Variables: pH Keywords: monitoring Substances: 5-Fluorouracil (GHASVSINZRGABV-UHFFFAOYSA-N) Acibenzolar-S-methyl (UELITFHSCLAHKR-UHFFFAOYSA-N) 1-Methyl-Benzotriazole (HXQHRUJXQJEGER-UHFFFAOYSA-N)