If you observe changing retention times of amino acids using a Cogent Diamond Hydride™ HPLCL column, consider the following .
Suggestions, tips and tricks
1. Acid in the Mobile Phase; Formic or acidic acid is generally used when analyzing amino acids, so the use of ammonium acetate (or formate) might be a problem.
2. Contamination from the biological samples. Try our conditioning protocol for biological samples.
3. Suggested Mobile phase: 50% methanol or 50% isopropanol +0.1 % formic acid or 0.2% acetic acid would be suggested to use with biological samples and amino acid analysis when using the Cogent TyPE-C™ Silica columns.
4. How long is your gradient’s re-equilibration time? Follow our protocol on choosing a proper post time.
5. Is the column thermostated? If not, the variation may be due to changes in lab temperature.