Porphyrins as carriers in poly(vinyl chloride)-based membrane potentiometric sensors for histamine

Iron(III) and manganese(III) tetraphenylporphyrins were explored as electroactive materials for preparing polymeric membrane-based sensors selective to histamine. The membranes, incorporating 30% poly(vinyl chloride) (PVC), 60% dioctyl phthalate (DOP), and 10% iron or manganese tetraphenylporphyrin, coated on the surface of graphite electrodes, exhibited near-Nernstian responses in the concentration range from 1 x 10(-6) to 1 x 10(-1) mol dm(-3) with detection limits of about 5 x 10(-7) mol dm(-3) histamine, and response times of < 30 s. The electrodes show high selectivity towards histamine over several amino acids and common inorganic anions and can be used in a wide pH range. They were applied to the determination of histamine in synthetic serum samples.