Draw each step of the procedures (TLC) 1. The developing chamber is prepared before carrying out any other works. It is cleaned and dried first. Prepare filter paper to coat the inner walls of the chamber. The filter paper should be immersed in the mobile phase to a height of 1cm. 2. Saturate the chamber with the developing solvent (ethyl acetate) by closing it tightly. 3. Place the silica plate under the applicator. Make a straight line, as the upper border so that the distance from the top edge is 1.5cm; mark the sample code spotted at the top of the line. The distance between samples is not less than 1.5cm but the distance of the spotting from the edge to the right and left of the plate should not be less than 2cm. 4. Place the silica plate under the applicator so that the spotting distance is 2cm from the bottom edge. 5. Take a standard solution of paracetamol and caffeine (already provided) using a microcapillary tube in an upright position. 6. Apply 2L of standard or sample solution on the plate, in line with the code above. The distance between the spots is not less than 1,5cm. Immediately after applying, run the spots with hot air from a hairdryer. 7. After all the samples are spotted, put the plate into the developing chamber that has been saturated, close it tightly, and observe the elution process so that it does not exceed the upper limit. 8. If the developing solvent reaches the upper limit line, take the TLC plate out of the chamber and remove the remaining solvent by placing it in a fume hood with the exhauster on. 9. After the plate is free of residual developing solvent, place the plate under a UV lamp and measure the distance traveled for each spot. Calculate the value of Rf for each spot. Determine the type of analyte by matching the Rf value of the sample spot with the Rf of the reference standard. 10. Next, scan the plate with a densitometer and record the data obtained for the peak area of the chromatogram. 11. Calculate the equation of the regression line between the concentration of the standard solution and the width area, and prove that this curve is linear. Also, calculate the value of the Vxo. 12. Calculate the analyte concentration using the regression line formula from the calibration curve