Traditionally, spectroscopy involved the visible spectrum of light but X-Ray, gamma and UV spectroscopy also are valuable. Analytical techniques spectroscopy may involve any interaction between light and matter including absorption, emission, scattering, etc.
Data obtained from spectroscopy is usually presented as a spectrum that is a plot of the factors being measured as a function of either frequency or wavelength.
Principle :
Spectroscopy is the measurement and interpretation of electromagnetic radiation which is absorbed or emitted by atoms of a sample. This absorption or emission happens when the atoms of the sample move from one energy state to another in presence of light.
Every sample has molecules consisting of some functional groups by which they may incur color or some nature to absorb light of specific wavelength. This wavelength at which sample absorbs to a greater extent is called as λ max.
When the light beam is passed on to the sample, the electrons in the molecules absorb energy in the light, and go for exited state. During this transition some of the light energy is absorbed while the remaining light falls on the photo-electric detector.
Applications :
1) Spectroscopy is the important detector system in advanced chromatographic methods like HPLC, HPTLC etc.
2) It is also important and a main detector system in multi sample analyzer instruments like Elisa test plate reader, electrophoresis, micro-plate reader, auto-analyzers etc.
3) It is also a part of continuous culture broths like in fermentation tanks to keep the concentration of microbes or any chemical substance at a constant and helps regulate the rate of addition or deletion into the tank.
4) It is useful to determine bio molecules like corticosteroids, testosterone, aldosterone etc.
5) It is also useful in analysis of phyto-chemicals like glycosides, tannins, alkaloids etc.
6) It is also useful in determination of inorganic substance like Fe, Mg, Ca, Cu and other salts and their derivatives. Further chemicals like potassium permanganate, Ferrous sulphate etc.
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OUTLINES OF DAIRY TECHNOLOGY
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2) It is also important and a main detector system in multi sample analyzer instruments like Elisa test plate reader, electrophoresis, micro-plate reader, auto-analyzers etc.
3) It is also a part of continuous culture broths like in fermentation tanks to keep the concentration of microbes or any chemical substance at a constant and helps regulate the rate of addition or deletion into the tank.
4) It is useful to determine bio molecules like corticosteroids, testosterone, aldosterone etc.
5) It is also useful in analysis of phyto-chemicals like glycosides, tannins, alkaloids etc.
6) It is also useful in determination of inorganic substance like Fe, Mg, Ca, Cu and other salts and their derivatives. Further chemicals like potassium permanganate, Ferrous sulphate etc.
———————————————————
OUTLINES OF DAIRY TECHNOLOGY
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1) Visible/UV Spectroscopy
Ultraviolet–visible spectroscopy or ultraviolet-visible spectrophotometry(UV-Vis or UV/Vis) refers to absorption spectroscopy or reflectance spectroscopy in the ultraviolet-visiblespectral region. This means it uses light in the visible and adjacent ranges. The absorption or reflectance in the visible range directly affects the perceived color of the chemicals involved. In this region of the electromagnetic spectrum, atoms and molecules undergo electronic transitions. Absorption spectroscopy is complementary to fluorescence spectroscopy, in that fluorescence deals with transitions from the excited state to the ground state, while absorption measures transitions from the ground state to the excited state.
Principle
UV spectroscopy obeys the Beer-Lambert law, which states that:
When a beam of monochromatic light is passed through a solution of an absorbing substance, the rate of decrease of intensity of radiation with thickness of the absorbing solution is proportional to the incident radiation as well as the concentration of the solution.
The expression of Beer-Lambert law is-
A = log (I0/I) = Ecl
Where, A = absorbance
I0 = intensity of light incident upon sample cell
I = intensity of light leaving sample cell
C = molar concentration of solute
L = length of sample cell (cm.)
E = molar absorptivity
From the Beer-Lambert law it is clear that greater the number of molecules capable of absorbing light of a given wavelength, the greater the extent of light absorption. This is the basic principle of UV spectroscopy.
