Amperometric detection of simple alcohols in aqueous solutions by application of a triple-pulse potential waveform at platinum electrodes

A sensitive and fast-responding amperometric sensor for the determination of ethanol in breath which eliminates oxygen interferences is described. It consists of a porous gold working electrode (facing the sample) supported on one face of an ion-exchange membrane which serves as a solid polymer electrolyte (SPE). The other side of the membrane faces an internal electrolyte solution (1 M aqueous NaOH) containing the counter and reference electrodes. The fouling of the gold working electrode, due to the ethanol oxidation process, is overcome by continuously cleaning and reactivating its surface by applying a triple-pulse potential waveform. The performance of this sensor has been tested in a closed-loop flow apparatus fed with synthetic ethanol-vapor samples obtained by evaporating aqueous solutions with known ethanol contents. The sensor displays a high current sensitivity and a low background noise, so that a low detection limit (2 mu g L(-1), 1 ppm v./v.) is estimated for a signal-to-noise ratio of 3. The responses are characterized by both a good reproducibility and a linear dependence on the ethanol concentration over a fairly wide range (more than three orders of magnitude), as well as by a short response time (ca. 1 s). This fast response time arises from the lack of a gas-permeable membrane and direct gas contact to the triple interphase among the gaseous analyte, the porous working electrode and the solid polymer electrolyte. The absence of significant interfering effects and the possibility of adopting such a device for the detection of ethanol in fermentation processes are also discussed

Section: Triple-pulse Amperometric Detectionmentioning

confidence: 99%

Pulsed amperometric detection of ethanol in breath by gold electrodes supported on ion exchange membranes (solid polymer electrolytes)

Schiavon¹,

Comisso

Toniolo

et al. 1996

“…They noticed that a significant signal was achieved for aliphatic alcohols when the potential applied to the working electrode was alternatively changed between positive and negative values. Following the first reports [1,2], a number of interesting and important articles appeared in the literature discussing different aspects and applications of the triple pulse potential waveform or pulsed amperometric detection (PAD) [3 -11]. PAD was subsequently matched with liquid chromatography, allowing for the separation and detection of alcohols, carbohydrates, thiols and amines without pre-or postcolumn derivatization chemistry.…”

Section: Introductionmentioning

confidence: 99%

Coupling Capillary Electrophoresis and Pulsed Electrochemical Detection

Garcı́a

Henry

2005

Pulsed electrochemical detection (PED) is an excellent method for detection of analytes that normally foul electrodes. In PED, the detection electrode is first cleaned at a high positive potential, then reactivated at a negative potential dissolving the surface oxide, and finally used to oxidize the analyte at a moderate positive potential. Due to the advantages and versatility of PED, many different variations of the detection waveform can be found in literature. This review focuses on application of PED to CE and in particular, the most commonly used modes: pulsed amperometric detection (PAD) and integrated pulsed amperometric detection (iPAD).

“…An alternate approach is to combine electrochemical detection with "on-line" cleaning. Hence, in order to maintain uniform and reproducible electrode activity at noble metal electrodes for polar aliphatic compounds, pulsed electrochemical detection (PED) was developed [4]. A complete description of PED and its application has been published [5].…”

Section: Electrocatalysis At Nobel Metal Electrodesmentioning

confidence: 99%

Microelectrode Applications of Pulsed Electrochemical Detection

LaCourse

Modi

2005

Pulsed electrochemical detection (PED) has been applied to the direct (i.e., requires no derivatization), sensitive and reproducible detection of numerous polar aliphatic compounds (e.g., carbohydrates, amines, and thiols). These compounds, many of which have biological significance, typically have been classified as non-electroactive for detection under constant applied potentials and have poor optical detection properties. PED exploits the electrocatalytic activity of noble metal (e.g., Au and Pt) electrode surfaces to oxidize various polar functional groups using multi-step potential-time waveforms to realize amperometric/coulometric detection while maintaining uniform and reproducible electrode activity. The response mechanisms in PED are dominated by the surface properties of the electrode, and as a consequence, members of each chemical class of compounds produce virtually identical voltammetric responses. Thus, the full analytical potential is achieved when combined with an a priori separation. Although popularized in combination with high performance liquid chromatography, the combination of PED with highly efficient microseparation techniques offer the analyst unique advantages. This paper reviews the fundamental aspects of PED especially at microelectrodes, and its application in microchromatographic and electrophoretic separation techniques, including microchip devices.