I'm attempting to develop a method for analyzing rare earth elements by ICP OES, and am hoping to find an internal standard to use for the analysis. I've tried several, and they simply do not work. Any tips or help would be greatly appreciated.
Hi!
Find and study answers in this forum by Nonka Nedjalkova Daskalova and her articles on rare earth analytics. Surely, you can also turn to Her directly.
ZJ
In what way do they "simply do not work"? There are a few questions you could answer to help sort out your problem: What is your sample material? What are you using to dissolve it, are you diluting the sample with water or matrix acids, is there too much interference from the matrix, is the ISTD too dilute, is there ISTD in the REE you are measuring, have you calibrated with the same matrix as the sample? Is your acid extraction chemistry suitable for the elements you are trying to test? Is the detection limit of the ICPOES suitable for both the REE and ISTD you are using? Have you tried other wavelengths and checked for overlaps and interferences across the entire range, is your acid clean enough to eliminate metal contamination as a source of interference (including non-target elements - Na and other macros can leach from glass acid containers).
Dear college
Please, show the all REEs, which must determinate as analytes in samples with the corresponding matrix constituents (show matrix constituents).
Please, show and ICP-OES system, which you will use, because the detection limits depend on the practical spectral bandwidths of the corresponding ICP-OES system.
With kind regards, N. Daskalova
Matthew Wheal
Sample material is high TDS brines, lots of group 1 and 2 elements. It arrived as a complete unknown, and I have since characterized the major elements. Everything else is unknown. Samples are dissolved in 5% HNO3. There are interferences from the matrix, and I've run into several IS candidates that are in the matrix already so I cannot use them. The acid is high purity and in HDPE, so no contaminants there.
I'm really just looking for established IS elements that work for the full range of REEs, so that I can try established knowns instead of working my way through a large list of unknowns. I realize they may not work for me, but I'm on a time crunch and am trying to expedite the process.
Nonka Nedjalkova Daskalova
I am using an Agilent 5800 ICP OES. See my answer to Matthew Wheal for matrix info. Unfortunately, the samples are mostly unknown. This is exploratory, so I am only trying to verify if there are REEs in these samples. If there are any, they will likely be in trace concentrations.
I will not be surprised if the OES does not have sufficiently low detection limits for this analysis. If so, I realize that I will probably need to analyze with an ICP-MS.
Thanks for your responses everyone. Its greatly appreciated!
Dear college,
Briny waters are with a high-concentration of salts of Na, Ca, K, Mg -
> 5% up to 26%–28% max. The solutions will introduce in the plasma with Meinhard concentric glass nebulizer, which provides excellent sensitivity and precision for aqueous solutions and samples with few dissolved solids (less than 1%). Therefore, the natural samples prior to analysis must be diluted with an appropriate dilution factor. The concertation of REEs in brines is very low and in this case the separation / pre-concentration procedures must be applied in other to improve the detection limits in the determination of REEs in briny waters. The REEs can be determined by ICP-OES or ICP-MS. If the RREs cannot be determined in the both cases, you must show the corresponding detection limits.
In the determination of REEs by ICP –OES you can use the most prominent lines of REEs in accordance with Line Coincidence Table for Inductively Coupled Plasma Atomic Emission [1] : La II 333 749 nm, Ce II 413 765 nm, Pr II 390 844 nm, Nd II 401 225 nm, Eu II 381.967nm, Gd II 342 247 nm, Tb II 350 917nm, Dy II 353 170 nm, Ho II 345 600 nm , Er II 337 271nm, Tm II 313 126 nm, Yb II 328 937 nm. There I will note, if Agilent 5800 ICP OES Company recommends different most prominent lines, you will use the corresponding recommended prominent lines for REEs, because the selected analysis line are chosen in accordance with the specific properties of the optical system.
References:
[1]. P.W.J.M. Boumans, Line Coincidence Table for Inductively Coupled Plasma Atomic Emission Spectrometry, Pergamon, Oxford, 1980, 1984.
With kind regards, N. Daskalova
- Badges
- Science topic
- Similar topics
- Correction