Bromophos-ethyl and dimethoate

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. 

Figure 2. Linear chromatograms for the separation of bromophos-ethyl and dimethoate on an HPTLC pre-coated plate silica gel 60 Cleft) and an HPTLC pre-coated plate RP-18 fright) (solvent system on silica gel 60 n-heptane/acetone 65/35 on RP-18 acetone/water 80/20 application from left to right—(1st band) bromophosethyl (2nd band) dimethoate (3rd-5th band) mixture migration distance 5 cm applied quantities 0.75 fiL =-- 750 ng detection spraying with PdCl2 in ethanol heating to 120°C)...

The solvent system most suitable for separating bromophos-ethyl and dimethoate is an 80/20 mixture of acetone/water for the HPTLC pre-coated plate RP-18, and a 65/35 mixture of n-heptane/acetone in the case of the HPTLC pre-coated plate silica gel 60. The optimum migration distance was 5 cm in both cases. 

The applied substance quantity was 0.75 1 on both plates, at a concentration of bromophos-ethyl and dimethoate of 10 mg/10 ml in methanol in both cases. 

These figures show that resolution between bromophos-ethyl and dimethoate on the HPTLC RP-18 plate is roughly 60 greater than on the silica gel 60 plate. Though the optimum migration distance of 5 cm is the same in both cases, the development time on the RP-18 plate is roughly twice as long as on the... 

Table III Retention data (hRf values) for bromophos-ethyl and dimethoate on an HPTLC pre-coated plate silica gel 60 (solvent system n-heptane/acetone 65/35) and on an HPTLC pre-coated plate RP-18 (solvent system acetone/water 80/20)...

Table IV Chromatographic data for the separation of bromophos-ethyl and dimethoate on HPTLC pre-coated plates silica gel 60 and HPTLC pre-coated plates RP-18...

Quantitative in-situ evaluation of the bromophos-ethyl and dimethoate separation in this case of visualization has no real value on account of the rather non-homogeneous background colouration produced by spraying with the detection reagent used here. Therefore the routine, quantitative in-situ evaluation of the unstained bromophos-ethyl and dimethoate in our laboratory is carried out by UV measurement in reflectance mode. 

Alachlor, benzene hexachloride, cycloodines, aldrin, chlordane, dieldrin, endrin, endosulfan, heptachlor, isodrin, telodrin and toxaphene, DDT and metabolites, dicofol, dimethoate, lindane, methoxychlor, mirex, pentachlorophenol, perthane Azinphosmethyl, bromophos ethyl, chlorpyrifos, crotoxyphos, demeton, diazinon, dichlorvos, ethion, fenitrothion, fensulfothin, fenthion, flusulfothin, methamidophos, mevinphos monocrotophos and dichrotophos, oxamyl, phorate, parathion (ethyl), parathion (methyl), phosphomidon, quinolphos temephos Aldicarb, benomyl, carbaryl, chlorpropham, fenvalerate, methomyl... 

---