Studies on response characteristics of drug ion-selective electrodes (II)--sulpha-drug sensitive electrodes using quaternary phosphonium and arsonium compounds.
Ion-pair complexes of sulphonamide derivatives with quaternary phosphonium and quaternary arsonium have been synthesized and their electrode performances studied. It has been found that the electrode functions depend mainly on the site cation rather than on the anionic species and deteriorate in the order of cetyltrioctylammonium greater than cetyltriphenylphosphonium greater than cetyltriphenylarsonium. The electrode selectivity for different sulpha-drugs decreases in the order of sulphathiazole greater than sulphamethoxazole greater than sulphadimethoxine, sulphadoxine greater than sulphacetamide greater than sulphadiazine greater than sulphanilamide. Selectivity coefficients depend not only on the molecular connectivity index chi, but also on the electronic charge at the ionizing amide nitrogen atom sigma and pKa according to the following formula: logKij = a chi + b sigma - CpKa - d. The quaternary phosphonium type electrodes have been suggested for use in the potentiometric determinations of sulpha-drugs.
Yao
S Z
SZ
New Material Research Institute, Hunan University, Changsha.
Xiao
J
J
Nie
L H
LH
D004566:Electrodes; D011199:Potentiometry; D013424:Sulfanilamides
D013424:Sulfanilamides