Bio-Rad BioFrac™ Fraction Collector - Manual (Page 65)

User Guide | 57
5 Stand-Alone Operation
Normal operation of the BioFrac™ fraction collector is in Local mode (stand-alone
mode). As a stand-alone fraction collector, the BioFrac device may be used to
collect fractions based on time (minutes), volume (milliliters), or drops (up to a flow
rate of 5.0 ml/min). In Local mode, the fraction collector controls all aspects of
fraction collection and is not in communication with Bio-Rad’s BioLogic DuoFlow™
chromatography system, BioLogic™ LP system, or Model EP-1 Econo™ pump.
However, it may be connected to separate components, such as a UV monitor, a
chart recorder, and a pump, as described in Connecting Instruments and Devices to
the BioFrac Fraction Collector on page 16 .
There are four modes of collection, each of which can include a delay function:
 Collect All — enables you to collect an entire run without diverting any
fluid to waste.
 Peak Detection by Threshold — enables you to collect peaks by defining
a threshold value (percent of full scale) above which fractions will be
collected. This method can be used only when the fraction collector is
connected to a UV monitor. When the UV signal is less than the threshold,
fluid is diverted to waste. Alternatively, it may be collected in tubes with a
non-peak fraction size. A slope function is built into the threshold function
so that double peaks above the set threshold level are detected and
collected separately.
Note: False peaks above a threshold (such as electrical noise or air
bubbles) may be filtered using the bubble filter time function. See Appendix
A, Bubble Filter Time , on page 83.