Currently I am working on a project that has 10% of magnesium oxide. It is pharmaceutical product. It dissolves freely in water. I am not digesting the sample. The acid matrix currently I am working is 2.5% nitric acid +0.5% hydrochloride acid+ 2% sulfuric acid. I am adding thiourea solution in dilution to get 0.1% concentration.
Calibration curve is good for all elements (cd, pb, as, hg, co, no, v), internal standards also the recovery is around 100%.
When it comes to samples and spiked samples the intensities are down to 75% (both analyte and internal standards). The intensities are same throughout the Samples.
I am thinking my sample containing magnesium oxide is causing suppression of intensities. The final concentration of magnesium oxide is going to ICPMS is 0.2mg/ mL. Anybody faced same issue ever before.
Thanks in advance