Multiple fraction collection using a peristaltic pump and a fraction collector modified for multiple channel operation

The fractionation of gradients in sedimentation analysis of proteins is a time-consuming operation. This operation can be performed more rapidly by using a multichannel peristaltic pump and two or more fraction collectors. Specifically designed fraction collectors are available for multiple fraction collection, notably the Slave Micro-Fractionator (Model SFC-80)¹ from Gilson Medical Electronics, Inc. Use of multiple fraction collectors during the fractionation of gradients has the disadvantage that these units occupy considerable space and are expensive. In addition, the total number of fractions collected from one gradient is often considerably less than the capacity of most fraction collectors. To offset the space and expense disadvantages, we have devised a modification for the Gilson Micro-Fractionator (Model FC-80H)¹ which permits three sets of 25 fractions each to be collected simultaneously from 3 gradients using only 1 fraction collector. A multichannel peristaltic pump is employed, and an attachment which permits three drop tubes to be positioned above the rack of fraction tubes is secured to the drop detector head¹ of the Micro-Fractionator. One drop tube is clamped in the normal manner in the drop detector head, and fraction size is determined by counting drops in the normal manner. Fractions from the other two drop tubes are not counted. Alternatively, fraction size can be determined by adjusting the pump speed and using the timer on the fraction collector.