We all know how EIE effects impact on axial/end on ICPOES but I am wondering if this happens with ICPMS, which after all is axial based system and is measuring ions?
We have recently been evaluating the purchase of an ICPMS Triple Quadrupole instrument which we are going to use for plant analysis on a large range of plant material types. As we routinely analyse between 25,000 - 30,000 samples per year we have developed a routine digestion and dilution technique that tries to cover the whole range of elements in the different sample types with minimal variation in the dilution step.
As you may be aware the concentration ranges in plant/grains etc. for the major elements (Na, K, Ca, Mg) and to a lesser extent P and S can vary hugely along with even elements such as Al and Fe.
For example we recently analysed:
1. Celery which had a K concentration of 8.0% w/w while Brown Rice can be as low as 0.28% K.
2. Celery which had a Na concentration of 9600 mg/kg w/w while Brown Rice can be as low as 5.2 mg/kg.
3. Camellia leaves which had an Al concentration of 8200 mg/kg while Brown Rice can be as low as 5.6 mg/kg.
To do this we have set up a calibration range on the ICPMS for:
1. K from 0 - 100 mg/L.
2. Na from 0 - 10 mg/L.
As part of our evaluation I think I saw what appeared to be upward curvature of the Na and K calibrations with these concentrations on the ICPMS - is this possible or is something else happening?
I know there are potential issues with how system ensure linearity over the total dynamic range of their detectors and how they cross calibrate their Pulse and Analogue modes but I thnk I have taken this into account.
Flinders University Plant Nutrition
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