TLC is a chromatography technique used to separate mixtures based on differences in how compounds partition between a stationary and mobile phase. It involves spotting a sample onto a plate coated with adsorbent particles and developing the plate by moving a solvent up the plate. Compounds separate based on differing interactions with the phases, appearing as spots with different distances traveled. The Rf value is used to identify compounds by comparing distances traveled to a reference. TLC is useful for qualitative analysis due to its low cost, simplicity, and ability to visualize results.
This presentation summarizes basic introduction, principle, working procedure, applications, adavantages and disadvantages on Thin Layer Chromatography
Thin-layer chromatography (TLC) is a chromatography technique used to separate non-volatile mixtures. Thin-layer chromatography is performed on a sheet of glass, plastic, or aluminium foil, which is coated with a thin layer of adsorbent material, usually silica gel, aluminium oxide (alumina), or cellulose.
This presentation summarizes basic introduction, principle, working procedure, applications, adavantages and disadvantages on Thin Layer Chromatography
Thin-layer chromatography (TLC) is a chromatography technique used to separate non-volatile mixtures. Thin-layer chromatography is performed on a sheet of glass, plastic, or aluminium foil, which is coated with a thin layer of adsorbent material, usually silica gel, aluminium oxide (alumina), or cellulose.
TLC is method for the purification and testing of compounds , separating non-volatile mixtures.
Chroma -"color" and graphein - "to write”.
Color bands - separation of individual compounds.
Thin-layer chromatography (TLC) is a chromatography technique used to separate non-volatile mixtures.[1] Thin-layer chromatography is performed on a sheet of glass, plastic, or aluminium foil, which is coated with a thin layer of adsorbent material, usually silica gel, aluminium oxide (alumina), or cellulose. This layer of adsorbent is known as the stationary phase.
After the sample has been applied on the plate, a solvent or solvent mixture (known as the mobile phase) is drawn up the plate via capillary action. Because different analytes ascend the TLC plate at different rates, separation is achieved.[2] The mobile phase has different properties from the stationary phase. For example, with silica gel, a very polar substance, non-polar mobile phases such as heptane are used. The mobile phase may be a mixture, allowing chemists to fine-tune the bulk properties of the mobile phase.
After the experiment, the spots are visualized. Often this can be done simply by projecting ultraviolet light onto the sheet; the sheets are treated with a phosphor, and dark spots appear on the sheet where compounds absorb the light impinging on a certain area. Chemical processes can also be used to visualize spots; anisaldehyde, for example, forms colored adducts with many compounds, and sulfuric acid will char most organic compounds, leaving a dark spot on the sheet.
To quantify the results, the distance traveled by the substance being considered is divided by the total distance traveled by the mobile phase. (The mobile phase must not be allowed to reach the end of the stationary phase.) This ratio is called the retention factor or Rf. In general,a substance whose structure resembles the stationary phase will have low Rf, while one that has a similar structure to the mobile phase will have high retention factor. Retention factors are characteristic, but will change depending on the exact condition of the mobile and stationary phase. For this reason, chemists usually apply a sample of a known compound to the sheet before running the experiment.
Thin-layer chromatography can be used to monitor the progress of a reaction, identify compounds present in a given mixture, and determine the purity of a substance. Specific examples of these applications include: analyzing ceramides and fatty acids, detection of pesticides or insecticides in food and water, analyzing the dye composition of fibers in forensics, assaying the radiochemical purity of radiopharmaceuticals, or identification of medicinal plants and their constituents [3]
A number of enhancements can be made to the original method to automate the different steps, to increase the resolution achieved with TLC and to allow more accurate quantitative analysis. This method is referred to as HPTLC, or "high-performance TLC". HPTLC typically uses thinner layers of stationary phase and smaller sample volumes, thus reducing the loss of resolution due to diffusion.
This presentation is all about chromatography, its types, different techniques of chromatography. Also it contains the principle, method, applications of column chromatography.
Silica Gel | Aluminium Oxide Column chroamtographySORBEAD INDIA
Buy Silica Gel Powder for Silica Gel, Aluminium Oxide, Paper and Flash Column Chromatography us in Pharmaceutical Industries – Bulk Drugs & API, Nutraceuticals, Herbal Extracts products manufacturers, Research Laboratories, Laboratories Chemical Repackaging, Contract Research Laboratories. Column Chromatography is one of the most useful methods for purification & separation (Isolation) of individual desire compound from mixture of unwanted compounds.
TLC is method for the purification and testing of compounds , separating non-volatile mixtures.
Chroma -"color" and graphein - "to write”.
Color bands - separation of individual compounds.
Thin-layer chromatography (TLC) is a chromatography technique used to separate non-volatile mixtures.[1] Thin-layer chromatography is performed on a sheet of glass, plastic, or aluminium foil, which is coated with a thin layer of adsorbent material, usually silica gel, aluminium oxide (alumina), or cellulose. This layer of adsorbent is known as the stationary phase.
