This article introduces the features and characteristics of Agilent ZORBAX Eclipse XDB series products. The series is designed for optimal lifetime at intermediate pH range.
This document discusses the degradation issues faced by column packings when used at intermediate and basic pH ranges (pH 7). It explains that silica dissolution creates hydroxyl groups, leading to retention time shifts and peak-shape changes for compounds reacting with silanols.
The text compares two C8 columns under identical conditions over a 125-day period using a phosphate buffer at pH 7. The Agilent ZORBAX Eclipse XDB-C8 (sol-gel type, doubly endcapped) showed only a 10% change in retention time for amitriptyline, whereas a standard xerogel C8 column (singly endcapped) exhibited a 55% increase. The document concludes that double endcapping acts as an effective protective coating against the mobile phase.
| Column Dimensions (Popular C8) | 3.9 x 150 mm |
|---|---|
| Column Dimensions (Eclipse XDB-C8) | 4.6 x 150 mm |
| Recommended pH Range | pH 6-8 |
The change is generally believed to be the result of additional hydroxyl groups created as the silica is dissolved.
Compounds which react with silanols will exhibit these changes.
Endcapping acts as a coating that protects against corrosive mobile phases, similar to how paint protects steel.