Chromatography Forum

I have developed and validated three analytical methods for detection of various bioactive molecules--Vitamin A; Thiamine; and Riboflavin. When I presented them at a "break out session" at a regional nutrition science conference, two of the audience members questioned--why I'm not using gradient elutions. I responded to them that why use a gradient when isocratic worked just fine--it's much simpler & faster to prepare runs (a major point) and less taxing on the software-regulated proportioning valves (but that is a minor issue). I'm curious--How would you'all here defend such a thesis?

isocratic methods are more robust when transferrring from instrument to instrument, especially if mobile phase is premixed (versus online mixing).

Remember the rule of K.I.S.S.

Isocratic method is faster as long as the capacity factor is similar for your analytes because there is no re-equilibration between runs. Faster means less expensive.

We always use isocratic if it works for the assay. Like the other posters stated: different systems will be "more different" with gradients, and I've seen many issues with insufficient post-run or re-equilibration time/volumes. So real throughput is usually more with isocratic.