Recovery of s-triazine herbicides and associated breakdown products from granular activated carbon using supercritical fluid extraction

摘要

S-triazine herbicides and associated breakdown products were recovered from granular activated carbon (GAC) using a dual pump supercritical fluid extraction (SFE) system capable of modifier addition. Analyte recovery was very low using supercritical carbon dioxide alone, was moderately improved by acetone modification in the static mode, and was significantly improved by dynamic acetone modification. Quantitative extraction of atrazine and simazine was achieved in 30 min using 50 mol% acetone in CO_2, although recoveries for associated breakdown products (deethylatrazine and deethylsimazine) were limited to 70%. S-triazine extraction rates were independent of the flow rate of the extracting fluid, indicating a significant interaction of s-triazine molecules with active sites on the GAC matrix surface and a kinetic limitation to the desorption process. SFE was as precise as, and much faster than, Soxhlet extraction for the determination of these priority pollutants and was advantageous in terms of improved analyte recovery and reduced solvent and labour requirements.