paraformaldehyde to IFA - (Aug/22/2005 )

Hello, I am preparing a fixation solution with paraformaldehyde 4% in PBS to my inmunofluorescence assay, but it does not dissolve, can anyone help me?

Thank you very much!

Hi, I just came across making up 2% paraformaldhyade solution. It took me a whole afternoon to get it dissolved. I tried to use NaOH and HCL to make final PH between 7.2-7.3, and leave it at 65-70 degrees in a 50 ml tube. Remember to give some shake every 5 minutes or so. I hope it works out for you too.

PFA is really not fun to dissolve, but I found making a 20% solution in milliQ water works best. 1st make a water bath on a heat plate (a 2000ml beaker filled 1/4 full H2O and get the temp up to 60 degrees C-use thermometer in water bath). For 1 liter of 20% PFA add 200g PFA intp a 1000ml beaker and add MilliQ up tp 800ml. Put in water bath with stir bar. Don't let heat get above 60 degrees. Let it stir at 60 degrees for 1/2 hour. Add about 0.5ml 10N NaOH to help dissolve. It should only take about another hour to dissolve. When is all dissolved, add rest of milliQ up to 1000ml. Cool, filter and store at 4 degrees C. Will last about 5-6 days. Make your 4% from this stock in your buffer no more than 2 days before use.
Good Luck.
CKern