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Anal. Chem. 1980, 52, 662-666
As additional evidence for the hydrogen bonding mechanism, the hydrocarbon analogue of BMQ, phenanthrene, was placed on a 5% polyacrylic acid-NaC1 mixture from ethanol solution. After drying, the phenanthrene exhibited a strong R T P . Phenanthrene also exhibited a moderate R T P on E M silica gel chromatoplates when spotted from 0.1 M HC1 ethanol solution. These results suggested the excess acid converted carboxylate groups to carboxyl groups which then interacted strongly with phenanthrene. Because phenanthrene has no heteroatom, i t seems reasonable to conclude the main interaction responsible for the enhanced R T P observed from this compound is hydrogen bonding between the carboxyl groups of the binder and the R electron system of phenanthrene.
de Lima, C. G.; de M. Nicola, E. M. Anal. Chem. 1978, 50, 1658-1665. Bower, E. L. Y.; Wlnefordner. J. D. Anal. Chim. Acta 1978, 102,1-13. Niday. G. J.; Seybold, P. G. Anal. Chem. 1978, 50, 1577-1578. Bower, E. L. Y.; Winefordner, J. D. Anal. Chim. Acta 1978, 701, 319-332. (22) Bower, E. L. Y.; Winefordner, J. D. Appl. Spectrosc. 1979, 33, 9-12. (23) Ford, C. D.; Hlrrtubise, R. J. Anal. Chem. 1979, 51, 659-663. (24) Winefordner. J. D.; Tin, M. Anal. Chim. Acta 1964, 31. 239-245. (25) Frei, R. W.; MacNeil, J. D. "Diffuse Reflectance Spectroscopy in Environmental Problem-Solving"; CRC Press: Cleveland, Ohio, 1973; p 5. (26) Majors, R. E.; Hopper, M. J. J . Chromatogr. Sci. 1974, 72,767-778. (27) Snyder, L. R. "Principles of Adsorption Chromatography"; Marcel Dekker: New York, 1968; pp 199-202. (28) Bruckner. K.; Halpaap, H.; Rossler, H. U.S. Patent No. 3 502 217. (29) Favaro, G.; Masetti, F.; Mazzucato, U. Spectrochim. Acta, PartA 1971, 27, 915-921. (30) Bayliss, N. S.; McRae, E. G. J . f h y s . Chem. 1954, 58, 1002-1006. (31) Schulman, S. G. In "Modern Fluorescence Spectroscopy", Volume 2, Wehry, E. L., Ed.; Plenum Press: New York, 1976; Chapter 6, pp 245-246. (32) Peri, J. B. J . f h y s . Chem. 1966, 70,2937-2945. (33) Silverstein, R. M.; Bassler, G. C.;Morriil, T. C. "Spectrometric Identification of Organic Compounds", 3rd ed.; John Wiley and Sons: New York, 1974; pp 99-102. (34) Radmacher, E.; Wollenweber, P. U.S. Patent No. 3 922 431. (35) Deanin. R. D. "Polymer SVucture, Properties and Applications"; Cahners Books: Boston, Mass., 1974; pp 384-392. (36) Nielsen, L. E. "Mechanical Properties of Polymers and Comosites"; Marcel Dekker: New York. 1974; p 39. (37) Kiseiev, A. V.; Lygin, V. I. "Infrared Spectra of Surface Compounds"; John Wiley and Sons: New York, 1975; pp 123-137. (38) Little, L. H. "Infrared Spectra of Adsorbed Species"; Academic Press: London, 1966; pp 234-243. (39) Snyder, L. R. J . f h y s . Chem. 1968, 72,489-494. (40) Snyder, L. R. J . f h y s . Chem. 1963, 67,2622-2628. (41) Deanin, R. D. "Polymer Structure, Properties and Applications"; Cahners Book-s: Boston, Mass., 1974; p 40. (16) (19) (20) (21)
LITERATURE CITED Lloyd, J. B. F.; Miller, J. N. Talanta 1979, 26, 180. Roth, M. J . Chromatogr. 1967, 30, 276-278. Schulman, E. M.; Walling, C. Science 1972, 778,53-54. Schulman, E. M.; Walling, C. J . f h y s . Chem. 1973, 77,902-905. (5) Paynter, R. A.; Wellons, S. L.; Winefordner, J. D. Anal. Chem. 1974, 46,736-738. (6) Wellons, S. L.; Paynter, R. A.; Winefordner, J. D. Spectrochim. Acta, Part A 1974, 30, 2133-2140. (7) Seybold, P. G.; White, W. Anal. Chem. 1975, 47, 1199-2000. (8) White, W.; Seybold, P. G. J . Phys. Chem. 1977, 81, 2035-2040. (9) Vo-Dinh, T.; Yen, E. L.; Winefordner, J. D. Anal. Chem. 1976, 48, 1186-1 188. (10) Vo-Dinh, T.; Yen, E. L.; Winefordner, J. D. Talanta 1977, 24, 146-148. (11) Vo-Dinh, T.; Walden, G. L.; Winefordner, J. D. Anal. Chem. 1977, 49, 1126-1130. (12) Jakovljevic, I. M. Anal. Chem. 1977, 49,2048-2050. (13) VOn Wandruszka, R. M. A.; Hurtubise, R. J. Anal. Chem. 1976, 48, 1784-1788. (14) Von Wandruszka, R. M. A,; Hurtubise, R. J. Anal. Chim. Acta 1977, 93, 331-333. (15) Von Wandruszka, R. M. A.; Hurtubise, R. J. Anal. Chem. 1977, 49, 2164-2 169. (16) Schulman, E. M.; Parker, R. T. J . fhys. Chem. 1977. 81, 1932-1939. (17) Ford, C. D.; Hurtubise, R. J. Anal. Chem. 1978, 50, 610-612. (1) (2) (3) (4)
RECEIVED for review November 9,1979. Accepted December 31, 1979. This work was supported partially by the Department of Energy's Laramie Energy Technology Center under Contract No. DE-A520-79-LC01761 to the Rocky Mountain Institute of Energy and Environment.
