Low but stable Internal standard recovery on ICPMS 7900

I am having a similar issue, but with my run this only happens after a more concentrated sample is added.  I can run a 1:10 dilution of that sample without a drop in recovery but more concentrated samples have issues.  My sample is 0.5g in 50 mL.  So the 1:10 is essentially 0.5g in 500 mL.  Everything else is the same as far as diluent goes.  I thought matrix issues at first until I noticed my QC's and blanks also had a low recovery.  Any idea's here?    

I am having a similar issue, but with my run this only happens after a more concentrated sample is added.  I can run a 1:10 dilution of that sample without a drop in recovery but more concentrated samples have issues.  My sample is 0.5g in 50 mL.  So the 1:10 is essentially 0.5g in 500 mL.  Everything else is the same as far as diluent goes.  I thought matrix issues at first until I noticed my QC's and blanks also had a low recovery.  Any idea's here?    

Hi Gavin, your sample is way too concentrated for ICP-MS. It is difficult to say before we see the replicates but I would recommend finding a way to measure it with 1:1000 dilution or you can go with UHMI (Ultra High Matrix Introduction) method, if you have it in your software available. 0.5 g in 50 mL = 10000 ppm. It is even for OES way too concentrated. 

So, am I seeing a result of saturation on the detector or have I contaminated my cones to the point they need to be cleaned?  I had a hunch the concentration was too high, but I wasn't sure why the QC's and blanks that ran after also registered with low ISTD recovery.  I did notice lower counts during the batch tune the next day so I thought maybe the cones were the issue. 

Hi Gavin 

You can clean/replace nebulizer,sampling tubes,cones and torch then run to see.

I hope, expected contamination will remove to get optimise result...