Variables: pH electric_conductivity Substances: 18-beta-Glycyrrhetinic acid (MPDGHEJMBKOTSU-YKLVYJNSSA-N) 3-5-6-Trichloro-2-pyridinol (WCYYAQFQZQEUEN-UHFFFAOYSA-N) 1-(3-Trifluoromethylphenyl)-piperazine (KKIMDKMETPPURN-UHFFFAOYSA-N) 1-Propanesulfonate (KCXFHTAICRTXLI-UHFFFAOYSA-N)