IMPURITIES

What is the fundamental definition of an impurity in chemistry and materials science?

• A substance that is always toxic.

• A substance that is intentionally added to a material.

• A chemical substance within a material that differs from the intended chemical composition.

• A substance that only affects the physical properties of a material.

In the oil and gas industry, what is an example of a "sour gas" impurity?

• Oxygen (O2​)

• Methane (CH4​)

• Carbon dioxide (CO2​) or hydrogen sulfide (H2​S)

• Nitrogen (N2​)

How can impurities be beneficial in certain applications?

• They are never beneficial and must always be removed

• They only increase the cost of production.

• They can be intentionally introduced to achieve desired functional properties

• They only serve to make a substance less pure.

Organic impurities are defined as what type of compounds?

• Non-carbon-based elements.

• Carbon-containing compounds that can arise during manufacturing or storage

• Inorganic salts.

• Elements with high atomic mass.

What are residual solvents?

• Solid impurities that do not dissolve in a substance.

• Non-carbon-based elements introduced during manufacturing

• Organic or inorganic liquids used in synthesis that remain in trace amounts after purification.

• Impurities that are formed during the degradation of a substance.

The International Council for Harmonisation (ICH) classifies residual solvents into three classes based on what?

• Their boiling point.

• Their potential toxicity.

• Their country of origin.

• Their molecular weight.

What are process-related impurities?

• Impurities that are intentionally added to a substance.

• Impurities that are introduced by contamination.

• Impurities that arise directly from the steps involved in the manufacturing or synthesis process.

• Impurities that only form during the storage of a substance.

Which of the following is NOT a general source of impurities mentioned in the text?

• Raw materials and starting materials.

• Manufacturing processes.

• Environmental contaminants.

• All of the above are sources of impurities.

What can manufacturing equipment and vessels contribute as impurities?

• Residual solvents.

• Unreacted reagents.

• Leached metallic elements (e.g., chromium or nickel) from wear and tear.

• All of the above

What can be a consequence of impurities in a drug with a narrow therapeutic index?

• An increase in the drug's potency.

• A diminished therapeutic effect or adverse effects.

• A longer shelf life for the product

• A change in the drug's color or odor.