Application
1. Detection of Impurities
2. Structure elucidation of organic compounds.
3. Qualitative analysis
4. Quantitative analysis
5. Dissociation constants of acids and bases.
6. Chemical Kinetics
7. Quantitative analysis of pharmaceutical substances
8. Molecular weight determination
9. As HPLC detector
2) Infrared (IR) Spectroscopy
Infrared spectroscopy (IR spectroscopyor vibrational spectroscopy) involves the interaction of infrared radiation with matter. It covers a range of techniques, mostly based on absorption spectroscopy. As with all spectroscopic techniques, it can be used to identify and study chemicals. Samples may be solid, liquid, or gas. The method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer (or spectrophotometer) to produce an infrared spectrum. An IR spectrum is essentially a graph of infrared light absorbance (or transmittance) on the vertical axis vs. frequency or wavelength on the horizontal axis. Typical units of frequency used in IR spectra are reciprocal centimeters(sometimes called wave numbers), with the symbol cm−1. Units of IR wavelength are commonly given in micrometers(formerly called "microns"), symbol μm, which are related to wave numbers in a reciprocal way. A common laboratory instrument that uses this technique is a Fourier transform infrared (FTIR) spectrometer.
Application :
1) Qualitative analysis:
For qualitative identification purposes, the spectrum is commonly presented as transmittance versus wavenumber. Functional groups have their characteristic fundamental vibrations which give rise to absorption at certain frequency range in the spectrum.
2) Quantitative analysis :
Absorbance is used for quantitative analysis due to its linear dependence on concentration. Given by Beer-Lambert law, absorbance is directly proportional to the concentration and pathlength of sample:
\[A=\epsilon c l\]
where
A is absorbance,
ε the molar extinction coefficient or molar absorptivity which is characteristic for a specific substance,
c the concentration, and
l the pathlength (or the thickness) of sample.
The conversion from transmittance to absorbance is given by:
\[ A=-\log T \],
where T is transmittance.
3) Nuclear Magnetic Resonance Spectroscopy
Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy, is a research technique that exploits the magnetic properties of certain atomic nuclei. This type of spectroscopy determines the physical and chemical properties of atoms or the molecules in which they are contained. It relies on the phenomenon of nuclear magnetic resonance and can provide detailed information about the structure, dynamics, reaction state, and chemical environment of molecules. The intramolecular magnetic field around an atom in a molecule changes the resonance frequency, thus giving access to details of the electronic structure of a molecule and its individual functional groups.
Most frequently, NMR spectroscopy is used by chemists and biochemists to investigate the properties of organic molecules, although it is applicable to any kind of sample that contains nuclei possessing spin. Suitable samples range from small compounds analyzed with 1-dimensional proton or carbon-13 NMR spectroscopy to large proteins or nucleic acids using 3 or 4-dimensional techniques. The impact of NMR spectroscopy on the sciences has been substantial because of the range of information and the diversity of samples, including solutions and solids.
Applications
1) Chemical research and development:
Organic, Inorganic and Physical Chemistry, Chemical manufacturing industry, Biological and biochemical research, Food industry, Pharmaceutical development and production, Agrochemical development and production, Polymer industry.
2) Common applications of NMR Spectroscopy include:
Structure elucidation, Chemical composition determination, Formulations investigation, Raw materials fingerprinting, Mixture analysis, Sample purity determination, Quality assurance and control, Quantitative analysis, Compound identification and confirmation, Analysis of inter- and intramolecular exchange processes, Molecular characterisation, Reaction kinetics examination, Reaction mechanism investigation.
Ultraviolet–visible spectroscopy or ultraviolet-visible spectrophotometry(UV-Vis or UV/Vis) refers to absorption spectroscopy or reflectance spectroscopy in the ultraviolet-visiblespectral region. This means it uses light in the visible and adjacent ranges. The absorption or reflectance in the visible range directly affects the perceived color of the chemicals involved. In this region of the electromagnetic spectrum, atoms and molecules undergo electronic transitions. Absorption spectroscopy is complementary to fluorescence spectroscopy, in that fluorescence deals with transitions from the excited state to the ground state, while absorption measures transitions from the ground state to the excited state.
