Bio-Rad BioFrac™ Fraction Collector - Manual (Page 75)

Collect Using a Delay Function
User Guide | 67
Collect Using a Delay Function
The delay volume is the volume of fluid contained in the path between the
significant detector, typically the UV monitor, and the fraction collector drophead.
When the system is plumbed, there is typically a length of tubing between the
detector(s) and the fraction collector. Fluid in the path of the detector must pass
through this tubing to arrive at the fraction collector. Thus the length of the tubing
defines the delay volume. Although the volume in the tubing is generally small, it
may be significant when collecting a small fraction size. To synchronize the detector
signal with the fraction collector, the fraction collector advance can be delayed while
the fluid passes through the tubing. The fraction collector advance can occur when
the fluid reaches the drophead of the fraction collector. Although this is most
important when using threshold fraction collection, it is advantageous to have this
synchronization at all times. Delay can be entered in units of time, volume, or drops
and has the same units as the fraction size. The delay volume can be determined by
either of the following methods.
 Use a syringe and fill the tubing (from the UV monitor outlet to the fraction
collector drophead) with water. Then expel the water into a separate
container and weigh it.
 Use the known volume of any inline devices and measure the length of the
tubing between the UV detector and the drophead. Table 20 lists the
volume of commonly used tubing and devices.
Table 20. Volume of commonly used tubing and inline devices
Tubing Dimensions PEEK Tubing Color Volume
0.005 inch (0.127 mm) ID* Red 0.322
l/inch
0.010 inch (0.254 mm) ID Blue 1.288
l/inch
0.020 inch (0.508 mm) ID Orange 5.145
l/inch
0.030 inch (0.762 mm) ID Green 11.577
l/inch
0.040 inch (0.016 mm) ID – 20.581
l/inch
0.050 inch (1.270 mm) ID – 32.160
l/inch