FTIR Applications Quiz and Flashcards

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Questions and Answers

What is the typical transmittance range for a C triple bond (alkyne) signal in IR spectrum?

80% or more (correct)

100% transmittance only

Less than 20%

Between 20% to 50%

What is the function of the beam splitter in a Michelson interferometer?

To split the light and direct it towards fixed and movable mirrors (correct)

To split the light into different wavelengths

To absorb the light and reduce noise

To reflect the light towards the detector

What is the main advantage of FT-IR over dispersive IR spectrometer?

Simultaneous measurement of all wavelengths (correct)

Sequential measurement of each wavelength

Higher signal to noise ratio

Faster measurement time

What is the purpose of the He-Ne laser beam in a Michelson interferometer?

To measure the distance of the moving mirror Signup and view all the answers

What is the first step in getting a sample's FT-IR spectrum?

Without sample, obtain raw signal called ‘interferogram’ Signup and view all the answers

What is the main advantage of FT-IR in terms of signal to noise ratio?

It has a higher signal to noise ratio Signup and view all the answers

What is the primary objective of dividing the FT spectrum of a sample by the reference spectrum?

To obtain the transmission spectrum Signup and view all the answers

What is the main advantage of FT-IR spectroscopy over dispersive IR spectrometers?

Ability to analyze liquids and solids Signup and view all the answers

What is the range of protein concentration that can be measured using FT-IR spectroscopy?

0.1μg/μl to >100 μg/μl Signup and view all the answers

What is the primary limitation of FT-IR spectroscopy in analyzing protein samples?

Water interference with the amide I band Signup and view all the answers

What is the primary application of FT-IR spectroscopy in protein characterization?

Characterizing the secondary structure of proteins Signup and view all the answers

What is the primary advantage of FT-IR spectroscopy in terms of sample preparation?

Requires minimal sample preparation Signup and view all the answers

What principle of IR spectroscopy allows for the identification of functional groups in a sample?

Energy absorption at specific wavelengths Signup and view all the answers

What frequency range is typically measured in wave numbers in FTIR?

4000 – 600 cm$^{-1}$ Signup and view all the answers

What does FTIR rely on to generate spectra?

Absorption in the infra-red region Signup and view all the answers

What is a key advantage of FTIR over dispersive IR spectrometer?

Faster data acquisition Signup and view all the answers

How can a sample's FT-IR spectrum be obtained?

Recording the sample's response to infra-red radiation Signup and view all the answers

What specific absorption corresponds to in FTIR spectroscopy?

Type of bonds present in the molecule Signup and view all the answers

Study Notes

Infrared (IR) Spectroscopy

IR spectrum measures absorption of IR radiation by molecules
Atoms are in continuous motion, and bonds are rotating, resulting in different types of motions occurring in bonded atoms
Each motion occurs at a specific energy, which is utilized to generate IR spectrum

IR Spectrum Measurement

IR source: Mid IR (Nernst glower, Globar source), Near IR (Tungsten halogen), Far IR (High pressure Mercury vapour lamp)
Traditional dispersive IR spectrometer: IR source, diffraction grating, light is directed towards diffraction grating, and each beam is mechanically directed towards the sample
FT-IR spectrometer: Michelson interferometer, beam splitter, fixed and movable mirrors, and simultaneous measurement of all wavelengths

Advantages of FT-IR

Improved signal to noise ratio
Fast
Accurate wavenumber

FT-IR Spectrum Application

Identify and verify samples
Characterize new materials
Useful in manufacturing, chemical synthesis, R&D, and pharma sector
Analyze chemical reactions, including those with functional groups
Protein characterization, including secondary structure, and ligand screening

FT-IR Spectrum of Proteins

Amide I: C=O stretching, characteristic of secondary structure
Amide II: N-H bending and C-N stretching
Shape and location of Amide I are characteristic of secondary structure

Protein Characterization using FT-IR

Application 1: Protein secondary structure characterization, particularly sensitive to β sheets
Application 2: Proteins structural transitions, stability
Application 3: Protein concentration estimation, accurate and precise, requires pre-calibration
Application 4: Identification and characterization of impurities, distinct peaks than proteins

Additional Benefits of FT-IR

Analyze sample as it is
Results within minutes
Not limited by buffer components
Liquids or solids can be analyzed, even opaque

Limitations of FT-IR

Water: Temperature sensitive, strong signal masks amide I band
Low concentration: Low signal
Atmospheric interferences: Water vapour, CO2, require high-end IR spectrometer

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Description

Explore the various applications of FTIR (Fourier Transform Infrared) spectroscopy such as identifying, verifying samples, characterizing new materials, and addressing questions about chemical reactions. Learn how FTIR spectra can be used in manufacturing, chemical synthesis, R&D, pharmaceuticals, catalysis, protein characterization, ligand screening, and more.

Applications of FTIR Spectroscopy

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