Completely Automated System for Determining Halogenated Organic Compounds by Multisyringe Flow Injection Analysis

Abstract

A new, multisyringe flow injection setup was designed to develop the first completely automated flow methodology for the expeditious, accurate in-line determination of halogenated organic compounds (HOCs) in water. The target compounds are preconcentrated and isolated by solid-phase extraction. Following elution, previously organically bound halogens are released as free hydrogen halides by the combined action of UV light and a chemical oxidant for their subsequent spectrophotometric determination by reaction with Hg(SCN) 2 and Fe(3+). Optimizing the major hydrodynamic and chemical variables resulted in improved performance. Recovery of various HOCs was assessed, and potential interferents were examined. Under the selected operating conditions, the proposed method exhibits variable analytical performance depending on the particular sample volume used (e.g., a sample volume of 5 mL provides a linear working range of 140-2000 microg L(-1), a LOD of 100 microg L(-1), and a throughput of 9 samples h(-1)). The method was successfully used to determine total adsorbable organic halogens (AOX) in well water and leachates, and the results validated against an AOX reference method. The role of the proposed system in the environmental analytical field is critically discussed.