Trevespan 6038, separation

A number of separations (of BHC isomers, of bromophos-ethyl and dimethoate. and of the active constituents of Trevespan 6038) were performed in order to provide a qualitative and quantitative comparison between TLC and HPTLC pre-coated plates, or between HPTLC plates coated with various sorbents, and in order to demonstrate their use in pesticide chemistry. 

Apart from the sorbents already mentioned in connection with HPTLC pre-coated layers, a micro-crystalline cellulose has also been produced in an average particle size and a narrow particle size distribution suitable for HPTLC (9.). HPTLC pre-coated plates cellulose P 254 s (E. Merck, Darmstadt), composed of this microcrystalline cellulose, were used to separate Trevespan 6058. This is a mixture of the substances ioxynil (3,5-diiodo-4-hydroxy-benzo-nitrile), flurenol (9-hydroxyfluorenecarboxylic acid) and MCPA (2-methyl-4-chlorophenoxyacetic acid). For comparison purposes Trevespan 6038 was also separated on HPTLC pre-coated plates silica gel 60 F 254 (E. Merck, Darmstadt). 

The solvent system most suitable for separating Trevespan on HPTLC pre-coated plates cellulose consists of tert. butanol/water/25 ammonia in a ratio of 80/20/1 by volume, whilst for HPTLC pre-coated plates silica gel 60 the best mixture is n-hexane/ethyl acetate/formic acid in the ratio 40/60/0,5. Prior to the separation proper, the HPTLC pre-coated plates were adjusted to a relative humidity of 20. Quantities of o.73 pi of a "test solution in methanol, composed as follows, were applied to the plates and migrated over 5 cm ... 

Table VI provides a further comparison of chromatographic data obtained for the separation of Trevespan 6038 on HPTLC pre-coated plates silica gel 60 and cellulose.

Improvements in the separating performance achieved with HPTLC pre-coated plates silica gel 60 with concentrating zone (E. Merck, Darmstadt) compared with HPTLC pre-coated plates silica gel 60 without concentrating zone, taking as an example the application of a relatively large sample volume of 0.75 ill (in HPTLC sample volumes of between 0.02 and 0.1 pi are common practice ), is demonstrated by the separation of Trevespan 6038, as already described. 

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