Introduction to HPTLC
HPTLC is a more complicated and automated version of thin-layer chromatography (TLC) that has better detection limits and separation efficiency. It is also known as flat-bed chromatography, planar chromatography, or high-pressure thin layer chromatography. It is a strong analytical instrument that works well for both qualitative and quantitative issues. [1,2] Depending on the kind of adsorbents used to the plates and the solvent system utilized during development, separation may arise from partitioning, adsorption, or both. Phytochemical analysis, biomedical analysis, quantification of herbal medications, analytical analysis, fingerprint analysis, and the possibility of hyphenation (HPTLC-MS, HPTLC-FTIR, and HPTLC- Scanning Diode Laser) are among the applications cited. [3] High resolution sorbents with specific particle sizes or chemically altered surfaces, more effective elution methods, the capacity to integrate with other instrumental techniques, the development of computer programmes for method optimization, and the application of modern tools such as chromatographic chambers, densitometers, and video scanners. [4] HPLC, a very sophisticated chemical standardization technique, is far more reliable and reproducible when used to standardize herbal compositions, both single and compound. The separation method called high-pressure liquid chromatography uses a stationary phase and liquid mobile phase. The size of stationary phase utilized determines whether ion exchange, adsorption, or partitioning is employed for separations. [5].
Principle:
- Separation: Components are separated by HPTLC. based on affinity between stationary and mobile phases
- Adsorption: Components interact with the adsorbent surface, resulting in separation.
- Components split into mobile and stationary phases.
Fig No.1. Principles of HPTLC
Benefits and drawbacks of HPTLC in comparison to TLC: In recent years, HPTLC has become a reliable identification technique and has replaced traditional TLC.The device is managed by software. The most efficient silica gel hydrophilic phasethat meets the requirements of most pharmacopeias is being utilized for HPTLC pollutants identification. [6]
Table No. 1: Difference between TLC and HPTLC [6]
|
Sr.No. |
Feature |
TLC |
HPLC |
|
1 |
Technique |
Manual |
Instrumental |
|
2 |
Plates |
Lab-made |
Pre-coated |
|
3 |
Plate height |
30 μm |
12 μm |
|
4 |
Layer of Sorbent |
250 μm |
100 μm |
|
5 |
Stationary Phase |
Silica gel, alumina, &Kiesulgur |
Numerous stationary phase options, such as C8, C18 for reversed phase and silica gel for normal phase |
|
6 |
Separations |
10-15 cm |
3-5 cm |
|
7 |
Analysis time |
20-200 min |
1-3 min |
|
8 |
Average Size of Particles |
10-12 μm |
5-6 μm |
|
9 |
Efficiency |
Less |
High |
|
10 |
Sample Holder |
Capillary/Pipette |
Syringe |
|
11 |
Sample Spotting |
Manual Spotting |
Autosampler |
|
12 |
Size of Sample |
Uncontrolled |
Controlled solvent Independence |
|
13 |
Sample Shape |
Circular |
Rectangular |
|
14 |
Sample tracks for each plate |
<10 |
<36 |
|
15 |
Volume Range |
1-10 μl |
0.1 to 500μl |
|
16 |
Development Chamber |
More amount |
Less amount |
|
17 |
Wavelength range |
254 or 366 |
190 or 180 |
|
18 |
Detection limit |
1-5 pg |
100-500 pg |
|
19 |
Limit of detection (fluorescence) |
50-100pg |
5-10 pg |
|
20 |
PC Connectivity |
No |
Yes |
|
21 |
Quantitative Analysis |
No |
Yes |
|
22 |
Scanning |
No |
UV/Visible/Fluorescence scanner |
|
23 |
Analysis Judgement |
By Analyst |
By machine |
Automation for HPTLC:
Modern TLC, often referred to as HPTLC, is primarily used for quantification, requires tools, and can only be carried out on precoated layers. Consequently, the terms TLC and HPTLC are used interchangeably. TLC is widely used around the world to teach the principle of chromatography. The sample's visibility during chromatography, the demonstration apparatus's extremely low cost, and its user-friendliness are the main justifications for this method. It employs a multifaceted technique to improve resolution under capillary flow-controlled circumstances. Planar chromatography can separate molecules in one or two dimensions. External control of mobile-phase velocity is also possible, as seen in forced-flow development. [7] HPTLC is the quickest chromatographic method. The samples are chromatographed in parallel. Each stage of the technique is completed individually, making In addition to being quicker, HPTLC is adaptable enough to evaluate several samples at once. The amount of stationary and mobile phase used depends on the number of samples being analyzed. [8]
Steps involved in HPTLC [9]:
L. P. Jain* 1
10.5281/zenodo.15585927