I am not sure about the alumina injector because we do not run with this
type of system, however I see a few other issues relating to the 10% H2SO4.
1. As you indicated there could be some issue transferring back and
forth between the HNO3/HCl and H2SO4 especially if you are trying to analyse
low levels of S.
We had a comparable problem when we were running 4% HClO4 digests of plants
for 20+ nutrient elements and then trying to analyse low levels of Cl from
plants on the same instrument using our newly published Cl method in plants
using a 4% HNO3 extraction.
"Chloride analysis of botanical samples by ICP-OES" - Matthew S. Wheal and
Lyndon T. Palmer
J. Anal. At. Spectrom., 2010, 25, 1946-1952
DOI: 10.1039/C0JA00059K, Paper
There is a need to complete disassemble all the components of the
introduction system (glassware, tubing etc) and rinse well. We have also
seen problems especially with the tubing used on the auto-sampler rinse
station etc. We found we had to replace this or keep separate systems for
the 2 acid matrices.
2. Also if you have any elements that potentially precipitate as the
sulphate in your samples then there is the possibility for these to
precipitate around the nebuliser orifice over any long runs which then cause
major drift problems. The only way to overcome this is to run an argon
wetting system for the nebuliser gas. This phenomenon occurs with any
nebuliser even those classified as high salt nebulisers.
Again we have seen this with running plant digests in 4% HClO4 which have
high levels of K. We routinely run 20 hour runs of this type of matrix and
without the argon wetting system it is possible to see drifts of 20 - 25%
and it is random because the crystals build up and break off around the
nebuliser orifice randomly and so it is impossible to drift correct post
run. However since we have been using the argon wetting system the drift is
reduced to below 5% in this 4% HClo4 matrix.
Mr. Lyndon Palmer
Waite Analytical Services
School of Agriculture, Food and Wine
The University of Adelaide
South Australia, AUSTRALIA 5064
Tel. +61 8 8303 7391
FAX. +61 8 8303 7109
email : [log in to unmask]
web : http://www.adelaide.edu.au/was/
From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's).
[mailto:[log in to unmask]] On Behalf Of Wels, Brian R
Sent: Friday, 17 December 2010 8:51 AM
To: [log in to unmask]
Subject: Sulfuric acid vs. alumina injector
We have been running an ICP-OES (Perkin-Elmer Optima 5300 DV) for five
years, feeding it a steady diet of a few percent nitric and/or hydrochloric
acid. Just your routine EPA 200.7 and 6010 type of work and everybody's
happy. Now we are confronted with a project requiring a matrix of up to 10%
sulfuric acid. Most sample introduction components are made of Teflon,
glass or quartz. The peri-pump tubing is Tygon and the injector is alumina.
Some concerns have been raised over the alumina injector suffering harmful
effects. I know alumina is resistant to chemical attack, but are the
concerns justified in this case?
Also, can we expect problems with interferences from residual sulfuric after
switching back to our routine workload?
Thanks for your input.
Brian Wels, Ph.D.
State Hygienic Laboratory at the University of Iowa
2220 South Ankeny Blvd.
Ankeny, IA 50023