Key Difference – TLC vs HPTLC
TLC and HPTLC are two chemical techniques used to separate non-volatile components in a mixture. The key difference between TLC and HPTLC is that the absorbent material in TLC plate has large particles whereas HPTLC plates have very small particles of adsorbent material.
TLC is thin layer chromatography. HPTLC is high-performance thin layer chromatography, which is an advanced technique when compared to the TLC method.
CONTENTS
1. Overview and Key Difference
2. What is TLC
3. What is HPTLC
4. Side by Side Comparison – TLC vs HPTLC in Tabular Form
5. Summary
What is TLC?
TLC or thin layer chromatography is a basic chemical technique used to separate non-volatile components in a mixture. This experiment is carried out using sheets of glass, plastic or paper. This sheet is coated with a thin layer of cellulose or silica gel (an adsorbent material). This thin layer is known as the stationary phase of TLC. The sheet is known as the TLC plate.
Prior to the experiment, a baseline and a topline are marked with a pencil on the TLC plate. Then the sample is spotted along this line using a capillary tube. After that, the TLC plate is placed vertically in a mobile phase. The mobile phase is a solvent (or a mixture of solvents) placed in a container. When placing the TLC plate in this mobile phase, one should keep the baseline over the margin of the solvent. Otherwise, the sample will be dissolved in the solvent.
TLC plate is allowed to stay in the mobile phase for some time. Then, with time, the mobile phase rises upward the plate due to capillary action. If the sample is soluble in the mobile phase, it will rise upward along with the mobile phase.
The “like dissolves like” principle is behind this TLC method. This means polar compounds dissolve in polar solvents whereas nonpolar compounds dissolve in nonpolar solvents. The stationary phase is usually silica gel or cellulose, which is a polar compound. The mobile phase used is a nonpolar solvent such as hexane. Therefore, if the sample contains any nonpolar components, these components will migrate upwards along with the mobile phase. Polar components will stick to the plate. Among the moving components, moderately nonpolar compounds will migrate slowly whereas highly nonpolar compounds will migrate quickly. When the solvent front has reached the top line of the TLC plate, the plate is taken out and let to dry.
Figure 01: TLC Technique
If the components in the sample were colored compounds, there should be colorful spots on the plate at different locations. But if the components were colorless, some other techniques should be used; for example, spraying ninhydrin to detect ammonia or amines (primary amines and secondary amines).
What is HPTLC?
HPTLC or high performance thin layer chromatography is the advanced form of thin layer chromatography (TLC). The resolution and the accuracy of HPTLC are very high. Most steps of this technique can be automated.
The plates used in HPTLC contain silica gel particles with a very small size and the packing density of the gel on the plate is high. The surface of the plate is smooth and gives efficient separation. The analysis is faster than the TLC technique. The sensitivity of this method is also high. In HPTLC, several different samples can be separated in the same plate without any sample preparation step.
What is the Difference Between TLC and HPTLC?
TLC vs HPTLC |
|
| TLC is thin layer chromatography. | HPTLC is high performance thin layer chromatography. |
| Technique | |
| It is a basic chemical technique used to separate non-volatile components in a mixture. | It is the advanced form of thin layer chromatography (TLC). |
| Plate | |
| TLC plate can be made of paper, plastic or glass which is applied with an adsorbent material having large particles. | HPTLC plates have very small particles of adsorbent material. |
| Resolution | |
| TLC method gives poor resolution when the sample has components having similar properties. | HPTLC method gives a high resolution. |
| Time | |
| TLC technique is a time-consuming technique. | HPTLC gives results at a higher speed than the TLC method. |
Summary – TLC vs HPTLC
HPTLC is the advanced form of TLC. The key difference between TLC and HPTLC is that the TLC plate can be made of paper, plastic or glass which is applied with an adsorbent material having large particles whereas HPTLC plates have very small particles of adsorbent material.
Reference:
1. “Thin-Layer Chromatography.” Wikipedia, Wikimedia Foundation, 6 Apr. 2018, Available here.
2. Libretexts. “Thin Layer Chromatography.” Chemistry LibreTexts, Libretexts, 3 Nov. 2017, Available here.
3. “High-Performance Thin-Layer Chromatography.” Wikipedia, Wikimedia Foundation, 17 Feb. 2018, Available here.
Image Courtesy:
1. “Tlc sequence”By Quantockgoblin – wiki (Public Domain) via Commons Wikimedia