I am also involved in analyzing metals such as uranium, PGM's and base metals directly in organic substances such as TBP, Kerosene, isodecanol, etc. and I cannot tell you how many torches I have melted when I started this exercise. I use the SPECTRO ARCOS ICP-OES and I had to reduced the pump speed to around 20 - 25 rpm, with the auxiliary gas flow rate of 2.5 L/min and a nebulizer flow rate of 0.8 L/min. We left the plasma power at 1500 W with the plasma gas flow rate at 15 L/min. We found this very helpful and we did not have any built-up of carbon onto the torch.
We had to resort, however, to decomposing the organic material and analyze the samples in aqueous medium owing to different sample matrices in a single batch of samples. I used sulphuric acid to decompose the organic matter and my colleagues preferred nitric and perchloric acids for this and we all obtained good recoveries.
Hope this helps.
TUMELO WA SEPENG
MINTEK, Analytical Services
From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's). [mailto:[log in to unmask]] On Behalf Of Julia Spraul
Sent: 2010 December 21 04:59
To: [log in to unmask]
Subject: Tertbutyl hydroperoxide (TBHP) analysis
I searched the archives for this before posting and did not find any info there, so here's some background on a problem I'm currently trying to solve. Any suggestions of things to try are welcome! Thanks in advance!
I have samples that are ~45% tertbutyl alcohol (TBA), ~45% tertbutyl hydroperoxide (TBHP), with the balance of water and iC4s. I'm trying to analyze these samples for corrosion metals (Fe, Cr) as well as Mo, Na, and P by ICP-AES. I've previously been able to analyze 20% TBA in water with no problems, however when I try to analyze these samples at a similar dilution, the plasma-Z is exceeded and the plasma extinguishes. I have also diluted the samples in isopropanol and had the same problems. We have a Perkin Elmer 5300 DV ICP. Settings used were 1500W, Plasma gas 15 L/min, Aux 0.5 L/min, Neb 0.45 L/min. 1.2 mm quartz injector, baffled cyclonic spray chamber, Meinhard C1 neb, flow rate 1.5 mL/min (tried lowering this too, with same results). Does anyone have suggestions of maybe some better settings for this sample type?
Some other things: We also have graphite furnace and flame AAs available for use if they'd handle this sample better. And we're also investigating ways to decompose the TBHP before analysis, but the ways we've come up with interfere with the elements we're looking for.
Any suggestions would be greatly appreciated. Replies here or offline are welcome.
Julia C. Spraul
Researcher, Analytical Services, Newtown Square
Lyondell Chemical Company
3801 West Chester Pike
Newtown Square, PA 19073
Office: +1 610.359.2357
Fax: +1 610.359.2442
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