Seeing precipitate in blood smear slides is a common issue when using classical hematology stains such as Wright or Wright-Giemsa stains. Precipitation can interfere with cell differentiation and sometimes result in misdiagnosis (such as toxic granulation). Ideally, precipitate will not be transferred to your slides, but if you notice this happening, read on.
The presence of precipitate in slides can be caused by a few different procedural issues. Check your procedures to see if any of these corrections should be applied to eliminate precipitate from your hematology slides when using Wright or Wright-Giemsa stains.
1. Swap for fresh solutions in your autostainer
If your stain, buffer, or stain/buffer mix solutions have been in your equipment too long (either you’ve run past the designated slide number or have extended the elements past their ideal out-of-bottle replacement date), they can form precipitate in your equipment. Start with fresh solutions. Create and maintain a schedule within your protocols for swapping these solutions regularly.
2. Clean your equipment
If the stain, stain/buffer, or buffer have been sitting for any length of time, they can form precipitate. To fix, run a cleaning cycle on your autostainer and then start with fresh solutions. Maintaining a cleaning schedule can improve consistency of slide staining and prevent precipitate from forming.
3. Dilute and filter the stain prior to adding to your equipment
If you observe precipitation in the stain, you may need to dilute and filter the stain. Sometimes the stain has been sitting too long and can separate out of the solution. It could also simply form precipitate within the bottle if not sealed properly. Dilute the stain five percent with methanol, shake well, and then filter. Add it to your machine and check for accuracy.
4. Increase the concentration of stain in your stain/buffer solution
Wright and Wright-Giemsa stains will precipitate in water, which is the main component of the hematology buffer solution. Therefore, if you are observing precipitation in the stain/buffer solution, you can try increasing the concentration of stain from 1:10 ratio (10% stain, 90% buffer) to 1:5 (20% stain, 80% buffer).
5. Store at or bring stain to room temperature
If the stain is cold (from transit or storage), warm it to room temperature before using it. Then, shake the stain well to ensure it hasn’t separated prior to adding it to your equipment.
Making these adjustments to your hematology stain protocol will help prevent precipitation or particulates from transferring to your histological slides. If you’re still noticing an issue with precipitate in your stains or hematology slides, consider switching to a new stain provider to avoid ongoing issues.
At Ethos Biosciences, we provide a range of Wright, Wright-Giemsa and Quick stains for hematology. For more helpful tips on staining, download our eBook: Lab Technician’s Guide to Troubleshooting Common Issues with Biological Stains. If you need additional details, please don’t hesitate to reach out. We’re happy to help. Call one of our microscopy experts at 856-224-0900 or email at firstname.lastname@example.org.