[Objectives]
The goal of this experiment is
(1) to identify an unknown compound based on comparing with known compounds and their Rf value,
(2) to observe the difference of the particular compounds' Rf value by changing the proportion of developing solvent,
(3) to identify the purity of unknown compound,
(4) to determine the number of components of mixture.
Solvent 높이에 유의하도록 한다.
(Substance를 적시지 않도록)
[Principles & Methods]
TLC is a solid-liquid form of chromatography of which the stationary phase is normally a polar absorbent.
The separation depends on the relative affinity of compounds toward stationary and the mobile phase. During this movement, the compounds with higher affinity to stationary phase travel slowly while the others travel faster.
Through Rf value, we can compare the sequence of each compound's polarity. Comparing the unknown compound's Rf value with known compunds' would enable a tentative identification to be made.
We will change only the proportion of developing solvent to observe the difference of the particular compound's Rf value by how to mix solvent.
* The procedure is as follows ;
(1) Prepare 2 TLC plates and dye mixture in methanol.
(2) Spot each sample on the TLC plate and let them travel with EtOAc.
(3) Switch mobile phase into 1:1 proportion of EtOAc and methanol.
(4) When the spots are visualized, then calculate Rf value.
* Identification of compounds by using TLC is as follows;
(1) Prepare TLC plate and 3 kinds of chemical samples (Sudan IV, Bismark Brown, Rhodamine B) melted into methylene chloride.
(2) Spot each sample on the TLC plate and let them travel with 4:1 proportion of n-Hexane and EtOAc.
(3) Identify using UV lamp, and indicate the spot with pencil.
(4) Put it into chamber and check it in 5 minutes.
(5) Calculate Rf value.
(6) Spot unknown sample on the TLC plate and traveling it.
(7) Identify by using UV lamp, and indicate the spot.
(8) Spot and travel 2 expected sample, unknown, co-spot on the TLC plate.
(9) Check it by using UV lamp and indicate the spot.
(10) Calculate Rf and identify what the unknown sample was.
댓글