High Performance Thin Layer Chromatography (HPTLC) is a very useful analytical technique and requires low sample preparation, here illustrated through the analysis of caffeine in coffee. Only extraction and filtration, through a 0.45 μm PTFE syringe filter, is needed for boiled coffee samples prior analysis. The HPTLC plate was pre-conditioned with the mobile phase, and a TLC-scanner was a used for the quantitation after the chromatographic separation was completed.
Caffeine was detected under UV light at 254 nm, hRf = 56, (Figure 1). A four-level calibration curve was constructed and used for quantitation purposes, (Figure 2). Each sample was analyzed in triplicate performed in parallel, a benefit with planar chromatography over both GC and HPLC.
Figure 1.Developed HPTLC plate at 254 nm, chromatographic data shown in the table above.
Figure 2.Calibration graph following the polynomial regression mode (r = 0.9970).
Caffeine can easily be quantitated in different coffee types with minimum sample preparation when using High Performance Thin Layer Chromatography.