On Monday, November 7, 1994 at 2:10:24 AM UTC-7, Glenn Johnson wrote:
I would appreciate anyone with experience in ICP-AES analysis who could comment on the following problem we have encountered.
On aspirating 8% perchloric acid plant digests through our old ICP (Labtest 710 sequential; 1980 model), signal intensities for all elements reduced. e.g. 20% reduction over 1minute for NBS tomato leaves. We presume this is because of Potassium Perchlorate precipitating on the Argon jet in the Babington nebuliser. The problem is greatest with high Potassium concentration
plant samples.
Has anyone found this problem and have solved it?
Would the latest instruments have this problem?
Thanks for any help,
Glenn Johnson.
Glenn, I noticed a long time ago that HClO4 tends to reduce the signal from the ICP Spectrometer. But I (perhaps mistakenly) attributed this to a change in viscosity, affecting the droplet size in the expansion chamber.You could fume the samples almost
to dryness to remove most of the HClO4, which I think helps a lot. You might try cutting down on the amount of HClO4 you're using in the digestion. HClO4 is only effective if the digestion is carried out to fuming HClO4, but this is where the danger
exists from unoxidized carbon species. Have you prepared your calibration standards to contain the same concentrations of acids as your samples? I think the ICP signal is significantly affected by even varying the solution matrix. But I do recall reading
Ti out of a H3PO4 digestion, so I know it can be done. Good luck! Jim
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