What is one of the key steps in ensuring the integrity of a solution before use?

Checking the expiration date of solutions is crucial for ensuring their integrity and safety before use. Over time, solutions can degrade, lose their effectiveness, or even become harmful. The expiration date indicates the period during which the manufacturer guarantees the full potency and safety of the product. Using solutions past their expiration date can lead to ineffective treatment or unintended side effects for the patient.

In clinical practice, it is essential to routinely verify expiration dates as part of maintaining proper inventory and ensuring that all products used are safe and effective. This process protects both patient health and the overall quality of care provided.

While the other options involve varying procedures, they do not adequately ensure the solution's effectiveness and safety in the same fundamental way as checking the expiration date does. For example, storing solutions in sunlight can cause degradation, shaking a vial can introduce air bubbles or particles, and mixing with saline may alter the intended concentration or efficacy of the solution.