Applications of AAS MCQs With Answer

Applications of AAS MCQs With Answer

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Applications of AAS MCQs With Answer

Atomic Absorption Spectroscopy (AAS) is a cornerstone technique in Modern Pharmaceutical Analytical Techniques for quantifying trace and ultra-trace metals in APIs, excipients, finished dosage forms, and biological matrices. Its variants—flame AAS, graphite furnace AAS (GFAAS), hydride-generation AAS (HG-AAS), and cold vapor AAS—allow sensitive and selective determination of critical elements aligned with ICH Q3D elemental impurity limits. From catalyst residue monitoring (Pt, Pd) to nutritional metals (Zn, Cu) and leachables from packaging (Al, Ni, Cr), AAS underpins quality, safety, and compliance. These MCQs emphasize practical applications, method development, sample preparation, interference control, and regulatory contexts to strengthen your M.Pharm-level mastery.

Q1. In determining arsenic contamination in an API to comply with ICH Q3D, which AAS approach is most suitable?

  • Flame AAS with air–acetylene
  • Graphite furnace AAS without modifiers
  • Hydride-generation AAS using a quartz cell
  • ICP-OES with radial view

Correct Answer: Hydride-generation AAS using a quartz cell

Q2. For estimating mercury in an ointment at sub-ppb levels, the most appropriate AAS technique is:

  • Flame AAS with air–acetylene
  • Cold vapor AAS after chemical reduction
  • Graphite furnace AAS with palladium modifier
  • Hydride-generation AAS with NaBH4

Correct Answer: Cold vapor AAS after chemical reduction

Q3. While quantifying iron in a colored cough syrup by GFAAS, which background correction is preferred to handle strong non-specific absorption?

  • No background correction
  • Zeeman-effect background correction
  • Smith–Hieftje background correction using the primary lamp
  • Second-derivative spectrophotometry

Correct Answer: Zeeman-effect background correction

Q4. Sub-ppb quantification of platinum catalyst residues in an API is best achieved by:

  • Flame AAS with air–acetylene
  • Graphite furnace AAS with Pd–Mg(NO3)2 matrix modifier
  • Hydride-generation AAS
  • UV–Vis spectrophotometry after complexation

Correct Answer: Graphite furnace AAS with Pd–Mg(NO3)2 matrix modifier

Q5. During potassium assay in an injection by flame AAS, ionization interference is minimized by:

  • Lowering the flame temperature
  • Using a nitrous oxide–acetylene flame
  • Increasing nebulizer flow to reduce residence time
  • Adding cesium chloride as an ionization buffer

Correct Answer: Adding cesium chloride as an ionization buffer

Q6. Routine monitoring of trace zinc and copper in parenteral nutrition solutions is most efficiently performed using:

  • Flame AAS after appropriate dilution and acidification
  • Graphite furnace AAS only
  • X-ray fluorescence spectroscopy
  • Electrothermal vaporization coupled to ICP-MS

Correct Answer: Flame AAS after appropriate dilution and acidification

Q7. For rapid, multi-element screening of 20+ elemental impurities across many batches per ICH Q3D, which technique is more appropriate than AAS?

  • Flame AAS
  • Graphite furnace AAS
  • ICP-MS
  • UV–Vis spectrophotometry

Correct Answer: ICP-MS

Q8. The most suitable sample preparation for determining zinc in compressed tablets by AAS is:

  • Simple water extraction at room temperature
  • Microwave-assisted digestion with nitric acid (with/without H2O2)
  • Dry ashing at 600°C followed by water dissolution
  • Alkaline fusion with Na2CO3

Correct Answer: Microwave-assisted digestion with nitric acid (with/without H2O2)

Q9. Pb and Cd determination in a high-carbon herbal extract is best conducted using:

  • Flame AAS without any background correction
  • Graphite furnace AAS with Zeeman background correction and matrix modifiers
  • Flame photometry with sodium filter
  • Conductivity measurement

Correct Answer: Graphite furnace AAS with Zeeman background correction and matrix modifiers

