Germanium as a internal standard

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wertik
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Germanium as a internal standard

 HI,

I wish this is the right place to write my issue.

I'm working with PerkinElmer Elan DRC-e. Our lab is spcialized in trace elements determination in serum. I've made an effort to create new method for Se measurment with Ge as internal standard. First problem occured when we tried to calibrate. The recoveries were getting higher with increasing concentration of calibration standards. We prove that Ge suffer from spactral interfernces based on iron isotope. Human serum have several times higher concentrations of iron than selenium so the recoveries in clinical samples were also that high like in standards [130-150%]
Do you have any ideas to solve this problem ? I have also tried with Rhodium and Tellurium. Both trials failed.

In addition, we have PerkinElmer Nexion 350D which works on the same matrices [sera] and there is no problem with Ge recoveries. 

DRC gas [both instruments]: Methane

wertik
wertik's picture
Hi, I solved my problem. The

Hi, I solved my problem. The reason was in DRC Ion Path parameters - CPV, CRO, AFT. Properly tuned DRC voltages bring Elan to life. Now recoveries are normal 90-110%. Precision was great - 30 measurement of CRM and +/- 1,7 ug/l.