Download Instrumental method of analysis Most important questions and more Summaries Pharmaceutical Analysis in PDF only on Docsity!
โข Instrumental method of analysis Important questions and
answers (10&5 marks questions)
10 - Mark Questions :
1. Explain the principles, instrumentation, and applications of UV- Visible Spectroscopy in pharmaceutical analysis. Ans. UV-Visible Spectroscopy in Pharmaceutical Analysis Principles : UV-Visible spectroscopy is based on the absorption of ultraviolet (200โ 400 nm) and visible (400โ800 nm) light by molecules. When light passes through a sample, certain wavelengths are absorbed, depending on the molecular structure. The absorbed light is related to the concentration of the substance (Beer-Lambert Law). Instrumentation :
- Light Source โ Provides UV and visible light (e.g., deuterium and tungsten lamps).
- Monochromator โ Selects specific wavelengths of light.
- Sample Holder โ Usually a quartz cuvette containing the sample solution.
- Detector โ Measures transmitted light and converts it into data.
- Computer โ Displays absorption spectra and calculates concentration. Applications in Pharmaceuticals: Identifying and quantifying drugs. Checking drug purity. Studying drug stability. Detecting impurities. This technique is widely used due to its simplicity, speed, and accuracy in drug analysis.
2. Describe the IR Spectroscopy technique, including its fundamental principles, sources of radiation, detectors, and applications. Ans. Infrared (IR) Spectroscopy is a technique used to study molecules by analyzing how they absorb infrared light. It helps identify different chemical bonds in a substance. Fundamental Principles When IR light passes through a sample, certain wavelengths are absorbed by the molecule, causing vibrations in its chemical bonds. The absorbed wavelengths create a unique pattern called an IR spectrum, which helps identify the substance. Sources of Radiation Globar (Silicon Carbide) โ Used in mid-IR range Nernst Glower โ A ceramic material for IR radiation Tungsten-Halogen Lamp โ Used for near-IR Detectors Thermocouples & Bolometers โ Detect heat changes Pyroelectric Detectors โ Fast response, used in FTIR Photoconductive Detectors โ Detect light intensity changes Applications Identifying organic & inorganic compounds Studying polymers and pharmaceuticals Environmental and forensic analysis 3. Explain the methodology, advantages, and applications of Adsorption and Partition Column Chromatography in drug analysis. Ans. Adsorption and Partition Column Chromatography in Drug Analysis
Instrumentation : It consists of a light source (hollow cathode lamp), atomizer (flame or graphite furnace to convert sample into free atoms), monochromator (selects a specific wavelength), detector (measures absorbed light), and readout system (displays results). Applications : AAS is used for metal analysis in water, food, pharmaceuticals, and biological samples. It helps detect toxic metals like lead and mercury in environmental samples. Flame Photometry (FP) Principle : FP is based on the fact that certain metal ions emit light at specific wavelengths when introduced into a flame. The intensity of emitted light is measured to determine the concentration of the element. Instrumentation : It includes a flame burner (converts sample into excited atoms), optical system (filters the specific wavelength), detector (measures emitted light), and readout system (displays concentration). Applications : FP is commonly used for detecting alkali and alkaline earth metals like sodium, potassium, calcium, and lithium in biological samples, agriculture, and industry. Both techniques are essential in chemical analysis for detecting and quantifying elements in various fields.
5. Compare and contrast Gas Chromatography (GC) and High- Performance Liquid Chromatography (HPLC) in terms of theory, instrumentation, and applications. Ans. Comparison of Gas Chromatography (GC) and High-Performance Liquid Chromatography (HPLC)
- Theory : GC: Separates compounds based on their volatility (ability to turn into gas). It is used for substances that can be easily vaporized without breaking down.
HPLC: Separates compounds based on their interaction with a liquid mobile phase and solid stationary phase. It is suitable for non-volatile, heat-sensitive, and large molecules.
2. Instrumentation
- Sample Application: A small spot of the drug mixture is placed on the stationary phase.
- Development: The plate or paper is placed in a solvent system. The solvent rises due to capillary action, carrying the sample components at different speeds.
- Separation: Components move at different rates based on their solubility and interaction with the stationary phase.
