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 (l uminol) within a hydrogel or polymeric, sorbent coating that is positi oned in front of a photomultiplier tube. Some selectivity is tailored into these devices by careful section of the polymer type, pH, and met al 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. catal yst, Fe-2(SO4)(3). For the detection of NO2(g), the use of sorbent, po lymer coatings such as fluoropolyol or polyethylenimine resulted in st rong humidity dependencies, exhibiting no chemiluminescence under dry conditions. Incorporation of the chemiluminescent reagents within a hy drogel (e.g., poly(vinyl alcohol) or superabsorbing polymer Waterlock) eliminated this effect. A survey of various hydrogel immobilization m atrices and metal catalysts found that, for the determination of NO2(g ), Cu(II) and the superabsorbing polymer Waterlock provided the best f ilm performance with respect to sensitivity (0.46 ppb) and stabitity. Discussions center about the complete characterization of these chemil uminescent chemical sensors and an examination of specific methods use d to extend the sensitivity and selectivity of these devices.