Bio-Rad MP-1M User Manual

AG®1, AG MP-1

and AG 2

Strong Anion Exchange Resin

Instruction

Manual

Table of Contents

Page

Section 1 Introduction ............................................ 1

Section 2 Technical Description............................. 1

Section 3 Mechanism .............................................. 5

Section 4 Resin Conversion.................................... 10

Section 5 Instructions for Use................................ 14

5.1 Batch Method.................................................... 14

5.2 Column Method................................................ 15

Section 6 Sample Protocols

Section 7 Applications............................................. 23

Section 8 Product Information............................... 32

Section 9 Technical Information............................ 39

for Anion Exchange Resins.................... 18

6.1 Separation of Metal Ions................................... 18

6.2 Glucose Binding on AG 1-X8 Resin ................ 21

Section 1
Introduction

AG 1, AG MP-1 and AG 2 resins are strongly basic
anion exchangers. They are capable of exchanging
anions of acidic, basic, and neutral salts, and ampholytes
on the basic side of their pI. Strong anion exchange
resins are used for sample preparation, enzyme assays,
metal separations, and peptide, protein, and nucleic acid
separations.

Section 2
Technical Description

Strongly basic anion exchange resins are available
as Analytical Grade AG 1 and AG 2 resins, AG MP-1
macroporous resin, and Biotechnology Grade AG 1
resin. The Analytical Grade AG 1, AG MP-1 and AG 2
resins have been exhaustively sized, purified, and con­verted to make them suitable for accurate, reproducible
analytical techniques. Biotechnology Grade AG 1 resin
is analytical grade resin which is certified to contain less
than 100 microorganisms per gram of resin.

1

AG 1 and AG 2 resins are strongly basic anion
exchangers with quaternary ammonium functional
groups attached to the styrene divinylbenzene copoly­mer lattice. The amount of resin crosslinkage determines
the bead pore size. A resin with a lower percentage of
crosslinkage has a more open structure permeable to
higher molecular weight substances than a highly
crosslinked resin. It also has a lower physical resistance
to shrinking and swelling, so that it absorbs more water
and swells to a larger wet diameter than a highly
crosslinked resin of equivalent dry diameter. For exam­ple, the lower crosslinked resins, particularly AG 1-X2
2% crosslinked resin, are useful for the sorption and
fractionation of relatively high molecular weight sub­stances such as peptides, ribo- and deoxyribo­nucleotides, and uranium. The higher crosslinked resins,
particularly AG 1-X8 8% crosslinked resin, are used for
sorption, exchange, and separation of low molecular
weight inorganic anions, and in applications such as
cyclic nucleotide assays and fractionation of organic
acids. Table 1 shows the approximate molecular weight

2

exclusion limits in water for resins of various crosslink­ages.

Table 1. Approximate Molecular Weight Exclusion
Limits for Ion Exchange Resins in Water

Percent Approximate MW Exclusion Limit

Crosslinking for Globular Molecules

2% 2,700
4% 1,400

8% 1,000
10% 800
12% 400

AG 2 resin is similar to AG 1 resin, but is slightly
less basic and slightly less resistant to oxidation due to
differences in the structure of the quaternary functional
group. It offers advantages in certain applications. For
example, it is capable of separating sugars, sugar alco­hols, and glycosides using a step gradient and borate
buffers without isomerizing some sugars, as AG 1 resin
tends to do.

3

Each AG 1 resin is supplied in the chloride form.
Selected resins are available in the acetate, formate, and
hydroxide form. These ionic forms may be considered
more activated forms than the chloride form, as may be
deduced from the order of selectivity information given
in Tables 2 and 3. AG 1 resins purchased in the more
active forms may be converted to any other form. The
chloride ion, because of its higher selectivity for the
resin, is relatively difficult to replace with formate,
acetate, hydroxide, or fluoride. Thus, if various ionic
forms are to be used, the formate or acetate forms pro­vide flexibility and convenience (see Table 3). Formate
and acetate forms may be used to separate most low
molecular weight biological compounds, such as
nucleotides, hormones, peptides, and carboxylic acids.
AG MP-1 resin is the macroporous equivalent of AG 1
resin. Its effective surface area approximates 23 square
meters per dry gram, 20% porosity.

