Measuring Cr in high ferrous material

Question

Hi
does anyone have an explanation for the fact, that I have a lower result for Cr (approx. 30%) with material with a high iron content, e.g. Millscale, with the measuring mode 'NoGas'? Measured with He mode, the results are correct. Measured with ICP-MS Agilent 7800, digestion in HNO3, HBF4 and water.
Thank’s and regards

johnkane · Accepted Answer

Hello 
 It is most likely an Argon Carbon interference. Ar(mass 40) + C (mass 12) will be the same mass as Cr most abundant isotope at mass 52. 
 He mode is great for avoiding polyatomic interferences. Since polyatomic species (ArC) are larger in size than individual atoms (Cr), the polyatomic species are slowed down in He mode by kinetic energy discrimination. 
 Hope that helps

Measuring Cr in high ferrous material

Top Replies