Abstract
A new densitometer CS-900, employing the dual-wavelength and the zig-zag scanning method, has been originally designed for the purpose of a direct quantitative measurement of the chromatogram spots developed and separated on a thin-layer plate. It has been proven that the dual-wavelength method can eliminate the baseline noise caused by local irregularities of thin-layer's thickness while the zig-zag scanning method can minimize all feasible errors based on non-uniformity in size and shape of the spot and also can improve the accuracy of the U.V. densitometry of invisible spots.
Repeatability was checked by 1-arninoanthraquinone using the internal standard method to eliminate the spotting errors of micro-syringe. Coefficients of variation were well within 1 to 2% even if the two different thin-layer plates are independently used for the standard samples to make a calibration curve and for the samples to be measured.
