Dear Mr. Romig:

Was your purchase of a new burner to reduce burner apparature plugging
due to the high solids in the samples?  If so, try diluting your sample
by 4X, then performing the method of standard additions with the dilute
solution.  Based upon the concentration you are measuring (125 mg/L),
a 4X dilution will still leave you in the manufacuterers recommended
operating range.

Have you attempted to employ a nitrous oxide/acetylene flame?  Although
this fuel mix is regarded as reducing sensitivity, we have had success
employing nitrous oxide/acetylene in the measurement of chrome.  Despite
the manufacturers suggestion, the nitrous oxide technique improved spike
recovery and duplicate relaibility without reducing sensitivity.  I
would also experiment with the flame stoichiometry to maximize
sensitivity.  There are several elements we test which are very
sensitive to the fuel flow.

Lastly, it is posssible to supress interferring speicies by adding 4%
wieght to volume uranyl nitrate to all samples and/or prepared standards
(See Varian technical literature). This may not be practical with the
method of standard additions however.

Good luck and feel free to call me if you have further questions.

Regards,
Ted Stern
Claude Romig wrote:
>
> We are running an Electroless Nickel/Immersion Gold line, one bath of
> which contains Ruthenium.  We use a Varian Spectra20 AA to measure the
> Ruthenium via method of additions.  I recently purchased a new burner to
> be used solely for this line.  The machine was inspected early this
> year.  Two analyses of the same sample yield values of 67 and 147 ppm
> (the specification is 125 ppm).  Frustrating.
>
> Does anyone know another method that I can use to measure the Ru?
> Thanks.
>
> Claude Romig, Process Engineer
> Westak, Oregon
>
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