Looking for extra-light mineral oil for PCR

Bryan L. Ford fordb at bcc.orst.edu
Tue Apr 29 03:27:27 EST 1997

MM wrote:
> Looking for extra-light mineral oil for PCR.
> I am doing PCR with robot. To prevent drying I add oil to the
> microplates first, than set up PCR mixes.
> In that case a drop of water phase is not centered in
> the microplate well: it often hangs on the side.
> I use Light Mineral Oil from SIGMA,
> 0.84 g/ml. Can anyone recommend any extra-light mineral oil?


Density of oils is unlikely to vary as much as you would like. But
density is not really the problem here. Once you are substantially below
the density of the PCR mix (and mineral oil is) the issue then becomes
the ease with which the oil flows up around the aqueous droplet. I
suggest you consider a lower *viscosity* oil. You can definitely find
oils with much lower *viscosities* than light mineral oils. Kerosene or
kerosene and mineral oil mixtures can readily be used. If you wish to
have a high purity oil, then some high purity n-alkanes could be used,
such as 99+% n-decane or n-dodecane; about $45 to $50 for 500 ml from
Sigma. Incidentally these two alkanes have densities of 0.73- 0.75 g/ml,
and thus meet your original request as well. Depending on the lid
retention scheme in your PCR thermocycler, you may want to make certain
that the vapor pressure of any light oil at 95 degrees is minimal enough
to prevent the tops from popping off.

Good luck,

Bryan L. Ford

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