FTIR spectroscopy

Question 1

What are the pharmaceutical applications of IR spectroscopy?

Answer 1

1. Identification of drugs
2. Identification of functional groups
3. Quantification of drug content
4. Identification of substandard and falsified medicine
5. Qualitative fingerprint check for identity of raw materials used in manufacturing
6. Fingerprint test for films, coatings and packaging plastics
7. Detection of polymorphism

Question 2

What is the fingerprint region?

Answer 2

900cm-1 to 1400cm-1

Question 3

True or false?
You must look inside the fingerprint region to identify functional groups.

Answer 3

False

Question 4

How does bond strength affect vibrational frequency?

Answer 4

Higher bond strength = higher frequency

Question 5

How does reduced mass affect vibrational frequency?

Answer 5

Lower reduced mass = higher frequency

Question 6

How do you calculate reduced mass?

Answer 6

reduced mass = (m1m2)/(m1+m2)

Question 7

How do you calculate the vibrational frequency of a bond?

Answer 7

v = 1/2pi (k/reduced mass)^0.5

(where k is the force constant)

Question 8

How does force constant determine bond strength?

Answer 8

Stronger bond = higher force constant

Question 9

What is vibrational coupling and how does it affect the frequency?

Answer 9

When there are 2 bonds close together that are vibrating with similar frequency (eg two -CH2 groups), they combine to give 2 coupled vibrations of different frequencies

Question 10

How does hydrogen bonding affect frequency?

Answer 10

It causes the peak to be broader and at a lower frequency

Question 11

How does conjugation affect frequency?

Answer 11

Conjugation reduces frequency