Modelling of solvent movement and separation of aflatoxins at Continuous TLC Chamber (a new apparatus)

On the Classical TLC plate, solvent migration can be performed by capillarity forces between solvent (front) and the plate particles. Although forces are constant, the resistance to the solvent development on the plate increases by the increasing solvent height, so; solvent progress velocity (dh/dt) is inversely proportional (1/h) with the solvent height (h) on the plate (dh/dt=k(1/h). Rearrangement of the equation (dh*h=k*dt) and integral of two sides, gave us a new equation (h(2)/2+C=k*t or t= (h(2))+C/2). After re-parameterization (t=ah(2)+h(0)) and accepting h=0 at t(0) ; equation change to a new form (=ah2 or h=a’t(0.5)). The parameter a reflects chromatography conditions, temperature, polarity and viscosity of mobile phases and some properties of stationary phase. Although it can be estimated by calculations, an experimental determination is more practice (by a few solvent-heights vs. time (mobile phase: acetone: chloroform, plate; silica gel 60), a is about 0.4-0.7 minute/cm2; so that 12 cm solvent migration on the plate take about one hour. The shorter distance provides a fast chromatography, but a worse resolution. Increasing the solvent developing distance to 16 cm does not help resolution, because of the spreading of the spots in 2-2-.5 hours of chromatography duration. At our Continuous TLC chamber, solvent never stops at the upper edge of the plate and continue to movement at a constant velocity. If you use small the upper edge of the plate and continue to movement at a constant velocity. If you use small TLC Plates, such as 10X10 cm, the solvent movement would be fast; spots of interest will raise until the upper part of the plate in a short time and spreading of spots would be minimum and an excellent resolution would happen. In the case of separation of aflatoxins (AFB1, AFB2, AFG1, and AFG2), You can obtain better resolution by CTLCC on 10X10cm TLC plates, then Classical TLC Chamber using 20X20 cm plates. The performance of the Continuous TLC Chamber will be explained on the separation of aflatoxins at the submission.

کلیدواژه ها:

Thin Layer Chromatography ، Aflatoxins ، Eesolution ، Modeling