dinoseb and diazomethane and EPA 8151

[ravenwork]

Greetings,

We experience low recoveries for dinoseb after hydrolysis and methylation by diazomethane, using EPA method 8151.

Is this a methylation issue? Would adding BF3 catalyst improve this?

E. L. Cooper

[vballchemist]

The method addresses this somewhat in the interferences section. " ...hydrolysis may result in the loss of Dinoseb and the formation of aldol condensation products if any residual Acetone (is present)..."

I experience this also and wonder if there are other problems associated with this loss. To check methylation you should obtain a reference standard in the acids form and methylate this without extraction.

[Steve Reimer]

For help with any EPA SW-846 method try the MICE service:
http://www.epa.gov/epaoswer/hazwaste/test/mice.htm
(703) 676-4690

This method (and the drinking water methods 515.x) are a compromise. Not all the target analytes work well under the specified conditions.
If you hydrolyze and back-extract you will lose any pentachloroanisole present as it won't hydrolyze and will be removed in the wash.