4% Paraformaldehyde in 0.1M Phosphate Buffer.
(Use special glassware for fix.)
To make 500mL:
1) Heat milli-Q water (200mL) to about 80 C using water bath.
2) Place hot water from step 1 on a stir plate.
3) Add 20 g paraformaldehyde crystals while stirring.
4) Add drops (about 20) of 1.0N NaOH slowly until paraformaldehyde is well dissolved.
5) Add 250mL 0.2M sodium phosphate buffer
(210mL dibasic and 40mL monobasic).
6) Transfer to graduated cylinder and add milli-Q water to get a final volume of 500mL.
7) Test pH of a small aliquot using pH test paper. Adjust to approx pH 7.4.
8) Filter and store in a fixative fridge.