This is very dangerous advice. Big samples can blow up big time. Despite
monitoring the degradation of the oven, the real issue is the built-in
safety mechanisms of laboratory systems.
Very best regards,
Scott W. McGeorge
Transition Technologies Inc.
3044 Bloor Street West, Suite 605
Toronto, ON, M8X 2Y8, Canada
[log in to unmask]
Transition Technologies is the Canadian Distributor for:
Transgenomic Inc. molecular biology workstations
CETAC Technologies elemental analysis instruments
----- Original Message -----
From: Bondarowicz, John <[log in to unmask]>
To: <[log in to unmask]>
Sent: 15-Nov-99 9:56
Subject: Re: Microwaving very large Samples
> Dear Friedholm,
> I have used ordinary "kitchen" model microwaves to do complete
> decompositions in microwave transparent Parr bombs. I have even used
> ordinary Pyrex glassware for the container. Naturally these machines
> were not designed to be used in corrosive atmospheres but they only
> cost about $100 US which is a small fraction of what commercial lab
> units cost. I got about 6 months for moderate use (10-20 samples per
> week). The wiring started to corrode so we disposed it and bought a
> new one (using petty cash). If you try this approach obtain a full
> power unit with a carousel. If you get serious about using these I
> have thought that spray painting the internal components with an
> based paint may extend the life of the unit but I am not sure of
> The bombs are expensive . I remember them to cost about $500 each
> from Parr. I do not think there is anything special about commercial
> oven type units except for there durability and programmability
> (which is special to some) but for this you pay dearly. If you have
> the time to develop a slower (one at a time) method you are limited
> the size of the ordinary microwave oven.
> Another unit I particulary liked was the Prolabo. (I think it is sold
> and distributed under other names as well). The unit I tried focused
> the microwaves on the sample rather that bounce them around a
> I do not mean to leave other manufacturers out but this is my
> experience. I am sure the commercial closed vessel ovens work great
> on some samples but I had my "challenges" with early versions on
> polymeric samples. It can get messy and dangerous in closed vessel
> Finally, I have done hundreds-thousands of sulfuric acid digestions
> in the Tecator block digestor (about $6000) US and found it to
> well with microwave for polymeric samples. Load up about 24 samples
> and forget about it for a day or so. You can also use quite a bit
> more sample material than you can with closed vessel bombs and you
> don't have to compromise on replicates and blanks because of time.
> The long tubes act as condensers when a capped with a glass funnel.
> These are commonly used for Kjeldahl digestions.
> Yes, I am aware of analyte loss in open vessel digestions so we know
> to use internal standards for critical elements.
> John Bondarowicz
> ______________________________ Reply Separator
> Subject: Microwaving very large Samples
> Author: "Friedhelm vonBlanckenburg" <SMTP:[log in to unmask]> at chicago1
> Date: 11/15/1999 8:03 AM
> Does anybody know of a microwave system that is capable to take very large
> reaction vessels; that is to decompose tens of grams of silicate with
> further tens of grams or more of HF ?
> Friedhelm v. Blanckenburg
> University of Berne