Determination of Polychlorophenols in River Bottom Sediments Using Dynamic Online Preconcentration

Abstract

An online system for the dynamic preconcentration of chlorophenols from bottom sediments is proposed. It comprises a preconcentration column with a magnetic sorbent based on aminated hypercrosslinked polystyrene immobilized by two magnets, a container with the sample solution, a sorbent suspension, and rinse water. After preconcentration, the analytes are desorbed with acetonitrile, and the magnetic sorbent is rinsed in a regeneration column with hexane, methanol, and water. A peristaltic pump moves the analyte solution and magnetic sorbent through the system, and performs desorption with acetonitrile. Control of the peristaltic pumps, magnets for sorbent immobilization, and sorbent movement through the system is automatic. Dynamic sample preparation enables 1550- to 2070-fold concentration. To determine analytes by GC-MS, derivatization is performed using N,O-bis(trimethylsilyl)trifluoroacetamide. GC-MS combined with dynamic preconcentration enables the determination of 16 di-, tri-, tetrachlorophenols, and pentachlorophenol in bottom sediments at levels of 3–8 ng/kg. Analysis of real samples reveals that all 16 chlorophenols from the control mixture are present in bottom sediments near the discharge point of municipal wastewater treatment plants. Dichloroparabens are also identified in some samples at these same points. In areas with active agricultural activity, 2,4-dichlorophenol is the main pollutant. Elevated levels of tri- and tetrachlorophenols are found in bottom sediments in water bodies located in forest fire zones.