W3 L1 - Intro to pharmaceutical analysis techniques Flashcards
(14 cards)
Pharmaceutical Applications of pharmaceutical analysis
- Drug discovery & development
- Formulation stability testing
- Drug metabolism
- Pharmacokinetics & Pharmacodynamics
- Quality control & Quality assurance
Why is sample preparation important in pharmaceutical analysis?
To isolate drugs from complex matrices, concentrate analytes, derivatize (chemical modification of a drug to improve its stability, solubility, detection, or pharmacokinetics) them, and stabilize them from degradation.
What are the main extraction and purification methods in pharmaceutical analysis?
- Solid-phase Extraction
You use a solid material (like a powder or cartridge) to grab the drug from the mixture.
It uses both stationary phase (solid) and a mobile phase (usually liquid).
Examples of techniques:
SPE / SPME (Solid Phase and Solid Phase Microextraction)
Filtration
Chromatography
- Liquid-phase Extraction
This uses liquids (solvents) to separate components based on how well they mix.
Solvents can be:
Immiscible (don’t mix, like oil and water)
Techniques:
Separating funnel
Counter-current distribution
Miscible (do mix, like alcohol and water)
Techniques:
Crystallisation
Fractional distillation
What is solid-phase extraction (SPE) used for?
- Removing interferences from samples
- concentrating analytes
What are the advantages of solid-phase extraction (SPE) over liquid-liquid extraction (LLE)?
Faster, less labor-intensive, lower solvent usage, better recovery, easier automation
How does liquid-liquid extraction (LLE) work?
Separation using Two Immiscible Liquids
- It separates substances based on how much they prefer to stay in one liquid over another (based on their distribution coefficients in two immiscible solvents)
Capture Step (SPE)
- The sample is passed through a material (called a sorbent) that acts like a filter.
- The important chemicals (analytes) stick to the sorbent, while the rest flows through.
Elution Step (Washing Off the Analytes)
- solvent is used to wash off the captured analytes
- This step concentrates the analytes into a smaller volume.
- The washed (eluted) solution is collected for testing.
How can pH be used to selectively extract weak acids or weak bases?
Lowering pH increases solubility of acidic drugs in organic solvents, while raising pH increases solubility of basic drugs.
What is an example of an acidic drug and a basic drug affected by pH in extraction?
Aspirin (acidic, requires lower pH); Procaine (basic, requires higher pH).
What are common methods for separating drugs from miscible phases?
Rotary evaporation, fractional distillation, crystallization, and sublimation (lyophilization)
What are the main analytical techniques used for quantitative pharmaceutical analysis?
Volumetric (titrimetric), spectroscopic, and chromatographic methods.
What is volumetric analysis (titration) used for?
Determining drug concentration through chemical reactions (e.g., acid-base, redox, complexation titrations).
How does back titration work, and when is it useful?
- Add too much of a known reactant (let’s call it Reagent A) to your sample.
→ All of the substance you’re testing reacts with part of A. - Now, some of Reagent A is left over (the extra).
- You then do a regular titration to figure out how much A is left over (using another solution, Reagent B).
- By subtracting the leftover A from the total A you added, you know how much A reacted — and from that, you can calculate how much of your original substance was present.
What is the complexation reaction for magnesium titration with EDTA?
Mg 2+ +EDTA 4− →MgEDTA 2− (1:1 ratio)
How is metal ion concentration determined if the exact formula of ingredients is unknown?
- Indirect methods such as ignition which converts the metal into its oxide form
- The residue (metal oxide) is then weighed, and the metal ion content is calculated based on the known chemical relationship between the metal and its oxide.
