Q&A: Out Of Office Reply

Nov 01, 2010
By LCGC Editors

Office chromatography (OC) aims to boost the performance of ultrathin-layer chromatography (UTLC). What obstacles were you aiming to overcome with this technique?


KEY POINTS
Firstly, miniaturized plate formats are very difficult to handle and manage with the thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) equipment currently available. This lack in instrumentation combined with the reduced surface activity of monolithic UTLC layers has hampered its progress for almost a decade. It is also not easy to find out how to use UTLC plates correctly. For example, when analysts transfer a particular HPTLC method to UTLC they get different chromatographic results. But for a successful transfer, the elution strength of the mobile phase has to be reduced significantly and nanolitre volumes of a more concentrated solution need to be applied to generate real sharp start zones, which is crucial.


PLANAR CHROMATOGRAPHY DEFINITIONS
Planar chromatography is the only chromatographic method that can synergetically benefit from print and media technologies because of its open planar format of the stationary phase. Office chromatography (OC), which aims to combine print and media technologies with chromatography, will lead to the development of instrumentation that will visibly improve the results that can be achieved on such small plates. The print of sharp start zones offers a good start for OC. Secondly, for UTLC plates particularly, the continuous print of the mobile phase is possible because the highly reduced layer thickness scales the relevant supply volume down; separations can be performed in 1 min2,3 with mobile phase consumption only in the microlitre range. Different types of UTLC plates have been reported to accelerate the chromatographic separation.4–8 Finally, this minor mobile phase volume can be evaporated by infrared (IR) bulb scans of a flatbed scanner positioned beneath the plate. Electronic documentation of the dry plate by different light bulbs, which also fit in the flatbed scanner, allows a high-resolution image of the small-scale plate dimension. All in all, OC will offer the first real chance for a one-click planar chromatographic system because all steps (application, development and evaluation) are integrated in one system. Of course, such a system will lower the degree of flexibility, but an online system would be convenient to many analysts because it increases the free time available for the analyst compared with TLC or HPTLC. OC is online and the whole proces can be started with one click.