Bio-Rad Bio-Rex® 5 Anion Exchange Resins - Manual (Page 5)

All three resins are available in several particle size
ranges. The flow rate in a chromatographic column
increases with increasing particle size. However, the
attainable resolution increases with decreasing particle
size and narrower size distribution ranges. Particle size is
given either in mesh size or micron size. Mesh refers to
the number of openings per inch on the screens used to
size ion exchange resins. Therefore, the larger the mesh
size number, the smaller the particle size. Table 3 shows
wet mesh and equivalent micron diameters.
Table 3. Wet Mesh and Equivalent Micron Diameters
Wet mesh 16 20 40 50 80 100 140 200 270 325 400
(U.S. Standard)
Micron diameter 1,190 840 420 297 177 149 106 74 53 44 37
Large mesh material (20-50 mesh and 50-100 mesh)
is used primarily for preparative applications and batch
operations where the resin and sample are slurried
together. Medium mesh resin (100-200) is also used in
batch operations, although the primary use of medium
mesh resin is for column chromatography in analytical
and laboratory scale preparative applications. Fine mesh
material (200-400 mesh) is used for high resolution
analytical separations.
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Table 2. Techniques for Resin Conversion
Resin: AG 4-X4 resin
AG 3-X4 resin
Bio-Rex 5 resin
Conversion from (1) : Cl - free base+OH -
Reagent used: 0.5 NaOH (2)
Volumes of solution per volume of resin: 2
Flow rate (3) ml/min/cm 2 of bed: 1
Test for completeness of conversion: Cl -(4)
Rinse: volume DI water per volume resin: 4
Test for completion of rinsing: pH <9
(1) Typical conversions are listed. The same reagents
can be used to convert from other ionic forms. Two
step regeneration, ion exchange followed by
neutralization, is included because of ease of
conversion and savings on expensive reagents.
(2) Use U.S.P. or C.P. grade (low chloride).
(3) For 50-100 or finer mesh resin. For 20-50 mesh,
about 1/5 the flow rate is recommended.
(4) Test for Cl - in effluent: Acidify sample with a few
drops of conc. HNO
3
. Add 1% AgNO
3
solution.
White ppt indicates Cl - , yellow Br - or too basic.
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LIT207B 9/2/98 10:03 AM Page 6