Lecture 02, 3

• What are the sample preparation techniques mentioned?

  Partition ratio, solvent extraction, SLE, LLE
• What does the partition ratio, KD, indicate?

  It determines solute distribution between phases

  
• How does the partition ratio vary?

  It varies with the choice of solvent
• How does a weak acid behave in extraction?

  Ionised species partition into the aqueous layer
• Why is not all of a weak acid extracted into organic solvent?

  Because Kp ignores the ionised species
• What is the distribution ratio, D?

  It is the ratio of concentrations of all species
• How does the distribution ratio relate to the acidity constant?

  It relates to the ionisation of weak acids

  
• What does the percentage extracted or recovered, R, depend on?

  It depends on the volume ratio of solvents
• What is solvent extraction?

  Separation based on relative solubilities
• What is solubility?

  Upper limit of solute dissolved at equilibrium
• How do polar and non-polar solutes behave in solvents?

  Polar solutes dissolve best in polar solvents
• What is Accelerated Solvent Extraction (ASE)?

  Extraction at temperatures above boiling point

  
• What are the advantages of ASE over Soxhlet extraction?

  Uses smaller solvent volumes and is faster
• What is Solid-Liquid Extraction (SLE) used for?

  Analysing tablets, capsules, and plant materials
• What is the purpose of Liquid-Liquid Extraction (LLE)?

  To remove interferent species before measurement
• What are the advantages of continuous extraction?

  Uses small solvent volumes and high solute extraction

  
• How does SLE differ from LLE?

  SLE is harder to extract from solids than LLE
• What is the role of Solid Phase Extraction (SPE)?

  Used for sample preparation of biological fluids

  
• What are the limitations of Liquid-Liquid Extraction (LLE)?

  Emulsions form and large solvent volumes used
• What is the conditioning step in SPE?

  Preparing the solid phase extraction cartridge
• What is reversed phase SPE based on?

  Hydrophobic interactions between analyte and phase

  
• What are the benefits of using SPE?

  Improves mass spectrometry sensitivity and removes interferents
• How does protein extraction affect proteins?

  It concentrates and purifies proteins from contaminants
• What types of solvents are used for extraction?

  Non-polar, aromatic, high-dipole moment, proton donors
• What is green extraction?

  Extraction processes that reduce energy consumption

  
• Why is solvent selection important in extraction?

  It affects the efficiency of the extraction process
• What is the significance of using green solvents in extraction?

  They reduce environmental impact and energy use
• What is the role of the washing step in SPE?

  It removes matrix interferents from the sample
• What is the purpose of using a separating funnel in LLE?

  To separate immiscible liquids during extraction

  
• What is the main advantage of dual phases in SPE?

  Extends the range of compounds extracted
• How does the choice of solvent affect KD?

  KD depends on the nature of the organic solvent
• What is the significance of the acidity constant Ka?

  It helps understand ionisation in the aqueous phase

  
• What is the main purpose of protein precipitation?

  To concentrate and purify proteins
• How does temperature affect protein solubility?

  It can denature proteins leading to precipitation
• What are the implications of using Class 1 solvents?

  They are highly toxic or carcinogenic
• What is the acceptable residual solvent in Class 3 solvents?

  Less than 0.5% w/w in products
• How does the extraction process differ between SLE and LLE?

  SLE is for solids, LLE is for liquids
• What is the main purpose of using a separating funnel in LLE?

  To separate immiscible liquids during extraction

  
• What is the role of the washing step in SPE?

  It removes matrix interferents from the sample
• What is the main advantage of dual phases in SPE?

  Extends the range of compounds extracted