To determine sodium and potassium in analytical chemistry, we can simplify the matrix by either wet or dry ashing methods and the sample solution can be analysed using flame photometry. What other methods can be applied simply?
Flame photometry used to be a fairly standard method in clinical laboratories before ISEs became more common. However, you do not need to dry and ash the sample, a simple dilution is enough, even better if the flame photometer you are using can use caesium as an internal standard. These methods are simple and cheap enough that they would generally be used ahead of a more costly ICP
Probably the simplest option (if you need this for a project and not as a teaching tool) is to talk to your local hospital's chemistry department. They should be able to do this for you easily and probably cheaper than you can set it up yourself. It also saves re-inventing the wheel.
Richard
Na and K can also be analyzed by ICP-OES. I would recommend upgrading to the ICP-OES if you are interested in analyzing multiple elements (Na/K/Li/Zn/Cu/Mn/Mg) with high sample output. No ashing is required and a digestion method is utilized instead.
Example article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4091818/
Ion selective electrode.Better would be direct ISE.You can measure sodium,potassium,chloride and even lithium.
I would recommend to take the sample, acid microwave digest it in a system such as the mars6 (cem), then dilute the sample 1:100 or 1:1000 (double dilution) and analyse it via ICP-MS. A Q-ICP-MS will give you the ability to measure almost the entire periodic table , given that you have the right standards and internal standards. This is particularly useful for low concentration elements. If you are though only interested in a Na and K, which are naturally found at high concentrations in most samples, then I agree with Valerie, ICP-OES is the way to go. It has the ability to process much higher concentrated samples, and the matrix does not need to be treated as harshly, as the detection limits are much higher. That means that you can get away with cooking your blood in some nitric acid over night, dilute and analyse it. Let me know if you have any further questions.
You might not have access to those costly instrument. For simple instrument, you can use photometry because ionization of Na and K is very low.
Flame photometry used to be a fairly standard method in clinical laboratories before ISEs became more common. However, you do not need to dry and ash the sample, a simple dilution is enough, even better if the flame photometer you are using can use caesium as an internal standard. These methods are simple and cheap enough that they would generally be used ahead of a more costly ICP
Probably the simplest option (if you need this for a project and not as a teaching tool) is to talk to your local hospital's chemistry department. They should be able to do this for you easily and probably cheaper than you can set it up yourself. It also saves re-inventing the wheel.
Richard
Thank you, Richard, for a correct, precise and concise answer. Flame photometry for Na and K in biological matrices IS the reference method (and cheap, to boot).
Ion Chromatography with a suitable cations column could be another alternative.
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