Planar Electrochromatography Using an Electrospun Polymer Nanofiber Layer

Electrospun polymer nanofiber stationary phases were examined for their application to planar electro­chromatography (PEC). Separations were performed on polyacrylo­nitrile nanofiber ultra-thin-layer chromatography (UTLC) plates in 1–2 min using a ternary mobile phase. The influences of buffer concentration and pH, ratio of organic modifier, and development time on analyte migration distances were studied. Band broadening in this system was studied as a function of distance. The plate height initially decreased and then plateaued with a minimum plate height value as low as 11 μm. Nanofiber alignment considerably increased analyte migration rate, but larger spot sizes were noted when nearly complete fiber alignment was used. The easily tunable stationary phase thickness can be tailored to a given separation, where thinner layers promote faster separations and thicker layers are ideal for more complex mixtures. Compared to UTLC, PEC offers unique selectivity and decreased analysis time (>4 times faster over 15 mm). Results for a two-dimensional separation using UTLC and PEC are also reported. These rapid separations required 11 min using a 40 × 40 mm plate and exhibited a significant increase in separation number (70–77).