Pharmaceutical Compounds & Analytical Chemistry Essentials

Posted on Jul 6, 2025 in Chemistry

Volumetric Analysis Fundamentals

Volumetric analysis is a method of quantitative chemical analysis where the amounts of substances are determined by measuring the volume they occupy in different proportions.

Types of Volumetric Methods

Volumetric methods are classified into types based on the reactions involved:

  1. Neutralization Titration
  2. Non-aqueous Titration
  3. Redox Titration
  4. Complexometric Titration
  5. Precipitation Titration

Neutralization Titration

Also known as acid-base titration in the aqueous phase, this method uses strong acids or bases as titrates or analytes. Other reagents or titrants are used as standard solutions to determine the analyte’s concentration.

Redox Titration

Chemical titrations employing both oxidation-reduction reactions are known as Redox Titration or Oxidation-Reduction Titration.

Oxidation and Reduction Reactions
  • Oxidation Reaction: Defined as the ‘addition of oxygen, loss of electrons, or removal of hydrogen’.
  • Reduction Reaction: Defined as the ‘removal of oxygen, gain of electrons, or addition of hydrogen’.
Redox Reaction Example

MnO4– + I– → Mn2+ + I2

Oxidizing and Reducing Agents
  • Oxidizing Agent: Substances containing an atom or ion that accept an electron during a reaction, resulting in either a decrease in their positive valency or an increase in their negative valency.
  • Reducing Agent: Substances containing an atom or ion that lose an electron during a reaction, resulting in either an increase in their positive valency or a decrease in their negative valency.
Theory of Redox Titration

Reduction potential measures how thermodynamically favorable it is for a compound to gain electrons. A high positive value for a reduction potential indicates that a compound is readily reduced and consequently is a strong oxidizing agent; that is, it removes electrons from substances with lower reduction potential. The oxidized and reduced forms of a substance are known as a redox pair.

Precipitation Titration Example

An indicator is used, and a red-brown precipitate of silver chromate will be formed, which gives the endpoint of the titration. This method is applied for the determination of chloride ion concentration in water samples from different sources, including river water, seawater, stream water, etc.

2Ag+ (aq) + CrO42-(aq) → Ag2CrO4(s)

Errors in Chemical Analysis

Errors can arise from various sources during analytical procedures:

Types of Errors

  • Chemical/Reagent Errors: These errors are based on the reactivity between the chemicals and reagents used.
  • Errors in Methodology: This is a most serious error in analysis, as it arises due to faulty methods.
  • Indeterminate or Random Errors: In this type of error, the specific, well-known reason cannot be defined, and they cannot be eliminated. They are also called accidental errors.

Key Analytical Terms

Accuracy

The nearest or most accurate value that matches the true value of any experiment defines the term accuracy.

Precision

Defined as the agreement among a cluster of experimental results.

Impurities

Defined as the presence of undesired or unexpected material during any procedure, which may alter the final products.

Limit Test

A quantitative or semi-quantitative test performed to identify and control small amounts of impurities likely to be present in the substance being analyzed.

Importance of Limit Test

  • A limit test denotes the incompatibility of a solution in the presence of other substances.
  • It defines the amount of impurities present in a solution.
  • It differentiates between avoidable and unavoidable impurities.
  • Overall, limit tests help ensure the purity and clarity of a solution.

Haematinics: Blood Formation Support

Haematinics are substances that provide suitable conditions for blood component formation and support blood formation (Erythropoiesis).

Classification of Haematinics

Based on dosages and activity, haematinics are mainly divided into three categories:

  1. Iron-Containing Substances: Divided into two parts based on dose administration:
    • Oral Iron: Ferrous fumarate, ferrous sulfate, carbonyl iron, ferric ammonium citrate.
    • Parenteral: Iron dextran, ferrous sucrose.
  2. Maturation Activity: Examples include Vitamin B12, folic acid.
  3. Haematinics Adjuvants: Examples include copper, pyridoxine, riboflavin.

