Introduction To Instrumental Analysis

Question 1

What is pharmaceutical analysis?

Answer 1

Analytical chemistry dealing with drugs both as bulk drug substances and pharmaceutical products (formulations).

Question 2

What is Analytical chemistry?

Answer 2

The study of the separation,identification,and quantification of the chemical components of natural and artificial materials.

Question 3

What is the difference between Qualitative and Quantitative analysis?

Answer 3

Qualitative analysis-Reveals the identity of elements and compounds in a sample.

Quantitative analysis indicates the amount or concentration of each substance in a sample.

Question 4

Which questions are pharmaceutical analysis methods used to answer?

Answer 4

1. Is the identification the drug in the formulated product correct?
2. Does this formulation contain solely the active ingredient or are additional impurities present?
3. What is the stability of the drug?
4. What is the rate of drug release from its formulation?
5. Do the identity and purity of the pure drug meet the specifications?
6. What are the concentrations of specified impurities?
7. What are the concentration of plasma or biological fluids?
8. What are the pKa values,partition coefficients,solubilities,and stability of drug under development?

Question 5

Define chemical purity.

Answer 5

Complete freedom from foreign matter. A state of absolute purity (100%) is virtually unattainable.

Question 6

List the criteria that determines the acceptance level of purity.

Answer 6

1. The cost effectiveness of the process.
2. The purification methods.
3. Partly on the stability of the product.
4. Toxicity of the impurities.
5. The dose of the active ingredient.

Question 7

List and describe the sources of impurities in pharmaceutical chemicals.

Answer 7

1. Raw materials
   Pharmaceutical chemicals may be isolated from:
   a) Biological souces: plant,animal,microbiological fermentation.
   b) Chemically synthesized
2. Manufacturing process
   a)The starting material and its impurities.
   b)The intermediates.
   c)Reagents,solvents, and catalysts used in the process.
   d)Reaction vessel,traces of metallic ions.

3.Chemical and physical instability.
a)Chemical instability:Pharmaceutical substances can undergo chemical decomposition when stored under non-ideal conditions such as light,traces of alkali and acids,water vapor,CO2.
E.g The acid degradation
Of B-lactam antibiotics (amoxicillin)is accelerated by heavy metals.
b)Physical instability : Change in crystal size and form,change in particle size.

4)Manufacturing hazards
Particulate contamination,cross contamination and microbial contamination.

Question 8

List and describe the various important terms used to describe analytical result.

Answer 8

1.Precision: Describes the reproducibility of the measurements,in other words,the closeness of results that have been obtained in the same way.It is determined by simply repeating the measuon replicate samples.Described by standard deviation and variance.

2. Accuracy:Indicates the closeness of the measurement to the true or accepted value or is expressed by the error.
3. Selectivity: The Selectivity of a method is a measure of how capable it is of measuring the analyte alone or in the presence of other compounds contained in the Sample.

4) Sensitivity: A measure of the ability of a method to determine low concentrations of an analyte.

5)Robustness:Refers to how resistant the precision and accuracy of an assay to small variations in the met e.g. changes to instrumentation,slight variations in extract procedures.

Question 9

What are Pharmacopeial standards?

Answer 9

Pharmacopeias are official documents that provide guidelines,specifications,and analytical procedures for various drug substances.

Question 10

Name the various Pharmacopeias available.

Answer 10

1. British Pharmacopeia (BP)
2. United States Pharmacopeia (USP)
3. European Pharmacopeia.
   4.Japanese Pharmacopeia.

*Drug manufacturers must comply with these Pharmacopeias according to the regulations of different countries.

Question 11

What is concentration?

Answer 11

A measure of how much of a material (solute) is dissolved in a certain solution. It can be expressed in different ways I.e. units of concentration.

There are physical and chemical basis of expressing concentration
a)Chemical units: Interested in knowing how many moles of the material present in each unit of volume (L) of the solution(mol/L)
b) Physical units: Interested in knowing how many grams (mg,ug…) present in unit volume( ml,ul,L).

Question 12

What does ppm mean?

Answer 12

Part per million.
-Number of mass units(mg,g…) in one million of that mass units(1/1000000)

Other units used:mg/ml, ug/ml.

Question 13

How are concentrations physically expressed using %?

Answer 13

1. (%w/w) :Indicates the number of grams of solute in 100g of a solution.
   E.g. Solids in semisolid(creams and Ointments)

2.(%w/v): Indicates the number of grams of solute in 100ml of solution.
E.g.Solution or suspension of a solid substance in a liquid.

3.(%v/v): Indicates the number of milliliters of solute in 100ml of solution.
E.g. Liquid in liquid.

4.(%v/w): Indthe number of milliliters of solute in 100g of a solution.
E.g.

Question 14

What is the difference between Normality and Molarity?

Answer 14

Normality (N): Number of equivalents in one liter of a solution (Eq/L).

Molarity(M): Number of moles in each liter of a solution (mol/L).

Question 15

Molarity concept.

Answer 15

1. Analytical molarity : Total number of a solute in one liter of the solution.
2. Equilibrium/Species molarity: The molar concentration of a particular species in a solution at Equilibrium.

Equilibrium molar concentrations are symbolized by placing square brackets around the chemical formulary of the species [H2SO4].