, through to ITP, dynamic pH junction, and sweeping. Attention is also given to on-line or in-line extraction methods that have been used for electrophoresis.

Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2010-2012).

CE has been alive for over two decades now, yet its sensitivity is still regarded as being inferior to that of more traditional methods of separation such as HPLC. As such, it is unsurprising that overcoming this issue still generates much scientific interest. This review continues to update this series of reviews, first published in Electrophoresis in 2007, with updates published in 2009 and 2011 and covers material published through to June 2012. It includes developments in the field of stacking, covering all methods from field amplified sample stacking and large volume sample stacking, through to isotachophoresis, dynamic pH junction and sweeping. Attention is also given to online or inline extraction methods that have been used for electrophoresis.