Trace Element - Internal Standard

ljstoot

Hi Team,

First off I am a fish scientist so I apologise for my lack of chemistry knowledge.

I ran some transects of otoliths (fish ear bones) using an ICPMS. And I am at the DRS and trying to input an internal standard. I have a couple questions;

1.) We ran Ca44 and I see that Ca43 is usually used as an internal standard.. is it ok to use Ca44? Does that mean that I am using the run Ca44 values as a standard and it will not produce Ca44 as a result?
2.) If I am using % wt for Ca44 do I need to input the oercent weight value (ie 39) for all NIST610, NIST612 and outputs or are the values individual to each number?

Apologies if these are silly questions!

Joe

Hi ljstoot

1) It will probably be fine to use Ca44, and yes, if you use it as an internal standard with the normal trace elements DRS, you will not get a Ca44_ppm output. You know the Ca concentration since it was used as an internal standard.

2) I don't quite follow the question here, but each analysis (/selection) in the internal standards table can have its own element, value, and units. So, for example, if you select everything in the table and set the element to to Ca44, the NIST Ca concentrations should be automatically picked up from the reference material data, and so you will likely see those values in ppm (₈₅₀₀₀ ppm Ca). Values for your otolith will not be picked up automatically, so you would then select the subset of rows in that table corresponding to your otolith and set the units and value as desired (wtpc is fine).

All the best,

ljstoot

Thanks Joe - this totally makes sense!

Appreciate the reply!