Visible Spectrophotometry and Colorimetry.pptx
Color comparison was one of the oldest methods used for quantitative
estimation of elements and substances. The variation of a color of a system with change
in concentration of some components forms the basis of colorimetric analysis. The color
is usually due to the formation of a colored compound by the addition of an appropriate
reagent at specific condition or it may be inherent in the desired constituent itself. The
intensity of the color may then be compared with that obtained by treating a known
amount of the substance in the same manner. Colorimetry is concerned with the
determination of the concentration of a substance by measurement of the relative
absorption of light with respect to a known concentration of a substance. In visual
colorimetry, natural or artificial white light.
This is mainly used to determine the scattering of the light by the suspended particles present in the sample solution. The instruments used for the measurement of the scattering are called nephelometer and turbidimeters. The choice between the nephelometry and turbidimetry depends upon the fraction of light scattered. This light scattering by the particles which are present in the colloids is known as the Tyndall affect.
Nephelometry is the measurement of the scattered light by the suspended particles at right angles to the incident beam. This method is mainly used for the determination of the low concentration suspensions.
Turbidimetry is the measurement of the transmitted light by the suspended particles to the incident beam. This is used for the determination of the high concentration suspensions.
AAS is an analytical technique used to determine the concentration of metal atoms/ions in a sample. Metals make up around 75% of the earth’s chemical elements. In some cases, metal content in a material is desirable, but metals can also be contaminants (poisons).
Flame Photometry is also called as flame emission spectroscopy. Flame Photometry is branch of atomic spectroscopy. It is used to detected certain metal ions like sodium,potassium,magenisum etc.
UV-Vis spectroscopy is an analytical technique that measures the amount of discrete wavelengths of UV or visible light that are absorbed by or transmitted through a sample in comparison to a reference or blank sample.
This is mainly used to determine the scattering of the light by the suspended particles present in the sample solution. The instruments used for the measurement of the scattering are called nephelometer and turbidimeters. The choice between the nephelometry and turbidimetry depends upon the fraction of light scattered. This light scattering by the particles which are present in the colloids is known as the Tyndall affect.
Nephelometry is the measurement of the scattered light by the suspended particles at right angles to the incident beam. This method is mainly used for the determination of the low concentration suspensions.
Turbidimetry is the measurement of the transmitted light by the suspended particles to the incident beam. This is used for the determination of the high concentration suspensions.
AAS is an analytical technique used to determine the concentration of metal atoms/ions in a sample. Metals make up around 75% of the earth’s chemical elements. In some cases, metal content in a material is desirable, but metals can also be contaminants (poisons).
Flame Photometry is also called as flame emission spectroscopy. Flame Photometry is branch of atomic spectroscopy. It is used to detected certain metal ions like sodium,potassium,magenisum etc.
UV-Vis spectroscopy is an analytical technique that measures the amount of discrete wavelengths of UV or visible light that are absorbed by or transmitted through a sample in comparison to a reference or blank sample.
details about uv-visible spectroscopy. intoduction to uv-visible spectroscopy with principle,
instrumentation, application, beers lamberts law , detectors. helps to know details about uv-visible spectroscopy. complete notes of uv-visible spectroscopy.
Presenting a topic which is entitled: Detectors
Above topic includes:
Types of detector
phototube detector
photomultiplier tubes
silicon photodiodes
photovoltaic cells
advantages
multi-channel photon detectors
linear photodiode arrays
photodiode array
with basics of instrumentation and science technology
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Atomic absorption spectroscopy is a method of elemental analysis. It is particularly useful for determining trace metals in liquids and is most independent of molecular form of the metal in sample.
Unlike a spectrometer (which is any instrument that can measure the
properties of light over a range of wavelengths), a spectrophotometer
measures only the intensity of light as a function of its wavelength.
details about uv-visible spectroscopy. intoduction to uv-visible spectroscopy with principle,
instrumentation, application, beers lamberts law , detectors. helps to know details about uv-visible spectroscopy. complete notes of uv-visible spectroscopy.
Presenting a topic which is entitled: Detectors
Above topic includes:
Types of detector
phototube detector
photomultiplier tubes
silicon photodiodes
photovoltaic cells
advantages
multi-channel photon detectors
linear photodiode arrays
photodiode array
with basics of instrumentation and science technology
https://www.linkedin.com/in/preeti-choudhary-266414182/
https://www.instagram.com/chaudharypreeti1997/
https://www.facebook.com/profile.php?id=100013419194533
https://twitter.com/preetic27018281
Please like, share, comment and follow.
stay connected
If any query then contact:
chaudharypreeti1997@gmail.com
Thanking-You
Preeti Choudhary
Atomic absorption spectroscopy is a method of elemental analysis. It is particularly useful for determining trace metals in liquids and is most independent of molecular form of the metal in sample.
Unlike a spectrometer (which is any instrument that can measure the
properties of light over a range of wavelengths), a spectrophotometer
measures only the intensity of light as a function of its wavelength.
