Hg drop electrodes

Fig. 5 Schematic representation of LAJs based on liquid metal electrodes, (a) The two Hg drops junction. The drops are extruded from two microsyringes and covered singularly by similar or different SAMs before being brought in contact, (b) An Hg-drop electrode covered by SAM(l) (usually formed by hexadecane thiol) is brought in electrical contact with a SAM(2) formed on a solid metal surface, (c) A drop of In/Ga eutectic alloy (E-Gain) contacts a SAM formed on a solid electrode surface...

Fig. 18b.1. Electrochemical cells and representative cell configurations, (a) Schematic diagram of a cell-potentiostat system, (b) Typical laboratory cell with Hg-drop electrode and drop knocker, (c) Voltammetric cell as detector at the end of a high-performance liquid chromatographic column, (d) A two-electrode (graphite) chip cell for biosensor development, (e) Three-electrode chip cells on a ceramic substrate for bioanalytical work.

The hydroperoxides of various phospholipids, such as phosphatidylcholine (PC— OOH, 155), phosphatidylserine (PS—OOH), phosphatidylethanolamine (PE—OOH), phos-phatidylinositol (PI—OOH) and cardiolipin (CL—OOH), can be determined by HPLC-ELD on a polar LC—NH2 column, using as mobile phase a MeOH//-PrOH/40 mM aqueous NaH2P04 mixture (61 30 9 by volume). ELD is by the hanging Hg drop electrode method set at —150 mV vs. SCSE. The relative mobility for the given chromatographic system is shown in equation 68, which is almost a reversal of the order shown in equation 63 for HPTLC. The LOD varies from about 0.5 to 1.0 pmol, depending on the class of phospholipid hydroperoxide . ... 

Table 23.3A Sample Calculation of ks for Ni(III)/Ni(II) Couple of [Ni(C2B9H9Me2)2] /2 in CH3CN/0.3 M Bu4NPF6 from CV Peak Separations at Hanging Hg Drop Electrode, T = ambient, E° = -0.92 V vs. Fc ...

Shain, AnalChem 30, 1808-10 (1958) (Differential voltammetry using the hanging Hg drop electrode) 24)N.Tanaka T.Murayama, ZPhysChem (Frankfurt a/M) 14, 370-74 (1958) (Analytical chronopotentiometry) 25)JSJ-Lingane, "Electroanalytical Chemistry , Interscience, NY (1958), Chap 22 (Chronopotentiometry) 26)G.Chariot, "Modern Electroanalytical Methods , Elsevier, Amsterdam... 

Fig. 14. Schematic of the Hg drop electrode set-up and current-voltage characteristics for a Si(lll) substrate modified by a decyl monolayer (Cio) and with a clean native oxide (SiC>2). The decyl monolayer was formed by a thermal reaction of decylmagnesium bromide with H/Si(lll). The contact areas of the Hg drop were measured optically and were typically 2 X 10-3cm-2. Reprinted from [81].

The dissociation constant and solubilities of rufloxacin HC1 (21 HC1) were measured (89MI4). An adsorptive stripping voltametric method with a hanging Hg drop electrode was developed for the determination of 21 in tablets and biological fluids (95MI20). 

Figure 1. Potentiostatic (pulse) current-time curves at hanging Hg-drop electrode. Solid line = 10 M Cd in 1 M KNOj dotted line = charging current from 1 M KNOj electrolyte.

Preparation of Hg film electrode. The Hg film electrode, although possessing superior sensitivity characteristics, is more subject to irreproducible behavior than is the hanging Hg drop electrode. The following plating procedure is satisfactory. 

Food crops Pb Cd Ash with H2SO4 ashing aid, diss HNO3 [DA] Measure voltammetric peak amplitudes in HOAc/NaOAc buffers with polarograph and static Hg dropping electrode [DPASV] [DA-DPASV] Satzger etal. 1982... 

High results and small standard deviations obtained by DPASV were questioned. The small standard deviation is inherent to the technique used but interferences and adsorption problems on the Hg drop electrode were suspected, which could explain the higher value found (50.4 pg L ). 

Figure 2. Linear sweep voltammograms at a hanging Hg drop electrode for Mn(III)bis-tris in seawater before and after addition of 1/2 an equivalent of sulfide at pH =7. The Mn(III) to Mn(ll) reduction peak at -1.05 V vs. SCE decreases after sulfide addition. The total current for the Mn(IlI) reduction plus the Mn(II) to Mn(0) reduction before sulfide addition (peak at -1.57 V vs SCE) equals the total current for Mn(II) to Mn(0) after sulfide addition indicating that Mn(II) is the final product.

Figure 1.15 Capacitance-potential curves for n-pentanol in 0,1 U KCl at a Hg drop electrode.

Fig. 4.6 Dependence of in-phase current, proportional to real part of total electrode admittance for Cd reduction at Hg dropping electrode in dimethyl-sulfoxide (From Ref. [150] with permission of author)...

The substitution inertness of Cr(III) and the lability of Cr(II) have allowed Hecht et al. to observe some ring-opening and ring-closing reactions of amino-carboxylate ligands. The experiments used a stationary Hg drop electrode in 1.0 M NajSO at pH 8.5, apparently at ambient temperature. Their observations can be explained by Scheme 10.2, where the aliphatic substituent R gives the trans-N,N geometry shown. 

Voltammetry is carri out on the sample, using a static Hg drop electrode,... 

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