Principle
UV spectroscopy obeys the Beer-Lambert law, which states that:
When a beam of monochromatic light is passed through a solution of an absorbing substance, the rate of decrease of intensity of radiation with thickness of the absorbing solution is proportional to the incident radiation as well as the concentration of the solution.
The expression of Beer-Lambert law is-
A = log (I0/I) = Ecl
Where, A = absorbance
I0 = intensity of light incident upon sample cell
I = intensity of light leaving sample cell
C = molar concentration of solute
L = length of sample cell (cm.)
E = molar absorptivity
From the Beer-Lambert law it is clear that greater the number of molecules capable of absorbing light of a given wavelength, the greater the extent of light absorption. This is the basic principle of UV spectroscopy.
Application
1. Detection of Impurities
2. Structure elucidation of organic compounds.
3. Qualitative analysis
4. Quantitative analysis
5. Dissociation constants of acids and bases.
6. Chemical Kinetics
7. Quantitative analysis of pharmaceutical substances
8. Molecular weight determination
9. As HPLC detector
2) Infrared (IR) Spectroscopy
Infrared spectroscopy (IR spectroscopyor vibrational spectroscopy) involves the interaction of infrared radiation with matter. It covers a range of techniques, mostly based on absorption spectroscopy. As with all spectroscopic techniques, it can be used to identify and study chemicals. Samples may be solid, liquid, or gas. The method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer (or spectrophotometer) to produce an infrared spectrum. An IR spectrum is essentially a graph of infrared light absorbance (or transmittance) on the vertical axis vs. frequency or wavelength on the horizontal axis. Typical units of frequency used in IR spectra are reciprocal centimeters(sometimes called wave numbers), with the symbol cm−1. Units of IR wavelength are commonly given in micrometers(formerly called "microns"), symbol μm, which are related to wave numbers in a reciprocal way. A common laboratory instrument that uses this technique is a Fourier transform infrared (FTIR) spectrometer.
Application :
1) Qualitative analysis:
For qualitative identification purposes, the spectrum is commonly presented as transmittance versus wavenumber. Functional groups have their characteristic fundamental vibrations which give rise to absorption at certain frequency range in the spectrum.
2) Quantitative analysis :
Absorbance is used for quantitative analysis due to its linear dependence on concentration. Given by Beer-Lambert law, absorbance is directly proportional to the concentration and pathlength of sample:
\[A=\epsilon c l\]
where
A is absorbance,
ε the molar extinction coefficient or molar absorptivity which is characteristic for a specific substance,
c the concentration, and
l the pathlength (or the thickness) of sample.
The conversion from transmittance to absorbance is given by:
\[ A=-\log T \],
where T is transmittance.
3) Nuclear Magnetic Resonance Spectroscopy
Most frequently, NMR spectroscopy is used by chemists and biochemists to investigate the properties of organic molecules, although it is applicable to any kind of sample that contains nuclei possessing spin. Suitable samples range from small compounds analyzed with 1-dimensional proton or carbon-13 NMR spectroscopy to large proteins or nucleic acids using 3 or 4-dimensional techniques. The impact of NMR spectroscopy on the sciences has been substantial because of the range of information and the diversity of samples, including solutions and solids.
Applications
1) Chemical research and development:
Organic, Inorganic and Physical Chemistry, Chemical manufacturing industry, Biological and biochemical research, Food industry, Pharmaceutical development and production, Agrochemical development and production, Polymer industry.
2) Common applications of NMR Spectroscopy include:
Structure elucidation, Chemical composition determination, Formulations investigation, Raw materials fingerprinting, Mixture analysis, Sample purity determination, Quality assurance and control, Quantitative analysis, Compound identification and confirmation, Analysis of inter- and intramolecular exchange processes, Molecular characterisation, Reaction kinetics examination, Reaction mechanism investigation.
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