Quantitative evaluation of 2D chromatograms with a CCD camera

A mixture of ten pesticides - MCPA, atrazine, propham, chloropropham, ofura ce, triadimefon, biteranol A, biteranol B, tetramethrin and alpha-cypermeth rin - has been separated by two-dimensional development on cyano HPTLC plat es with a polar mobile phase (methanol-water) in the first dimension and a nonpolar mobile phase (hexane-diethyl ether) in second dimension. Chromatog rams were recorded with a sensitive color CCD camera and evaluated with Cam ag VideoScan software. Two quantification modes were compared - scanning of the whole plate and scanning of manually defined bent tracks. The precision of video-densitometric quantitation of the 2D chromatogram, e xpressed as the repeatability of image capturing and track setting, was det ermined. The lowest RSD was obtained when the image was captured at a focal distance of 15 mm and at F-stop number 2 and the chromatogram was quantita tively evaluated using complete scanning with 30 tracks positioned without overlapping.