Localization of Light Emission in Microporous Membrane Chemiluminescence Cells David Pilosof and Timothy A. Nieman School of Chemical Sciences, University of Illinois, Urbana, Illinois 6 180 1
A transparent cell was constructed and mounted on an X-Y positioning assembly to permit movement of the cell relative to a slit placed in front of the photomultiplier tube (PMT) detector. This arrangement allowed observation of the profile of the chemiluminescent (CL) emission intensity as a function of the distance from the microporous membrane surface and from the flow cell solution inlet. The Co(I1)-luminol reaction was used for this characterization. CL emlssion intensity profiles were examined as a function of the pressure applied to the reagent compartment, the analyte flow rate, and the volume of sample injected into the flow stream. Maximum emission intensity is generally observed to occur approximately 1 mm from the membrane and approximately 13 mm from the cell inlet.
A microporous membrane chemiluminescence (CL) cell consists of a microporous membrane separating a pressurized reagent reservoir from an analyte stream ( I ) . The light emitted in the zone contiguous to the membrane is monitored by 0003-2700/80/0352-0662$01.00/0
a detector placed in front of the cell. This method provides certain advantages over other common solution chemiluminescent techniques: (a) a high economy of reagents is attained owing to t h e low flow rate through the membrane, usually in the range of a few microliters per minute; (b) comparing this rate to a reasonable analyte flow rate, 1-20 mL/min, it can be concluded that the reagent is diluted several orders of magnitude by the analyte stream, resulting in negligible contamination and reducing the degree of self-absorbance ( 2 ) ;(c) the reagent delivery system is simple and easy to construct with no moving parts (excluding valves) required; (d) the light emission occurs mainly within a narrow layer near the membrane, allowing minimization of the total cell volume; (e) the system can be easily adapted to multicomponent analysis by allowing the analyte solution to flow along a series of membrane CL cells, each of them optimized for a given analyte. A transparent cell was constructed and mounted on an X-Y positioning assembly to permit movement of the cell relative to a slit placed in front of a photomultiplier tube ( P M T ) detector. This arrangement allowed us to observe the profile 0 1980 American
Chemical Society
ANALYTICAL CHEMISTRY, VOL. 52, NO. 4, APRIL 1980
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Figure 1. Flow system
of the CL emission intensity as a function of the distance from the membrane and from the solution inlet to the flow cell. We have studied the degree of localization of the CL emission and the dependence of this phenomenon on experimental parameters such as the pressure applied to the reagent compartment, the analyte flow rate, and the volume of sample injected into the flow stream. The well known luminol-OH--H2O2-Co(1I) reaction was used for this characterization.
EXPERIMENTAL Reagents and Solutions. The CL reagent solution was prepared in agreement with the best results obtained for similar experiments previously reported (1). The concentrations of reagents in this solution were as follows: luminol (Pfaltz & Bauer) 2X M, KOH M, HzOz M, and EDTA lo4 M. The EDTA was added to eliminate background and other effects as will be explained below. The reagent reservoir was flushed and refilled daily. No reagent degradation was noted on this time scale. Preliminary studies indicated no need to use buffers. The analyte solution was prepared by diluting CoClZ~6Hz0 to lo4 M from a M stock solution and the rinse solution was M EDTA. In every case, distilled deionized water (DDW) was used for solution preparation. Membrane, Cell, and Flow System. The flow system, shown in Figure 1,was basically the same as that previously described by Nau and Nieman ( I ) . The only modifications introduced were the flow cell itself and the flow controls (micrometer needle valves) that permitted equalization of the rinse and analyte flow rates and selection of the total flow rate. The flasks containing the analyte and the EDTA rinse solutions are pressurized with 3 psi nitrogen; the appropriate solution (selected by a 3-way solenoid valve controlled by hardware logic) flows through the cell. Two additional 3-way solenoid valves are used to vent the pressurized vessel and flush tubing when the analyte solution is changed. The reagent reservoir is filled from a gas/liquid-tight syringe, and then pressurized at 6-12 psi to cause flow through the membrane. The modified graduated pipet placed in the reagent line can be used to calibrate the reagent flow rate. Analyte flow rates were in the range of 8-20 mL/min, with 15 mL/min as a standard value. The reagent reservoir pressures were in the range of 6-12 psi, with 12 psi as the most common value. A reagent reservoir pressure of 12 psi causes a flow rate of 4.3 pL/min/cm2 ( I ) . The membrane surface area in our cell is 1.76 cm2,so the reagent flow rate is typically 7.5 KL/min. The analyte flow rate is therefore 2000 times the reagent flow rate. Reagent concentrations will decrease from a maximum a t the
