Strategies for optimizing the mobile phase in planar chromatography

A new procedure for separation of complex mixtures of pesticides by multidimensional planar chromatography

“…Good results (shown in Fig. 1) were obtained with ethyl acetate -n-heptane (25:75, v/v) as mobile phase in the first direction, which separated the investigated pesticides into five groups: first (1, 5, 8), second (11,3,6,13), third (7, 2), fourth (9, 12, 14, 4), and fifth (10).…”

“…After drying in air for 20 min, the plate was turned by 908 (so that the preliminarily separated mixture of pesticides was at the start of the next step). Next, two lines (or all lines for all spots) were scraped in the stationary phase (about 1 mm wide) perpendicular to the first development, in such a way that the spot(s) of compounds from the second group (3,6,11,13) were between these lines (Fig. 2b).…”

Multidimensional Chromatography in Pesticides Analysis

“…The planar response function PRF has been used as optimization criterion by Nurok et al (Nurok et al, 1987). Strategies for optimizing the mobile phase in planar chromatography (including two-dimensional separation) (Nurok, 1989) and overpressured layer chromatography (including two-dimensional overpressured layer chromatography) (Nurok et al, 1997) have also been described. Another powerful tool is the use of graphical correlation plots of retention data for two chromatographic systems which differ with regard to modifiers and/or adsorbents (De Spiegeleer et al, 1987).…”

Liquid Chromatography in Studying Lipophylicity and Bioactivity of Pesticides

“…Next complications are connected with reproducibility of results on columns or chromatoplates delivered by various producers or even from different batches of the same manufacturer. The dissimilarities between chromatographic and shake-flask partition coefficients result also from problems with accurate measurements of the dead volume in column technique (Poppe, 1993) or thin-layer effects in planar chromatography (Nurok, 1989). Summarizing the above considerations it should be emphasized that chromatographic parameters depend not only on solute but also mobile and stationary phases properties and don't form universal scale of lipophylicity, which is limited for structurally diverse substances.…”