Field amplified sample injection

Sensitivity can also be enhanced by the use of field-amplified sample injection (FASI).2 In the FASI technique, sample is injected into the capil-... 

Chien R-L, Burgi DS. Field amplified sample injection in high-performance capillary electrophoresis. J Chromatog 1991 559 141-52. 

The injection methods used in (iCE can either be stacking- or extraction-based methods. Stacking methods such as mediated stacking [236], gated injection [237], field amplified sample injection [238], the staggered-T configuration [239], field-amplified sample injection [238], and pressure-driven injection [10, 86] are widely adopted in pCE because they are simple to implement. Extraction-based techniques, such as membrane filtration [240, 241], SPE [32, 242], liquid-liquid extraction [243], and bioaffinity purification [53, 244] offer a more scalable platform for complete sample injection. 

Sample concentration is another way to increase the sensitivity of a method. Besides liquid-liquid and solid-phase extraction protocols, which result in more concentrated solutions in addition to sample cleanup, several electrokinetic concentration techniques can be applied including sample stacking and field-amplified sample injection/stacking. Over 1000-fold sensitivity enhancement compared to hydrodynamic sample injection without stacking has been reported. When acetonitrile has been used for the removal of proteins from plasma, sample injections of up to 50% of the capillary volume become possible. Stacking techniques are also available for MEKC. 

Ryan R, Donegan S, Power J, Altria K (2010) Advances in the theory and application of MEEKC. Electrophoresis 31 755-767. doi 10.1002/elps.200900568 Yu L, Xu X, Huang L, Lin J, Chen G (2008) Microemulsion electrokinetic chromatography coupling with field amplified sample injection and electroosmotic flow suppressant for analysis of some quinolizidine alkaloids. J Chromatogr A 1198-1199 220-225. doi 10.1016/j.chroma2008.05.024... 

Deng, D., Deng, H., Zhang, L., Su, Y Determination of ephedrine and pseudoephedrine by field-amplified sample injection capillary electrophoresis. J. Chromatogr. Sci. 52(4), 357-362 (2014)... 

In an effort to build up a food LOG, preconcentration, separation, and AD, all of them integrated in a microchip, has also been proposed for the analysis of dyes in several food samples [35]. The microchip layout was comprised of three parallel channels. Two of them were for field-amplified sample stacking and the subsequent field-amplified sample injection steps, while the third one was reserved for the AD. The preconcentration method was used to analyze the dyes in several food samples (juice, traditional Korean alcohol, fish, noodles, and red pepper powders). 

Bovine serum albumin (BSA) in combination with the partial filling technique and field-amplified sample injection was used for the separation of OL-tetrahydropalmatine (dl-THP). D- and l-THP could be resolved completely within 9 minutes when a 20-mM phosphate buffer with pH 7.4 containing 50-mM BSA was used in a 50- xm-i.d., uncoated, fused-silica capillary (65.2/57.6 cm total/ effective length). 

Ye H, Yu L, Xu X, Zheng C, Lin W, Liu X, Chen G. Affinity capillary electrophoresis coupling with partial filling technique and field-amplified sample injection for enantiosepara-tion and determination of DL-tetrahydropalmatine. Electrophoresis 2010 31 2049-2054. 

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