Novel polymeric membrane sensors based on Mn(III) porphyrin and Co(II) phthalocyanine ionophores for batch and flow injection determination of azide

Two novel potentiometric azide membrane sensors based on the use of manganese(III)porphyrin [Mn(III)P] and cobalt (II)phthalocyanine [Co(II)Pc] ionophores dispersed in plasticized poly(vinyl chloride) PVC matrix membranes are described. Under batch mode of operation, [Mn(III)P] and [Co(II)Pc] based membrane sensors display near- and sub-Nernstian responses of - 56.3 and - 48.5 mV decade(-1) over the concentration ranges 1.0 X 10(-2) - 2.2 x 10(-5) and 1.0 X 10(-2) -5.1 X 10(-5) mol L-1 azide and detection limits of 1.5 X 10(-5) and 2.5 x 10(-5) mol L-1, respectively. Incorporation of both membrane sensors in flow-through tubular cell offers sensitive detectors for flow injection (FIA) determination of azide. The intrinsic characteristics of the [Mn(III)PI and [Co(II)Pc] based detectors in a low dispersion manifold show calibration slopes of - 51.2 and - 33.5 mV decade(-1) for the concentration ranges of 1.0 x 10(-5) - 1.0 X 10(-2) and 1.0 x 10(-4) - 1.0 X 10(-2) mol L-1 azide and the detection limits are 1.0 x 10(-5) and 3.1 X 10(-5) mol L-1, respectively. The detectors are used for determining azide at an input rate of 40 - 60 samples per hour. The responses of the sensors are stable within +/- 0.9 mV for at least 8 weeks and are pH independent in the range of 3.9 - 6.5. No interferences are caused by most common anions normally associated with azide ion.