Carbon dioxide significantly enhances the chemiluminescence of 5-amino-2,3-dihydrophthalazine-1,4-dione (luminol) in the absence of added oxidant. The effect in presence of a variety of rate modifiers (e.g., metal ions and some metal ion complexes) is described in detail. A postulation of the species responsible for enhancement, the role of dissolved oxygen, the influence of the form in which the rate modifier is present and a possible mechanism to explain the enhancement by C02 (g), are also presented. The potential analytical applications of this effect are mentioned and illustrated with the analytical figures of merit for the chemiluminescence determination of Col* in the 5 x 10-13-10-7 moll-1 range.

A study of the enhancement of the fluorescence intensity of the Eulll -thenoyltrifluoroacetone (-A) -trioctylphosphine oxide (TOPO) system by Lalll, Gdlll, Lull1 and Ylll has been carried out in a colloidal-like suspension. Gadolinium(ll1) caused the largest enhancement of the fluorescence intensity. In the presence of this element the weak fluorescence of the Eulli-TTA -TOPO system was enhanced by a factor of about 18 at a pH of between 5.5 and 6.5. The excitation and emission wavelengths were 343 and 61 5 nm, respectively. The fluorescence intensity was linear up to 10-8 M of europium; the detection limit was found to be 5 x I O -I~M and the precision at 8.0 x 1 0 -1 1~ of europium was 1.4%. By stabilising the fluorescence with cetyltrimethylammonium bromide (CTAB), the Eulll -TTA -TOPO -Gd"1 system together with three other enhancing systems could be applied to the determination of trace amounts of europium in lanthanide oxides and yttrium oxide. The fluorescence intensity of the Srnlll -TTA -TOPO system was also enhanced by La"1, Gdlll, Lull1 and Ylll. The factors influencing the fluorescence enhancement are discussed and a general mechanism involving an intermolecular transfer of energy from the enhancing complex to the fluorescing complex is proposed.In solution, the ternary complexes formed by the reaction of europium or samarium with thenoyltrifluoroacetone (TTA) and certain substituted ammonium cations or neutral ligands, such as nitrogen and phosphorus oxides (L), will usually emit an intrinsic fluorescence for the metal ion when exposed to ultraviolet radiation.'-3 However, the fluorescence is seriously interfered with by other lanthanide ions and europium and samarium mutually interfere. In the past, the solvent extraction method was commonly employed for the elimination of interferences, whereas nowadays an organic solvent or a surfactant is added to the system in order to increase selectivity and sensitivity."-7 Compared with the solvent extraction method, the latter procedure is a simple and efficient means of improving the fluorimetric determination of europium and samarium. Over the last few years interest in the application of micellar systems has increased. So far, the micellar-enhanced fluorimetric method seems to be the only type of enhanced fluorimetric method available for the determination of trace amounts of lanthanide ions.Recently, it has been shown that some of the lanthanides, yttrium and the alkaline earth metal ions can enhance the intrinsic fluorescence of a lanthanide comp1ex.x-1" For example, the sensitivity and selectivity of the Eu"' -TTA -L and Sm"1 -TTA -L systems were increased by the addition of trivalent lanthanum, gadolinium, lutetium or yttrium ions; in all instances Gd"' caused the largest enhancement of the fluorescence intensity. Early in 1967, during a study of the fluorescence characteristics of the ion associate of Eu"I (or SmIrr) with TTA -H-collidine, Melenteva et al. I 1 observed that the fluorescence intensity of the system was enhanced dramatically by the addi...

The fluorescence Intensity of the samarlum(III) (or europium( 111))-thenoyItrlfluoroacetone-1,10-phenanthroline [Sm-(III) (or Eu( 111))-TTA-Phen] ternary complex can be greatly Increased by La(III), Gd(III), Tb(III), Lu(III), and Y(III), and Gd(III) brought about the greatest enhancement

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