High performance thin layer chromatography (HPTLC) is an advanced form of thin layer chromatography that provides high resolution separation and quantitative analysis of compounds. HPTLC uses plates coated with a thin and finely divided stationary phase allowing for shorter run times and better separation efficiency compared to traditional TLC. The document discusses the principles, instrumentation, applications, and factors affecting HPTLC analysis.
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Hptlc (rajat)
1. HIGH PERFORMANCE THIN LAYER CHROMATOGRAPHY By:Rajat Pandey [email_address] NIET Gtr.Noida
2. INTRODUCTION Chromatography is a physical method of separation in which the components to be separated are distributed between two phases, one of which is stationary (stationary phase) while the other (the mobile phase) moves in a definite direction. HPTLC is a well known and versatile separation method which shows a lot of advantages and options in comparison to other separation techniques. The method is fast and inexpensive. It does not require time consuming pretreatments. The basic difference between conventional TLC and HPTLC is only in particle and pore size of the sorbents. It is very useful in quantitative and qualitative analysis of pharmaceuticals.
3. ADVANTAGES High resolution of zones due to higher number of theoretical plates. Shorter developing times Less solvent consumption Enormous flexibility Parallel separation of many samples with minimal time requirement Simplified sample preparation due to single use of the stationary phase.
4. PRINCIPLE Principle Same theoretical principle of TLC. The principle of separation is adsorption.
5. Major difference between TLC and HPTLC Parameter TLC HPTLC Mean particle size 10-12袖m 5-6袖m Distribution 5-20袖m 4-8袖m Layer thickness 250袖m 200袖m Plate height 30袖m 12袖m Separation time 20-200min 3-20min Sample volume 1-5袖L 0.1-0.5袖L
8. 1.Plate coater , a.Hand operated The manual plate coater functions in the same manner as the automatic coater , except with this model the plates are pushed through by hand , one after the other and lifted off on the other slide.
9. b.AUTOMATIC PLATE COATER The glass plates to be coated are conveyed underneath a hopper filled with the adsorbent suspension. The plates are moved by a motorized conveying system at a uniform feeding rate of 10cm/s, to ensure a uniform speed.
10. 2.Drying Rack The Drying Rack consists of ten individual aluminum trays. A tin box for storing the trays and two wire handles , to move the stack while hot ,are supplied. The drying rack is convenient to use , particularly when TLC plates are prepared with the automatic plate coater in large runs.
11. 3.PLATE CUTTER Used to cut HPTLC plates easily and more precisely. Cuts plates with a thickness up to 3mm. Does not damage the sensitive layer. Easy to handle .Read the required size from the scale directly. Helps saving costs on pre-coated plates of high quality by preventing off cuts .
12. 4.Immersion Devise For proper execution of the dipping technique , the chromatogram must be immersed and withdrawn at a controlled uniform speed. Key features Uniform vertical speed Immersion time selectable between 1 and 8 seconds. The device can be set to accommodate 10cm and 20cm plate height. Battery operated , independent of power supply.
13. 5.Plate Heater The TLC plate heater is designed for heating TLC plates to a given temperature , while ensuring homogenous heating across the plate. The TLC plate heater has a heating surface which is resistant to all common reagents and is easily cleaned. Programmed and actual temperature are digitally displayed. The temperature is selectable between 25 and 200 0 c. The plate heater is protected from overheating.
14. 6.Sample Application Usual concentration of applied samples 0.1 to 1 袖g / 袖l for qualitative Analysis and quantity may vary in quantitation based on UV absorption 1 to 5 袖l for spot and 10 袖L for band application. MANUAL , SEMI-AUTOMATIC , AUTOMATIC APPLICATION Manual with calibrated capillaries Semi and auto-application through applicators Applicators use spray on or touch and deliver technique for application.
