Just be sure your mobile phase pH and sample preparation solvent is lower than your lowest pKa. Keep all species protonated and you shouldn't have any problems with pKa issues. Also, make sure your using an HPLC column that can withstand low pH. Going to pH 2 and below can several degrade most silica-based columns.
Another alternative is to go to a high pH buffer, keep the analytes ionized and use an anion exchange (SAX) HPLC column. However, given the high pHa of 12 for one of your analytes, I probably wouldn't go that round as your mobile phase pH would have be ~13+. Personally, I don't like working with cautics in HPLC because they are extremely damaging to silaca-based columns and eye/skin.
You need to provide details. Are we talking about reversed phase chromatography? What compounds are we talking about? For rp-hplc keeping all things protonated is not a general rule to favor adsorption.
Hi Omer,
Target compounds are inositol phosphates. We have selectd reverse phase anion exchange Chromatography .
It is better choice, anion exchange column can help to separate conveniently. However, the selection of mobile phase could be tricky.
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