After the sample has been applied on the plate, a solvent or solvent mixture (known as the mobile phase) is drawn up the plate via capillary action. Because different analytes ascend the TLC plate at different rates, separation is achieved.[2] The mobile phase has different properties from the stationary phase. For example, with silica gel, a very polar substance, non-polar mobile phases such as heptane are used. The mobile phase may be a mixture, allowing chemists to fine-tune the bulk properties of the mobile phase.
After the experiment, the spots are visualized. Often this can be done simply by projecting ultraviolet light onto the sheet; the sheets are treated with a phosphor, and dark spots appear on the sheet where compounds absorb the light impinging on a certain area. Chemical processes can also be used to visualize spots; anisaldehyde, for example, forms colored adducts with many compounds, and sulfuric acid will char most organic compounds, leaving a dark spot on the sheet.
To quantify the results, the distance traveled by the substance being considered is divided by the total distance traveled by the mobile phase. (The mobile phase must not be allowed to reach the end of the stationary phase.) This ratio is called the retention factor or Rf. In general,a substance whose structure resembles the stationary phase will have low Rf, while one that has a similar structure to the mobile phase will have high retention factor. Retention factors are characteristic, but will change depending on the exact condition of the mobile and stationary phase. For this reason, chemists usually apply a sample of a known compound to the sheet before running the experiment.
Thin-layer chromatography can be used to monitor the progress of a reaction, identify compounds present in a given mixture, and determine the purity of a substance. Specific examples of these applications include: analyzing ceramides and fatty acids, detection of pesticides or insecticides in food and water, analyzing the dye composition of fibers in forensics, assaying the radiochemical purity of radiopharmaceuticals, or identification of medicinal plants and their constituents [3]
A number of enhancements can be made to the original method to automate the different steps, to increase the resolution achieved with TLC and to allow more accurate quantitative analysis. This method is referred to as HPTLC, or "high-performance TLC". HPTLC typically uses thinner layers of stationary phase and smaller sample volumes, thus reducing the loss of resolution due to diffusion.
This presentation is all about chromatography, its types, different techniques of chromatography. Also it contains the principle, method, applications of column chromatography.
Silica Gel | Aluminium Oxide Column chroamtographySORBEAD INDIA
Buy Silica Gel Powder for Silica Gel, Aluminium Oxide, Paper and Flash Column Chromatography us in Pharmaceutical Industries – Bulk Drugs & API, Nutraceuticals, Herbal Extracts products manufacturers, Research Laboratories, Laboratories Chemical Repackaging, Contract Research Laboratories. Column Chromatography is one of the most useful methods for purification & separation (Isolation) of individual desire compound from mixture of unwanted compounds.
chromatography, principle, adsorbent of TLC, mobile phase of TLC, techniques in TLC, preparation of TLC plate, standards for TLC, advantages, disadvantages of TLC, Application of TLC.
Thin Layer Chromatography - TLC- by Aloo Denish and Oloo Boniface.pdfDenish Aloo
Thin Layer Chromatography (TLC)
By Aloo D. and Oloo B.
- Principle of TLC
-Components of TLC
-Procedure of TLC
-Interpretation of TLC Results
-Advances in TLC
-TLC Techniques - Coupling TLC
-Thin-layer radiochromatography (TLRC)
-Application of TLC
Thin layer chromatography technique - easier, cheaper.
Handling is easy. Used as an identification test also purity test. It comprises of stationary and mobile phase. There are various types of chromatography technique. TLC consists of three steps - spotting, development, and visualization. The Rf value is used to quantify the movement of the materials along the plate. Rf is equal to the
distance traveled by the substance divided by the distance traveled by the solvent. Its value is
always between zero and one. A TLC analysis might be summarized something like, "Using a silica
gel plate and ethyl acetate as the development solvent, unknown mixture X showed three spots
having Rf's of 0.12, 0.25, and 0.87". CThere are three components in TLC:
(1) the TLC plate (stationary phase), the development solvent (mobile phase), and the sample to be
analyzed (solute). In our experiment the TLC plate consists of a thin plastic sheet covered with a
thin layer of silica gel.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
2. What is Chromatography
and Thin layer
Chromatography?
Principle of TLC
Follows which specific
principle for
chromatography?
TLC technique
Method and steps of TLC . How TLC
works and generate reults.
Analysis
Analysis of Retention
factor for separtion,
identification and
purification purpose
Limtations & Application
Importance of TLC in
different fields, advantages
of process and its some
limitations.
01 02
04 05
03
Introduction
3. ● TLC is a technique used to isolate non-
volatile mixtures. It is a method for analyzing
the mixtures by separating compounds in the
mixture. TLC is a form of liquid
chromatography consisting of two phases:
A mobile phase (liquid) and
A stationary phase (solid).
• Differences in the interactions between the
solutes
and stationary and mobile phases enable
separation.
4. TLC is based on separation principle i.e. Major
priciple involves in TLC is Adsorption.
• TLC technique involves the distribution of
components of a mixture to be separated between
two phases.