The physical properties of the resins are listed in
Table 2. The anion exchange resins are thermally stable
and resistant to solvents (alcohols, hydrocarbons, etc.),
reducing agents, and oxidizing agents.

4

Table 2. Guide to Analytical Grade Anion
Exchange Resins

Resin Active Order of Thermal Solvent to Oxidizing
Type Group Selectivity Stability Stability Agents

AG 1

R-CH2N+>phenolate OH-form, Very good Slow

and (CH3)3>HSO4>ClO3fair to 50 °C; solution
AG MP-1 >NO3>Br> Cl-and other in hot 15%
Resins CN>HSO3> forms, good HNO3or

AG 2 R-CH
Resin (CH3)2>HSO4>ClO3to 30 °C; Cl

NO2>Cl> to 150 °C conc. H2O
HCO3>IO3>
H2COO>Ac>
OH>F

N+phenolate>I OH-form, Very good Slow

2

C2H4OH >NO3>Br> forms, good in hot 15%

CN>HSO3> to 150 °C HNO3 or
NO2>Cl>OH conc. H2O
>IO3>H2COO
>Ac>F

-

Resistance

solution

Section 3
Mechanism

In an ion exchange procedure, the counterions on
the resin are replaced by sample ions that have the same
charge. With anion exchange resins such as AG 1 and

5

2

2

AG MP-1, neutral species and cations do not interact
with the resin. In the chloride form of AG 1, AG MP-1,
and AG 2 resin, the counterion on the resin is Cl

-

. A
resin can be converted from one ionic form to another.
Usually the resin is used in an ionic form with a lower
selectivity for the functional group than the sample ions
to be exchanged. The sample ions are then exchanged
onto the resin when introduced, and can be eluted by
introducing an ion with higher affinity for the resin or a
high concentration of an ion with equivalent or lower
affinity. Table 3 shows the relative selectivity of various
counterions. In general, the lower the selectivity of the
counterion, the more readily it exchanges for another ion
of like charge. The order of selectivity can also be used
to estimate the effectiveness for different ions as eluants,
with the most highly selective being the most efficient.
Finally, the order of selectivity can be used to estimate
the difficulty of converting the resin from one form to
another. Conversion from a highly selected to a less
highly selected form requires an excess of the new ion.

6

Table 3. Relative Selectivity of Various Counterions

Relative Selectivity Relative Selectivity

Counterion for AG 1 and for AG 2 Resin

AG MP-1 Resins

OH

-

1.0 1.0
Benzene sulfonate 500 75
Salicylate 450 65
Citrate 220 23

-

I
Phenate 110 27

-

HSO

4

-

ClO

3

-

NO

3

-

Br

-

CN

-

HSO

3

-

BrO

3

-

NO

2

-

Cl

-

HCO

3

-

IO

3

-

HPO

4

Formate 4.6 0.5

175 17

85 15
74 12
65 8
50 6
28 3
27 3
27 3
24 3
22 2.3

6.0 1.2

5.5 0.5

5.0 0.5
Acetate 3.2 0.5

Propionate 2.6 0.3

-

F

1.6 0.3

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The AG 1 and AG MP-1 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. The larger the mesh size number, the small­er the particle size. Table 4 shows wet mesh and equiva­lent micron diameters.

Table 4. Wet Mesh and Equivalent
Micron Diameters

Wet Mesh

(U.S. Standard)

16 20 40 50 80 100 140 200 270 325 400

Micron Diameter

(1 µm = 0.001 mm)
1,180 850 425 300 180 150 106 75 53 45 38

Large mesh material (20-50 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) may be used in

8

batch as well as column applications. Medium mesh is
an ideal, general purpose particle size for use in analyti­cal and preparative scale column chromatography. Fine
mesh material (200-400 and minus 400 mesh) is used
for high resolution analytical separations.

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