Trace determination of phenolic compounds in water by reversed phase liquid chromatography with electrochemical detection using a carbon-polyethylene tubular anode

Abstract

A llquld chromatographic system, capable of selectlvely detecting individual phenolic compounds at 1-ppb levels in water, is described. A polymeric-cation-exchange resin column, acidic acetonitrile-water eluent, and an electrochemical detector containing a unique carbon-black/polyethylene tubular anode are employed. Various types of carbon electrodes have been evaluated, as well as elution order and detector sensitivities for numerous phenolic compounds. Applications of the system to water analyses are presented.Phenolic compounds, especially halogenated ones, are of concern in the environment because of their toxicity to fish and other aquatic life and their adverse affect on water and fish taste ( I ) . Colorimetric analysis with 4-aminoantipyrene usually is employed to measure total phenols (2). However, most para-substituted phenols will not respond adequately, and no information concerning identity is obtained. T o identify and quantitatively measure total phenols a t ppb levels, procedures generally involve solvent extraction and either extensive solvent concentration followed by gas chromatography/mass spectrometry (GC/MS) or selective derivatization and GC with electron capture detection ( 3 ) . Disadvantages of the GC methods are sample preparation time, cost of MS equipment, incomplete recoveries for most phenols, and the lack of detector selectivity when only phenols are desired.A variety of liquid chromatographic (LC) columns have been used to separate mixtures of phenols in water samples (4-8). A major consideration when choosing a column for waste stream analysis is long term stability. Experience in our laboratories (9, IO) and studies by Walton et al. (11,12) have shown that good chromatographic resolution can be obtained with styrene-divinylbenzene base cation-exchange resins. Also these resins are totally unaffected by repeated injections of strong acids, bases, or concentrated brine solutions. If necessary, the columns can be emptied, cleaned, and refilled easily.Electrochemical detection of phenols after LC separation was demonstrated in 1973 by Takata and Muto (7). Since then, numerous publications describing electrochemical cell constructions and applications have appeared in the literature and were reviewed by Kissinger through December 1977 (13-15). Until recently, the material of choice for oxidative working electrodes was carbon paste. It is inert, easily replaced when fouled, and yields a low and stable residual current. However, it is unsuitable for LC eluents containing appreciable methanol or acetonitrile because the organic binder of the paste dissolves. Thus, a more universally applicable anode material is required.Glassy carbon is presently the alternative anode material of choice. It performs well in an electrochemical detector once the surface has been rigorously polished (16). In our experience, the electrode will become passivated during wastewater analysis and provision must be made for renewing the surface when this occurs.We were searching for an anode material that possess...

Composite electrodes for electroanalysis: Principles and applications

“…as low as 0.02 have been reported [ 491, and this approach to composite fabrication is an effective way of reducing the amount of conductor required for conductivity [ 521. As noted earlier, the Kel-F composite electrodes [42-481 are examples of segregated composites and exhibit a lowx., Figure 3 shows a plot of log u versus .f for the Kel-F/silver composite electrode [ 15,24,27,31,331. These values reflect the generally higher k. for dispersed composites compared to segregated composites.…”

“…Armentrout et al employed a polyethylene/carbon black dispersed composite electrode for the LCEC determination of phenolic compounds in surface drainage water, in wastewater treatment plant streams, and in recycle waste brine from the production of chlorinated phenols [31]. This electrode material gave a better SIN ratio than other materials tested, including polyethylene/graphite and Teflodgraphite (both dispersed materials) and various forms of impregnated graphite rod.…”

Electrochemical analysis of organic pollutants

“…The application of high performance liquid chromatography with electrochemical detection for the determination of phenols in ground and waste waters has been reported by several authors (ref. [30][31][32] and the limits of detection for compounds such as resorcinol, phenol, xylenols and chlorinated phenols quoted to be in the 10-8 -lO mol F1 range. The sensitivity is thus much better than corresponding methods employing ultraviolet detection (phenols generally have low extinction coefficients), and should provide a complimentary method to capillary gas chromatography, which is recognised as the forerunner in this area of analysis (ref.…”

Nanointegration: Sensor Enhancement using Nanomaterials to Detect the Pharmaceutical Residue

“…The RPLC method can give ultrahigh sensitivity in the parts-per-billion (ppb) range (Hoffsommer et al, 1980;Wegman & Wammes, 1983;Lee et al, 1984aLee et al, , 1984b. Other chromatographic methods (Armentrout et al, 1979) include ion-pair chromatography (Tomlinson et al, 1978) followed by RP separation have been reported with a LOD in the (< 0.1 -30) microgram / liter range (Goulden et al, 1973;Chau & Coburn, 1974;Kuehl & Dougherty, 1980;Mathew & Elzerman, 1981;Ribick et al, 1981;Lindinger et al, 1998).…”