Titration 2

Comprehensive vocabulary flashcards covering Pharmaceutical Quality Control, including error types, gravimetric and volumetric analysis methods, indicators, and specific redox and complexation titrations.

Quality Control

Part of Good Manufacturing Practice concerned with sampling, specifications, and testing, and with organization, documentation, and release procedures to ensure materials and products reach satisfactory quality before use or sale.

Determinate/Constant Errors

Errors that recur in a constant manner in each of a series of determinations, are usually detectable, and may be eliminated; causes include personal errors, faulty procedure, and apparatus errors.

Indeterminate/Accidental Errors

Slight variations in a series of observations made by the same observer under identical conditions due to unknown and intangible causes that make elimination by the analyst impossible.

Accuracy

The closeness of a result to the true value.

Precision

The closeness of results with one another.

Absolute error

The difference between the mean and the true value.

Relative error

Found by dividing the absolute error by the true value.

Gravimetric Analysis

Analytical method involving the measurement of the weight of a substance in a sample or calculating the weight from a chemically equivalent amount of another substance.

Dried to constant weight

Two consecutive weighings do not differ by more than $0.5\,mg/g$ of the substance when the second weighing is made after an additional hour of drying.

Constant weight (object)

An object is at constant weight when two consecutive weighings after heating and cooling do not differ by more than $0.2\,mg$.

Volumetric (Titrimetric) Analysis

Analytical method in which the volume of a solution of known concentration consumed is taken as a measure of the amount of active constituent in a sample.

Analyte

The chemical substance being analysed.

Titrant

A solution of known concentration, usually added by means of a buret.

Standardization

The determination of the concentration of a solution.

Standard Solution

A solution which contains a known weight of reagent per unit of volume.

Indicator

A chemical which changes color at or very near the point where equivalent quantities of analyte and titrant have reacted.

End point

The practical point at which the titration is stopped, marked by a sudden change in some property of the reaction mixture.

Stoichiometric / Equivalence Point

The theoretical point at which equivalent amounts of analyte and titrant have reacted.

Primary standard

A substance of known purity used to determine the concentration of a standard solution.

Titer

The weight of a substance chemically equivalent to $1\,mL$ of a standard solution.

Residual Titration / Backtitration

Method where an excess reagent is added to the analyte and then the excess is determined; used if reactions are slow or end points are not sharp.

Blank Titration

Repeating the titration procedure using the same quantities of reagent solutions and indicator but omitting the sample.

Acidimetry

The analysis of bases using an accurately measured volume of acid as the titrant.

Alkalimetry

The analysis of acids using an accurately measured volume of base/alkali as the titrant.

• Potassium biphthalate

• Crystal violet

What is the primary standard and indicator used for the standardization of $0.1N$ Perchloric Acid.

• 0.1N Perchloric acid in GAA

• 0.1N Sodium Methoxide

• Most used titrant in non aq acidimetry

• Most used titrant in non aq alkalimetry

• Benzoic Acid

• Thymol blue

What is the primary standard and indicator used for the standardization of $0.1N$ Sodium Methoxide in non-aqueous alkalimetry.

Complex

A compound formed when a metal ion combines with a molecule that can donate electrons.

Chelate

A complex where the combining molecule has two or more groups that donate electrons.

EDTA (Ethylenediaminetetraacetic Acid)

A widely used complexing agent standardized against Calcium Carbonate using Hydroxynaphthol Blue indicator.

Reducing agent

A reactant which loses electrons and is oxidized (e.g., $Fe^{2+} \rightarrow Fe^{3+} + e$).

Oxidizing agent

A reactant which gains electrons and is reduced (e.g., Fe^{3+} + e \rightarrow Fe^{2+}).

Permanganometry

Redox titrimetry using Potassium permanganate ($KMnO_4$) as a self-indicating titrant that imparts a pink color at the endpoint.

Cerimetry

Redox titrimetry using Ceric Sulfate ($Ce(SO_4)_2$) as the titrant and Orthophenanthroline TS as the indicator.

Iodimetry

A direct redox titration where reducing agents (e.g., thiosulfates) are titrated directly with Iodine ($I_2$) using Starch TS as an indicator.

Iodometry (Indirect lodimetry)

Method where an oxidizing agent is reduced with excess $KI$, producing an equivalent amount of $I_2$ which is then titrated with $Na_2S_2O_3$.

Koppeschaar's Solution

A standard solution of $0.1N$ Bromine containing Potassium bromate ($KBrO_3$) and excess Potassium bromide ($KBr$).

Direct Titration Formula (%)

\text{%P} = \frac{N \times V\,(mL) \times \frac{MW}{f \times 1000}}{\text{Wt sample (g)}} \times 100

Residual Titration with Blank Formula (%)

\text{%P} = \frac{N(V_b - V_a) \times \frac{MW}{f \times 1000}}{\text{Wt sample (g)}} \times 100

Proximate Assay

Determination of the total amount of a class of plant principles, such as alkaloids or glycosides.

Ultimate Assay

Determination of a single chemical species, such as morphine.

Malachite green

Color change: Acid - Yellow, Base - Green.

Bromothymol blue

Color change: Acid - Yellow, Base - Blue.

Bromocresol purple

Color change: Acid - Yellow, Base - Purple.

Phenol red

Color change: Acid - Yellow, Base - Red.

Cresol red

Color change: Acid - Yellow, Base - Red.

Thymol blue

Color change: Acid - Yellow, Base - Blue.

Methyl red

Color change: Acid - Red, Base - Yellow.

Methyl yellow

Color change: Acid - Red, Base - Yellow.

Phenolphthalein

Color change: Acid - Colorless, Base - Pink.

Thymolphthalein

Color change: Acid - Colorless, Base - Blue.

• AgNO3

• AgCl

Determination of chlorine content in a soluble chloride

• Prectipiatating agent:

• Precipitate:

• BaCl2

• BaSO4

Determination of sulfate content in a soluble chloride

• Prectipiatating agent:

• Precipitate:

• Hydrogen sulfide

• HgS

Determination of mercury content in a soluble chloride

• Prectipiatating agent:

• Precipitate: