Calibration Curves, Part 3: A Different View

This is the third instalment in a series of "LC Troubleshooting" columns that focus on calibration curves used for liquid chromatography (LC) methods. We started by looking at the issue of whether or not to force a calibration curve through the origin (x = 0, y = 0).1 Last month we looked at some techniques to determine the limits of detection and quantification,2 specifically looking at the signal-to-noise ratio (S/N) as a tool in this process. This month we will consider some alternate ways to look at the data to determine if they appear to be normal or are trying to tell us that something is amiss. Next month we'll look at some different calibration techniques.