Table 111.
High-Purity Boiler Water Condensates
Al,P.P.B. Sample
By morin
By
alummon
of the experimental work for this paper was done a t room temperature. Reproducibility. The reproducibility of several aluminum concentrations are shown in Table I.
Effecf of Diverse Ions. The interferences of diverse ions on the determination of aluminum in the concentration .range used in this paper were studied. The effect of each ion on a 2-p.p.b. AI solution was studied in increasing amounts until the fluorescent intensity was outside the limits of the reproducibility for a 2-p.p.b. Al solution (Table 11). Figure 2 shows the interference of C U + ~Cr+S, , and F- above the limiting concentrations. The and CufZ interferences were checked using a 25-p.p.b. Al solution. The limiting concentration was 50 and 500 p.p.b. for PO&-8 and Cu+2, respectively. Application of Procedure. Highpurity boiler water condensates were analyzed for aluminum by the reeommended procedure (Table 111).
ACKNOWLEDGMENT
The author acknowledges the assist. anee of Robert Beduarik in performing the experiments in this investigation. LITERATURE CITED
(1) Boahevol’nov, E. A., Yanishevskayya, V. M., Zhur. Vsemyua. Khim. Obshcheslua im. D. I . Mendelema 5.356-7 (1960). (2) Collat, J. W., Rogers, L. B., ANAL. CHEM.27,961-5 (1955). (3) Simons, L. H.,Monaghm, P. H., Taggart, M. S., Jr., Ibid., 25, 989-90
\_””_,.
11452)
(4) White, C. E., Ibid., 32,48R (1960).
(5) White, C. E.,in “Trace Analysis,” J. H. Yoe and H. J. Koch, Jr., eds., Chap. 7, Wiley, New York, 1957. (6) White, C. E., Lowe, C. S., IND. ENQ. CHEM.,ANAL.ED.12,229-31 (1940).
RECEIVEDfor review April 6, 1961. Accepted July 3, 1961.
A Versatile High-Resolution Spectrofluorometer ROBERT E. REHWOLDT and RICHARD M. KING Department of Chemisiry, lehigh Universiiy, Befhlehem, Pa.
DAVID M. HERCULES Deportment of Chemistry, Juniafa College, Huntingdon, Po,
b Construction and calibration of a versatile, high-resolution, recording spectrofluorometer are described. Commercially available components were used wherever possible. Fluorescence or excitation spectra may b e recorded automatically in the visible and ultraviolet regions of the spectrum. The spectrofluorometer has a sensitivity equivalent to 0.01 p.p.m. of quinine sulfate and a resolution of 4 A., at a slit width of 0.2 mm. The cell compartment was constructed to permit recording of fluorescence spectra at the temperature of liquid nitrogen.
R
ECENT investigations
of the effect of structure on fluorescence of organio compounds and their metal chelates (6, 8, 14, 16) have indicated the desirability fluorescence spectra a t high r olution. Commercially available spectrofluorometers designed for routine fluorescence analysb (1, 4) do not offer high resolution, although they d o r d good sensitivity. A number of commercial spectrophotometers have heen modified to record fluorescence spectra (2, 3, 6, 7, 10,13), but generally these do not d o r d sufficient sensitivity and versatiity. Two reports of elaborately constructed spectrofluorometen have appeared recently (21,16),hut the cost of constructing such instruments is prohibitive to the 1362
ANALYTICAL CHEMISTRY
Figure 1. Spectrofluorometer A.
Wave lenglh control did
B.
Power supply for radiation source
C. D.
Control box for starting recorder ond wave length drive Monochromdor E. Sample c o m p o h e n t F. Cooling comporhent for phototube G. Recorder H. Multiplier phototube ampliflcr 1. Power supply for multiplier phototube and omplifler
A. 8. C.
Wave length drum Badine motor Control box
usual laboratory concerned with analytical fluorescence investigations. The instrument reported in this communication yas constructed for approximately the cost of a commercial spectrofluorometer, but has the advantages of high resolution, good sensitivity, and versatility. Two interchangeable detectors allow investigation of fluorescence spectra from 2000 to 7000 A. Dry ice cooling of the detectors diminishes thermal noise, thereby improving available signal strength. A particularly valuable feature of the present instrument is that it allows one to obtain fluorescence spectra a t the temperature of liquid nitrogen, a tool which is becoming increasingly useful. Although a spectrum cannot be scanned as rapidly as in commercial spectrofluorometers (in order to retain maximum resolution), the instrument can scan 1000 A. in 4 minutes. DESCRIPTION OF INSTRUMENT
Figure 1 shows the spectrofluorometer and associated apparatus.
Figure 4.
Attenuator circuit
BAl. 9 voIts EA,. 9 YO Ih
R,.
R,. R,.
Radiation Source. The radiation source was a General Electric AH-6 water-cooled, high pressure mercury arc, powered by a George Gates (Brooklyn, N. Y.) 1-M power supply. The steel case holding the lamp was tripod-mounted to allow ease of focusing radiation on the sample. Monochromator. The spectrofluorometer incorporates a 500-mm. Baush & Lomb Ehert-mount grating monochromator having a 1200 lines per millimeter grating blazed for the near-ultraviolet. I$ has a dispersion of 16.5 A. per mm. with 0.03% stray light a t 3000 A. The monochromator has a maximum efficiency of 22% a t A. .3100 To check the calibration of the monochromator wave length drum, a low pressure mercury lamp was directed into the monochromator and its spectrum recorded. Various peaks were selected
20-ohm, 1 0-turn, wilh Berg microdiol 50-ohm 1/2-wm carbon SO-ohm 1/2-wan carbon
throughout the spectrum auu p-.-" tothe wave lengthslisted in the literature (la). No corrections were necessary. The wave length drive mechanism is shown in Figure 2. A Bodine 11&volt, 1-r.p.m. motor, B, was mounted on top of the monochromator and connected to the wave length drum, A , through a sprocket gear and chain system, eliminating the possibility of any slippage. A spring was attached underneath the motor mounting to provide tension to keep the chain taut a t all times. The control box, C,synchronizee the Bodine motor with the recorder motor. Figure 3 shows the circuit diagram for the chart and wave length drive control. The motor control circuitry of the recorder appears to the left of TB-1, as it has been slightly modified to allow for external control. Two microswitches, SWs and SWs mounted inside the monochromator housing automatically stop the wave length drive motor, B1, the chart drive motor, Bzoe or Bm, and the pen drive motor, Blor, a t the end of a scan. These switches are actuated by the wave length control linkages on the
Figure 3. Chart and wave length drive control 0,.
Wa*e longlh motor
Bsm.
Chart motor lhighl
ha,. Pen motor
&or. Chart motor llow) CI.
Capocitor supplied with wave lenglh drive motor F,. 3-ampere fuse P2. Three-connector plug Pa. Two-connedtor plug h. Three-come
