Hello Unni and other FCers, I know everyone says one should always make up fresh paraformaldehyde each time, but I make up a big batch of 10% paraformaldehyde (from powder) in PBS, pH it, aliquot it, and freeze the aliquots at -20°C. I make up the aliquot size so that each aliquot has to be thawed and refrozen only a few times. So far, this has been fine for my applications (immunofluorescence and flow cytometry one time) and I use 0.5% to 4% paraformaldehyde. After I take out the required amount of PF from the 10%stock, the aliquot goes back in the freezer until the next experiment. Sincerely, Min At 10:21 07.06.99 +0000, Unni Hadeland wrote: > >Para- or not-formaldehyde? > >I`ve learned that when you dissolve 1g of solid paraformaldehyde in 10 ml PBS >by extensively heating (boiling) and shaking you get 10% fresh paraformaldehyde >which at 4% is perfect for fixing cells for Flow cytometry if used whithin for 4 >days, then you have to make a new fresh one. By reading the e-mails here, I >understand what I really have is hydrolysed paraformaldehyde, i.e. formaldehyde. >But will it be completely hydrolysed? Or do I have to by the solution of >formaldehyde containing 10-15% methanol? Or the methanol-free commercially >available formaldehyde? (Why is the commercially made "ultrapure" formaldehyde >fresh/unpolymerized for one year, whereas the home-made hydrolysed >paraformaldehyde (i.e. formaldehyde) is fresh for only 4 days?) > >Thanks much! > >Unni Haddeland >Research Laboratory >Akershus College >Ringstabekkvn 105 >1365 Bekkestua >NORWAY > Min Ku, Ph.D. c/o Schuemperli Lab University of Bern Zoology Institute Baltzerstr. 4 3012 Bern Switzerland phone: 031 631 4681 email: min.ku@zoi.unibe.ch
This archive was generated by hypermail 2b29 : Wed Apr 03 2002 - 11:53:35 EST