MP-AES 4210 As in water

Unfortunately, As does not have a very low limit of detection (LOD) on the MP-AES, but you can improve it significantly by adding the Multimode Sample Introduction System (MSIS) accessory and taking advantage of the fact that As is a hydride forming element. What concentration levels are you trying to achieve for As in water? 

Hi Tina

Thank you very much for your answer!

I had contemplated the use of msis and the concentration levels are around 20µg/L.

In an application note for measuring in wines, I found the msis configuration seen in the image and from what I see you have to add an Ar current. Is that always like this? Is it configured the same in water?
I don't know if there is any other consideration to have when measuring in water (in principle they would not be real samples, but rather inoculations in mq water)

You should be able to do 20ug/L As with the MSIS on the MP-AES 4210. That is well above the LOD which is single ppb.  The argon current you refer to is just the nebulizer gas. You can operate the MSIS multiple ways: either in "simultaneous" mode with the nebulizer inserted on the side of the MSIS (this allows you to do both As and other non-hydride forming elements at the same time) or in "Hydride only" mode in which you tie off the nebulizer line and only do As- the hydride forming element. For either mode, you will be pumping the reductant solution through the top of the MSIS, and your sample through the bottom of the MSIS. You can also operate the MSIS in "conventional" mode where you tie off the top and bottom lines and use the nebulizer only for standard analysis. You will need a 5 channel peristaltic pump if you do simultaneous mode. Be aware of the chemistry involved. You need to do a pre-treatment of the samples and standards (unless you buy a calibration standard with the right oxidation state) ahead of time to get the right oxidation state for As. 

Thank you very much again for taking the time to answer my questions.
Now the following question arises: should the nebulizer gas be Ar? Because we have the mp-aes 4210 coupled to an N2 generator, in that case we must change to Ar or with N2 the determination can also be carried out.
Finally, do you know if there is an application note or can you recommend bibliography on the matter?

You use the nebulizer gas associated with the instrument. For ICP-OES, the nebulizer gas is argon, but for the MP the nebulizer gas is nitrogen. So you don't need to add anything different. There are several app notes for MSIS, most of them are with ICP-OES but there is a good MP wine app note on As. I will attach some here. I have used the MSIS quite a bit through the years and have taken specific info from each of the app notes to take the best approach. For very clean water samples, you could add the pre-treatment on-line via the pump as in the ICPOES fish app note, which would save time and be easier. Or you can add the chemical pre-treatment to the blank, samples, and standards manually. I recommend 1% L-cysteine in 2.5% HCl as the pre-treatment to reduce As5 to As3 (only the As3 forms the hydride easily). Or you can purchase an As3 calibration standard, but I would still add the pretreatment to everything to keep matrix matching. Use 1.5% NaBH4 + 0.2% NaOH as the reductant. Follow the MP operating parameters in the wine app note. Hope this helps. Agilent offers applications training if you want to consider that. 

All the recommendations you have given me have been very helpful, thank you for that.
Where can I get information about the training you mention? Taking into account that I am in Uruguay, therefore they should be in the region or can be done online.

best regard