split peak

[mk12]

I am getting split peak for my standard. My analyte is free base and standard is made in 100 ACN while mobile phase contains 0.1% TFA.

Samples are diluted in mobile phase I donot see the split peak for same analytes in samples

what could be the reason

[Uwe Neue]

The sample solvent is a strongly eluting solvent. Make the sample in the starting mobile phase, instead of MeCN (my book on HPLC Columns, in the section on Troubleshooting, page 360).

[mohan_2008]

Typically, they use a 100% ACN (strong solvent) to dissolve the standards (as the weighed material is in powder form). This is to enhance solubility and nothing more.

However, samples (already in solution or suspension form) will be made in a less stronger solvent such as 50:50 ACN:Water or something like that.

Hence,

Use mobile phase as your secondary diluent for both standards and samples and re-inject. Should solve the problem.