Fast assessment of planar chromatographic layers quality using pulse thermovision method

• Thermovision investigations of commercially available TLC plates revealed problems with layers thickness equability.
• Adsorbent irregularities concern edge and internal plates areas, which affect chromatographic migration of analytes.
• Thermovision method allows fast detection and visualization of thickness non-uniformities of TLC plates.
• Correlation images allow very sensitive detection of TLC plates non-uniformities.
• Invented detection protocol can be used as an efficient tool for determining the overall heterogeneity of layered materials.

The main goal of this paper is to demonstrate capability of pulse thermovision (thermal-wave) methodology for sensitive detection of photothermal non-uniformities within light scattering and semi-transparent planar stationary phases. Successful visualization of stationary phases defects required signal processing protocols based on wavelet filtration, correlation analysis and k-means 3D segmentation. Such post-processing data handling approach allows extremely sensitive detection of thickness and structural changes within commercially available planar chromatographic layers. Particularly, a number of TLC and HPTLC stationary phases including silica, cellulose, aluminum oxide, polyamide and octadecylsilane coated with adsorbent layer ranging from 100 to 250 μm were investigated. Presented detection protocol can be used as an efficient tool for fast screening the overall heterogeneity of any layered materials. Moreover, described procedure is very fast (few seconds including acquisition and data processing) and may be applied for fabrication processes online controlling. In spite of planar chromatographic plates this protocol can be used for assessment of different planar separation tools like paper based analytical devices or micro total analysis systems, consisted of organic and non-organic layers.