- Detection: After drying, components are visualized using UV light, iodine vapors, or chemical reagents. The Rf (Retention factor) value is calculated to identify substances. Applications in Drug Analysis: 1.Identification of Drugs: Helps in detecting unknown drugs or their impurities. 2.Purity Testing: Checks for contamination or degradation in pharmaceuticals. 3.Comparison with Standards: Confirms if a drug matches a known standard sample. 4.Forensic Applications: Used in crime investigations to analyze drugs in body fluids or seized samples. 5.TLC is faster and more precise, while Paper Chromatography is simpler and cost-effective. Both techniques play a crucial role in pharmaceutical and forensic labs for drug analysis. 7. Explain Nephlometry and Turbidimetry, including their principles, instrumentation, and applications in pharmaceutical analysis. Ans. Nephelometry and Turbidimetry in Pharmaceutical Analysis 1. Introduction Nephelometry and Turbidimetry are techniques used to measure the amount of particles suspended in a liquid. They help in analyzing . pharmaceutical samples, especially in quality control and drug formulation.
2. Principle: Nephelometry: Measures the light scattered by particles in a solution. When light passes through a sample, some of it is scattered in different directions. The intensity of scattered light is measured at an angle (usually 90ยฐ). Turbidimetry: Measures the reduction in light intensity as it passes straight through a sample containing suspended particles. More particles in the sample cause more light absorption and scattering, leading to a decrease in transmitted light. 3. Instrumentation Light Source: Usually a tungsten or laser light. Sample Holder: A transparent cuvette containing the liquid sample. Detector: In Nephelometry: Placed at an angle to measure scattered light In Turbidimetry: Placed directly in line to measure transmitted light. Display System: Shows the measured values in absorbance or intensity units. 4. Applications in Pharmaceutical Analysis Protein Analysis: Used in immunological tests to detect proteins and antigens. Drug Formulation: Helps in studying suspensions and emulsions. Quality Control: Detects impurities in solutions. Microbial Growth Monitoring: Measures bacterial concentration in antibiotics. Both techniques are useful for ensuring the safety and effectiveness of pharmaceutical products.
1. Principle Ion Exchange Chromatography (IEC) is a technique used to separate charged molecules based on their attraction to an oppositely charged resin. The resin contains either positive (cation exchanger) or negative (anion exchanger) charged groups. When a sample is passed through, molecules bind to the resin based on their charge and are later eluted using a salt solution. 2. Advantages High Selectivity: Separates molecules based on charge differences. Efficient Purification: Provides high purity of pharmaceutical compounds. Applicable to Biomolecules: Suitable for proteins, peptides, and nucleotides. Reproducibility: Delivers consistent and reliable results. 3. Applications in Pharmaceutical Analysis Purification of Drugs: Used in the purification of antibiotics and vaccines. Protein Separation: Helps in analyzing and purifying therapeutic proteins. Quality Control: Ensures drug formulations meet purity standards 10. Discuss Electrophoresis, including the factors affecting. electrophoretic mobility, techniques of paper, gel, and capillary electrophoresis. Ans. Electrophoresis in Pharmaceutical Analysis 1. What is Electrophoresis? Electrophoresis is a technique used to separate charged molecules, like proteins and DNA, based on their movement in an electric field. When an electric current is applied, molecules move towards the oppositely charged electrode, allowing separation. 2. Factors Affecting Electrophoretic Mobility Charge of Molecule: Higher charge leads to faster movement.
Size of Molecule: Larger molecules move slower. Strength of Electric Field: Higher voltage increases speed. Type of Medium: Paper, gel, or capillary affects separation. Buffer pH and Ionic Strength: Affects molecule charge and movement.
3. Techniques of Electrophoresis Paper Electrophoresis: Uses a special paper as the medium for separation. Gel Electrophoresis: Uses agarose or polyacrylamide gel, commonly for DNA and proteins. Capillary Electrophoresis: Uses a thin capillary tube, offering high-speed and precise separation. Electrophoresis is widely used in pharmaceutical analysis for drug testing, protein analysis, and genetic studies. **5 - Mark Questions:
- Define chromophores and auxochromes and explain their role in UV- Visible Spectroscopy.** Ans. Chromophores are the parts of a molecule responsible for absorbing light in the UV-Visible region. They contain double bonds or conjugated systems, which interact with light energy and cause electronic transitions. Examples include โ C=Cโ, โ C=O, and โ N=Nโ groups. Auxochromes are groups attached to chromophores that do not absorb light themselves but enhance absorption by increasing conjugation or donating/withdrawing electrons. Examples include โ OH, โ NHโ, and โ OCHโ.
