Drastic fall in the recovery of Internal standard ICP MS ELAN 9000

Dear Sir,

There is a drastic fall in the recovery of internal standard (Y, Bi, Tb, In) to the tune of 50 %. That too after 2-3 samples.
Kindly help,

Do the recoveries come back up when you run a blank or CCV? Have you tried diluting the samples? It could be the matrix.

yes when I run a blank sample or standard recovery comes back.

It's the sample matrix, you'll need to dilute them.

I have been having the same problem with Bi for Tl and Pb in my sample.  My internal drops about half and my sample RSD is about 30%.  When I further dilute the internal standard drops further but the RSD is much better at 2%.  If I dilute less then the internal standard comes up but my RSD goes back to 30%.

Any suggestions would be helpful.

Thanks

If you dilute your sample 5-fold, it's normally your IR drops also 5 fold, unless you use an online addition system for your IR or spike additional IR on your dilution

What's weird is that this only happens with Tl and Pb internal Standard...the rest of them are fine.  Could it be specific to those two masses?

How is your IR added?
Do you add it to a sample prior to sample digestion? Do you add it after sample digestion? Do you use a mixing tee and add it prior to analysis?

What are your other IR? Are they added in the same way?

I add the internal standard directly into my sample.  I added Pb and Tl to my In internal standard reading and it seems to have worked out.  I think Bi just did not like Pb and Tl.