Frequently asked questions
Question 1: How many columns can I run simultaneously with one vacuum chamber and fraction collector?
In principle, one can run up to four columns simultaneously with this fraction collector. To do this, one has to modify the test tube racks so that they advance one rack at a time (there are 17 six-position racks), rather than one position at a time. Furthermore, one has to modify the cover plate of the vacuum chamber, so that the four columns can drip simultaneously into four different test tubes. Although this is possible for small columns, it is not very practical for larger columns. The reason is that with this arrangement there are only 17 tubes for each column. If each of these tubes holds 10 ml effluent, then only 170 ml can be collected from each column before one needs to open the vacuum chamber to replace the filled tubes with empty ones. This is less than one pore volume for many columns filled with soil (note that the volume of one collected pore volume depends on the size of the column and its water content). Thus one has to open the vacuum chamber and replace the full test tubes frequently.
Copyright © 2005 Soil Measurement Systems. All rights reserved.