WeaponsRx - 4-1-2015 at 01:43
Hey guys, So I have a question regarding the whole buchner filtration apparatus. I have a Millipore 47mm Buchner Filtration apparatus with a PTFE
faced filter holder. What im filtering must go through a .22um PTFE membrane filter so that the filtrate is properly filtered, but the filter paper
has to be sterile of course as well. So with all the choices of .22um 47mm PTFE filters out there on the market, 90% of which are NOT sterile, How
does one go about making these "unsterilized" filter papers Sterile and ready to filter my liquids? I've heard that you actually place the filter
paper in position on the Buchners filter holder, line up the top funnel, place the clamp on and throw that into the autoclave, and once finished out
comes a sterile filter paper indeed ready to use but can anyone confirm this? I do have a automated autoclave with dry cycles and all, but I dont see
that being the only way, or even the correct way to being able to utilize these unsterilized filters... I know many will say just purchase sterilized
paper then... well I cant afford it obviously lol, but how is it that THEY have sterilized the papers then? wonder if I placed them in pouches and
then autoclaved them would also obviously be an option, then when ready removing them from the pouches accordingly? Any help would be very much
appreciated as this is by far the most important for my experiment. Thanks guys.
Chemosynthesis - 4-1-2015 at 04:16
I have been lucky enough to be in labs that were well enough funded to buy the fancy pre-sterilized filters in the events I needed them, and never
needed them when I wasn't in a well-funded lab, so I am not as certain as I would like to be... but I believe the filters are industrially sterilized
with cobalt-60 gamma sources. Depending on the setup, the radiation can actually produce the pores.
Your idea sounds feasible, and I would give it a try.
Pasrules - 4-1-2015 at 05:14
Radiation is the way to go and I doubt you have isotopes on hand so instead you can bag your filter and subject it to a high intensity antibacterial
dark light or if you want to do it on the really cheap side and throw it in the microwave however I highly disrecommend the second option for
analytical testing.
Dr.Bob - 4-1-2015 at 18:04
Heating in an autoclave would work. Or you could filter some ethanol for a while (no vacuum), that would likely remove any bacteria. not sure about
viruses. They do sell sealed filters for those guys, Pell sells some, I believe. I'll look and see if I have any of them, I have a few 47 mm
filters floating around. Many people use the syringe filters for sterile applications, as you can buy sterile syringes and then suck up the liquid
w/o a filter and then filter out through a sterile filter. I use that technique (not in a sterile manner) sometimes for filtering air sensitive
reactions, using a PP syringe and a PTFE filter, great for removing Pd/C or Raney nickel residue. I have lots of those filter assemblies if anyone
else wants one, they are great for filtering biologicals.
macckone - 4-1-2015 at 19:32
Depending on what you are trying to ensure isn't present on the filter then autoclaving is the way to go. PTFE is stable up to about 200C. Keep in
mind that dead bacteria can contaminate things as well as live ones. Also some bacteria are resistant to 'dry' heat while others are resistant to
'wet' heat. But usually even they can't live much beyond 100C.
WeaponsRx - 4-1-2015 at 21:05
Yea unfortunately I dont have any spare isotopes im willing to part with at the moment haha so thats not an option.. but @ Dr.Bob, yea I actually have
used syringe filters before, do you have any sterile .22um or .45um hydrophilic PTFE ones you'd like to sell? Let me know unless you believe you may
have some of the 47mm filter papers that are the same! I just have a lot of solution to filter so my hands begin to get sore as hell. There is the
caulking gun method which works well, but i'd really like to take advantage of the apparatus of course... But alright so most of you think if I place
them in autoclave bags it should be sufficient enough to deem them sterile? I could put them in at 121*C for 30 min. with a 30 min dry cycle but I
just cant run the risk of contamination if it doesnt do the job correctly.
@Macckone well honestly I just need to assure that my filtrate is free of all that a .22 micron filter is intended to filter out of the solution, how
ever I can best make the solution sterile... Now I understand that dead bacteria can be a contaminant, so after autoclaving, how would one go about
removing all thats been killed from the filter? Filtering methanol after? Problem is methanol cant be in the solution so how would I go about purging
the methanol from the filter if that would work? in this case im better off finding sterile filter paper hahaha
WeaponsRx - 7-1-2015 at 18:12
thats it huh? ended there?
