We have a number of strategies for fixing problems with peak shape for phosphorylated compounds:
- Ensure the column is not overloaded. We recommend an injection volume of 1 µL or less with aqueous normal pase ANP methods.
- Use Teflon bottles instead of borosilicate glass for your mobile phase reservoirs. Sodium from the glass can cause peak shape problems for anionic compounds.
- Use 5–10 microM EDTA or medronic acid in the mobile phase and sample diluent. This will help chelate metals that cause problems for phosphates.
- Try adding 0.01% ammonia to the sample diluent.
- Try using a Cogent, metal free, coated stainless steel column.