Gradient Master - Wolf Laboratories

A before and after scan of a gradient showing how tilted tube rotation can quickly, accurately and
reproducibly produce a linear gradient from the two endpoint solutions layered in the tube.
2.4 Cushions and shelves
Cushions are often applied to the bottom of gradients to trap particles that might otherwise
pellet to the bottom. The best way of doing this is to remove the cushion’s volume from the bottom
of a finished gradient and layer the cushion solution under the gradient. Its volume and density are
determined by the type of particles to be trapped.
2.5 Temperature
Temperature is an important part of gradient use, since some particles are very
thermolabile. There are two ways to make gradients that will be used at non-ambient temperatures:
Make them in the cold room with cold solutions and keep them cold until use or make them warm
and then chill them before use. While the “all cold” method is theoretically the best, it requires
unreasonable temperature rigor to reproduce, since temperature has such a drastic effect on the
density and viscosity of density media. The chilling of room temperature gradients will lead to some
convective mixing, but experience has shown that it is minimal. Since virtually all the run parameters
for gradient forming were developed at room temperature, chilling the room temperature gradients
is the way to go.
8