In Situ Measurement of Polymer Layer Thickness in Porous Layer Open Tubular (PLOT) Columns Using Optical Absorbance in the Near-IR Range

• Main Authors: David Collins, Ekaterina Nesterenko, Brett Paull
• Format: Article
• Language: English
• Published: MDPI AG 2016-12-01
• Series: Separations
• Subjects: PLOT columns; polymerisation; in-process layer thickness measurement
• Online Access: http://www.mdpi.com/2297-8739/3/4/34

Highly reproducible fabrication of porous layer open tubular (PLOT) structures in fused silica capillaries is often challenging; thus, methods to measure layer thickness growth in real time represent a powerful tool for the production of such columns. The work presented herein demonstrates the application of optical absorbance in the near-infrared (near IR) range for the in-process measurement of polymer layer growth inside fused silica capillaries during the fabrication of PLOT columns. The proposed technique can be used for both on- and off-line measurements of layer thickness for thermal- and photo- initiated polymerisation methods, performed in either polytetrafluoroethylene (PTFE)- or polyimide-coated capillaries. Measurements of layer thickness were carried out at λ 700 nm, using 100 μm and 8 μm optical fibres, yielding relative standard deviation (%RSD) values of 27% and 22%, respectively.