Lecture 03

• What is the purpose of qualitative analysis?

  To carry out quantitative analysis of substances
• What are the methods used for quantitative analysis?

  1. External calibration
  2. Internal calibration
  3. Standard addition
  4. Normalisation
• What is standard addition used for?

  To determine analyte concentration in complex matrices
• Why might a calibration line from pure analyte standards be incorrect?

  Other substances may interfere with detector response
• How does adding known concentrations of a reference standard help?

  It corrects for interference in the measurement
• What is the process of multiple standard addition?

  • Known amounts of reference standard added
  • Same amount of sample used
  • Flask diluted to volume
  • Concentration increases, signal resembles calibration curve
• What is sunset yellow in the context of this study material?

  It is a substance in Irn Bru
• What are the advantages and disadvantages of single standard addition?

  Advantages:

  • Improves accuracy from matrix interference

  
  

  Disadvantages:

  • Time-consuming
  • Uses larger sample volumes
• What is normalisation in quantitative analysis?

  It provides analysis of mixtures separated by chromatography
• How is normalisation applied in chromatography?

  By expressing peak area as a percentage of total areas
• What is the formula for calculating area normalisation?

  A (%) = $\frac{A}{\sum_{i=0}^{n} A_i} \times 100$
• Why is area normalisation used in the pharmaceutical industry?

  To ensure impurities do not exceed limits
• What is the limit for impurities in Caffeine Citrate Injection?

  NMT 0.2% for each impurity
• What does the British Pharmacopoeia (BP) provide?

  Public standards of quality for medicines
• What are monographs in the context of the BP?

  Validated procedures for testing substances
• How many monographs does the current edition of the BP contain?

  Over 3,000 monographs
• What are the advantages and disadvantages of pharmacopoeia standards?

  Advantages:

  • Objective quality standards

  
  

  Disadvantages:

  • Do not provide absolute quantitative results
• What is the purpose of validating analytical methods?

  To ensure measuring devices work properly
• What are the key aspects of validation for analytical methods?

  • Specificity
  • Linearity
  • Range
  • Accuracy
  • Precision
  • Detection limit
  • Quantitation limit
  • Robustness
• What does specificity in analytical methods refer to?

  Complete discrimination for a particular analyte
• What should be evaluated to establish linearity in analytical procedures?

  Plot of signals as a function of analyte concentration
• How many concentrations are recommended for establishing linearity?

  A minimum of 5 concentrations
• What is the specified range in analytical procedures derived from?

  Linearity studies and intended application
• What does accuracy in analytical methods refer to?

  • Closeness to the true value
  • Determined by comparison to known values
• What does precision in analytical methods indicate?

  Repeatability of replicate measurements
• How is precision often calculated?

  As standard deviation or % RSD