Product
Review
What's current in potentiostats Good news for electrochemists: It's a buyer's market for anyone looking to purchase a potentiostat. Numerous companies are vying with each other in a competitive market, offering a wide range of instruments with price tags that start at around $2500 and go up to $25,000. For most manufacturers, the research community working in academic and government labs remains an important market. Other buyers cited by company representatives include the chemical and nuclear industries, along with small R&D companies involved in product development. These buyers are using potentiostats for basic research, biosensor and sensor development, corrosion and battery studies, synthesis, and the monitoring of industrial processes. According to electrochemist David Wipf of Mississippi State University, the classic cyclic voltammetry experiment is still the most popular potentiostat technique, followed in no particular order by differential pulse polarography, square-
A surprisingly competitive market offers lots so choices wave voltammetry, and chronoamperometry. Many of the other electrochemical techniques are built on the principles behind these methods. Nearly all manufacturers sell computercontrolled general-purpose instruments that allow researchers to run not only the popular experiments but many of the specialized techniques. However, one doesn't need an expensive system to perform sophisticated experiments. "With appropriate software programming, you can do just about anything on the basic hardware," says Wipf. "All the fancy techniques really need is a good A to D (analog to digital) converter and a good D to A board."
Some experiments, such as corrosion studies, stripping, deposition, bulk electrolysis, or synthesis using 'large" electrodes, are typically best run with a constantcurrent galvanostat and can often require high voltages and currents. A galvanostat with a high-current output can also be found combined with a potentiostat in some general-purpose systems. "There is no compromise in combining a potentiostat and galvanostat, [manufacturers] use basically the same electronics " reports Wipf. In fact, Wipf recommends buying a combined system with as many features as can be afforded, arguing that in the long run it is cheaper than purchasing separate systems. "For many analytical researchers, a galvanostat is not something that you use every day—but when you want it, you have to have it," he says. "If you are going to buy a potentiostat for research purposes, you don't want to lose that investment by not having a wide range of capabilities." Others
Analytical Chemistry News & Features, June 1, 1997 3 6 9 A
Product
Review
Table 1 . Examples of potentiostats System Manufacturer or distributor
URL or e-mail Description
I BAS 100B/W Bioanalytical Systems 2701 Kent Ave. West Lafayette, IN 47906 800-845-4246 www.bioanalytical.com Electrochemical analyzer capable of handling 38 techniques
Compliance voltage ±12 V Applied voltage ± 3.276 V range Current range 100nAto 190 mA
ICS2000 I System 5000 Cypress Systems The Electrosynthesis Co 2500 West 31st St. 72 Ward Road Suite D Lancaster, NY 14086 Lawrence, KS 66047 716-684-0513 800-235-2436 www.cypresshome.com www.electrosynthesis. com Computer-controlled Computerized electrogeneral purpose poten- chemical interface with tiostat-galvanostat a built-in microprocessor analysis system ±36 V ±120 V + 2 V, + 4 V, or + 8 V ±8.192 V o r ± 2.048 V
I Autolab PGSTAT20 Brinkmann Instruments One Cantiague Road P.O. Box 1019 Westbury, NY 11590 800-645-3050 www.brinkmann.com
I Model 600 series CH Instruments 676 Germantown Pkwy. Suite 517 Cordova, TN 38018 901-754-2688
[email protected] Modular, computer controlled, power potentiostatgalvanostat ±30 V ± 10V
Electrochemical workstation, potentiostat-galvanostat ±12 V ±10V
1Ato50nA
1Ato100nA
100nAto1A
Minimum potential 100uV step Linear voltage scan- 100 uV/sto300+V/s rate range iR compensation Positive feedback
31 uV
6.25 uV
160 uV
1 0 0 p A t o 2 5 0 m A (1 pA with booster) 100 uV
31 jiV/s to 200 V/s
1 aV/s to 100 V/s
5 mV/s to 50 V/s
1 uV/s to 4000 V/s
Positive feedback
Currrent interrupt and positive feedback
Current interrupt and positive feedback
Positive feedback
Rise time AC techniques Software
