Silver working

Silber-homerz, n. horn silver, cerargyrite. -hiitte, /. silver foundry, silver works. 

All SERS experiments were conducted with a polycrystalline silver working electrode prepared by press-fitting a 6 mm diameter cylinder of silver into one end of a 0.375 inch diameter Teflon rod through which a 6 nm diameter concentric hole had been drilled. Electrical contact was made via a copper wire soldered to the silver. The geometric area of the silver disk was 0.28 cm2. 

D. Ions that react with Ag+ can be determined electrogravimet-rically by deposition on a silver working anode ... 

Rocklin and Johnson [48] used an electrochemical detector in the ion chromatographic determination of cyanide and sulphide. They showed that by placing an ion exchange column in front of an electrochemical detector, using a silver working electrode, they were able to separate cyanide, sulphide, iodide and bromide and detect them in water samples at concentrations of 2, 30, 10 and lOpg L 1 respectively. Cyanide and sulphide could be determined simultaneously. The method has been applied to the analysis of... 

This method is based on the work of Pihlar and Kosta [50,51] who showed that a silver working electrode has the ability to produce a current that is linearly proportional to the concentration of cyanide in an amperometric electrochemical flow through cell. The reaction for cyanide is ... 

Urinary iodide was measured using paired-ion reversed-phase high-performance liquid chromatography (HPLC) with electrochemical detection employing a silver working electrode (Rendl etal., 1994). A detection limit of 5 pg was achieved. 

The other was constructed from Upchurch P-200 series fittings as illustrated in Fig.l. The silver working electrode was a 2 mm diameter disk. The Water s cell contained a Ag/AgCl reference electrode, while the homemade cell used an SCE. Unless otherwise indicated all potentials are with respect to SCE. 

Environmentally relevant anions such as sulfide and cyanide are detected on a silver working electrode under strongly alkaline conditions (see Figure 3.126 in Section 3.7.3.1). The carbon paste electrode is used for detecting nitrite and chlorite under acidic conditions and at neutral pH. Nitrite and chlorite can also be oxidized at a glassy carbon electrode, but the resulting sensitivity is significantly lower because the surface is less electrochemically active. 

C eluent 50mmol/L HNO3 flow rate 1.5mL/min detection IPAD on a silver working electrode waveform see Table 10.30 injection volume 100 (it sample A 0.04 mg/L iodide in deionized water, sample B milk-... 

Cyanide detection is accomplished by using an FIA system in which a 200 pi aliquot of the pretreated sample is injected. The addition of hydrochloric acid converts cyanide ion to hydrogen cyanide (HCN) that passes selectively through a gas-diffusion hydrophobic membrane into an alkaline-receiving solution where it is converted back to cyanide ion. The latter is monitored amperometri-cally with a silver-working electrode, silver/silver chloride reference electrode, and platinum/stainless steel counter electrode, at an applied potential of zero volt. The current generated is proportional to the cyanide concentration present in the original sample. 

Flow system for total cyanide analysis by ASTM Method D 7511-09e2. Detector silver working electrode, Ag/AgCI reference electrode, stainless steel counter electrode IV Injection valve RC reaction coll. 

Our efforts in this area were initiated in 1995 with investigations of the electrodeposition of silver (26, 27) and, soon thereafter, platinum (28) nanoparticles on HOPG surfaces. The primary characterization tool employed in these experiments was ex situ non-contact atomic force microscopy (NC-AFM). In the silver work, HOPG electrode surfaces were examined by NC-AFM after the application of large amplitude potentiostatic pulses with amphmdes of —100 to —500 mV (vs. Ag/Ag+) and durations of 10-50 msec in dilute silver-plating solutions. These images looked dramatically different from the... 

Ion-exclusion chromatography is also suited for the determination of cyanide, which can be oxidized on a silver working electrode at low potential. Nitric acid (c = 0.1 mol/L) is used as the eluant Because an alkaline medium is required for... 

Fig. 9-156. Separation of iodide in low-fat milk. — Separator column lonPac AS11 eluant 5 mmol/L HNO3 flow rate 1.5 mL/min detection DC amperometry on a silver working electrode oxidation potential 0.05 V injection volume 100 pL sample low-fat milk sample preparation see text solute concentration ...

Aleksandrova and Kletenik [49] proposed voltammetric method for the determination of chloride concentration in different water samples. They use renewable silver working electrode. Both direct anodic voltammetry and cathodic stripping voltammerty could be successfully used in 1 M sulfuric acid. In the case of cathodic stripping method, 3 min per electrolysis step was employed at —0.07 V to obtain silver chloride film at the electrode surface. 

Silver disk microelectrode and differential pulse voltammetry can be used successfully for trace level iodine determination in tap water samples. According to Fang and coworkers [76], the mixture of 4 cm acetate buffer (pH 5), 1 cm 1 M EDTA solution, and 5 cm water sample are separated, after the silver working electrode is preconditioned by cycling between +0.1 and 0.6 V. A 1 min electrolysis time follows and the differential stripping pulse voltammetry step is performed with 50 mV pulse amplitude. The peak at —0.32 V is evaluated. A calibration graph, which is linear in the range of 50 nM—1.2 xM is used for the evaluation. 

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