Author Archive

The Raptor Biphenyl blows away a conventional C18 in this gunpowder assay

A very enjoyable aspect of my position within Restek is the opportunity to work with an experienced and interesting network of chromatographers throughout Europe. This includes the talented scientists at ALSAC in Uppsala, Sweden, who recently evaluated a Raptor Biphenyl column in a customer assay of gunpowder materials. ALSAC (Addtech Life Science Applications Center) has […]

What pesticides have you eaten today?

This was the question asked by Texas middle school student Liesl Krone, and the driver behind her recent (award winning) science fair project. Liesl became interested in food safety after hearing news reports on food quality issues. She loves fruit and wondered if she was consuming pesticides along with beneficial nutrients. To answer that question, […]

Selectivity and the HPLC Mobile Phase

Stationary phase (i.e. column type) is a key contributor to selectivity in LC. But what about the mobile phase? A significant advantage, and sometimes challenge, in LC is that both the stationary and mobile phase chemistries can be modified to optimize our method. This contrasts with GC, where the main selectivity option is the stationary […]

HPLC Guard Cartridges and Extra-Column ‘Dead’ Volume

The benefit of using a guard column with dirty samples is clear. By adding a short sacrificial column before the analytical column, column life increases due to trapping of particulates and strongly-retained compounds. However, adding the guard cartridge does increase the extra-column volume of our flow path. And, extra volume leads to lower efficiency and […]

Improve Retention and Peak Shape for Early-Eluting Pesticides in LC-MS/MS

How important is the HPLC column in a comprehensive LC-MS/MS screening method? LC-MS/MS is quickly gaining acceptance for residue testing, and can simultaneously monitor hundreds of pesticides, including those difficult to detect by GC. With such a powerful detector, hasn’t the column become simply a sample inlet device? While the MS/MS detector allows for specific, […]

Feeling Lost in a Sea of C18s? Try the New USP Column Comparison Tool

With well over 500 available, it is easy to become overwhelmed when selecting a C18 column. Many chromatographers stick with what they know, and use the same C18’s for all method development work. I have certainly been guilty of this! However, very few C18 columns are exactly alike. With a wide range of physical properties […]