Ans. Fluorescence in fluorimetry is affected by several factors:
1. Nature of the Molecule โ Only certain molecules with conjugated double bonds fluoresce. 2. Solvent โ Polar solvents can enhance or reduce fluorescence. 3. pH โ Changes in pH can alter the fluorescence of some compounds. 4. Temperature โ High temperatures reduce fluorescence by increasing molecular motion. 5. Quenching Agents โ Some substances absorb energy and reduce fluorescence. Quenching occurs due to: 1. Collisional Quenching โ Molecules collide and lose energy. 2. Static Quenching โ Quencher forms a complex with the fluorophore, preventing fluorescence.
- Explain the principle and advantages of Flame Photometry in drug analysis Ans. Principle of Flame Photometry: Flame photometry works on the principle that when certain metal ions (like sodium, potassium, calcium) are heated in a flame, they emit light at specific wavelengths. The intensity of this emitted light is measured to determine the concentration of the metal in a sample. Advantages in Drug Analysis:
- High Sensitivity: Detects even trace amounts of metals.
- Fast & Simple: Quick analysis with minimal sample preparation.
- Cost-Effective: Requires inexpensive equipment.
- Accurate & Reliable: Provides precise results for metal quantification in pharmaceuticals. It is widely used in quality control of medicines to ensure safety and effectiveness.
5. What are detectors used in IR Spectroscopy? Explain any two in detail. Ans. In IR spectroscopy, detectors are used to measure the infrared radiation absorbed or transmitted by a sample. Common detectors include Thermocouples, Bolometers, Pyroelectric Detectors, and Photoconductive Detectors.
- Thermocouple: It converts heat energy from IR radiation into an electrical signal. The voltage generated is proportional to the temperature change.
- Pyroelectric Detector: It uses materials like lithium tantalate, which generate an electric charge when heated by IR radiation. This charge is then measured to determine the IR intensity. These detectors help analyze molecular structures in chemicals and materials. 6. Define Retention Factor (Rf value) in Thin Layer Chromatography (TLC) and its significance. Ans. Retention Factor (Rf value) in Thin Layer Chromatography (TLC) is a measure of how far a compound moves on the TLC plate compared to the solvent. It is calculated using the formula: Rf = Distance traveled by the compound / Distance traveled by the solvent The Rf value helps identify compounds by comparing them with known values. It is important in chemistry, pharmaceuticals, and forensic science for analyzing mixtures. A higher Rf means the compound is less attracted to the stationary phase, while a lower Rf means it interacts more with it. Different Rf values help separate and identify substances effectively. 7. Write a short note on HPLC instrumentation and its advantages over traditional chromatography.
Destructive Method: Some samples may be altered or destroyed during analysis.
9. Differentiate between Affinity Chromatography and Ion Exchange Chromatography. Ans. Affinity Chromatography and Ion Exchange Chromatography are both techniques used to separate molecules, but they work differently. Affinity Chromatography separates molecules based on specific binding interactions. It uses a stationary phase with ligands that attract a particular molecule, like an enzyme binding to its substrate. Ion Exchange Chromatography separates molecules based on their charge. It uses a charged resin that attracts oppositely charged molecules, allowing separation based on charge differences. In short, affinity chromatography focuses on specific binding, while ion exchange chromatography focuses on charge differences for separation. 10. Explain temperature programming in Gas Chromatography and its significance in separation techniques. Ans. Temperature programming in Gas Chromatography (GC) is a technique where the column temperature is gradually increased during the separation process. This helps in separating compounds with different boiling points more efficiently. At the beginning, a low temperature allows better separation of low-boiling compounds, while a gradual increase speeds up the elution of high-boiling compounds. This reduces analysis time and improves peak resolution. The significance of temperature programming is that it enhances the separation of complex mixtures, prevents peak broadening, and ensures accurate identification of compounds. It is widely used in analyzing petroleum products, food flavors, and environmental samples.
