I have been following your Iodine problem thread and would like to point you to our paper where we addressed the issue of iodine blanks on ICPMS systems as part of our method development for Iodine in breast milk analysis using 1% TMAH.
We found 2 significant areas within the ICPMS that showed memory effect i.e. iodine baseline slow to come back to low acceptable levels; the auto-sampler wash station and the uptake tubing/nebulizer/spray chamber area. Depending on the prior use of the ICPMS instrument (nitric acid digests or TMAH digestions) the system showed various levels of iodine contamination.
We found that the auto-sampler rinse station was often the worst affected area with iodine build up and as soon as TMAH was pumped through it and the solution monitored for iodine the baseline went up significantly especially if other jobs had been analysed on the system previously. We found the best agent for producing low baseline was to wash with 1% ammonia. For the auto-sampler there was a need to flush the auto-sampler rinse station with 1% ammonia for some time before returing to TMAH to monitor the baseline. For the normal sample path through the tubing/nebuliser/spray chamber etc. washing with 1% ammonia soon produced a good baseline.
Clean up by pumping the 1% ammonia through tubing etc. could be carried out in 10 minutes with good baselines achieved in the 1% TMAH after this. However by just pumping 1% TMAH it could 2 - 3 hours to get the baseline down.
The auto-sampler rinse station could take longer depending on prior contamination.
NOTE: We used solva flex pump tube for all TMAH processes on the ICPMS. Thus you can run ammonia and TMAH with long runs without any deterioration.
This information plus many other helpful hints are available in the noted paper below
Huynh D, Zhoua S J, Gibson R, Palmer L, Muhlhausler B. Validation of an optimized method for the determination of iodine in human breast milk by inductively coupled plasma mass spectrometry (ICPMS) after tetramethyl ammonium hydroxide extraction.
Journal of Trace Elements in Medicine and Biology 2015; 29: 75-82.
If you contact me on my email address I can send you a copy of the paper if you so desire
Mr. Lyndon Palmer
Flinders University Plant Nutrition
School of Biological Sciences
South Australia, AUSTRALIA 5042
Tel. +61 8 8201 3536
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From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's). [mailto:[log in to unmask]] On Behalf Of Mukul N. Patel
Sent: Wednesday, 29 March 2017 7:46 AM
To: [log in to unmask]
Subject: Iodine blank values too high
When I try to measure iodine using the following diluent, I get very high Iodine intensities as seen in the attached screen shot. I shall be thankful for your advise and suggestion to bring the iodine background intensities to as low as possible in order to determine iodine conc. in calibrators, QCs and sample.
50 mL solution contains:
50 uL Triton X-100
1 mL 25% TMAH
50 uL of 10 ug/mL Te
48.9 mL of water
Thank you for your help and advise.
Mukul N. Patel
Accu Reference Medical Lab
1901 East Linden Avenue, Suite 4
Linden, NJ 07036
Mobile: (732) 599-6137