Neutral bidentate organophosphorus compounds as novel ionophores for potentiometric membrane sensors far barium(II)

Bis(diarylphosphine oxide) naphthalene compounds are used as novel ionophor es in plasticized poly(vinyl chloride) matrix membrane sensors for barium i ons. The most favorable sensor was 1,2-bis(diethyl-phenylphosphine oxide)na phthalene containing potassium tetrakis(4-chlorophenyl)borate as lipophilic salt and o-nitrophenyloctyl ether as plasticizer for ion-selective electro de membrane construction. The electrode showed excellent properties. It gav e a linear response with a Nernstian slope of 30 mV per decade within the c oncentration range 10(-1)-10(-5) mol L-1 BaCl2. The electrode exhibits a hi gh selectivity towards Ba2+ with respect to Li+, Na+, K+, Rb+, Cs+, NH4+, A g+, Mg2+, Ca2+, Sr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+, Al3+, La3+, and Ce3+ ions. The electrode response was stable over a wide pH rang e (3-11). The lifetime of the electrode was about 2 months. It was successf ully applied to the determination of Ba2+ contents in some rocks.