Precision in the direct densitometry of coloured compounds on thin layer chromatograms

Determination of caffeine in APC tablets by densitometry on chemically bonded C18 reversed phase thin layers

“…Reproducibility was checked by applying six spots containing 1.2 pg of caffeine each on two plates, developing, and scanning. The coefficients of variation of the peak areas on the respective plates were 7.02 and 6.16%, which are within the generally acceptable precision level for analytical densitometry [4,5]. The slope values of 8 calibration plots constructed from densitometric data on different plates over a six-week period had a CV of 7.40%.…”