These columns, packed with 1.8mm particles, are said to be an ideal choice for analyses with difficult-to-separate components and for methods that have minimum resolution requirements
Agilent Technologies Europe has introduced new 1.8 mm-particle Zorbax rapid resolution high throughput (RRHT) columns for liquid chromatography (LC) which, it says, double the efficiency of a standard 3.5mm column.
The high efficiencies of the RRHT columns provide improved resolution between peaks and faster analysis times.
These columns, packed with 1.8mm particles, are said to be an ideal choice for analyses with difficult-to-separate components and for methods that have minimum resolution requirements.
These small particle columns are available in short (15 to 50mm) lengths with the most popular Zorbax bonded phases for very high throughput applications.
The RRHT columns can provide efficiency gains of two to five times over more conventional sized particles if an optimised LC system is used. To determine the efficiency gain, Agilent scientists tested the efficiency of a 4.6mm x 30mm RRHT column versus comparable 3.5mm and 5mm columns under the same conditions.
For the analysis of acetylsalicylic acid, the calculated efficiency of the RRHT column was 6474 plates, twice as high as the 3.5mm column (3170) and more than three times the value of the 5mm column (1980).
The high efficiency of the new columns is due to the continuous improvements in silica manufacturing, which have enabled the development of high-purity silica and smaller silica-based particles.
High-purity silica with low metal content allows separation of polar compounds without the peak tailing associated with less pure silicas.
Small particles of 3.5mm, and now 1.8mm, have very narrow particle size distributions and produce highly efficient columns.
LC columns packed with small particles can be shorter and have efficiencies comparable to longer columns packed with larger particles.
This allows shorter analysis times, with the added benefit of using less solvent.
Even with the increase in speed, resolution between closely eluting peaks is not compromised.
One issue with using small-diameter particles is the possibility of premature plugging by particulates present in the packing material, which reduces column life.
To test the lifetime of the RRHT columns, a series of injections was performed on a 4.6mm x 30mm RRHT column.
The RRHT column demonstrated excellent column life, with no plugging problems evident and no change in retention time or peak tailing, even after more than 2500 injections.