Ferrous Sulfate

  • Chemical Formula: FeSO4
  • Molar Mass: 151.91 g/mol

Introduction to Ferrous Sulfate

Ferrous sulfate is an iron salt preparation used to manage iron deficiency symptoms. It is popularly known as green vitriol, melanterite, or copperas. Its hydrated form is used medically to treat iron deficiency and for industrial applications.

Properties of Ferrous Sulfate

  • Color and State: It is a white crystalline powder, but its heptahydrate form shows a blue-green color.
  • Odor and Taste: It is odorless with a metallic taste.
  • Solubility: It is soluble in water but shows negligible solubility in alcohol and ethylene glycol.
  • Chemical Property: Chemically, it is a reducing agent, so in pharmaceuticals, it reduces other substances into useful forms.

Pharmaceutical Preparations

Pharmaceutically, it is prepared as tablets, capsules, syrups, pills, oral drops, etc.

Brand/Market Names

Folfes-plus, Feosol, Ferroealth, E-Folifer kid, etc.

Storage Conditions

It is stored in a well-closed, airtight, unopened container and kept away from incompatible materials at room temperature, and also away from light and moisture.

Uses and Applications

  • Ferrous sulfate is a medicine used to treat and prevent iron deficiency anemia.
  • Ferrous sulfate provides iron supplementation during pregnancy and maintains iron status in both child and mother.

Dental Products and Oral Care

Dental products are substances that prevent dental caries and decay, providing freshness and cleanliness to the mouth and teeth. In the market, they are mainly available as toothpaste, tooth powder, mouthwash, tooth gel, dentifrice, etc.

Key Dental Conditions

  • Dental Caries: Defined as the demineralization or destruction of the inorganic and organic matrix from the calcified tissue of the tooth by microbial activity. This process involves the destruction of the mineral phase, primarily hydroxylapatite crystals, by organic acids produced by bacterial growth.
  • Dental Plaque: Defined as whitish or pale yellowish soft accumulations of bacterial colonies (mainly Streptococci) and their substrate, which deposit on teeth when not cleaned adequately.
  • Gingivitis: A form of gum disease that happens when plaque, a naturally occurring sticky film containing bacteria, builds up on teeth and causes the inflammation of the surrounding gum tissue.

Sodium Fluoride

  • Chemical Formula: NaF
  • Molar Mass: 41.99 g/mol

Introduction to Sodium Fluoride

Sodium fluoride is an inorganic chemical widely used as a source of fluoride ions in dental product preparations. It protects the teeth from acid demineralization during bacterial growth. It provides strength to tooth enamel and prevents tooth decay. A minor quantity of sodium fluoride is used in drinking water.

Preparation of Sodium Fluoride

It is prepared by the reaction of hydrofluoric acid with sodium carbonate, yielding an insoluble precipitate:

2HF + Na2CO3 → 2NaF + H2O + CO2↑

Properties of Sodium Fluoride

  • Color and State: It is a colorless crystalline powder.
  • Odor and Taste: It is odorless with a salty taste.
  • Solubility: It is readily soluble in water but insoluble in alcohol.

Pharmaceutical Preparations

Tablets, solutions, drops, toothpaste.

Brand/Market Names

Optifresh, NuNof, D Flour, Vinaflour.

Storage Conditions

It is stored in a well-closed, airtight, unopened container and kept away from incompatible materials at room temperature, and also away from light and moisture.

Uses and Applications

  • Sodium fluoride is an ingredient in various dental preparations used to support tooth mineralization and the prevention of dental caries.
  • It is also used in water treatment.

Denture Cleaners

Denture cleaners are substances or equipment designed for the safe removal of stains, deposits, and debris from dentures or the mouth, caused by diet, tobacco, coffee, and tea consumption, etc. Their main use is to control the growth of microorganisms (e.g., Candida albicans, a yeast) on dentures, thereby preventing denture-related stomatitis.

