Supported liquid membrane extraction for identification of phenolic compounds in the nutrient solution of closed hydroponic growing systems for tomato Original Research Article

The objective of the present study was to adapt and develop suitable methods to study the occurrence metabolites in the nutrient solution of hydroponically grown tomato. The organic–chemical nature of the nutrient solution from tomato grown in closed hydroponic systems was studied by supported liquid membrane technique (SLM) and analyzed by high-performance liquid chromatography (HPLC). Further, we aimed to identify and quantify metabolites present the growing system. In this context, the analyses focused on benzoic acid, ferulic acid, p-hydroxybenzoic acid, salicylic acid, vanillic acid and phenazine-1-carboxylic acid. Results showed that supported liquid membrane technique is a suitable tool for analyzing nutrient solution of closed hydroponically grown tomatoes, with respect to the studied compounds. Both extraction efficiency and detection limits varied between the compounds. To enable all compounds to be seen in one chromatogram a gradient was used for high-performance liquid chromatography. Agreement of retention times for standards and samples showed occurrence of vanillic acid, ferulic acid, phenazine and p-hydroxybenzoic acid. Vanillic acid was present in concentrations around 60 nM in almost all samples.