Capital HPLC

The Inertpak family of LC columns from Capital HPLC is based on a new generation high purity silica which
exhibits a remarkable degree of chemical inertness and stability. The Inertpak range is therefore particularly
effective in the analysis of amines, basic pharmaceuticals andotherchemicalspecieswherehydrogenbondingmay
occur. This also makes Inertpak columns generally suitable for the vast range of non-basic applications
currently performed on older technology stationary phases.

In the reversed phaseanalysis of basic /aminecompounds,severe peak tailing often occurs, and is mainly due to the material.
This leads to strong electrostatic interactions with the electron deficient regions of basic molecules resulting in peak tailing.

The tendency for a silanol group to undergo self ionisation depends on its electronic environment and is exceptionally strong when the adjacent silicon atom is substituted by a metallic impurity. Figures 1 and 2 above
illustrate the stabilising effect of metal impurities on ionised silanols.

Existing silica technology produces LC packing materials
which contain substantial amounts of metallic impurities,

Figure 1
Free Silanol (Moderately Acidic)

            Figure 2
            Metal Activated Silanol (Highly Acidic)

presence of surface silanol groups which remain after the
derivatisation procedure. End capping with trimethyl silyl
groups helps to eliminate surface silanols, but is never
completely resolves the problem.
The material used for the Capital HPLC Inertpak column
family represents an innovative solution to the problem
of residual silanol interactions.
Surface silanols are known to undergo self-ionisation
leading to fixed negative charges on the surface of the

notably sodium and iron which lead to the presence of
highly activated silanols which contribute to peak tailing.
The inert silica used in Inertpak columns uses a synthesis
route producing a high purity material with a very low
metal content. Consequently residual silanols following
the end capping process are inactive and therefore do not
create the interactions which cause peak tailing.

Specifications

Phases:

Particle Diameter:

Carbon Loading

: Spherical

: 5 micron

: C8(10.5%)
: C4(7.5%)
: Ph(10.0%)
: ODS2(18%)
: ODS-80Å(17.5%)

Mean Pore Diameter                 : ODS2 (150Å or 80Å)
                                                  : Ph,C8,C4 (150Å)
Surface Area                             : 320-350m2/g
                                                  : 450m2/g (ODS-80Å)
Assured Efficiency                    : 55,000 plates/m
                                                  (Typically 75,000)

 - Chemically Inert
- Excellent for Basic Compounds
- High Efficiency
- Good Peak Shape
- Stable over a Wide pH Range

In addition to the inertness towards basic compounds, Inertpak columns can also be operated over a wider pH range than conventional materials. The above tests illustrate the good stability of Inertpak in contact with aggressive mobile phases at high and low pH values.

New packing materials create morestring entrequirements when it comes to packing procedures. The proprietary packingprotocol, designed by our development laboratory, allows us to supply columns in all formats from capillaries to preparative scale columns, exclusive to Capital HPLC.
This packing procedure, in concert with Capital HPLC's stringent quality control assures you of reproducible cost effectiveanalysis.
Amitryptyline, the antidepressive drug, is known to be particularly sensitive to the presence of active silanol groups when analysed by reversed phase LC.
The Inertpak Inertness Test shows a comparison of the analyses of this compound on a conventional ODS; a leading brand base deactivated material; and Inertpak.

In the case of the conventional ODS material, the drug is irreversibly adsorbed onto the packing material and does not elute, whereas the base deactivated material elutes the drug with severe peak tailing. With Inertpak a perfectly formed symmetrical peak is observed.

Bases of Nucleic acid and Nucleosides

Column : Inertpak ODS2 5μm
150 x 4.6 mm I.D.
Eluent :
0.1M H3PO4 + 0.2M NaClO4 (pH2)

Flow rate : 1.0 ml/min.
Detector : UV 260nm

1. Cytosine         2. Uracil
3. Guanine          4. Adenine
5. Cytidine          6. Uridine
7. Thymine         8. Adenosine
9. Guanosine      10.Thymidine