Abstract
Three main types of PVC-liquid membrane ISEs for diquat and paraquat are described. They are based on the crown ether DB30C10 and/or the diquat-paraquat ion pair with tetraphenylborate (DQT.2TPB or PQT.2TPB). With DB30C10-based ISEs (type 1), selectivity for diquat and paraquat over other cations is greatly improved after the addition of DQT.2TPB to the membrane to yield type 2 electrodes. Electrodes based entirely on DQT.2TPB or PQT.2TPB (type 3) also give excellent characteristics with appropriate solvent mediators.Selectivity coefficient data (kpotDQT,B and kpotPQT,B) have been determined with respect to B = Li, Na, K, Mg, Ca, Ba, ammonium, di-methyl ammonium, anilinium and guanidinium. Although the selectivity coefficients frequently exceeded unity for interferents of singly charged B ions, the modifying influence of the square power term in the selectivity relation enhances the selectivity towards diquat and paraquat. For doubly charged B ions the selectivity coefficients for types 2 and 3 electrodes were normally
Original language | English |
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Pages (from-to) | 121-127 |
Journal | ANALYST |
Volume | 112 |
Issue number | 2 |
DOIs | |
Publication status | Published (in print/issue) - Feb 1987 |