Choosing a PCR machine
kaplan at research.nj.nec.com
Sun Aug 27 08:51:09 EST 1995
I've just gone through a search for a PCR machine and thought I should
share some of my experiences/impressions. I looked only at machines
with heated lids.
Perkin Elmer 2400:
We bought one, use it, and find it to be great. They are coming out
with a new version of the software soon which is supposed to implement
some of the diagnostic buttons that don't work currently. Older models
should be upgradable by changing a chip.
Limitation: 24 wells.
Perkin Elmer 9600:
We bought one and find it to be good, but difficult to program
compared to the 2400. Built like a tank. And about as large.
The 9600 is a dinosaur that will be overtaken by smaller machines in the
next few years.
Limitation: It cools very slowly below ambient temperature.
Apparently the cold side of the condensor is warmer than for the 2400.
MJ Research DNA Engine:
Beautiful machine. Almost the same price as a 9600 demo. The PE2400
is easier to program (the 9600 is harder).
At one point I had the PE2400, PE9600, and MJ Engine next to each other on
the bench racing. They all kept the same
pace within a few seconds until the final cool to 4 C. The 2400 was
almost twice as fast at the MJ and the PE9600 took over 10 minutes
(15 minutes is spec for the 9600). MJ's heated lid is less substantial
than PE's designs making it possible to close the lid tightly and have
unsealed tubes in the machine.
Limitation: The peltier elements (according to MJ) have a finite
lifetime of about 5 yrs. The peltier part of the system can be easily
swapped out so failure shouldn't result in much down time. MJ's older
machines have a reputation for having Peltier failures. The DNA engine
is too new to have a substantial track record. MJ claims to have changed the
mechanical engineering of their heating block to reduce mechanical
strain and prolong Peltier lifetime.
Good machine. Substantially cheaper than the others (except the
2400). Heated lid has a very different, and good (tight and firm)
design. Blocks can be swapped.
Limitation: To avoid peltier failures, Techne machines change
temperature slower than MJ and PE. Heated lid is a separate
unit with a separate power cord.
Beautiful, fast, and inexpensive. Reasonable heated lid. Has almost all
the features of the 2400 for less money and holds 96 tubes. I think
that Savant also markets this model (but repaints it).
Limitations: Fan cooling, not compressor or peltier. Can't cool below
ambient. Perfect second machine. Software is changing faster than
the operators manual.
Ericomp Delta Cycler:
Cheap and fast. Heated lid is terribly designed. Lid does not make
contact with the tubes (you hope! when I saw the lid touch the tubes,
the caps melted). Programming is more confusing than any other machine.
Limitations: Terrible mechanical design. Insists on using -in
sample- temperature probe (because they don't believe in the heat
diffusion equation?) which uses up one of your 96 tubes. Ericomp's
reputation is based on their water cooled devices without heated lids.
The Delta Cycler is a venture into very new territory for them.
--Peter (kaplan at nec.research.nj.com)
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