Variables: pH Keywords: high resolution mass spectrometry Substances: 1-Propanesulfonate (KCXFHTAICRTXLI-UHFFFAOYSA-N) 1-(3-Chlorophenyl)-piperazin (VHFVKMTVMIZMIK-UHFFFAOYSA-N) 1-Naphthylacetic acid (PRPINYUDVPFIRX-UHFFFAOYSA-N)