# Instrumental Methods Of Analysis (2023-24)
**BPharm Semester VII – Complete Solution PDF**
## I. Multiple Choice Questions (MCQs)
1. The following quantitation methods in UV - Visible spectroscopy need a reference
standard except
**d. Use of standard absorptivity**
2. Molar absorptivity is expressed as?
**d. Moles/litre**
3. Example of wavelength selector in UV-visible spectroscopy?
**b. Monochromator**
4. Paracetamol and Ibuprofen combination can be analyzed by?
**b. Simultaneous equation**
5. IR spectrum is a plot of?
**a. % Transmittance versus wavenumber**
6. Stretching vibration is associated with?
**c. Change in bond length**
7. Used in preparation of solid sample for IR spectroscopy
**b. Potassium bromide**
8. In flame photometry, as the energy gap increases, the proportion of atoms in
ground state:
**a. Increases**
9. Atomic absorption spectroscopy involves?
**a. Measurement of concentration of elements**
10. Nephelometry is based on?
**a. Light scattering**
11. The term __ is independent of the flow rate of mobile phase in column
chromatography
**a. HETP**
12. In paper chromatography, separation is based on?
**a. Partition**
13. In electrophoresis, as the ionic strength of buffer decreases:
**b. Rate of migration of the charged particle increases**
14. In Gas chromatography, derivatization of sample is carried out to:
**b. Increase volatility of the analytes**
15. Parameter for qualitative analysis by HPLC is:
**a. Retention time**
16. Selectivity Factor in column chromatography is associated with:
**b. Ability of the column to efficiently separate components of a mixture**
17. Most non polar component (RP HPLC, retention times X=2.5, Y=2.8, Z=12, M=15
min):
**d. M**
18. Resin of ion exchange are formed by polymerization of styrene and?
**c. Divinylbenzene**
19. Separation based on molecular size occurs in __ chromatographic technique
**b. Gel**
20. Chromatographic separation based on specific biological interactions:
**c. Affinity**
## II. Long Answer Questions
1.a. **Beer Lambert’s Law derivation:**
Statement: The absorbance (A) of a solution is directly proportional to the path
length (l) and the concentration (c):
A = εlc.
Beer-Lambert law is a combination of Beer’s Law and Lambert’s Law. Refer to
derivation and its application[2][5][8][11].
1.b. **IR Spectroscopy Principle and Applications:**
Principle: IR measures vibrational frequencies, indicating function groups. The
spectrum of absorption is a molecular fingerprint. Applications:
- Identification of unknown compounds
- Purity analysis[3][6][9][12]
2.a. **Radial Chromatography and Paper Chromatography Spraying Agent:**
Radial chromatography (circular TLC) uses a stationary phase on a plate spinning
around a central axis. The solvent flows from the center outward, and compounds
separate radially. Spraying agents: Ninhydrin for amino acids.
2.b. **Types of ion exchange resins:**
- Cation exchange resins: Example—sulfonated polystyrene
- Anion exchange resins: Example—quaternary ammonium polystyrene
- Mixed bed resins: Both types[12]
3.a. **Detectors in Gas Chromatography; Explain one:**
Detectors: Flame ionization detector (FID), Thermal conductivity detector (TCD),
Electron capture detector (ECD), Nitrogen-phosphorus detector (NPD).
**FID**: Detects ions formed during organic molecule combustion in a flame; current
generated is proportional to the number of carbon atoms[34][37].
3.b. **Chromatographic Column Efficiency Calculation:**
Given—Column A (12cm, tR=7min, W1/2=0.54min); Column B (25cm, tR=12min,
Wb=0.72min).
Number of theoretical plates (N):
- Column A: N = 5.54*(7/0.54)^2 = 931
- Column B: N = 16*(12/0.72)^2 = 4444
HETP:
- A: 0.0129 cm
- B: 0.0056 cm
Column B is more efficient (higher N, lower HETP).
## III. Short Answer Questions
1. **Multicomponent analysis in UV-Visible:**
- Simultaneous equation method
- Absorbance ratio method
- Derivative spectrophotometry
- Multivariate calibration
*Molar absorptivity for C8H9NO2:* Given 12 µg/ml, A=0.86, l=1cm. MW = 151.16 g/mol.
Concentration = 0.00007939 mol/L.
ε = 0.86 / (1 × 0.00007939) = **10833 L mol⁻¹ cm⁻¹**
2. **Fluorescence vs Phosphorescence and Factors Affecting Fluorescence:**
- Fluorescence: No electron spin change, emission occurs quickly
- Phosphorescence: Electron spin change, delayed emission
Factors: Temperature, pH, solvent, oxygen, molecular rigidity, substituent
groups[30][41][42]
3. **Atomic Absorption vs Flame Photometry and Principle:**
- AAS: Measures absorption of light by ground state atoms; more precise
- Flame photometry: Measures light emitted by excited atoms; less precise
AAS Principle: Quantitative measurement based on absorption by ground state metal
atoms[17][20][23]
4. **UV-Visible Detectors:**
Examples: Photomultiplier tube, photodiode array, barrier layer cell. (Detailed
note on photomultiplier tube: amplifies weak optical signals by electron
multiplication.)
5. **TLC Principle and Detection:**
Separation: Based on differential adsorption of compounds on stationary phase.
Detection: Iodine chamber, UV light, spraying agents.
6. **Guard Column in HPLC, Isocratic Elution:**
- Guard: Protects main analytical column from contaminants
- Isocratic Elution: Constant mobile phase composition; simple and reliable
Advantage: Simpler repeatable separations
Disadvantage: Slower for complex mixtures[32][35][38][40]
7. **Paper Electrophoresis and Applications:**
- Principle: Separation of charged particles under electric field on paper
Applications: Serum protein separation, analysis of nucleic acids
8. **Headspace Analysis in Gas Chromatography:**
- Collect and analyze volatile compounds from the gas phase above a sample.
Applications: Analysis of volatile drugs, solvents
Carrier gases: Helium, nitrogen, hydrogen[37]
9. **Affinity Chromatography Phases:**
- Stationary: Ligand covalently attached (e.g., antibody)
- Mobile: Buffer
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*Prepared for BPharm students for academic reference*
