Icp oes MSIS

Hi everyone,  need your help

i am in development MSIS for determination of mercury. 

I have read article about msis, and used the set up msis spraychamber, but i didnt use l-cystine or tartaric. I just used NaBH4

I get intensity in 50ppb Hg that i wanted, although that just used NaBH4, so i continue the test with sample and i get good recovery.. But after 5 sample i saw droping intensity and my recovery CRM also droping. 

My problem is dropping intensity,  any sugestion? 

Was this helpful?