% % % % P found Cu found, corrected, certified, 0.098 0.017 0.095 0.095 0.041 8j 36 2 0.148 0.486 0.044 a Correction factor = 0.213 ppm P/ppm Cu.-_ _ _ l -l _ _ _ _ _ _ 1 1 --~prominent Fe line shown in Figure 8 was used as the side line, and the reference solutions were matrix matched with the samples to contain 1.00% Fe (w/v). The small Fe peak located approximately 0.005 nm to the long wavelength side of phosphorus does not interfere with the analysis as long as both SLIM and matrix matching are applied. Both P and Cu were determined (at 214.91 nm and 327.40 nm, respectively) and the P results corrected for Cu spectral interference; analytical resulta are shown in Table (1) Floyd, M. A.; Fassel, V. A,; Winge, R. K.; Katzenberger, J. M.; D'Silva, (2) Nygaard, Danton D.; Chase, Duane S.; Lelghty, David A. Appl. Spec-A. P. The first optical sensor for halides and pseudohaildes Is described. It is based on dynamic fluorescence quenchlng of acrldlnlum and qulnoiinlum Indlcators, which were immobilized vla spacer groups onto a glass surface. The sensors are able to indicate the concentration of halides in solution by virtue of the decrease in fluorescence intendty due to the quenching process. The sensltivity toward different halides can-to some extent-be varied by the cholce of the indicator. The method Is increasingly sensitlve on going from chloride to bromide to iodlde. Detection limits are 0.15 mM for iodide, 0.40 mM for bromide, and 10.0 mM for chiorlde. The errors of determination in the concentratlon range from 0.01 to 0.1 M are 1 % for Iodide, 1.5% for bromide, and 3-5% for chloride.The development of sensors based on immobilized fluorescent reagents is a matter of growing interest (1-4). Sensors offer advantages over conventional solution fluorescence measurements, since they allow the determination of concentrations without significantly perturbing the sample. In addition, they can be used for continuous sensing. Fluorescence-optical sensors are based on three fundamental principles: (a) changes in acid-base equilibria of indicators (2,5); (b) reversible formation of fluorescent chelates (3); (c) dynamic fluorescence quenching (4). The first two principles are similar in that they are based on processes that occur in the ground state, whereas the latter occur in the first excited singlet state.In this paper we report the characteristics of a sensor for halides that is based on the dynamic quenching of glass-immobilized heterocyclic indicators 1 and 2, whose structures are shown in the formula scheme.The quenching of quinoline-type fluorophores was first described by Stokes as early as 1869 (6), when he observed that the fluorescence of quinine in dilute sulfuric acid was reduced after addition of hydrochloric acid or halide ions. The involved process is now known to obey the Stern-Volmer equationHere, Fo is the fluorescence intensity of a solution in the absence of a quencher, F is the fluorescence intensity in the presence of a quencher, [Q] is the concentration of the quencher, and Kq is the so-called q...

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Highly fluorescent cationic indicators have been obtained by reaction of heterocyclic nitrogen bases with 1,3‐propane sultone. Unlike the bases themselves, the fluorescence intensity of the cationic salts is practically pH‐independent in the neutral pH‐range, which makes them useful reference substances in measuring fluorescence intensities in physiological studies. Furthermore, they are sufficiently water soluble, the fluorescence maxima covering the wavelength range from 440 to 530 nm. 2‐(3‐Sulfonatopropyl)harmanium, (5) appears to be the most useful compound for intra‐ and extracellular liquids, since its fluorescence is not quenched by chloride ion.

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Die mit dem Sulton (V) aus entsprechenden Ausgangsmaterien erhaltenen Farbsalze (I)‐(IV) werden hinsichtlich ihrer fluoreszierenden Wirkung quantitativ untersucht.