The electrochemical behavior of 1-(2-phenyl-2-hydroxyiminoethyl)-l-quinolinium chloride (F-1) and 1-(2-phenyl-2-hydroxyiminoethyl)-l-isoquinolinium chloride (F-2) was investigated using dc and differential pulse polarography (DPP) and cyclic voltammetry. Well-defined, diffusion-controlled, cathodic waves were observed for F-1 only in strong acidic solution (pH 1.25 HCI) and for F-2 in the pH range 1. . The overall reduction of the azomethine group to a primary amine, a process that involves the uptake of four electrons, is irreversible. For both oximes a mechanism of reduction has been proposed. The rapid and accurate determination of these quinolinium and isoquinolinium oximes is possible by dc polarography and by DPP. Limits of detection are 5 X lo-' M for both oximes using DPP.
IATRODUCTIONIn addition to the quaternary pyridinium oximes (PAM-2C1, TMB-4, Toxogonin, and HI-6), which are presently used as antidotes in poisoning by organophosphorus compounds, such as pesticides or nerve gases [l, 21, a new group of oximes, phenacyloximes, has been recently investigated for their antidotal properties. Quinolinium oximes are new synthetic phenacyloximes, and it was found that 1-phenacyloxime quinolinium chloride (F-1 ) and 1-phenacyloxime isoquinolinium chloride (F-2) were promising antidotes [3-51.We have described the spectrophotometric behavior of quinolinium oxime-palladium( 11) complexes [ 61 and also, on the basis of the formation of these complexes, the potentiometric titrations of F-1 and F-2 oximes for ~ To whom correspondence should be addressed their determination [ 71. We also have proposed using the UV spectrophotometric method in acidic media for determination of these compounds [ 81. Previous studies in this laboratory explored the polarographic behavior and determination of pyridinium oximes, which are of pharmaceutical importance as antidotes [ 9-13], and also of 4' and 6'-methyl derivatives of 1-(2-phenyl-2-hydroxyiminoethyl)-1-quinolinium chloride [ 14, 151. Having in mind the sensitivity of the polarographic method, we decided to apply it for the analytical determination of F-1 and F-2 oximes, as well. These compounds have not been investigated polarographically.
ApparatusThe direct current (dc) and differential pulse polarographic (DPP) studies were carried out with a Cambridge 0 1991 VCH Publishers, Inc.