Uranyl Formate Solution

Preparation of a 0.75% uranyl formate solution for negative staining for single-particle applications

Notes

Uranyl formate is light-sensitive.

Procedure

1. Weigh out 37.5 mg of uranyl formate into a small beaker.

2. Add 5 mL boiling deionized water and stir it for 5 minutes in the dark.

3. Add 5 $\mu$L of 5 M NaOH to the solution, which will become slightly darker yellow (do not add too much NaOH) and stir it for another 5 minutes in the dark.
4. Filter the solution with a 0.2-$\mu$m syringe filter into a 15-mL Falcon tube wrapped with an aluminum foil.
5. One preparation of solution can be only used for a few days.