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Med Subs > UV-VIS LECTURE > Flashcards

UV-VIS LECTURE Flashcards

1
Q

What is the range of the ultraviolet-visible (UV-Vis) spectrum?

A

UV-Vis spectrum covers wavelengths from 800 nm to 100 nm.

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2
Q

What does UV-Vis spectroscopy measure?

A

It is a quantitative technique that measures the amount of light absorbed by a sample but cannot identify the substance.

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3
Q

How does UV-Vis spectroscopy work?

A

Monochromatic light passes through a sample, and the detector compares the transmitted light (𝐼) to the incident light (𝐼0) calculating absorbance.

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4
Q

What is a chromophore?

A

A functional group in drug molecules that forms conjugated pi-bond systems, responsible for absorbing UV-Vis light.

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5
Q

What features do chromophores exhibit?

A

Alternating C=C bonds
Planar geometry
Heteroatoms (O, S, N)
Cyclic aromatic groups

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6
Q

State the Beer-Lambert Law.

A

A=Ο΅β‹…cβ‹…l
Where
𝐴
A is absorbance,
πœ–
Ο΅ is the molar absorptivity,
𝑐
c is concentration, and
𝑙
l is the path length (usually 1 cm).

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7
Q

What are the conditions for Beer-Lambert Law accuracy?

A

No interference from excipients (e.g., fluorescence)
No suspended matter causing light scattering
Sample concentration within the linear range

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8
Q

List some clinical applications of UV-Vis spectroscopy.

A

Analysis of active pharmaceutical ingredients (APIs)
Impurity detection
Cancer marker detection
Drug stability testing
mRNA vaccine development

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9
Q

Why is
πœ† max used in concentration measurements?

A

It offers higher sensitivity, reliability, and reduced machine error.

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10
Q

What are some limitations of UV-Vis spectroscopy?

A

Overlapping absorbance spectra in mixtures can make analysis difficult.
Sensitivity depends on concentration; very high or low concentrations reduce validity.
pH and ionization can alter molecule conjugation and absorption.

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11
Q

What is a calibration plot, and why is it used?

A

A graph plotting absorbance vs. concentration, used to determine the concentration of unknown samples within a linear range (
𝑅
2
>
0.95

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12
Q

What is the significance of limits like LOD, LOQ, and LOL?

A

LOD (Limit of Detection): Minimum detectable concentration.
LOQ (Limit of Quantitation): Minimum concentration that can be quantified.
LOL (Limit of Linearity): Maximum concentration before deviation from linearity.

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13
Q

Which wavelength range is covered by UV-Vis spectroscopy?
A. 400-700 nm
B. 10-400 nm
C. 100-800 nm
D. 800-1600 nm

A

c

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14
Q

What is the role of chromophores in UV-Vis spectroscopy?
A. To reflect UV-Vis light, reducing absorbance.
B. To absorb UV-Vis light through conjugated pi-bond systems.
C. To identify molecules in a sample.
D. To measure the fluorescence of a compound.

A

b

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15
Q

Which of the following factors can lead to deviations from the Beer-Lambert Law?
A. High sample purity
B. Multiple species with overlapping absorbance spectra
C. Use of monochromatic light
D. Proper calibration of the spectrophotometer

A

b

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16
Q

Why is
πœ†
max
Ξ»
max
​
chosen for measuring absorbance in UV-Vis spectroscopy?
A. It corresponds to the lowest absorbance point, minimizing error.
B. It ensures maximum absorbance, improving sensitivity and reliability.
C. It reduces sample scattering and fluorescence.
D. It increases the molecular weight of the compound.

A

b

17
Q

What is a calibration plot used for in UV-Vis spectroscopy?
A. To calculate the molar mass of the compound.
B. To determine the path length of the cuvette.
C. To identify the chromophore in a sample.
D. To measure the concentration of unknown samples.

A

d

18
Q

Which of the following describes a drawback of UV-Vis spectroscopy?
A. It can identify compounds based on absorption spectra.
B. It is unaffected by the pH of the solution.
C. Overlapping absorbance spectra can complicate analysis.
D. It has unlimited sensitivity for all concentrations.

A

c

19
Q

What is absorptivity in the context of UV-Vis spectroscopy?
A. The wavelength where absorption is minimal.
B. The efficiency of light scattering in a solution.
C. A molecule’s unique signature for absorbing light.
D. The path length of light through a sample.

A

c

20
Q

Which clinical application is NOT typically associated with UV-Vis spectroscopy?
A. Cancer marker detection
B. Protein crystallography
C. Drug stability testing
D. mRNA vaccine development

A

b

21
Q

What happens to the HOMO-LUMO gap in conjugated systems as conjugation increases?
A. It remains constant.
B. It becomes larger, making electron excitation less efficient.
C. It becomes smaller, allowing easier electron excitation.
D. It becomes smaller, reducing light absorption.

A

c

22
Q
A

Med Subs (12 decks)

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