Which one of the following factors can contribute to the contamination of a sterile product?

The factor that can contribute to the contamination of a sterile product is the chemical composition. Certain ingredients in a formulation may be more susceptible to degradation or contamination due to their chemical nature. For instance, some excipients might enhance microbial growth or lack sufficient stability when exposed to common sterilization methods. Understanding the chemical compositions of ingredients is crucial in sterile compounding, as this knowledge can help identify potential risks for contamination and guide the appropriate handling and sterilization techniques.

In contrast, while time of preparation, method of delivery, and manufacturer can influence overall product safety and quality, they do not directly relate to the inherent risk of contamination as understood in this context. Time of preparation could affect sterility if prolonged in non-sterile environments, and method of delivery could impact the integrity of the product post-preparation. Manufacturer quality systems and standards impact the final product's quality but are less related to the specific risk factors within the chemical composition of the ingredients themselves.