We have looked at trace metals, (usually indium), in rat tissue by ICP-MS and noted some effects that we attributed to EIEs (Na, K, Mg, & Ca). In the case of indium we observed a decrease in signal intensity with increasing EIEs. For one other element (I can't recall what it was), we observed an increase in intensity with increasing EIEs. We ended up running the samples through an ion exchange column to remove most of the EIEs, and that seemed to fix things.
Also, if you have enough EIEs in your sample to cause problems, you may be simply putting more dissolved solids through the system than it can handle. One of the service engineers who performed maintenance on our system said that dissolved solids above 0.5% can adversely affect the nebulizer and cause odd behavior, due to variations in surface tension caused by variations of EIE concentrations.
William P. Chisholm, Ph.D.
National Institute for Occupational Safety and Health
Health Effects Laboratory Division
Exposure Assessment Branch
1095 Willowdale Road
Morgantown, WV 26505
OFFICE & LAB: 304-285-5977
From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's). <[log in to unmask]> On Behalf Of Lyndon Palmer
Sent: Thursday, May 17, 2018 7:18 AM
To: [log in to unmask]
Subject: Does ICPMS suffer Easily Ionizable Element (EIE) Issues?
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
College of Science & Engineering
Sturt Road, Bedford Park South Australia 5042 GPO Box 2100 Adelaide SA 5001
M: +61 422 737 742
P : +61 8 8201 3536
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