Chromatography Forum

Hi all ,

What is the best way to remove carbonates when you measure Carbohydrates on an HPAEC - PAD ?

thx

What brand of instrument do you have? Are you concerned with carbonate in the eluent or samples? Are you manually preparing your eluent?

Assuming you're preparing eluents and don't have an eluent generator. If you're analyzing a lot of sugar samples, I HIGHLY recommend purchasing an eluent generator. No carbonate issues and pump pistons and seals last so much longer!

Here's a list of things I'd do before obtaining a generator.

• Prepare eluents weekly using high purity 50% NaOH.
• Never pour from or shake the 50% bottle - only pipette and never closer than 1-2 inches from the bottom of the bottle. When the bottle gets crusty, time to replace.
• Change the piston/seal wash weekly. Carbonates tend to build up on the pistons and score the pistons and seals.
• Sparge if you have helium available. If not, a slow flow of nitrogen gas into the bottle to blanket the eluent and keep the CO2 out helps a lot.

Hi Guys,
Best practice: remove carbonates by converting them to CO₂ and removing the gas, or by trapping bicarbonate on an ion-exchange cartridge — then filter and degas.mpbhulekh
For example, acidify gently (e.g., dilute acetic acid to pH ≈4), immediately sparge or vacuum-degas to remove CO₂, centrifuge and 0.2 µm filter before HPAEC-PAD. Alternatively, pass samples through a small anion-exchange (H⁺-form) cartridge to remove HCO₃⁻. Always validate that the prep doesn’t hydrolyse or alter your carbohydrates.