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Category: p1
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Published on 11 March 2013
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Capital Inertpak
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,
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Figure 1 Free Silanol (Moderately Acidic)
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Figure 2 Metal Activated Silanol (Highly Acidic)
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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
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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.
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Specifications
Phases:
Particle Diameter:
Carbon Loading
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: Spherical
: 5 micron
: C8(10.5%) : C4(7.5%) : Ph(10.0%) : ODS2(18%) : ODS-80Å(17.5%)
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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)
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- 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.
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INERTNESS TEST

Inertpak Ordering Information
Catalogue numbers refer to 5μm materials 4.6mm column i.d. only. For 2.1mm or 3.2mm diameter
columns please add D2 and D3 respectively to the standard 4.6mm i.d. columns. Prices for 2.1mm and
3.2mm i.d. columns are as for 4.6mm i.d.
Conventional Column Format
5μm prices only
Phase 2cm 5cm 10cm 15cm 20cm 25cm |
(guard) |
Silica 5MA102 5MA105 5MA110 5MA115 5MA120 5MA125 |
C4 5MD102 5MD105 5MD110 5MD115 5MD120 5MD125 |
C8 5MF102 5MF105 5MF110 5MF115 5MF120 5MF125 |
ODS-2 5MG102 5MG105 5MG110 5MG115 5MG120 5MG125 |
Phenyl(Ph) 5MK102 5MK105 5MK110 5MK115 5MK120 5MK125 |
ODS(80Å) 5ML102 5ML105 5ML110 5ML115 5ML120 5ML125 |
PRICE/£ see price list - page 3 |
Universal Cartridge Columns (UCC)
5μm prices only
Phase 2cm 5cm 10cm 15cm 20cm 25cm |
(guard) |
Silica 5MA102 5MA305 5MA310 5MA315 5MA320 5MA325 |
C4 5MD102 5MD305 5MD310 5MD315 5MD320 5MD325 |
C8 5MF102 5MF305 5MF310 5MF315 5MF320 5MF325 |
ODS-2 5MG102 5MG305 5MG310 5MG315 5MG320 5MG325 |
Phenyl(Ph) 5MK102 5MK305 5MK310 5MK315 5MK320 5MK325 |
ODS(80Å) 5ML102 5ML305 5ML310 5ML315 5ML320 5ML325 |
PRICE/£ see price list - page 3 |
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
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