Electrodes glassy

Figure 2 Selective electrochemical detection of a mixture on multielectrode amper-ometry. AA = Ascorbic acid, NE = norepinephrine, DOPAC = 3-4-dihydroxy-phenylacetic acid, E = epinephrine bitartrate, 5-HIAA = 5-hydroxyindole-3-acetic acid, HVA = homovanillic acid, TRP = tryptophan, 5-HT = 5-hydroxytryptamine, and 3-MT = 3-methoxytyramine (separated by RPLC). Detection was with a 4-electrode glassy carbon array, with electrode 1 at 500 m V) electrode 2 at 700 mV, electrode 3 at 900 mV, and electrode 4 at 1100 mV. Note that at electrode 1, HVA, TRP, and 3-MT are not seen. At electrode 2, only TRP is not seen. A standard calomel electrode was used as reference. (Reprinted with permission from Hoogvliet, J. C., Reijn, J. M., and van Bennekom, W. P., Anal. Chem., 63, 2418, 1991. 1991 Analytical Chemistry.)...

Fig. 30 Cyclic voltammograms of [57] (1.0 X 10 3 mol dm-3) in acetonitrile in the absence (a) and the presence of 0.3 equiv (b) and 1.0 equiv (c) of sodium cations added as the perchlorate salt. Supporting electrolyte 0.1 mol dm-3 NBU4BF4. Scan rate 100 mV s Working electrode, glassy carbon.

Working electrode glassy carbon, Ref electrode Hg-pool counter graphite scan rate 0.1 V/s Simulation Estimated Reaction but not determined No reaction From (ip)c/(ip)a and switching time... 

Tab.6 Cyclic voltammett7 data for the reduction of 10 M solution of a-K4SiWi2O40 or a-K6P2Wig062 in various solvents. T = 25 °C working electrode glassy carbon disk. Sweep rate 100 mV s (taken from Ref 34)...

Fig. 23 Cyclic voltammograms in a 2 10 M solution of Fe6Ge2Wig complex in pH = 3 media working electrode glassy carbon reference electrode SCE. pH = 3 sulfate medium (0.2 M Na2S04 + H2SO4) superposition of the CVs restricted to the Fe-wave and to the Fe-wave and the first W-redox processes scan rate ...

Figure 13.7 Raman spectra of Nile Blue A on roughened Ag electrode, glassy carbon electrode (GC), and in solution pH = 9.0. Excitation wavelength = 488 nm. Laser power for Ag, 10 mW for GC, 200 mW for solution, 180 mW. Raman shifts in cm 1 shown above peaks. [From Ref. 59.]...

AA and IAA simultaneously Yeast Metaphosphor ic acid/cold perchloric acid extraction Precolumn ODS-IO (40 X 2.6 mm Bio-Rad). Analytical Spherisorb ODS-2 (250 X 4.6 mm, 5 jum Rainin). 35°C. Isocratic 0.1 mM EDTA and 1.0 mM tetrabutyl-ammonium phosphate in 0.08 M acetate buffer, pH 4.2 + methanol (95 + 5, v/v). No flow rate reported. Electro- chemistry + 0.72 V vs. Ag/AgCl reference electrode, glassy carbon working electrode. External standardization. Linear range = 0-60 /ug/g yeast (dry weight). Reproducibility CV 2.3% for IAA, 1.2% for A A. Recoveries quantitative for both vitamers. 59... 

Molecular hydrogen (H2 AHDBE, 435 kJ mol-1) is resistant to electrochemical oxidation at inert electrodes (glassy carbon or passivated metals Ni, Au, Hg, Cu). At passivated Pt and Pd dissolved H2 exhibits only broad, diffuse, anodic voltammetric peaks with irreproducible peak currents that are not proportional to the partial pressure of dissolved H2 (PH2). However, with freshly preanodized Pt and Pd electrodes well-defined oxidation peaks for H2 are obtained, which have peak currents that are proportional to P (Figure 8.3).14 The surface... 

