Development of a new flow-through bulk optode for the determination of manganese(II)

A flow-through bulk optode based on the use of 1-(2-pyridylazo)-2-naphthol (PAN) immobilized in a plasticized poly(vinyl chloride) membrane entrapped in a cellulose support, in conjuntion with the flow injection analysis tech nique, is proposed for the determination of manganese(II). The calibration graph obtained at 570 nm was linear in the range 0.27-27.5 mg L-1 (5 x 10(- 6)-5;( 10(-4) M) MN(II) with a detection limit of 0.18 mg L-1. The coeffici ents of variation of the sensor response for 5.5 mg L-1 of Mn(II) were +/-0 .22% for consecutive measurements (n = 10). +/-0.48% between days in = 5) a nd +/-0.38% between different membranes (n = 6). The sensor was readily reg enerated with the carrier acetic acid/acetate buffer of pH 4.5. The method was applied to the determination of manganese in steels, waters and lemon t ree leaves.