Voltammetric Sensor for General Purpose Organohalide Detection at Picogram per Liter Concentrations Based on a Simple Collector−Generator Method

Abstract

With the aim of producing a general purpose sensor for environmental analysis, we describe a simple and sensitive method for organohalide detection, based on an electrochemical collector-generator process. The sensor consists of four coplanar electrodes contacting a solution volume of 300 microL, containing organohalide. At the first working electrode (a Zn/PTFE composite), the analyte is electrolyzed to liberate halide ions. At the second working electrode (Ag), the halide ions are detected by cathodic stripping voltammetry. Using a preconcentration time of 600 s, with differential pulse voltammetry for stripping, the responses to 1-chloropropane, chloroform, carbon tetrachloride, iodoethane, and bromoethane can be plotted on a common calibration curve, with a detection limit of 0.1 nM (1.3 pg L(-1) or less depending on the organohalide). To the best of our knowledge, this is the lowest reported organohalide detection limit by an electrochemical method and is so far the only general purpose electrochemical method sensitive enough for regulatory requirements. The sensor response was invariant for approximately 40 measurements. Analysis of tap water, spiked with chloroform or carbon tetrachloride, gave recoveries within 1.0-2.6% of the recoveries by the standard GC method.

Electrochemical Dehalogenation of Organic Pollutants

“…Dobson et al [185] indicated that haloalkanes have a limit of detection of 5 µM at porphyrin-modified electrodes. To date, one of the most sensitive sensors for organohalides is a zinc metal-polytetrafluoroethylene particle (PTFE) composite-plated electrode, with a detection limit of 0.1 nM, that was designed by Wiyaratn and co-workers [186][187][188]. In our own investigation [174] of the determination of THMs in drinking water by means of stripping analysis with silver electrodes, detection limits of 3.0 µg L -1 (12 nM) and 6.0 µg L -1 (50 nM) for bromoform and chloroform, respectively, were achieved.…”

Electrochemical Sensors

“…Wiyaratn et al described a simple but highly sensitive electrochemical collector-generator process to detect organohalides with a 0.1 nM detection limit. 73 Analyte electrolysis and release of halide ions was achieved at a first Zn/PTFE composite working electrode, followed by the detection of the released halides at a second silver working electrode by cathodic stripping voltammetry. The continuous collection of electrolysis product at the second electrode for a period of 600-s was responsible for the low detection limit.…”

Electrochemical Determination of Tetracycline Using Molecularly Imprinted Polymer Modified Carbon Nanotube‐Gold Nanoparticles Electrode

“…Electrochemical techniques have been proposed as a promising method for the measurement of environmental pollutants due to their fast, simple and inexpensive equipment [10,11]. The oxidation of tetracycline (TC) has been reported by gold [12], ruthenium oxide-hexacyanoruthenate (RuO-RuCN) [13] or multiwall carbon nanotubes (MWNTs) [14] modified electrodes.…”