Chromatography Forum

I have been asked to carry out analysis on 0.9% NaCl to ensure the correct concentration. They have mentioned using USP 29, but I believe this is wet chemistry and they want HPLC. Does anyone know a good HPLC method for this analysis?

I would think regular 'ion chromatography' (IC is a form of HPLC) for both the Na and Cl ions. Depends on whether you have the column, detector...

My 2st choice (after the USP) would have been ISE (ion selective electrode). They do like to spend money since HPLC is an expensive technique:)

We used automatic titrator and silver nitrate titrant to determine chloride in all our antiperspirant products, met all cGMP requirements. Our boss even made us validate this on all forms of products.

I once explained to a university instructor of Analytical Chemistry, who posed the question of what if it was a solution of NaCl in water. I replied we'd do the same technique, but he said he'd simply dry down and weigh, because weighing was more accurate. I didn't contradict him, but told him that while he was waiting hours for that sample to dry, I'd be home in half an hour drinking a beer....

HPLC method with Evaporative Light Scattering detector (ELSD) is very popular for this application. FDA does like stability indicating HPLC methods. However, depending upon the final consumer application, I have validated Atomic Absorption, titration, and other methodologies to prove suitable potency assay or stability indication.

FDA does like stability indicating HPLC methods.

I think one could convince the FDA that NaCl is stable. All the antiperspirant active suppliers and manufacturers of finished antiperspirants use titration for chloride level.

[quote="Consumer Products Guy"]We used automatic titrator and silver nitrate titrant to determine chloride in all our antiperspirant products, met all cGMP requirements. Our boss even made us validate this on all forms of products.

I once explained to a university instructor of Analytical Chemistry, who posed the question of what if it was a solution of NaCl in water. I replied we'd do the same technique, but he said he'd simply dry down and weigh, because weighing was more accurate. I didn't contradict him, but told him that while he was waiting hours for that sample to dry, I'd be home in half an hour drinking a beer....[/quote
Nicely replied

You can do something like this:
https://helixchrom.com/compounds/sodium ... ode-column

Your detection limit is going to be around 50 ppm with ELSD.

Let me know if you have any questions.