Have samples whose metal concentrations are expected to be between 10 ppb and 500 ppb. That is nearly at the borderline of ppbs and ppms. I have two options, either I dilute samples and use ICP-MS or gamble with OES?
Which option would you advise?
Why don't you ask the analytical staff in your facility what they recommend and/or can achieve?
There is no hard-and-fast "rule" on the concentration that can be detected by each instrument, it will depend to an extent on which element you have in mind, the wavelengths of the ICP-OES you are measuring, the m/z you are using in the ICP-MS and so on.
It sounds like you have cost in mind (I'm assuming the ICP-OES is cheaper per sample than the ICP-MS). Why not spend a little bit of money and time and test the ability of the ICP-OES by preparing some test solutions in a similar matrix to your experimental material at these "borderline" concentrations.
My experience is that you won't break an ICP-MS measuring diluted samples. You also won't break the ICPMS measuring 1 ppm of anything, [but you might upset future users if you contaminate it with other elements (Boron for one)]. You will also be frustrated by a lack of results if 10 ppb is too far below the reporting limit of the ICP-OES.
It'll also depend on your analytes, sample matrix and sample volume for example. If you need to dilute a 10 ppb solution 100 times for ICPMS analysis, you may end up below LOD for certain elements (e.g. Se, Ca,...) unless you use sector-field or MS/MS technology. On the other hand, LODs with ICPOES can also be lowered by e.g. ultrasonic nebulizers or sample pre-concentration.
I agree with Matthew Wheal that testing instruments with your typical samples will be the best way to decide.
Best
Bodo
I totally agree with Matthew Wheal and Bodo Hattendorf . They have explained all the aspects of both the instruments. I have also learned something new from them.
My suggestion is if ICPMS is available then you should go for it. 10 ppb to 500 ppb range can be easily covered by ICPMS. The only precaution you need to take is to put a blank sample after the analysis of each sample so that any residue of the previous samples can be cleared out.
Hi Fabrice
As it was very well explained above, that will depend on the metals of interest and the sample matrix.
If you have an ICP-MS available, I would recomend using it because it is a very powerful technique and covers practically all the analytes of interest with very few exceptions and with excellent quantification limits, even after sample dilution.
The main issue when working with ICP-MS is the cost per sample.
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