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❃HPTLC (HIGH PERFORMANCE THIN LAYER CHROMATOGRAPHY) DETAILED NOTES


HPTLC (HIGH PERFORMANCE THIN LAYER CHROMATOGRAPHY) DETAILED NOTES

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1. INTRODUCTION

HPTLC is an advanced form of Thin Layer Chromatography (TLC) that allows high-resolution separation and quantitative analysis of chemical compounds.
It combines classical TLC principles with automation, precise sample application, and densitometric detection.
HPTLC is widely used in pharmaceuticals, herbal medicine, food analysis, and chemical research.
Compared to TLC, HPTLC offers:
Better resolution
Higher sensitivity
Quantitative capabilities
Example: Fingerprinting of plant extracts, identification of drugs in mixtures, detection of contaminants in food.


2. PRINCIPLE


HPTLC separates compounds based on differential migration on a stationary phase under the influence of a mobile phase.
Principle: Adsorption chromatography
Compounds interact with the stationary phase (silica gel, alumina, or cellulose) differently depending on polarity, molecular size, or functional groups.
More polar compounds interact strongly and move slowly; less polar compounds move faster.
Detection is done using:
UV light (254 nm or 366 nm)
Densitometry for quantification
Chemical derivatization for color development
Key Concept: The Rf value (Retention factor) is used for identification:


3. COMPONENTS OF HPTLC

Stationary Phase

HPTLC plates coated with silica gel 60 F254, alumina, or cellulose
Uniform particle size (5–10 μm) for high resolution
Mobile Phase
Solvent or solvent mixture (e.g., hexane:ethyl acetate, methanol:water)
Optimized for compound separation

Sample Application System
Automatic applicator for precise sample spots or bands
Reduces variability and improves reproducibility.
Chamber for Development
Saturated with mobile phase vapor
Ensures consistent solvent migration
Detection System
UV lamp (254 nm/366 nm)
Densitometer for quantitative analysis
Scanner for peak measurement
Documentation
Photographic recording or digital densitogram

4. PROCEDURE OF HPTLC
Step-by-step process:

Step 1: Plate Preparation
Pre-activated plates by heating at 110–120°C for 30 min
Ensure a clean, dry surface

Step 2: Sample Application
Dissolve sample in suitable solvent
Apply small volume (1–10 µL) as bands using automatic applicator
Record position for reference

Step 3: Development of Plate
Place plate in chamber saturated with mobile phase vapor
Allow mobile phase migration up the plate by capillary action
Remove plate when solvent front reaches predetermined distance
Mark solvent front immediately

Step 4: Detection
Examine plate under UV light (254 nm or 366 nm)
Apply derivatization reagents if compounds are not UV-active
Densitometry/scanner measures peak area for quantitative analysis


Step 5: Data Analysis
Calculate Rf values
Compare with standards for identification
Quantification by peak area vs standard calibration curve


Step 6: Documentation
Record plate images, Rf values, and densitograms
Store results for reference


5. ADVANTAGES OF HPTLC
High resolution and sensitivity
Simultaneous analysis of multiple samples on a single plate
Quantitative and qualitative analysis possible
Low solvent consumption
Cost-effective compared to HPLC
Can analyze complex herbal and natural products
Minimal sample preparation required
Reproducible results due to automatic application and densitometry


6. LIMITATIONS OF HPTLC


Lower sensitivity compared to HPLC or LC-MS for trace analysis
Manual interpretation may lead to subjective errors (if densitometer not used)
Limited automation compared to HPLC
Requires careful optimization of mobile phase for reproducibility
Not suitable for very polar or very non-volatile compounds

7. APPLICATIONS OF HPTLC
Pharmaceutical Industry
Drug identification and purity testing
Quantification of active pharmaceutical ingredients (API)
Detection of adulterants
Herbal and Natural Products
Fingerprinting of plant extracts
Quality control of herbal formulations
Identification of phytochemicals (flavonoids, alkaloids, phenols)
Food Industry
Detection of food additives, preservatives, and contaminants
Analysis of vitamins and natural pigments
Environmental Analysis
Detection of pollutants in water, soil, and air
Forensic Science
Detection of drugs of abuse
Analysis of toxins and poisons
Research
Screening of secondary metabolites
Monitoring chemical reactions and product formation

