CHEMILUMINESCENT CHEMICAL SENSORS FOR OXYGEN AND NITROGEN-DIOXIDE

Chemiluminescent chemical sensors for oxygen and nitrogen dioxide have been investigated via the immobilization of 3-aminophthalhydrazide (luminol) within a hydrogel or polymeric, sorbent coating that is positioned in front of a photomultiplier tube. Some selectivity is tailored into these devices by careful section of the polymer type, pH, and metal catalyst incorporated within the film. Oxygen levels as low as 2.4 ppm in nitrogen have been detected using the oligomer fluoropolyol as the support matrix for immobilizing luminol, KOH, and the metal. catalyst, Fe-2(SO4)(3). For the detection of NO2(g), the use of sorbent, polymer coatings such as fluoropolyol or polyethylenimine resulted in strong humidity dependencies, exhibiting no chemiluminescence under dry conditions. Incorporation of the chemiluminescent reagents within a hydrogel (e.g., poly(vinyl alcohol) or superabsorbing polymer Waterlock) eliminated this effect. A survey of various hydrogel immobilization matrices and metal catalysts found that, for the determination of NO2(g), Cu(II) and the superabsorbing polymer Waterlock provided the best film performance with respect to sensitivity (0.46 ppb) and stabitity. Discussions center about the complete characterization of these chemiluminescent chemical sensors and an examination of specific methods used to extend the sensitivity and selectivity of these devices.