PURGE AND TRAP METHOD 8260 1, 4-DIOXANE

[msbonner]

We are having difficulty with 1,4-dioxane. We are using EPA method 8260 and have increased the purge temperature to 60 C. We must achieve a relative response factor of 0.005 for this analyte. We can do this when purging 5ml samples but not when we purge 25ml samples. Has anyone solved this problem?

[JI2002]

Why do you have to achieve RRF of 0.005?

[msbonner]

The epa requires it.

[JI2002]

Where can I find the document? I like to read about it. Thanks.

[msbonner]

it is in the current epa contract laboratory statement of work. you can get it off the epa web site.

[JI2002]

I searched the EPA website and still could't find the document, could you please provide a link here?

Go back to the question: There are a few ways to increase the response of 1,4-Dioxane and other water soluble compounds such as tert-butanol, acetone.
1) temperature: Obviously you have tried this. But improving the purging efficiency by rising the temperature has its disadvantages. This will bring a lot of water into the system, it could compromise the detection of other analytes. You have to increase the dry purge time to minimize the effect of water(if you are using OI #10 trap, dry purge doesn't help much). Another problem is breakdown of MTBE and other ethers, high temp and acid solution is the recipe for them to degrade.
2)salt: Using salt to improve the sensitivity of 1,4-Dioxane can be very helpful. This may require using soil mode instead of water mode of the autosampler. This can take a toll on the autosampler.
3)Increase perge flow rate: This can be successful if your system can tolarate high purge flow rate(make sure gases still have decent peak shape and sensitivity)
4)Bypass the water management(Tekmar) or change the default desorb temp of the water management from 0C to 100C(OI)

You didn't give any detail about your system and parameters used, don't know if you have taken some of the measures. Otherwise, could give it a try.

I know a lot of labs struggling with this compound on RL, but not on RRF. The lowest one I heard of was about 15 ug/L running with whole 8260 list. If using SIM, RL of 2 ug/L is achievable. But using SIM doesn't help with RRF, it only decrease the background. ( A service technician from a company making P&T once claimed he can calibrate 1,4-Dioxane to about 2.5 ug/L using SCAN, it's just hard to believe). The new Agilent 5975, I think, can do SCAN and SIM in one run. This can potencially solve the 1, 4- Dioxane RL issue, but not sure about RRF>0.005. If EPA requires RRF>0.005, you need to have a RRF of about 0.008 consistently. Otherwise you can have QC pass this time, but fail the QC the next time. Don't know if EPA labs can do it. The bottom line is 8260 is not a goog method to run 1,4-Dioxane, 8270 is the way to go.

Please post here if you solve the problem.