ABSTRACT
Separation ratios obtained from two different chromatographic procedures, such as gas chromatography (GC) and liquid chromatography or GC and thin layer chromatography (TLC), might, again, be even more convincing. The basic parameter used in TLC for solute identification is the Retardation Factor. Spot patterns on a TLC plate can be very complex and extremely difficult to interpret. Two-dimensional separations are easier to achieve with TLC than any other chromatographic system. The chapter shows that further qualitative information from a TLC spot can be obtained by scanning densitometry. There are a number of ways in which scanning densitometry can be used for qualitative assessment. The incident light directed on the spot can have a single wavelength from a specific light source such as a mercury lamp or have a broad range of wavelengths such as that derived from a deuterium lamp. Scanning densitometry can provide qualitative information to confirm solute identity and can enhance the accuracy of quantitative measurements.
