Amperometric, Bipotentiometric, and Coulometric Titrations John T. Stock University of Connecticut, Storrs, Conn. 06268
The period covered by this survey is from the previous reviews (82, 342, 343) through October, 1975. Unless otherwise specified, potentials are with respect to the saturated calomel electrode (SCE). In each area, the intended order of treatment is amperometric, bipotentiometric, and nonamperometric or coulometric. Many coulometric titrations are monitored amperometrically. When thus identified, they have been treated as amperometric titrations. Reviews of amperometric titrimetry include general as-. pects (326, 335), continuous analysis (185), nonaqueous systems (382),trace determinations (336),inorganic microanalysis (309), determination of antibiotics (364),measurements for industrial uses (253), determination of niobium (234), uses of 8-mercaptoquinoline (28),and of organic reagents in general (265).The value of polarized electrode titrimetry has been discussed (201). In addition to general aspects (31, 67, 142), reviews of coulometric titrimetry concern the electrogeneration of reagents (94),the titration of organic compounds (205), and continuous analysis (186, 344,350). Theoretical studies on dc and ac amperometric titrations involving complexometric reactions ( 1 7 ) and on errors related to incomplete reactions (180) have been reported. The end-point location in amperometric titrations by multiparametric curve fitting (244) and mathematical simulation of bipotentiometric titration curves at pretreated electrodes has been described ( I 7 7 ) . Phenomena associated with periodic polarization techniques have been extensively examined (34-36). The effect of cell geometry in coulometric titrations ( 7 7 ) ,the dynamics of continuous coulometric titrations (104), and the status of the Faraday constant as an analytical standard (160)have been discussed.
APPARATUS AND METHODOLOGY Various amperometric (96, 277, 380), biamperometric ( 8 5 ) , amperometric-coulometric (65, 256, 379), bipotentiometric-coulometric (251), and controlled-current (106) automatic titrators have been reported. Bipotentiometric titration apparatus ( 8 ) and a stable electrode polarization source (136)have been described. Coulometric titration apparatus includes a commercial universal titrator (75, 76), a versatile integrated-circuit titrator (137), circuitry to improve sensitivity (254,255), and a titrator in which the current is proportional to the difference between the potential and a predetermined final value (14). Other developments are a simple constant-current source (206), a simple fluorescence detection system (165), and a small-scale cell for the external generation of coulometric titrants (18). Titration times of
