Hey, Tharanga,

Mariane makes a good point about matrix matching of standards and samples. This allows for comparable behavior of your standards and samples in the plasma and ensures acceptable analytical results.

With regards to addition of acid beyond the acid that comes from your stock standards, we pretty much always add acid beyond the amount that's in the stocks. This provides greater stability of your standards and samples by ensuring that the analytes remain in solution for longer periods of time. This is particularly important with the transition metal analytes, which are prone to hydrolysis and precipitation at lower acid concentrations. The less acid you have in solution, the more likely it is that you will lose some of your analyte to adsorption onto container walls or precipitation. If you rely only on the acid that is in the stock solutions, there may not be enough to ensure long-term (or even short-term, depending on the analyte) stability of your standards and samples. We pretty much always add enough acid to make it at least 2% acid, either nitric or hydrochloric depending on the analyte.

Hope this answer helps!

Dear Tharanga,

When I prepare my water samples to analyse them by ICP-AES or -MS, I dilute them with the same matrix (HNO3 in your case) used for the standard solutions. I try also to get the same concentration (1M in your case). This prevents me to face any matrix effect.

Hey, Tharanga,

Mariane makes a good point about matrix matching of standards and samples. This allows for comparable behavior of your standards and samples in the plasma and ensures acceptable analytical results.

With regards to addition of acid beyond the acid that comes from your stock standards, we pretty much always add acid beyond the amount that's in the stocks. This provides greater stability of your standards and samples by ensuring that the analytes remain in solution for longer periods of time. This is particularly important with the transition metal analytes, which are prone to hydrolysis and precipitation at lower acid concentrations. The less acid you have in solution, the more likely it is that you will lose some of your analyte to adsorption onto container walls or precipitation. If you rely only on the acid that is in the stock solutions, there may not be enough to ensure long-term (or even short-term, depending on the analyte) stability of your standards and samples. We pretty much always add enough acid to make it at least 2% acid, either nitric or hydrochloric depending on the analyte.

Hope this answer helps!

Thanks Mariane.

Thanks James for the detailed answer. Could you please suggest me a book or any other materiel where i can learn more about this sort of sample and standard preparation? I guess this matrix matching depends on the instrument as well, for example, I haven't done standard preparation in HNO3 matrix for normal AAS with FLUKA standard solutions.

Hey, Tharanga!

 I was able to find an application note in Spectroscopy Magazine that demonstrates the effect of matrix composition on analyte signal. The focus is on both salts (sodium, potassium, etc) and acids (HNO3 and HCl), and it shows how the ionization efficiency of a range of elements is affected by the content of both.

 http://www.spectroscopyonline.com/spectroscopy/data/articlestandard//spectroscopy/442007/469966/article.pdf

 There are a variety of other publications that briefly discuss matrix-matching and acid-matching. A couple of caveats here: Often times in ICP-OES and ICP-MS, differences in acid content can be accounted for by the use of an appropriate internal standard. Also, with higher concentration analyses, standard stability may be less of an issue (so, if you lose 10 ppb of a 10 ppm standard due to adsorption, that's still a pretty darned good standard).

 Hope this helps!

For  ICP -EM   or ICP-MS,  application of 2% N  nitric acid is  giving good result. This is used widely.

Thanks James, thanks a lot

Thanks Virendra and Trevor

For the ICP-MS analysis, applicable the HON3 in both the matrix ( sample and standard) for better result..

with regards

in ICP -EM or ICP-MS, 2% N  nitric acid is good result.

Yes I agree with the Dr A H Salimi ie HNO3

Dear brother,

I think it depends on your standard. If you use liquid standard (Ex. 1000ppm or 1000mg/L), you no need to prepare with nitric acid 2% or 5% because in the standard mostly they prepared with Nitic acid already for keep that metal. If you prepare with nitric acid, it can effect you pH standard solution.

# if you use solid standard, it is sure to prepare with Nitric 2% or 5%, it would be great

#finally for sample: yes should prepare by adding nitric acid for water sample or can add HCl too.

for sediment, soil, plant, fish,.. should prepare with HNO3, HCL, H2O2 but use difference volume.

for sample use high concentration for all acid and H2O2

sorry brother, this is just my idea. Tharanga Udagedara

Standard solutions of heavy metals in distilled water can under hydration of transitional metals, may adsorb with the container, may bio-accumulate and these makes the metals unavailable for he analysis. Besides, all metallic nitrates are soluble in water. In order to reduce all these things, HNO3 is used.