FLOW DIAGRAM OF HPTLC PROCEDURE
Sample Prep → Plate Activation → Sample Application → Plate Development → Detection → Data Analysis → Documentation




50 MCQs – HPTLC (WITH ANSWERS)
BASIC CONCEPTS


HPTLC stands for:

A) High Precision Thin Layer Chromatography
B) High Performance Thin Layer Chromatography
C) High Pressure Thin Layer Chromatography
D) High Polarity Thin Layer Chromatography
Answer: B


HPTLC is an advanced form of:
A) Column chromatography
B) Paper chromatography
C) Thin Layer Chromatography
D) Gas chromatography
Answer: C

HPTLC mainly works on the principle of:
A) Partition
B) Adsorption
C) Ion exchange
D) Size exclusion
Answer: B

The stationary phase in HPTLC is usually:
A) Cellulose paper
B) Silica gel
C) Resin beads
D) Polymer membrane
Answer: B

The mobile phase in HPTLC is:
A) Solid
B) Gas
C) Liquid
D) Gel
Answer: C

HPTLC PLATES & STATIONARY PHASE

HPTLC plates have particle size of about:
A) 50–100 µm
B) 25–40 µm
C) 5–10 µm
D) >200 µm
Answer: C

Commonly used HPTLC plate is:
A) Silica gel 60 F254
B) Alumina gel F366
C) Cellulose F120
D) Resin F500
Answer: A

“F254” on HPTLC plates indicates:
A) Fluorescence at 254 nm
B) Flow rate 254 mL
C) Film thickness
D) Particle diameter
Answer: A

Uniform particle size in HPTLC improves:
A) Color intensity
B) Resolution and reproducibility
C) Solvent consumption
D) Sample volatility
Answer: B

Before use, HPTLC plates are often:
A) Frozen
B) Activated by heating
C) Washed with water
D) Scratched
Answer: B

SAMPLE APPLICATION

Sample application in HPTLC is done using:
A) Capillary tubes
B) Automatic sample applicator
C) Syringe pump
D) Pipette only
Answer: B

Sample is applied in HPTLC as:
A) Large spots
B) Bands or spots
C) Continuous line
D) Droplets
Answer: B

Automatic application improves:
A) Solvent polarity
B) Accuracy and precision
C) Plate thickness
D) Rf value
Answer: B

Typical sample volume in HPTLC is:
A) 50–100 µL
B) 20–30 µL
C) 1–10 µL
D) 100–200 µL
Answer: C

Overloading sample may cause:
A) Better resolution
B) Tailing and poor separation
C) Faster development
D) Increased Rf
Answer: B

DEVELOPMENT & CHAMBER

HPTLC development occurs in a:
A) Vacuum chamber
B) Saturated chamber
C) Gas chamber
D) UV chamber
Answer: B

Chamber saturation helps in:
A) Faster drying
B) Uniform solvent migration
C) Plate activation
D) Ionization
Answer: B

Solvent movement in HPTLC occurs by:
A) Pressure
B) Gravity
C) Capillary action
D) Centrifugation
Answer: C

Solvent front should be marked:
A) After detection
B) Immediately after development
C) Before development
D) During scanning
Answer: B

Mobile phase composition affects:
A) Rf value
B) Plate thickness
C) Sample volume
D) Detection wavelength
Answer: A

DETECTION & IDENTIFICATION

UV detection in HPTLC is commonly done at:
A) 200 nm and 300 nm
B) 254 nm and 366 nm
C) 420 nm and 520 nm
D) 600 nm only
Answer: B

Compounds invisible under UV can be detected by:
A) Increasing solvent strength
B) Derivatization
C) Cooling plate
D) Increasing sample volume
Answer: B

Densitometry is used for:
A) Plate activation
B) Quantitative analysis
C) Sample application
D) Mobile phase preparation
Answer: B

