PCR thermal cyclers.

Andy Law Big Nose lawa at bbsrc.ac.uk
Fri Aug 12 05:11:38 EST 1994

In article <776448610snz at compo.demon.co.uk>, Peter at compo.demon.co.uk wrote:

> Dear Bionauts,
>   My wife is examining the cytokine profiles of various tissues from
> patients using PCR. She is about to purchase a thermal cycler for the lab but
> wonders if anyone has any advice to give on the relative advantages, and dis-
> advantages, of different makes? To me these cyclers just sound like VERY
> expensive, admittedly very precise, heating blocks.
> Thanks in anticipation
> Pete and Anne Crilly

My advice would be to get the reps from each company to bring in their
respective models and leave it with her to try out for a few weeks. As you
say, these machines are damned expensive. It is in their interests to keep
the customer happy. Also, the only real way to get acquainted with how the
machines operate is to get in there and get your hands dirty as it were.
Plus, you get some work done (admittedly not much if you are doing
properly controlled evaluations) for free.

Things to consider are:-

1) Ease of programming. All PCR machines appear to have been built by
people who don't do PCRs for a living. Those that have been built by
people who know what Taq polymerase is are tested by people who never have
to change the program parameters once they have been set up. In the real
world, users often need to change program parameters, especially during
the first few weeks of operation when conditions are being optimised. If
you are faced with a choice between two machines which seem to offer the
same performance, then take the one that you find easiest to program. IMHO
some of the operations required to program some of the machines are
downright BIZARRE.

2) Tube handling. Most machines offer the capability to deal with a
variety of tube sizes. Others don't. Look at what you are doing now and
what you think you might be doing in the future and see if the machine you
are investigating can deal with that. In particular, there are decisions
to be made with regards to 0.5ml tubes vs 0.2ml tubes vs 96 well plates vs
96 well plate format tubes.

3) Heated lids versus oil. Oil overlays are time consuming and messy. A
lot of the newer machines offer sealing technologies (which work to lesser
or greater degrees) and heated lids that eliminate the need for oil. This
is a big bonus in labs where large numbers of samples are processed
(providing that the lids actually work!)

4) Peltier vs non Peltier technology. Swings and roundabouts really.

5) Price. Don't be afraid to hammer the reps down on price. You have the
money. They want it. Competition is fierce. Make them work for it.

Probably everyone who expresses an opinion on this subject will prefer a
different machine. There really is only one way to decide and that is to
get in there and play with the machines until you find one that works.

Hope this is helpful

Andy Law

( Lawa @ bbsrc.ac.uk                     Big Nose in Edinburgh )

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