Polarographic analyzer

Fig. 3.83. Potentiometric dead-stop (1) and reversed dead-stop (2) end-point titrations, (a) Metrohm Polarecord 626 PARC Model 174A Polarographic Analyzer, (b) Radiometer ISS 820 Ion Scanning System, (c) Tacussel PRG4 Polarograph. 

Fig. 5.10. PARC Model 384B polarographic analyzer and Model 303A static mercury drop electrode. 

The current limit is set by die rate of diffusion (of the ion being discharged) through the depleted layer surrounding the electrode. This diffusion rate is proportional to the ion concentration. For application of this effect, sec Polarographic Analyzers. 

The electrochemical characteristics of pantoprazole sodium was studies using an EG G model 264A polarographic analyzer stripping voltammeter in conjunction with a model 303 static mercury drop electrode. A differential pulse amplitude of 50 mV and a scan rate of 20 mV/sec were used. 

The amount of some gases, such as SO2 [73], CO [74], can be automatically continuously measured by polarographic analyzers [75]. Measuring electrodes with a constant surface, e.g. carbon, platinum, gold disks or rods are most often used. Present research is concentrated on the so-called coulometric analyzers [73]. The analysed gas is brought by the shortest route directly to the measuring electrode. The substance to be determined is completely reduced or oxidized electrochemically at a large area electrode. 

Electrochemical instrumentation included a PAR model 174A Polarographic Analyzer and a homebuilt waveform generator (16). 

Figure 23-20 (a) Differential pulse polarogram 0.36 ppm tetracycline-HCl in 0.1 M acetate buffer, pH 4, PAR Model 174 polarographic analyzer, DME, 50-mV pulse amplitude, 1-s drop, (b) DC polarogram 180 ppm tetracycline-HCl in 0.1 M acetate buffer, pH 4, similar conditions. (Reprinted with permission from J. B. Plato, Ana/. Chem., 1972,44, 75A. Published 1972, American Chemical Society.)... 

For the determination of tin(ll) in kits an EG 8c G polarographic analyzer (model 384) with a static mercury drop electrode (model 303) and a cabinet reference electrode was used. Model 384 is a microprocessor-based polarographic analyzer with built-in floppy disk memory to store and recall analytical curves. By controlling each step of the analysis, the microprocessor automates polarographic and voltammetric measurements. All experimental parameters may be chosen by the operator. Concentrations are computed automatically aud recorded iu the rauge from 0.001 ppb to 9999 ppm. 

Nephelometry analyzers Potentiometry Conductimetry Oscillometric analyzers pH Meters Polarographic analyzers Coulometers process control... 

NIES biological CRMs Zn Cd Pb Cu Digest with FlNOs, in a Fligh Pressure Asher [WDCCV] Measure square wave ASV with polarographic analyzer with HMDF [SWASV] [WDCCV- SWASV] Wtirfels 1989... 

Yarnitzky, C.N. (1985). Automated cell a new approach to polarographic analyzers. Anal. Chem. 57, 2011. 

Detector Chemiluminescence following post-column reaction. A 1 mM solution of Ru(2,2 -bipyridine)3 in 50 mM sodium sulfate (continuously sparged with helium) was oxidized to Ru(2,2 -bipyridine)3 " using a Princeton Applied Re arch Model 174A polarographic analyzer with a platinum gauze working electrode, a platinum wire auxiliaty electrode, and a silver wire reference electrode. The Ru solution pumped at 0.3 mL/min mixed with the column effluent in the flow cell of the detector, a fluorescence detector with the li t source removed. 

The three-electrode system is connected to the polarographic analyzer which maintains the working electrode potential using a potentiostat which also controls the potential scan applied at the DME whilst monitoring reduction/oxidizing currents. 

These instruments led to the much more simple PAR 174 Polarographic Analyzer, which through integrated circuit technology provided both classical and pulse polarographic capabilities with fixed pulse width at a price ( 1925 in 1971) equivalent to that of simple dc polarographs. This basic instrument is still available today. 

In 1975, the PAR Model 374 Polarographic Analyzer was introduced, at a price of 9500. This instrument employed a 16-bit microprocessor to control acquisition and analysis of data. During data collection, scale expansion and autoranging were automatic, and invalid data points could be rejected by comparison with pre-set criteria. In the PLAYBACK mode, the entire curve was reread and plotted on the recorder, with all peaks on scale. If desired, baseline and background corrections were measured, and concentrations calculated from pre-set standards. This was the first pulse voltammetric instrument designed around a microprocessor. Like the Southern Analytical pulse instrument based on vacuum tube technology, it came a bit too soon, before the technology (or the customer) was quite ready. 

Differential pulse polarographic analyzer equipped with a PARC Droptimer. 

---