Silica nanoparticle-templated methacrylic acid monoliths for in-line solid-phase extraction-capillary electrophoresis of basic analytes.

Polymeric ion-exchange monoliths typically exhibit low capacities due to the limited surface area on the globules of the monoliths. The ion-exchange binding of protonated weakly basic analytes on deprotonated carboxylate sites on methacrylate polymer monoliths has been increased by templating the monoliths with silica nanoparticles. The templating method is achieved by adding the nanoparticles as a suspension to the polymerisation mixture.

Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2006-2008).

Poor sensitivity is still considered to be one of the major limitations of electrophoresis, which is surprising given the power, flexibility and versatility of many of the approaches to on-line concentration that have developed over the last 20 years. This is still a very active area of interest and this review will cover developments in the field over the last two years since the last review (Electrophoresis 2007, 28, 254-281) through to June 2008. It includes developments in the fields of stacking, covering all methods from field-amplified sample stacking and large volume sample stacking, through to ITP, dynamic pH junction and sweeping.

Selective extraction and elution of weak bases by in-line solid-phase extraction capillary electrophoresis using a pH step gradient and a weak cation-exchange monolith.

A polymer monolith bearing weak cation-exchange functionality was prepared for the purpose of demonstrating pH-selective extraction and elution in in-line solid-phase extraction-capillary electrophoresis (SPE-CE) utilising a model set of cationic analytes, namely imidazole, lutidine and 3-phenylpropanamine. Optimization of the electrolyte conditions for efficient elution of the adsorbed analytes using a moving pH boundary required that the capillary and monolith be filled with 44 mM sodium acetate at high pH (pH 6) and a low pH electrolyte of 3 mM sodium acetate pH 3 was placed in the electrolyte vials. This combination allowed the adsorbed analytes to be simultaneously eluted and focused into narrow bands, with peak widths of the eluted analytes having a baseline width of 1.

Capillary electrophoresis of neurotransmitters using in-line solid-phase extraction and preconcentration using a methacrylate-based weak cation-exchange monolithic stationary phase and a pH step gradient.

A novel approach for in-line solid-phase extraction capillary electrophoresis (SPE-CE) for basic analytes was developed. The method is based on the use of a weak cation-exchange monolith synthesised in situ in the front end of the CE capillary via photoinitiated polymerization to form poly(methacrylic acid-co-ethylene glycol dimethacrylate), which was used to create the SPE phase in-line with the CE separation capillary. The monolithic SPE material exhibited a surface area of 23.