Practical aspects of preparation, optimization, and evaluation of poly(styrene-divinylbenzene)porous-layer open tubular (PLOT) columns for capillary liquid chromatography

Abstract

Using open tubular (OT) capillary columns in the nano and micro liquid chromatography scales has several advantages over conventional large-bore packed columns. Among the open tubular columns, those of the PLOT (porous layer open tubular) type are more suitable for liquid chromatography due to the porous character of the stationary phase that provides more significant interaction with the analytes. In addition, recent instrumental advances in capillaryLC coupled with mass spectrometry (MS) have opened up new avenues for developing and applying OT-LC-MS. This work discusses the possibility of applying PLOT columns in the capillary LC flow range (0.5–2 μL min−1) and describes the preparation, optimization, and evaluation of those columns. Poly(styrene-divinylbenzene) (PS-DVB) was used as the stationary phase, and the internal diameter of the columns discussed in this work was 10 and 25 μm. A comparison between these diameters is presented regarding fabrication and practical aspects of the operation. Additionally, for the 25 μm PLOT column, the gradient window and the flow rate effects on the system's performance were investigated. Flow rates of 1 μL min−1 and a gradient window of 60% (from 20 to 80% of acetonitrile) were the best conditions to work on this column in capillary LC conditions.