HPTLC scanner records:
A) Color only
B) Peak height and area
C) Solvent front
D) Plate thickness
Answer: B

Rf value is calculated as:
A) Distance by solvent ÷ distance by compound
B) Distance by compound ÷ distance by solvent
C) Time ÷ distance
D) Volume ÷ distance
Answer: B

DATA ANALYSIS

Rf value ranges between:
A) 0–10
B) 1–100
C) 0–1
D) –1 to +1
Answer: C

Compounds are identified in HPTLC by:
A) Retention time
B) Rf value and color
C) Molecular weight
D) Boiling point
Answer: B

Quantification is done by comparing with:
A) Blank plate
B) Solvent front
C) Standard calibration curve
D) Plate thickness
Answer: C

Fingerprinting refers to:
A) Detection of impurities
B) Characteristic chromatographic pattern
C) Molecular ion peak
D) Derivatization process
Answer: B

Documentation in HPTLC includes:
A) Visual observation only
B) Densitogram and plate image
C) Only Rf values
D) Solvent volume
Answer: B

ADVANTAGES

One major advantage of HPTLC is:
A) High solvent consumption
B) Simultaneous analysis of many samples
C) Requires vacuum
D) Very high cost
Answer: B

Compared to TLC, HPTLC has:
A) Lower resolution
B) Higher sensitivity
C) No quantification
D) Less reproducibility
Answer: B

HPTLC requires:
A) Large sample quantity
B) Minimal sample preparation
C) High temperature
D) High pressure
Answer: B

HPTLC is more economical than:
A) TLC
B) HPLC
C) Paper chromatography
D) Column chromatography
Answer: B

HPTLC is suitable for:
A) Herbal drug analysis
B) Radioactive samples only
C) Gas analysis
D) Metal alloys
Answer: A


LIMITATIONS

HPTLC has lower sensitivity compared to:
A) TLC
B) Paper chromatography
C) HPLC
D) Column chromatography
Answer: C

Manual handling may cause:
A) High precision
B) Subjective errors
C) Better reproducibility
D) Ion suppression
Answer: B

Very volatile compounds are:
A) Ideal for HPTLC
B) Difficult to analyze
C) Easily quantified
D) More stable
Answer: B

HPTLC is less suitable for:
A) Herbal extracts
B) Multi-component mixtures
C) Ultra-trace level analysis
D) Fingerprinting
Answer: C

Mobile phase optimization is:
A) Not required
B) Critical for separation
C) Only for detection
D) Only for quantification
Answer: B

APPLICATIONS

HPTLC is widely used in:
A) Pharmaceutical quality control
B) Nuclear physics
C) Astronomy
D) Metallurgy
Answer: A

In herbal industry, HPTLC is used for:
A) Plant breeding
B) Fingerprinting and standardization
C) DNA sequencing
D) Soil testing
Answer: B

Food analysis using HPTLC includes detection of:
A) Proteins only
B) Additives and adulterants
C) Water content
D) Metals only
Answer: B

Forensic application of HPTLC includes:
A) Blood grouping
B) Drug and poison analysis
C) Fingerprint lifting
D) Ballistics
Answer: B

Environmental application includes detection of:
A) Pollutants and pesticides
B) Stars and planets
C) Magnetic fields
D) Minerals
Answer: A

GENERAL

HPTLC allows analysis of samples:
A) One at a time
B) In batches
C) Only manually
D) Only automatically
Answer: B

HPTLC plates are usually:
A) Reusable many times
B) Single-use
C) Washed and reused
D) Heated repeatedly
Answer: B

Visualization reagent is used to:
A) Increase Rf
B) Develop colored spots
C) Reduce solvent use
D) Increase flow rate
Answer: B

Compared to TLC, HPTLC offers better:
A) Plate size
B) Automation
C) Sample volatility
D) Solvent boiling point
Answer: B

HPTLC provides:
A) Only qualitative analysis
B) Only quantitative analysis
C) Both qualitative and quantitative analysis
D) Neither qualitative nor quantitative
Answer: C

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