EXPERIMENT 3: IDENTIFICATION TEST FOR ATROPINE SULFATE USING INFRARED SPECTROSCOPY

SPECTROSCOPY

• Interaction between matter & electromagnetic radiation (EMR)

SPECTROSCOPY

main purpose

• identify & analyze a molecule based on their interaction with EMR

Infrared (IR) Spectroscopy

• a technique in analytical chemistry that measures interactions between matter and the infrared portion of the electromagnetic spectrum

Infrared (IR) Spectroscopy

method

• absorption of IR relation by the functional groups within the molecule

Infrared (IR) Spectroscopy

matter is important as_

there would be different ways for the spectra to be absorbed.

FT-IR

• Fourier Transform Infrared Spectroscopy

  • collects IR spectra

FT-IR

use _to convert the raw data (from the IR) into a spectrum that’s readable to the analyst

mathematical frontier transform

MID-IR SPECTROSCOPY

• A specific range of infrared spectroscopy that focuses on the mid-infrared region of the electromagnetic spectrum 

MID-IR SPECTROSCOPY

used to 

• nalyze the molecular vibrations and chemical bonds of compounds, particularly in the mid-infrared range, which is approximately 4000 to 400 cm^-1 (wavenumbers)

MID-IR SPECTRUM

• Displays absorption bands at different frequencies, representing the

• vibrational modes of the sample’s chemical bonds 

MID-IR SPECTRUM

• The positions and intensities of these bands are

• characteristic of the functional groups present in the compound, allowing for the identification and structural analysis 

Applications

• chemical identification

• quality control

• environmental monitoring 

• forensic analysis

• material characterization

CHEMICAL IDENTIFICATION

• Mid-IR spectra serves as unique “fingerprints” for compounds, enabling differentiation between similar compounds

• Look at functional groups present in the compounds

QUALITY CONTROL

• Widely used in industries such as pharmaceuticals, food, and polymers for product composition and to ensure product quality and consistency  

• detect presence of adulterants in our product (via presence of different peaks in the reading)

ENVIRONMENTAL MONITORING

• Mid-IR spectroscopy is applied in the detection of pollutants and environmental contaminants e.g., in air and water

• toxic metals in our material (usually in water)

FORENSIC ANALYSIS

• It can be applied in forensic investigations to identify unknown substances found at crime scenes

MATERIAL CHARACTERIZATION

• Mid-IR spectroscopy aids in analyzing the composition and properties of various materials, including solids, liquids, and gases

Bond length

• distance between 2 atoms

Stretching

• changes in the bond length

  • symmetric or asymmetric 

symmetric:

the bonds extend and contract at the same time

asymmetric:

a bond lengthens, while the others shorten

Bending

• change based on the angle of the body

  • scissoring & rocking

  • wagging & twisting 

Scissoring & Rocking

within plane

Wagging & Twisting

outside plane

SAMPLE

• Thin Film

• Mixing it with an infrared-transparent matrix (solid)

• Using specialized cells or cuvettes (liquid)

3000-4000

Bonds to Hydrogen

• Alcohol

• Amide

• Hydrocarbon

2000-3000

triple bonds

1500-2000

double bonds

1000-1500

single bonds

The C-H bonds of the Carbonyl part of the Propyl Benzene are found in the region of

3100-3000

The C-H bonds of the Propyl Group are found in the region of

3000-2850.

SP3

Below 3000

SP2

Above 3000

Lesser Region (Fingerprint region)

• is 500-1500

•  there are many fluctuations, which is why the analytical regions are easier to read

Atropine Sulfate is a _salt that exhibits distinct IR absorption bands corresponding to the functional groups present (ester, hydroxyl, amine).

tropane alkaloid

Atropine Sulfate is a tropane alkaloid salt that exhibits distinct IR absorption bands corresponding to the functional groups present

(ester, hydroxyl, amine).

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The substance under examination is intimately in contact with an internal reflection element for attenuated total reflection (ATR) analysis.

ACCEPTANCE CRITERIA

• The IR spectrum of the preparation of the sample exhibits maxima only at the same wavenumbers as that of the appropriately prepared corresponding USP Reference Standard

MID-INFRARED SPECTROSCOPY

• provide valuable insights into the

• molecular composition and structure of various substances

MID-IR REGION

• Of great interest because it corresponds to the fundamental vibrational frequencies of many chemical bonds

• When infrared light in this range interacts with a sample, it is absorbed by the compound's specific vibrational modes, producing characteristic absorption bands in the mid-IR spectrum. 

• These absorption bands provide valuable information for identifying and analyzing the structure of various compounds.

Principle

• Similar to that of general infrared spectroscopy

• When infrared light passes through a sample, it interacts with the compound's molecules, causing specific vibrational modes to absorb energy at specific frequencies.

mid-IR light source

• a globar (a heated silicon carbide rod) or a Fourier transform infrared (FT-IR) spectrometer with a built-in infrared light source

• emits a broad spectrum of mid-infrared light

monochromator or interferometer

• selects specific wavelengths for analysis

holder or cell

• where the sample is placed

detector

records the intensity of transmitted or absorbed light