• The components of the mixture are partitioned
between an adsorbent (stationary phase), and a
solvent (mobile phase).
• Different compounds will have different solubility
and adsorption to the two phases between which
they are to be partitioned.
• In TLC separation of the individual substances is
based on their relative affinities towards stationary
and mobile phases.
01
5. The stationary phase
It is a thin layer of
adsorbent . (usually
silica gel or alumina)
coated on a plate.
The mobile phase
It is a developing liquid
which flows through the
stationary phase,
carrying the samples
with it.
Nature
Components with more
affinity towards
stationary phase travels
slower. Components
with less affinity towards
stationary phase travels
faster.
6. Selection of
Adsorbents and
Solvents:
• Adsorbent should not adhere to
glass plate.
• Solvents should be of high
purity.
• Selected based on the nature of
the compound to be separated
(polar or non polar).
01
02
03
Solvents used as
Mobile Phase:
Inorganic: Silica Gel, Aluminium
Silicate, Bentonite.
Organic: Cellulose & its
acetylates,
Charcoal & activated Charcoal,
Dextran Gel, Polyamides.
Adsorbents used as
Stationary Phase:
Petroleum ether,
Benzene, Carbon
tetrachloride.
7. TLC plate
Preferably ready made with a
stationary phase. These are
stable and chemical inert plates
where a thin layer of stationary
phase is applied on the whole
surface layer.
Mobile Phase
This comprises a solvent or
solvent mixtures. The mobile
phase used should be particulate
–free for proper development of
TLC spots. The solvents
recommended are chemically
inert.
TLC Chamber
This is used for the
development of TLC plate. The
chamber maintains a uniform
environment inside for paper
development of spots.
Filter paper
This is moistened in the mobile
phase to be placed inside the
chamber . This helps develop a
uniform rise in a mobile phase
over the length of stationary
phase.
1 2
3 4
Diagrammatic Representation Of components
System Components
8. Spotting
the sample visualization
The visualization of colored
spots is easy as the colored
spots can be directly seen on
the silica gel plate.however,
most of compounds are
colorless and so visualization
method is required to see the
separate component.
The sample containing
mixture of compounds , which
is to be analyzed is dissolved
in a suitable volatile solvent
to produce a very dilute
solution. A pencil line can be
drawn near the bottom.The
spoting solvent evaporates
quickly leaving behind a small
spot.
Development
Once the spot is dried the
TLC plate is placed
vertically into a tight jar
containing the solvent.this
result depends upon 3
components. Polarity of
the plate ,the polarity of
development solvent and
polarity of components in
spotting sample.
01 03
02
9. .
The Components
visible as separated
spots can be
analyzed by distance
traveled by the
Then
Rf value is
calculated as
shown in
diagram.
component
to that reference
values. once the
solvent reaches the
top the plate is
removed and the
distance travelled by
the component is
measured
10. Different adsorbents will give different values for same
solvents.
Although precise control of temperature is
not necessary , the tank should be kept
away from draughts, sources of heat and
direct sunlight etc.
Nature of adsorbent
Mass of sample
Increasing the mass of sample on the
plate will often increase the Rf of a
drug , especially if it normally tail in
the system.
Temperature Thickness of layer
Standard plates approximately
250micro meter is preferable
thickness of layer. The layers may
be of higher or lower thickness in
individual compounds
Technique
Depending upon the development
technique used i.e. ascending ,
descending , horizontal etc. the Rf value
changes for the same solvent system.
Mobile phase
The purity of solvents and quantity
of solvents mixed should be strictly
controlled.
11. It is a simple process with a short development
time.
It helps with visualization of separated
compounds spots easily.
The methods help to identify the individual
compounds.
The purify standards of the given sample can
be accessed easily.
It is a cheaper chromatography technique.
It is possible to visualize the components
through UV light.
It is also useful if a small volume of a sample is
available and does not require large volume of
a sample.
12. Do not recogonize the
differences between isomeric
and enantiomeric forms of a
compound
. It gives best results for qualitative
analysis but not for quantitative
analysis.
.
Some of the TLC plates do not have long
stationary phases. In such cases, it poses the
problem of the limitation of the length of
separation for the mixture because greater the
length of the plate, finer would be the
separation of the mixture into individual
components
02
01 03 04 05
Since TLC operates as an open
system, some factors such as
humidity and temperature can
be the consequences of the
final outcome of the
chromatogram
.
TLC is applicable to only non-
volatile compounds, thus limiting its
use.
13. It is widely used in separating multi
components pharmaceutical
applications. It is used in food
industry to separate and identify
colors , sweetening agents and
preservatives.
The qualitative testing of
various medicines such as
sedatives, local anesthetics
and steroids is done by TLC.
TLC can be used to identify
natural products like essential
oils, or volatile oil, fixed oil ,waxes
,alkaloids etc.
separation
Qualitative testing
purification
It is used to purify any sample and
direct comparison is done between
the sample and authentic sample.
Identification
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