0.2 um filters for sterile filtering/possibly viscous solutions

[Eugen Leitl]

Happy $holidays!

A quick question: I need to sterile-filter several 10 l of a
reasonably viscous solution into autoclavable borosilicate
lab bottles.

This is typically done with syringe filters,

http://www.gilsonuk.com/catalogue/product/itemNo/ALG422A

but that's on a too small scale, and for rather nonviscous
solutions.

I was thinking about repurposing household items like
http://www.amazon.de/Keramikfilter-Wasserfilter-NEU-Filter-Feinfilter/dp/B002RLKE7O/
or http://www.amazon.de/Polypropylene-Auswaschbar-UMKEHROSMOSE-WASSERFILTER-SEDIMENTFILTER/dp/B002RLZS7U/

Has any of you done that? How did you sterilize the assembly?
(Polypropylene is obviously only cold-sterilizable, and
I suspect the plastic parts of the ceramics one won't
survive autoclaving either).

At this point I'm thinking about overnight soaking the ceramics
filter/whole filtering assembly in hydrogen carbonate/hydrogen
peroxide, 70% isopropanol or bleach, and flushing out the assembly
for an hour with reverse osmosis water, possibly prefiltered.

Thanks and a nice 2013 to ye all.

[Sebastian S. Cocioba]

Almost all PP is autoclavable but may risk slight deformation over a long period of time. At standard autoclave temp of 121 C it will be 9c below polyprop melting point. I sterilize my eppitubes, cutting sheets, etc if i see the PP 5 symbol on the plastic. Tips may deform if your autoclave is not steady at 121.

Sebastian S Cocioba
CEO & Founder
New York Botanics, LLC

Sent via Mobile E-Mail

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[Eugen Leitl]

On Mon, Dec 31, 2012 at 11:53:27AM -0500, Sebastian S. Cocioba wrote:
> Almost all PP is autoclavable but may risk slight deformation over a long period of time. At standard autoclave temp of 121 C it will be 9c below polyprop melting point. I sterilize my eppitubes, cutting sheets, etc if i see the PP 5 symbol on the plastic. Tips may deform if your autoclave is not steady at 121.

Thanks, but this is a 0.2 um PP filter. Not only will it warp to the point where
it might leak at the sames, it will likely ruin the pore size.

I'm not sure how gentle the local autoclaves are, as this is a shared
facility. It will certainly reach 121 deg C, but is arguably likely to
exceed it.

[John Griessen]

On 12/31/2012 10:43 AM, Eugen Leitl wrote:
> At this point I'm thinking about overnight soaking the ceramics
> filter/whole filtering assembly in hydrogen carbonate/hydrogen
> peroxide, 70% isopropanol or bleach,

Sounds good. No experience though.

and flushing out the assembly
> for an hour with reverse osmosis water, possibly prefiltered.

How would you be sure that RO water stream is sterile? Run through tubing
past a UV light source?

[Eugen Leitl]

On Mon, Dec 31, 2012 at 11:08:14AM -0600, John Griessen wrote:

> and flushing out the assembly
>> for an hour with reverse osmosis water, possibly prefiltered.
>
> How would you be sure that RO water stream is sterile? Run through tubing
> past a UV light source?

The reverse osmosis plant arguably does UV-sterilization but there's
no accounting for biofilm colonization downstream. I will check using
a microscope, of course, but for time being I consider the reverse
osmosis water to be bacterially contaminated. I will make sure that
everything downstream of the filter will be sterile, and the filter
assembly itself will be sterilized by cold wet sterilization (abovementioned
soaking) prior to flushing it.

In case of success all the biocontaminants will be contained within
the ultrafilter. Residual ones will be killed during autoclaving.

[Avery louie]

It might be possible to get pre sterilized filtration bottles.  Nalgene makes them pretty cheap.  No muss, no fuss, and they are vacuum assisted!

--A

[Eugen Leitl]

On Mon, Dec 31, 2012 at 12:49:17PM -0500, Avery louie wrote:
> It might be possible to get pre sterilized filtration bottles. Nalgene
> makes them pretty cheap. No muss, no fuss, and they are vacuum assisted!

We'll just flush
http://invitroshop.de/shop/laborbedarf/laborglas/laborflasche-simax-371.html
with ultrafiltered reverse osmosis water, and autoclave these prior
of sterile-filtering into them, then autoclave them prior to
fastening the cap.

This is labor-intensive, but the result should have some pretty
good shelf half life.

