Hi Jacob,
An additional technique to identify sodium is microPIXE, which can be used for elemental mapping. I'm not sure if the sulfur signal would be strong enough to be quantitative.
A ref:
https://www.cell.com/structure/pdf/S0969-2126(00)88335-5.pdf
Hope that helps,
Sarah
Sarah EJ Bowman, PhD
Associate Research Scientist, Hauptman-Woodward Medical Research Institute
Director, High-Throughput Crystallization Screening Center
Research Associate Professor, Department of Biochemistry, University at Buffalo
From: CCP4 bulletin board <[log in to unmask]> on behalf of Artem Evdokimov <[log in to unmask]>
Reply-To: Artem Evdokimov <[log in to unmask]>
Date: Sunday, November 3, 2019 at 9:20 PM
To: "[log in to unmask]" <[log in to unmask]>
Subject: Re: Sodium Ion Binding?
Hi Jacob
Not the easiest task... Based on past experience your major issue will be the incredible abundance of sodium ions in everything.
So assuming you have high quality sodium free solutions and are willing to work exclusively in plastic, quartz or fused silica - here are a few thoughts:
1. Na-22 isotope binding. An oldie but goodie.
2. Sodium-reactive dye equilibrium (see e.g. reference I put at the end)
3. Flame or ion coupled plasma spectroscopy. Very nice to do given the marvellous sodium band.
4. Sodium selective glass electrode (requires more solution of your analyte than the other methods)
Overall the key component to these methods is your ability to displace the sodium with something else prior to measuring the effect of titration the ion back. Isotopic Na is easier in this regard - but at a cost...
Hope this helps.
Artem
On Sun, Nov 3, 2019, 20:41 Keller, Jacob <[log in to unmask]> wrote: