Dry heat sterilization – Hot air oven selection: Which of the following materials are appropriately sterilized by heating at 160 °C in a hot air oven for about one hour (dry heat method)?

Introduction / Context:
Dry heat sterilization in a hot air oven is suitable for moisture-sensitive, non-aqueous, or items that may corrode with steam. Understanding which materials tolerate dry heat ensures both sterility and preservation of function. This question targets common items often processed by dry heat rather than moist heat.

Given Data / Assumptions:

• Dry heat works by oxidative damage and protein denaturation at high temperatures.
• Typical regimens include 160 °C for approximately 1–2 hours or 170 °C for shorter durations.
• Materials must withstand high temperature without deformation or loss of properties.

Concept / Approach:
All-glass items, dry swab sticks, and non-aqueous substances like oils and jellies are classic candidates for dry heat. Steam does not penetrate oils effectively, and moisture can degrade certain formulations. Plastics (e.g., latex gloves) generally deform—hence they are not ideal for dry heat, reinforcing why the inclusive option refers specifically to items known to be compatible: glassware, dry swabs, and oils/jellies.

Step-by-Step Solution:
1) Identify materials compatible with dry heat: glass, metal, powders, oils, greases, and dry swabs.2) Confirm that all-glass syringes withstand 160 °C.3) Recognize that oils/jellies are not effectively sterilized by steam; dry heat is preferred.4) Conclude that each listed item (A–C) is appropriate; therefore choose “All of these.”

Verification / Alternative check:
Pharmacopeial and lab standards list dry heat for depyrogenation and sterilization of oils and heat-resistant glassware, supporting the selection of all listed materials.

Why Other Options Are Wrong:

• Each of A, B, and C alone is correct, but the stem expects the comprehensive choice.
• Latex gloves: deform with heat; typically sterilized by gamma irradiation or ethylene oxide, not hot air ovens.

Common Pitfalls:
Applying moist heat universally; overlooking that oils resist steam penetration; assuming plastics tolerate 160 °C without damage.

Final Answer:
All of these.