Excellent Run to Run Precision

Tizanidine has several amine groups which can present problems to chromatographers. Residual silanols on the surface of ordinary Silica-based Columns can electrostatically interact with these groups, causing peak tailing.

The Cogent Amide Column, used in the Application Note is virtually free of residual silanols and therefore a symmetrical peak shape can be obtained. An overlay of five consecutive runs demonstrates the run- to-run precision when using these columns.


Method Conditions
Column: Cogent Amide™, 4μm, 100Å
Catalog No.: 40036-05P
Dimensions: 4.6 x 50mm
Mobile Phase:
A: 90% DI Water / 10% Acetonitrile / 0.1% Formic Acid (v/v)
B: Acetonitrile / 0.1% Formic Acid (v/v)

Time (Minutes) %B
0 90
2 90
6 40
7 90

Flow rate: 1.0 mL/minute
Detection: UV @ 230nm
Injection vol.: 3μL
Sample Preparation:
4 mg strength Tizanidine HCl tablet was ground and weighed in a 10 mL volumetric flask. A portion of 50/50 solvent A/ solvent B diluent was added and the flask was sonicated 10 minutes. It was then diluted to mark and filtered with a 0.45µm Nylon syringe filter (MicroSolv Tech Corp). An aliquot was then diluted 1:10 with a diluent of 10% solvent A / 90%.

Note: Tizanidine is a centrally acting α2- adrenergic agonist used to treat spasms, cramping, tightness of muscles, and related conditions. It is available under the trade name Zanaflex® as well as generic versions.


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