Chromatography Forum

Does anyone have any suggestions on how to obtain a RRF of 0.05 or higher for 1,4-dioxane using EPA 8260B by purge and trap? It would have to be part of a regular run so no SIM method. We have a client that requires RRF of 0.05 or higher for all TCL compounds except ketones which they will accept 0.01.
Any suggestions would be appreciated or you can just tell me, no way!

My current RRF for 1,4-Dioxane under a regular 8260 Method is 0.001-0.002 using 1,4-Difluorobenzene as the internal standard.

Unless you choose some internal standard that has very poor response I really don't see how you can get that response factor up to 0.05. I have to put 1,4-Dioxane into my calibration mixes at 4x concentration just to get it to show up on my lower standards. You may increase the response factor if you start doing a heated purge but I don't know how much it would improve purgeability.

Oh, also looking back at EPA8260 it lists 1,4-Dioxane with a PP for purge and trap which is poor purgability and only list Azeotropic Distillation(EPA 5031), Vacuum Distillation(EPA5032) and direct injection as adequate sample introduction techniques. So from that alone I would say that it would not have acceptable RRFs for regular purge and trap methods. If the client absolutely needs that RRF then they will have to be willing to pay to have it run with as a separate method, otherwise they will have to settle for poor RRFs.

Quick way to do it is to use dioxane-d8 as the internal standard. Set it up as a special analysis and charge extra for it. Your RRF will be ~ 1.0.
Their insistance on a minimum relative response factor is a back door way to keep the internal standards similar to the targets. Works well if you can afford it, most customers won't want to pay for it. As an example of how far you can go with it check out method 8261.

Quick way to do it is to use dioxane-d8 as the internal standard. Set it up as a special analysis and charge extra for it. Your RRF will be ~ 1.0.
Their insistance on a minimum relative response factor is a back door way to keep the internal standards similar to the targets. Works well if you can afford it, most customers won't want to pay for it. As an example of how far you can go with it check out method 8261.

That would be something that would work, and if it is still down to cost for two runs, you could add that internal standard to your 8260 run because 8260 allows for other internal standards to be used, the ones listed I believe are labeled as suggested internal standards.

I can suggest the extra internal standard, but the client has very specific requirements. At least it's an alternative to keep in mind if they are as insistent as they seem to be.

Thanks for the suggestions.

It works better with a VOCARB trap than with the tradition Tenax/Silica/Carbon trap, but I would be surprised to see 0.05 RRF for this analyte when used with the ordinary 8260 internal standards.