Spectrophotometer instrumentation & working Sabahat Ali
Spectrophotometric analysis is a technique to measure the concentration of solute solution by measuring the amount of light absorbed by solution.
Absorption can be calculated in terms of transmittance by using Beer's Lambert law.
http://www.redicals.com
The spectrophotometer technique is to measures light intensity as a function of wavelength.
• Measures the light that passes through a liquid sample
• Spectrophotometer gives readings in Percent Transmittance (%T) and in Absorbance (A)
spectroscopy, classification of spectroscopy, history, UV-VIS spectrophotometer, principle, beer lambert law instrumentation, detector, single beam, double beam in time, double beam in space, application, merits, and demerits
A spectrophotometer is an instrument containing a monochromator, a device which produces a light beam containing wavelengths in a narrow band around a selected wavelength, and a means of measuring the ratio of that beam's intensity as it enters and leaves a cuvette 99 This describes a single-beam photometer.
Spectroscopy using spectrophotometers of different types like: U.V, Mass Spectrophotometer, absorption , Emission, Nuclear magnetic resonance and X-rays Spectrophotometer
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
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.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
DERIVATION OF MODIFIED BERNOULLI EQUATION WITH VISCOUS EFFECTS AND TERMINAL V...Wasswaderrick3
In this book, we use conservation of energy techniques on a fluid element to derive the Modified Bernoulli equation of flow with viscous or friction effects. We derive the general equation of flow/ velocity and then from this we derive the Pouiselle flow equation, the transition flow equation and the turbulent flow equation. In the situations where there are no viscous effects , the equation reduces to the Bernoulli equation. From experimental results, we are able to include other terms in the Bernoulli equation. We also look at cases where pressure gradients exist. We use the Modified Bernoulli equation to derive equations of flow rate for pipes of different cross sectional areas connected together. We also extend our techniques of energy conservation to a sphere falling in a viscous medium under the effect of gravity. We demonstrate Stokes equation of terminal velocity and turbulent flow equation. We look at a way of calculating the time taken for a body to fall in a viscous medium. We also look at the general equation of terminal velocity.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
Salas, V. (2024) "John of St. Thomas (Poinsot) on the Science of Sacred Theol...Studia Poinsotiana
I Introduction
II Subalternation and Theology
III Theology and Dogmatic Declarations
IV The Mixed Principles of Theology
V Virtual Revelation: The Unity of Theology
VI Theology as a Natural Science
VII Theology’s Certitude
VIII Conclusion
Notes
Bibliography
All the contents are fully attributable to the author, Doctor Victor Salas. Should you wish to get this text republished, get in touch with the author or the editorial committee of the Studia Poinsotiana. Insofar as possible, we will be happy to broker your contact.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
2. Instrumental visible spectroscopy is a
logical extension of the color tests and
visual observations. It is a sensitive,
accurate method of measuring the
colors or mixtures of colors that our
eyes perceive.
3. Spectrophotometry is the quantitative measurement
of how much a chemical substance absorbs light by
passing a beam of light through the sample using a
spectrophotometer. By measuring the intensity of
light detected, this method can be used to determine
the concentration of solute in the sample.
4.
5. The visible light spectrum is the segment of
the electromagnetic spectrum that the
human eye can view. More simply, this range
of wavelengths is called visible light.
Typically, the human eye can detect
wavelengths from 380 to 700 nanometers.
6. Spectrophotometer
The spectrophotometer refers to an
instrument that measures the absorbance of
the test sample at a specific wavelength by
measuring the amount of light transmitted by
the sample. This device contains several
components like a light source, collimator,
monochromator, cuvette, light detector, and
digital meter.
7. Colorimetry is a scientific technique that
is used to determine the concentration of
colored compounds in solutions by the
application of the Beer–Lambert law,
which states that the concentration of a
solute is proportional to the absorbance.
8.
9. Theory of spectrophotometry and
colorimetry
When light (monochromatic or heterogeneous) is
incident upon a homogeneous medium, a part of the
incident light is reflected, a part is absorbed by the
medium, and the remainder is transmitted as such.
Color comparison was one of the oldest methods
used for quantitative estimation of elements and
substances. The variation of a color of a system
with change in concentration of some components
forms the basis of colorimetric analysis.
10. In visual colorimetry, natural or artificial white light
(the whole range of the visible radiation is from
400-760 nm) is generally used as a light source
and determinations are usually made with a simple
instrument termed as colorimeter or color
comparator.
11. Lambert’s and Beer’s law.
When light (monochromatic or heterogeneous) is
incident upon a homogeneous medium, a part of the
incident light is reflected, a part is absorbed by the
medium, and the remainder is transmitted as such. If I0
denotes the intensity of the incident light, It, the
transmitted light, Ir the reflected light and Ia the
absorbed light, then it may be written:
I0 = Ia + It + Ir
Ir is very small then
I0 = Ia + It
12. Lambert’s law: When a monochromatic light passes through a
transparent medium, the rate of decrease in intensity (I) with thickness
(l) of the medium is proportional to the intensity of light.
