How Redox Titration is Used in the Pharmaceutical Industry?

Titration is the name given to a pre-programmed process used to ascertain the concentration level in a solution whose composition is primarily known. A titrant (one reactant with known concentration) solution is carefully added to another solution of unknown concentration (the other reactant).

It is important to learn the nature of the interaction between the molecules in the distinct solutions, particularly in terms of their molar ratios. In the titration of a known amount of acetic acid with sodium hydroxide (shown merely as the hydroxide ion OH below), water and the acetate ion are gradually generated:

CH3CO2H + OH−⟶ CH3CO2− + H2O

You can calculate the number of moles of acid consumed using a series of complicated but basic calculations if you know the concentration of sodium hydroxide applied. 

Applications of Redox Titration in Pharmacy

Redox titration techniques work by monitoring the change in electrochemical potential as the titrant is added to an analyte solution using a suitable electrode.

• In pharmaceutical analysis, redox titration is used to determine the concentration of valganciclovir hydrochloride (VLGH) in pure medicines and tablets.

• Two spectrophotometric approaches that are simple, selective, and sensitive have been devised and verified.

• The first approach used VLGH to reduce iron(III) to iron(II) and then generate an iron(III)-ferricyanide complex (Prussian blue) in an acid solution, which was detected at 730 nm (method A).

• The absorbance of permanganate was measured at 610 nm in the second approach (method B), in which VLGH converted permanganate to bluish green manganate in an alkaline solution. The VLGH concentration was linked to the absorbance in each case.

Example for Redox Titration

Potassium Permanganate Titration against Oxalic Acid is a good example of Redox Titration; the details of the titration are given below:

Potassium Permanganate Titration(KMnO4) against Oxalic Acid (C2H2O4) 

This experiment uses a titration procedure to assess the strength of potassium permanganate against a standard solution of 0.1M oxalic acid.

The strength of KMnO4 is determined using a typical oxalic acid solution.

In the following titration, the analyte is oxalic acid, and the titrant is potassium permanganate. Oxalic acid is a reducing agent in this titration, while KMnO4 is an oxidising agent.

• To begin this titration, make a standard 250mL oxalic acid solution.

• The atomic mass of each constituent atom is then used to calculate the molecular mass of oxalic acid.

Using standard oxalic acid solution to determine the strength of KMnO4

In the following titration, the analyte is oxalic acid, and the potassium permanganate is the titrant. Oxalic acid is a reducing agent in this titration, while KMnO4 is an oxidising agent.

The oxidising power of permanganate ions rises when an acidic media is generated from dilute sulphuric acid.

MnO4– + 8H+ + 5e– → Mn2+ + 4H2O

The rich purple colour of permanganate ions is indicated by the indicator KMnO4. The acidic media reduces MnO4– to colourless manganous ions (Mn2+). Finally, as it approaches its finish, the permanganate takes on a bright pink hue.

Redox Titration and Pharmaceutical Analysis

The pharmaceutical industry employs a variety of industrial titration processes. The following are examples of Redox Titration:

• Acid-base titrations are commonly employed in purity analysis. The purity control of the medication ephedrine, which is contained in various cough syrups, is a good example. This reaction uses perchloric acid as the titrant.

• Content analysis, in which redox (oxidation-reduction) reactions are used to verify the purity of raw materials, such as binding chemicals in oral medications, rather than the completed product itself.

• Titrations of precipitation that result in the development of a solid product. Clotrimazole, an antifungal medication, is one example.

• The pH-stat titration is a technique for determining the purity of enzymes as well as the speed and other characteristics of chemical reactions.

Conclusion

Titration is a widely used laboratory technique for quantitative chemical analysis in the pharmaceutical business. Depending on the molecular weight and amount of titratable functional groups, a pharmaceutical molecule may require up to several hundred milligrammes of sample for accurate titration. A medical expert can quickly change the dosage of a prescription with the help of titration to get the desired effects for a certain patient.