How is optimization done for a SPE method?

During SPE method development, it is essential that all fractions (load, wash, elution) are collected for further examination.  Causes of recovery problems such as analyte breakthrough, wash solvent being too strong, elution solvent being too weak, etc., can be identified by studying what is present in these fractions.  Generally, optimizing & troubleshooting a SPE method best starts by analyzing the information found from these fractions.