For those electrophiles (El) that undergo direct electron-transfer reduction at an inert electrode (glassy-carbon), the reduction potential ( red) is a measure of their electron affinity and electrophilicity [relative to that for H30+ (-2.10 V vs. NHE in aqueous media)] (the more positive the potential the more electrophilic the molecule see Chapter 1] ... 

Sample preparation pooled urine (pH 2) spiked to SO ppb tetrachlorohydroquinone, hydrolyzed 30 min at 90°-100°C 5-mL volume extracted three times with ether, combined extracts evaporated and redissolved in 0.5 mL 40% methanol, 0.1 mL injected. Column 15 cm X 4.6 mm Waters fi Bondapak CIS mobile phase 0.1 M ammonium acetate pH 6, 38% methanol, 1.0 mL/min detector electrode glassy carbon, TL-5 2 mil gasket potentials vs. Ag/AgCl/3M NaCI reference electrode. 

Figure 3. Differential pulse voltammogram of a mixture of dibenzothiophene and benzothiophene in acetonitrile. Supporting electrolyte 0.1 M tetraethylammonium perchlorate. Indicator electrode glassy carbon disk, rotated at 1800 rpm. Linear potential ramp, 0.002 volt/s. Pulse amplitude, AE = 0.025 V. Pulse duration, 57 ms. Current sampling time, 17 ms.

Figure C. V. of 5 (5x1 Cr3 M) and C60 (2.5x1 O 3 M) in o-dichlombenzene suporting electrolyte 0.1 M Bu4NC104 working electrode glassy carbon counter electrode Pt wire reference electrode Ag/O.OIN AgN03 in acetonitrile with 0.1 M "Bu4C104 ( E,n (ferrocene/ferrocenium) = 180V) scan rate 100 mVs-1.

Detection electrochemical amperometric detector LC-4B (Bioanalytical Systems Inc.) mode single electrode cell geometry thin layer, 2 pm working electrode glassy carbon reference electrode silver / silver chloride range 10 nA. 

Detector E, Metrohm Model 656 electrochemical and Model 641VA detectors, working and auxihary electrodes glassy carbon, reference electrode Ag/AgCl, 1200 mV UV 280... 

Optical sensor Amperometric sensor Amperometric sensor Oxygen electrode/polysulfone membrane Platinum electrode Glassy carbon electrode/ methylene blue mediator Three separate enzyme electrodes of pH electrode/cellulose acetate membrane Platinum electrode... 

Fig. 18 Current, beam deflection, and frequency change responses (panels (a-c), respectively) of a poly(l-hydroxyphenazine) film to a redox cycle under cyclic voltammetric conditions. Electrodes glassy carbon (probe beam experiment) and Au (area = 0.36 cm ) on 5-MHz AT-cut quartz crystals (QCM experiment). Solution 1 mol dm HCIO4. Potential scan rate 50 mV s (Reproduced from Ref. [122] with permission from Elsevier.)...

Figure 8.8. (A) Evolution of the cyclic voltammograms of complex Co(II)-32 in DCM containing 0.1 M TBABF4 during repeated successive scans (only 15 scans are shown). Scan rate = 200 mV s , concentration 3 mM, electrode = glassy carbon. (B) Absorption spectra of poly[Co(II)-32] films on ITO electrodes prepared with 30 (curve 1), 60 (curve 2) and 120 (curve 3) electropolymerizing scans. Curve 4 corresponds to Co(II)-32 monomer in DCM solution. Reprinted from ref. [82]. Copyright (2003) Society of Porphyrins Phthalocyanines.

Figure 7.20 (A) Electron-transfer numbers for the ORR catalyzed by 5wt% Co-N/C catalyst obtained after heat treating 5wt % Co-TPTZ/C at 700 °C (B) the corresponding %H202 produced. Data obtained using rotating ring (Pt)-disk electrode (glassy carbon coated by Co-N/C) in an 02-saturated 0.5 M H2SO4 solution Co-N/C catalyst loading in the disk coating 0.1 mg cm. Reprinted with permission from Ref. 65.

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