[Avery louie]

They also make filters to go on bottles:

http://fishersci.com/ecomm/servlet/fsproductdetail_10652_12704331_29104_-1_0?LBCID=26030796

--A

[Brian Degger]

Something like this?
http://vgdusa.com/pall-capsule-filters.htm
Cheers
Brian

--
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Brian Degger

twitter: @drbrian

http://makerspace.org.uk

http://transitlab.org

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[Nathan McCorkle]

the pore size is what's going to determine the pressure requirement for forcing the fluid past the membrane, so you could just parallelize with the smaller filters if you can't find a larger diameter one.

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-Nathan

[Nathan McCorkle]

I called these folks last week looking for filters, they're pretty much the industry standard for this sort of thing in biotech, they were very helpful to me so maybe you can give a call and ask for higher volume items

http://www.millipore.com/membrane/flx4/millipore_filters_hm#tab1=1

--
-Nathan

[Eugen Leitl]

On Mon, Dec 31, 2012 at 01:08:27PM -0500, Avery louie wrote:
> They also make filters to go on bottles:
>
> http://fishersci.com/ecomm/servlet/fsproductdetail_10652_12704331_29104_-1_0?LBCID=26030796

Thanks, these look just the ticket. Water jet vacuum with a sterile syringe membrane
in between to prevent contamination and sucking back of liquid, and we're in business.

[Josiah Zayner]

If something is highly viscous try and use a centrifugation step before you filter or even Wattman paper. I have used those filter you found and they will be clogged just as fast as a syringe filter.

[Eugen Leitl]

On Fri, Jan 04, 2013 at 02:13:25PM -0800, Josiah Zayner wrote:
> If something is highly viscous try and use a centrifugation step before you
> filter or even Wattman paper. I have used those filter you found and they
> will be clogged just as fast as a syringe filter.

The solution itself is viscous. There's another complication:
the components (ethanediol/Me2SO) might well destroy the
filtering membrane.

I just checked http://www.spectrumlabs.com/dialysis/Compatibility.html
and it seems limited exposure will be doable.

However, the solutions themselves have turned out to be
not autoclavlable, so we'll have to settle to add a few
ml injection-grade water to bottles and autoclave these,
then sterile-filter and store under vacuum in the fridge.

> On Tuesday, January 1, 2013 5:09:32 AM UTC-6, eleitl wrote:
> >
> > On Mon, Dec 31, 2012 at 01:08:27PM -0500, Avery louie wrote:
> > > They also make filters to go on bottles:
> > >
> > >
> > http://fishersci.com/ecomm/servlet/fsproductdetail_10652_12704331_29104_-1_0?LBCID=26030796
> >
> > Thanks, these look just the ticket. Water jet vacuum with a sterile
> > syringe membrane
> > in between to prevent contamination and sucking back of liquid, and we're
> > in business.
> >
> >
>

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Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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[Cathal Garvey]

I bought some ceramic "candle" filters for water sterilisation which would probably be good for sterilising large volumes of non-viscous liquid. You can autoclave them, AFAIK.

However, I've never had call to sterilise volumes large enough to test them; they are large enough that filter losses would be significant.

www.indiebiotech.com
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PGP Public Key: http://bit.ly/CathalGKey

[Sebastian S. Cocioba]

http://vgdusa.com/whatman-syringe-filters.htm

These are autoclavable. 

Sebastian S Cocioba

CEO & Founder

New York Botanics, LLC

Sent via Mobile E-Mail 

[Eugen Leitl]

On Sat, Jan 05, 2013 at 06:00:39PM +0000, Cathal Garvey wrote:
> I bought some ceramic "candle" filters for water sterilisation which would
> probably be good for sterilising large volumes of non-viscous liquid. You
> can autoclave them, AFAIK.

You're probably looking at http://www.amazon.de/Keramikfilter-Wasserfilter-NEU-Filter-Feinfilter/dp/B002RLKE7O/
or http://www.amazon.de/Keramikfilter-Kartusche-Wasserfilter-Partikelfilter-Filterkerze/dp/B00AAV53O2/

How do you know the plastic parts would not warp
and cause leaks?

Also, this is just the filter cartridge, you'd need to sterilize
the whole assembly.

> However, I've never had call to sterilise volumes large enough to test
> them; they are large enough that filter losses would be significant.

At volumes of 30+ liters, that's the least of my worry.

[Cathal Garvey]

> How do you know the plastic parts would not warp
> and cause leaks?

Only the vague recollection that the seller said they were sterilisable.

> Also, this is just the filter cartridge, you'd need to sterilize
> the whole assembly.

Yea, I was planning to just screw the thing into the bottom of a large container with an O-ring sealing with the bottom of the vessel, but I discovered to my dismay that the thread pitch on the fitting of the filter cartridge is really annoyingly non-standard, and it's hard to find a matching tap. So, as I had no pressing need to continue, I shelved it until TEOTWAWKI ( https://en.wikipedia.org/wiki/TEOTWAWKI ). :P

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