Denture Adhesives

Denture adhesives are substances that act as adhesive materials between the gum and denture. They create a sticky layer between the tissue and the denture surface that helps keep the denture in place during function and prevents unwanted movements.

Mouthwashes

Mouthwashes are liquid preparations intended for preventing dental caries and oral contamination. They remove bad breath and maintain freshness for a long time.

Medicinal Gases

Medicinal gases are defined as preparations intended for patient diagnosis and treatment during emergency conditions.

Antiseptic Silver Compounds

Silver cation (Ag+) is very sensitive to anions like chloride:

Ag+ + Cl– → AgCl(S)

Properties of Silver Compounds (General)

  • Color and State: Silver ions (Ag+) are typically found in clear, colorless solutions. Elemental silver is a solid.
  • Odor and Taste: It is odorless with a metallic taste.
  • Solubility: Under normal conditions, elemental silver is insoluble in water.

Pharmaceutical Preparations

Creams, gels, solutions.

Brand/Market Names

Sulfhex, Sildaflo, AgNeon, Silvebel.

Storage Conditions

It is stored in a well-closed, airtight, unopened container and kept away from incompatible materials (like copper) at room temperature, and also away from light and moisture. It is very sensitive to heat and decomposes into its ionic form.

Uses and Applications

Silver is used in the manufacturing of antiseptic creams, solutions, liquids, etc. Silver reduces or prevents infection and has been used in the topical treatment of burns and chronic wounds, as well as a coating for many medical devices. It is also used in toothpaste manufacturing.

Antacids: Gastric pH Neutralizers

Aluminium Hydroxide Gel

  • Chemical Formula: Al(OH)3
  • Molar Mass: 78.00 g/mol

Introduction to Aluminium Hydroxide Gel

Also known as Aluminic Acid or Hydrated Alumina, it is a basic inorganic compound that reacts with HCl and works quickly by lowering the acidic pH of the gastric cavity. It does not affect acid production. Liquid antacids usually work faster and better than tablets or capsules.

Properties of Aluminium Hydroxide Gel

  • Color and State: It is a white or pale yellow amorphous powder.
  • Odor and Taste: It is odorless with a mucilaginous taste.
  • Solubility: It is insoluble in water but soluble in both acidic and basic media.

Pharmaceutical Preparations

Suspensions, syrups, tablets, capsules, boluses.

Brand/Market Names

Digene, Gelusil, Vicid, Alqure, Asinil-T.

Storage Conditions

It is stored in a well-closed, airtight, unopened container and kept away from incompatible materials at room temperature, and also away from light and moisture.

Uses and Applications

Aluminium hydroxide is used to treat gastric problems by neutralizing increased pH. It also provides relief from heartburn, upset stomach, and sour stomach. Aluminium hydroxide is also used to reduce phosphate levels in people with certain kidney conditions.

Magnesium Hydroxide

  • Chemical Formula: Mg(OH)2
  • Molar Mass: 58.32 g/mol

Introduction to Magnesium Hydroxide

Also known as Milk of Magnesia, it acts as an antacid by neutralizing gastric pH, reacting with H+ from HCl to produce water. It acts as a laxative, increasing the volume of feces in the intestine by stimulating intestinal motility. On a commercial scale, it is prepared by the reaction of calcium hydroxide or lime.

Reaction for Magnesium Hydroxide Preparation

Mg+2 + Ca(OH)2 → Mg(OH)2 + Ca+2

Properties of Magnesium Hydroxide

  • Color and State: It is a white crystalline solid or powder.
  • Odor and Taste: It is odorless with a milky or chalky taste.
  • Solubility: It is slightly soluble in water.

Pharmaceutical Preparations

Suspensions, syrups, tablets, capsules.

Brand/Market Names

Digene, Gelusil, Antanil plus, Cremaffin, Maalox.

Storage Conditions

It is stored in a well-closed, airtight, unopened container and kept away from incompatible materials at room temperature, and also away from light and moisture.

Uses and Applications

Magnesium hydroxide reduces stomach acid and increases water in the intestines, which may induce bowel movements.