The protocol for a new automated stainer: one thing that must be decided is how often to change solutions. The best choice is to rotate solutions

• A. Based On Manufacturer Recommendations
• B. Based On Time Of Day
• C. Based On Number Of Slides Processed
• D. Based On Slides Stained

Answer: (D)

In automated staining, keeping reagents fresh and performing consistently is tied most closely to how much they have been used. Rotating solutions based on the number of slides stained ensures that a stain’s potency, potential contamination, and overall performance are kept in line with actual workload, so the staining results stay uniform across runs. If you rely on time of day or simply on how many slides are processed, you can either refresh too early and waste reagents or refresh too late and risk drift in staining intensity or background. Using the actual usage signal—slides stained—directly addresses when a solution is likely to start underperforming, making it the best basis for rotation. Manufacturers’ recommendations are guidelines, but aligning rotation with how many slides have been stained captures real-world usage and maintains consistent quality.