15. a. Manual Sample Applicator The Nanomat serves for easy application of samples in the form of spots onto TLC and HPTLC layers . The actual sample dosage performed with disposable capillary pipettes , which are precisely guided by the capillary holder. The nanomat is suitable for Conventional TLC plates including self-coated Plates up to 20 20cm HPTLC plates 10 10 cm and 20 10 cm TLC and HPTLC sheets up to 20 20 cm
16. b.Semi automatic sample applicator The instrument is suitable for routine use for medium sample throughout . In contrast to the Automatic TLC sampler , changing the sample the Linomat requires presence of an operator. With the linomat , samples are sprayed onto the chromatographic layer in the form of narrow bands. During the spraying the solvent of the sample evaporates almost entirely concentrating the sample Into a narrow band of selectable length.
17. c.AUTOMATIC SAMPLE APPLICATOR Samples are either applied as spots through contact transfer (0.1-5 micro lit) or as bands or rectangles (0.5->50 micro lit) using the spray on techniques. Application in the form of rectangles allow precise applications of large volume with out damaging the layer. ATS allows over spotting.
19. 1.TWIN TROUGH CHAMBER Low solvent consumption: 20 mL of solvent is sufficient for the development of a 20x20cm plate. This not only saves solvent , but also reduces the waste disposal problem Reproducible pre equilibrium with Solvent vapor: For pre-equilibration, the TLC plate is placed in the empty trough opposite the trough which contains the pre-conditioning solvent. Equilibration can be performed with any liquid and for any period of time. Start of development : It is started only when developing solvent is introduced into the trough with the plate.
20. 2.Automatic developing chamber (ADC ) In the ADC this step is fully automatic and independent of environmental effects. The activity and pre-conditioning of the layer , chamber saturation ,developing distance and final drying can be pre-set and automatically monitored by ADC .
21. 8. DERIVATIZATION DEVICE a) Spraying b) Dipping c) Derivatization through gas phase
22. Reasons for Derivatization: Changing non-absorbing substance into detectable derivatives. Improving the detectability. Detecting all sample components. Selectivity detecting certain substance. Inducing fluorescence.
23. a) Derivatization by spraying It comes with a rubber pump but may also be operated from a compressed air or nitrogen supply. It also consists of a charger and a pump unit with two kinds of spray heads. Spray head type A is for spray solutions of normal viscosity , e.g. lower alcohol solution. Spray head type B is for liquids of higher viscosity , e.g. sulphuric acid reagent
24. b) Derivatization by Dipping For proper execution of the dipping technique the chromatogram must be immersed and withdrawn at a controlled uniform speed. By maintaining a well defined vertical Speed and immersion time , derivatization Conditions can be standardized and tide Marks , which can interfere with densitometry evaluation , are avoided.
25. c)Derivatization through gas phase It offers rapid and uniform transfer of the reagent. It is unfortunate that only few reagents are suitable they include I,Br,Cl, as well as volatile acids, bases and some other gases like H 2 S , NO. In gas phase derivatization can be easily accomplished in twin trough chambers where the reagent is placed or generated in the rear trough , while the plate facing the inside of the chamber is positioned in the front trough.
26. 9. Scanning densitometer The scanner is connected to a computer. The scanner features three light sources ,a deuterium lamp , a tungsten lamp and a high pressure mercury lamp. The scanning speed is selectable between 1 and 100 mm/s
28. Factor affecting HPTLC : Type of stationary phase Mobile phase Layer thickness Temperature Mode of development Amount of sample Dipping zone & others
29. Product formulation Mobilephase Quantitation Propanol hydrochloride 0.3M Sodium chloride, methanol-glacial acetic acid Densitometry at 254nm or 275nm Paracetmol, caffeine, Ascorbic acid Dichloro methane-Ethylacetate Ethanol Densitometry at 254nm Omeprazole Methanol-water Densitometry at 320nm Ampicillin,Cloxacillin sodium Methanol-Dipotassium Hydrogen phosphate Densitometry at 490nm.
30. REFERENCES www.wikipedia.com www.google.com Instrumental method of chemical analysis-G.R.Chatwal A text book of pharmaceutical analysis-Instrumental methods-KASTURE A text book of pharmaceutical analysis- DEVALA RAO