Millipore filters can be successfully CPD'd in envelopes made from
folded filter paper, closed with a staple at the open edge. I use Whatman
541 4.25cm papers routinely with 12mm filters. The sample code can be written on
the paper with pencil, and this mark can then be used to determine the "up"
side of the sample e is invisible to the eye.
John Warrack- John Warrack-lnotes@sb.com
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From: GVKM07Aprodigy.com (DR CHARLES A GARBER)
Subject: Curling of membrane filters
If the curling of membrane filters is a problem, then try using our
silver membrane filter product, exactly like the polymer membrane
(e.g.MCE) product in structure but made out of pure silver. Any curling
is very slight and the bonus is that what ever conductive layer is
eventually applied can be much less (maybe no conductive coating at
all in fact) because of the inherent conductivity of the substrate. The
aluminum oxide membrane filters are even stiffer, but are not
conductive, but the pores are the smallest available in any membrane
filter product (e.g. 20 nm). These are on pages 53 and 54 of our SPI
Supplies 1991 SourceBook (catalog) of products for the EM laboratory.
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From: GVKM07Aprodigy.com (DR CHARLES A GARBER)
We have been making for some years a product called "Microporous
Specimen Capsules". The original product had a pore size range of
120-200 um, and is our part SPI #13215 and has overall dimensions of 10
mm x 10 mm. However, you will have to cut out a small piece of the
membrane filter prior to insertion of the piece into the capsule.
We have a second product, exactly like the first, but with a pore slze of 78um which
should be used if the features on the membrane at that small. Be very certain that your Millipore filters are of the polycarbonate
type and NOT nitrocellulose, as these will not survive the CPD. The
problem with the polycarbonate filters though, is that they tend to roll up
into tight tubes when dried. To hold them in place during CPD, I cut them
into grid-sized pieces and clamp them between a 50 mesh folding (oyster)
grid. Several of these can then be mounted on a single stub.
-=W.L. Steffens=-
In reply to your question about handling millipore filters
containing bacteria and zooplankton for SEM, we do this sort of thing by
covering the filter containing the sample with a spacer (which comes packaged
between the filters) and sandwich that between two washers which are held
together with small alligator clamps. Be sure when you purchase the washers that
they are made of a material which will not rust. I'm not sure what the ones I
use are made of....perhaps stainless or aluminum. I took them to a
trophy shop and had numbers engraved on them to help with sample identification. What we have done is to put two filters face to face and hold them
together using the cap of a BEEM capsule that has had a large hole
punched in it with a cork borer and a ring cut from the top of the capsule
that will fit inside the cap. SO it qoes cap, then two filters, then the ring on top and
push them together. Something like an embroidery hoop. FROM: Greg Erdos gwe@biotech.ufl.edu
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FROM:Tamara Howard,
A lab I used to work in had Millipore filter cassette dealies - you
could put a filter in, your sample, then another filter, and the cassette part
was sort of the "bread" for this sandwich. The cassettes could be processed
and CPD'd, then the filters removed and stuck down to stubs. The problem is that
I've tried to find these things in catalogues and can't, and the filter
people don't know what I want. But you can try to make them - from the syringe
filters (the kind that screw together) - just cut the ends off a bit. I've
tried that, and it worked, but I've only used them for TEM samples, so I
don't know if these holders will CPD without bubbling. I hope this makes some
sort of sense! If not, write and I'll try to explain, or FAX a design or
something
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College of Veterinary Medicine
University of Georgia
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From: sfzaneunccvm.uncc.edu (Sandra F. Zane)
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