John Dolan has been writing "LC Troubleshooting" for LCGC for over 25 years. One of the industry's most respected professionals, John is currently a principal instructor for LC Resources, Walnut Creek, California He is also a member of LCGC's editorial advisory board.
Count the Cost, Part 2: Increasing Resolution by Increasing Retention
April 1st 2017We will discover how to find the “sweet spot” in terms of retention for a liquid chromatographic separation as well as how much retention change can be expected for a selected change in organic mobile-phase percentage or column temperature.
Count the Cost, Part I: Increasing Resolution by Increasing Column Efficiency
March 1st 2017When considering column efficiency, more is not always better. We look at some ways to quickly estimate the effects of changes in column length and particle diameter rather than trying the experiments in the laboratory.
Count the Cost, Part 1: Increasing Resolution by Increasing Column Efficiency
March 1st 2017When considering column efficiency, more is not always better. We look at some ways to quickly estimate the effects of changes in column length and particle diameter rather than trying the experiments in the laboratory.
Reader’s Question: Early Eluted Peak
November 1st 2016What could be causing a peak to be eluted before the column dead time? In last month’s “LC Troubleshooting” (1) we looked at problems two readers had with ghost peaks in gradient runs. This month, we’ll continue looking at submitted questions and examine one submitted by another reader of this column.
The Hydrophobic-Subtraction Model for Reversed-Phase Liquid Chromatography: A Reprise
September 1st 2016Reversed-phase liquid chromatographic columns can be compared quantitatively for differences in selectivity by means of the hydrophobic-subtraction model. This allows selection of columns that are either equivalent or different in selectivity. The present paper both presents a summary of this approach and shows in detail how to use it in practice.