Q10. For aluminum leachables from glass vials, the preferred flame for AAS is:

  • Air–acetylene
  • Nitrous oxide–acetylene
  • Hydrogen flame
  • Propane–air flame

Correct Answer: Nitrous oxide–acetylene

Q11. To quantify zinc migration from rubber stoppers into aqueous drug product, the recommended sample preparation is:

  • Alkaline fusion at 900°C
  • Acid extraction with dilute HNO3 at 50–80°C, then AAS
  • Dry ashing followed by dissolution in water
  • Direct aspiration without treatment

Correct Answer: Acid extraction with dilute HNO3 at 50–80°C, then AAS

Q12. If only flame AAS is available, achieving a 5 ppb lead LOD in purified water can be facilitated by:

  • Direct aspiration of the sample
  • Adding lanthanum chloride as a releasing agent
  • Solvent extraction with APDC into MIBK prior to measurement
  • Switching to a nitrous oxide–acetylene flame

Correct Answer: Solvent extraction with APDC into MIBK prior to measurement

Q13. For calcium assay in a high-strength antacid suspension, the preferred AAS strategy to address chemical interference is:

  • Measure the undiluted suspension by flame AAS
  • Dilute the sample and add lanthanum chloride to suppress phosphate interference
  • Use hydride-generation AAS
  • Use cold vapor AAS

Correct Answer: Dilute the sample and add lanthanum chloride to suppress phosphate interference

Q14. In which situation is the standard addition method in AAS most justified to ensure accuracy?

  • Analyzing metals in high-purity nitric acid
  • Measuring sodium in isotonic saline
  • Determining lead in a complex herbal extract
  • Preparing a calibration curve with certified standards in water

Correct Answer: Determining lead in a complex herbal extract

Q15. Regarding speciation, which statement best describes AAS capability in pharmaceutical analysis?

  • AAS alone provides complete oxidation-state speciation
  • Only ICP-MS can measure total metals
  • AAS measures total element unless coupled with a separation step (e.g., HPLC) or selective chemistry
  • Speciation is impossible even with hyphenation

Correct Answer: AAS measures total element unless coupled with a separation step (e.g., HPLC) or selective chemistry

Q16. For sensitive determination of As, Se, and Sb in drug substances with minimal matrix effects, the optimal atomization approach is:

  • Flame atomizer with air–acetylene
  • Graphite furnace atomizer
  • Hydride-generation atomizer with quartz cell
  • Electrothermal vaporization in ICP-OES

Correct Answer: Hydride-generation atomizer with quartz cell

Q17. When checking Fe, Ni, and Cr leachables from stainless steel processing equipment into a parenteral, which statement about AAS is correct?

  • Flame AAS measures all elements simultaneously
  • Flame AAS requires sequential measurement for each element
  • AAS cannot quantify iron in aqueous matrices
  • AAS cannot be used for parenteral products

Correct Answer: Flame AAS requires sequential measurement for each element

Q18. For blood lead monitoring in exposed pharmaceutical personnel, the appropriate preparation and AAS technique is:

  • Direct aspiration of whole blood by flame AAS
  • Hemolyze and dilute blood with Triton X-100 and nitric acid, then measure by GFAAS
  • Dry ashing of blood followed by flame AAS
  • Protein precipitation and flame photometry

Correct Answer: Hemolyze and dilute blood with Triton X-100 and nitric acid, then measure by GFAAS

Q19. While measuring copper in nitric-acid digests of capsules, which practice best maintains accuracy?

  • Prepare external standards in deionized water
  • Prepare standards in methanol
  • Prepare standards in the same HNO3 concentration as the samples
  • Prepare standards in phosphate buffer

Correct Answer: Prepare standards in the same HNO3 concentration as the samples

Q20. For therapeutic drug monitoring of lithium in serum, which AAS approach is most suitable?

  • Cold vapor AAS after stannous chloride reduction
  • Flame AAS with deproteinized and diluted serum
  • Hydride-generation AAS
  • Graphite furnace AAS with selenium modifier

Correct Answer: Flame AAS with deproteinized and diluted serum

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