Separation Science

• What are the types of errors in analysis

gross errors

random errors

systemic errors

• What is precision

closeness of results taking from measurements of the same sample

• What is accuracy

closeness between known amount and amount given by analysis

• What is reproducibility

precision taken between labs

• What is equation of concentration

concentration = mass/volume

• What is a solute

solute is the substance dissolved in a solvent to form a solution

• What is solvent extraction

transfer of a solute from one phase to another by separation and purification using their solubilities to separate 2 immiscible liquids

• Why is solvent extraction possible

due to their different solubilities allowing separation

• What does immiscible liquid mean

liquids that do not mix and form layers

• What is the common type of solvent extraction

extraction of an aqueous solution with an organic solvent

• Why is solvent extraction important

used for separation and purification of drugs from formulations

• Strengths of solvent extraction

simple and easy method for separation and purification

• Limitations of solvent extraction

limited efficiency and selectivity

• What is efficiency

How much of the solute you can remove from the original mixture.

• What is selectivity

How well the solvent extracts only the desired solute and not other substances.

• Why are efficiency and selectivity important in solvent extraction

high efficiency and high selectivity depend on solute’s solubility in each phase

• Why must extraction solvent be inert

so it doesn’t react with the drug or solute being extracted

• Why is a low BP preferred for extraction solvents

allows easy removal of solvent after extraction

• What is the partition coefficient

(K) the equilibrium constant for extraction

• What does partition coefficient describe

describes how a solute distributes between 2 immiscible phases

• Which species are more soluble in organic solvents

less polar (uncharged) species

• Which species are more soluble in aqueous solvents

polar (charged) species

• How does pH change affect extraction of weak acids and bases

alters charge of molecule controlling if it prefers organic or aqueous phase

• What is solid-phase extraction

isolating solutes from large volumes of liquid