I am using Agilent 7700x (He collision mode) for Hg quantification in blood.
No memory effects we have.Calibration curve is linear,recovery is correct, QC and background are good.
But when we read "normal" samples (expected concentration below 5 ppb) ,in some samples , (20-30%) ,we found values about 10-15 ppb. Wht?s hapenning? .