AMD technique

It is also possible to perform preparative TLC, developing the sample with AMD technique [36a]. After a solid-phase extraction of the waste water with C18-Empore discs, alkanesulfonate is isolated by using a specially dimensioned TLC plate and by scraping out the surfactant-containing zone. 

It is described in ISO method 11370 entitled Determination of selected organic plant protection agents—automated multiple development (AMD) technique . 

ISO 11 370, Water Quality — Determination Of Selected Organic Plant Protection Agents — Automated Multiple Development (AMD) Technique, 1999. 

Conversely successful on-line coupling of HPLC to TLC is also possible. Hofstraat [15-17] and Baeyens and Lino[18] have described suitable apparatus. Burcsr, for instance, was able to demonstrate that adsorptive separation of selective cut fractions of an HPLC eluate from RP partition chromatography could be separated into up to 700 individual peaks [19, 20]. Here the thin-layer chromatographic step employed the Automated Multiple Development (AMD) technique. These investigations and the results of Kkoker, Funk and Eisenbeiss [21, 22] demonstrate the enormous power of such online coupling techniques in a very impressive manner. 

The AMD technique finds application in various fields, such as, for example, the determination of pesticides in water,herbicides in plants, and biogenic amines in fish meal, the separation of gangliosides, and the analysis of plant material by coupling with other... 

The first automated multiple development (AMD) technique was termed programmed multiple development (PMD). The commercial device for PMD originally manufactured by Regis is no longer available. 

Davies and Kost (1988) noted that TLC of carotenoids is one of the most modem methods of earotenoid separation. TLC of carotenoids has been done on a variety of layers using many different solvent systems. Davies and Kost (1988) provided an extensive list of tables on the TLC of carotenoids. Cikalo et al. (1992) used automated multiple development (AMD) techniques for the separation of complex plant carotenoid mixtures they also evaluated the use of scanning densitometry for spectral identification and quantification of these carotenoids. 

AMD chromatography employing a universal gradient is suitable for the separation of complex samples differing widely in the polarity of their components. It is a remarkable feature of the AMD technique, that the migration distance of the individual component is largely independent of the sample matrix (see Fig. 9). 

Figure 11 An application of the AMD technique. The denstitometric scanning curve is superimposed on the diagram of the gradient profile. (Reprinted from Ref. 19, with permission.)...

K. Burger, Thin-Layer Chromatographic Analysis of Pesticides and Metabolites using the Automated Multiple Development (AMD) Technique, in Manual of Pesticide Residue Analysis Vol. 11. (H. P. Thier and J. Kirchhoff, eds.) VCH Verlagsgesellschaft mbH Weinheim, 1992, p. 423. 

K. Burger, Examples for Applying AMD Technique to the Determination of Pesticide Residues in Ground... 

In recent years, TLC has gained attention for pesticide residue analysis by virtue of its evolving into an automatable instrumental technique, especially after the advent of the automated multiple-development (AMD) technique [1,156-159]. High-performance thin-layer chromatography (HPTLC) has been used for the determination of pesticides in water (Table 18.2) [113,159-161]. Thus, Butz and Stan developed an AMD-HPTLC method for the determination of 265 pesticides in drinking water [161]. 

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