Novel optical bulk membrane sensor and its application for determination of iron in plant and cereal samples

A new ion selective optical bulk membrane sensor is fabricated for the highly sensitive and selective determination of iron(III) ion that is ion concentrations based on plasticized poly vinyl chloride containing 3% 1,1′-(iminobis(methan-1-yl-1-ylidene))dinaphthalen-2-ol as a chromo-ionophore, 3% sodium tetraphenylborate as an anionic additive and 64% tris(2-ethylhexyl)phosphate as a plasticizer. The proposed sensor displays a wide linear dynamic range from 1.0 × 10−9 to 1.0 × 10−3 mol L−1 with a low limit of detection of 6.2 × 10−10 mol L−1 at pH 4.7. The sensor has a fast response time of less than 80 s. In addition to its high stability, reproducibility and stability over long life time period, the optical sensor shows a unique selectivity toward Fe(III) ions over a large number of organic and inorganic substances such as metal ions, sugars, amino acids and vitamins. The proposed optical sensor could readily be regenerated by exposure to 1.0 × 10−1 mol L−1 sodium thiourea solution and is also applied successfully determination of the iron contents in plant and cereal samples with satisfactory results.