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Cyanide Gold Solution Analysis By XRF

I am currently working for a company that performs Au analysis of their cyanide-based baths (type 1 and 3) by XRF. Although this instrument is over ten years old, it appears to furnish results that are well within the degree of accuracy required for Au add determination, etc... The problem arises from a new XRF that was recently purchased in order to take advantage of the advances in software, multiple layer thickness determination and real-time emission analysis of unknown metallic samples. I have not been able to obtain usable results whatsoever when analyzing said cyanide gold solutions. My cyanide gold salts in DI water standards are not effective on this new instrument. If I didn't know better, I would suspect matrix interference/ signal supression, but why? And why not on the older XRF? Different X-ray lamp energies? Any input would be of help. I can easily say more, but I'll throw this out there for the time being!

Robert Belter
- San Diego, California, USA
2003

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I have used this instrument. It operates on radio active isotopes. The older unit may have been loosing it's energy. The newer unit is full. If your standards do not work, contact the company and ask them for a set of new standards. This may be the problem. If their standards are still out, the instrument is faulty.

Good luck. It is a nice instrument and should work for you. First impression is it is out of spec.

Bob Forrest
- Maine
2003

I don't think you quite understand. I make my own standards and it's the NEW instrument that's giving me grief. The same calibration run on the two XRF's give me two totally different results. Outside gravimetric analysis shows that our old XRF is close to the mark whereas the new instrument will give me 60% of actual value, at best.

Robert Belter
- El Cajon, California, USA
2003

I think you should go back to the supplier or manufacturer of the new XRF. They may be able to give you specific recommendation on its use or applicability to the specific type of sample at hand. Just like most analytical instruments, absolute accuracy is not possible, if they are dependent on synthetic calibrations standards. Based on what you said you are getting, 40% less than the actual value is quite significant and could indicate errors in standard preparation.

PANCHO MACALINCAG
- Auckland, New Zealand
February 23, 2011