Mathematically, –dI/dl∞I
On deduction it stands to It = I0 × e –kl (k is a proportionality constant)
On changing the above equation from natural to common logarithm,
It = I0 × 10–0.4343kl or
It = I0 × 10–Kl (K is called absorption coefficient)
The absorption coefficient is generally defined as the reciprocal of
the thickness (l cm.) required to reduce 1/10th of its intensity.
It/I0 = 0.1 = 10–Kl
or
K × l = 1
or
K = 1/l So unit of K is cm–1
13. The ratio (It/I0) is termed as Transmittance (T)
The ratio (I0/It) is termed as Opacity
log(I0/It)is termed as the Absorbance (A) of the medium or
Optical density (OD).
14. Beer’s law: When a beam of monochromatic light is allowed to pass
through a solution, the intensity of the light beam decreases
exponentially with the increase in concentration as well as thickness
of the solution. The equation becomes:
It = I0 × 10–a.c.l (a is called molar absorption coefficient)
The value of ‘a’ depends on the unit of concentration. If c is expressed in
gm-moles/litre, l in cm, then a is replaced by ε and is termed as molar
extinction coefficient.
The equation becomes: It = I0 × 10–ε.c.l
A = ε.c.l
or, ε = A/c.l
The unit of ε thus becomes litre gm-moles–1cm–1 Absorbance per unit
path length (l) per unit concentration (c) is known as specific extinction
coefficient
15. Instrumentation
All spectrophotomete, Photometers and Colorimeters have the following
basic components.
Source of continuous radiation over the wavelengths of
interest.
A Filter or Monochromator for selecting a narrow band of
wavelengths from the source spectrum.
Sample cell A container for the sample.
A Detector for converting radiant energy into electrical
energy, and
A Read out system device to read out the response of the
detector.
16. The radiation source
Tungsten filament (300–2500 nm)
.
Filter
It can transmit or reflect a specified range of wavelength.
Filters are classified into three
types
Long wave pass filters,
Short wave pass filters
Band pass filters
17. Types of filter from the viewpoint of function
(1) Absorption filter : a filter which absorbs a specific
range of wavelengths, for examples, colored filter
glass and gelatin filter.
(2) Interference filter : a filter which transmits a specific
range of wavelengths by utilizing the interference effect of
a thin film.
18. Prisms
A prism disperses polychromatic light from the source
into its constituent wavelengths by virtue of its ability to
reflect different wavelengths to a different extent
Two types of Prisms are usually employed in commercial
instruments. Namely, 600 cornu quartz prism and
300 Littrow Prism.
19. Grating
Gratings are often used in the monochromators of
spectrophotometers operating ultraviolet, visible and infrared
regions.
20. Monochromator
(1) entrance slit, (2) collimating mirror (to form a parallel beam after the slit),
(3) diffraction grating (dispersive element), (4) camera mirror (focuses light from
the dispersive element onto the exit slit), and (5) exit slit.
21. Detectors
Detectors are instruments that measure the amount of
ultraviolet or visible light absorbed by the sample
molecules.
In order to detect radiation three types of photosensitive
devices are
Photovoltaic cell
Phototubes
Photomultiplier
22. Photovoltaic cell
The Photovoltaic cell is the semiconductor device that converts the light
into electrical energy. The voltage induces by the PV cell depends on the
intensity of light incident on it.
23. Phototubes
Phototube is also known as a photoelectric cell.
It is filled with gas under low pressure.
It contains a light-sensitive cathode and anode inside an evacuated
quartz envelope.
A photon entering the tube strikes the cathode and leads to the ejection
of an electron.
Electrons strikes the anode and results in the flow of current. The
resulting current is of low intensity and requires amplification.
The response in the phototube depends on the wavelength of incident
light.
25. Photomultiplier tube is used in UV-Vis spectrophotometers.
It has an anode, cathode, and many dynodes.
Photon when entering the tube, strikes the cathode, resulting in
the emission of electrons.
The emitted electrons are accelerated towards the first dynode,
An electron striking the first dynode will result in the production of
several electrons.
The process repeats itself continuously from one dynode to
another and after passing to 10 dynodes.
Photomultiplier Tube
26.
27.
28. A colorimeter is an instrument that compares the amount of
light getting through a solution with the amount that can get
through a sample of pure solvent.
Visual comparators
•Multiple standard method
•Duplication Method
•Dilution methods
•Balancing method
Colorimeter
31. Application of colorimetry and
spectrophotometry:
(i) Determination of molar composition of complexes.
(ii) Determination of instability constants of complexes.
(iii) Determination of pK value of an indicator.
(iv) Elucidation of structures of organic as well as
inorganic compounds.
(v) Determination of molecular weight of colored
substances.