standard deviation of 1.4 seconds. Xo cycle was shorter than 615 seconds, or longer than 622 seconds. The apparatus has performed well in isolation experiments.
hydrostatic head, which may be varied by varying the position of P on its supporting rod. 0 discharges \Then it has received 130 ml. of water; the escapement trips when S contains 70 ml. of mater; and N begins t o discharge when it has received 90 ml. of water. Approximately 9 seconds are required for one operation of the escapement. The precision of the clepsydra mas tested by cementing a piece of copper wire to H , so that each end of the wire, when the outer end of H was depressed, dipped into a separate small pool of mercury and so closed the electric circuit of a signal magnet. The signal magnet and a time marker were arranged to write on the paper of a kymograph. The flow of water to 0 was adpsted so the operating cycle of the escapement required approximatel). 10 minutes. The fraction collector was allowed to operate, m-ithout adjustment, for 40 escapement operations. The kymograph record TT as measured; the average
Figure 3. Plan of fraction collector
escapement of
8. Disk, 5'/8 inch radius (arrow shows direction of rotation) M. Pins, set a t 5' intervals H. Lever of escapement (cut from '/a-inch iron plate) I , L'. Pollets o f escapement W, W'. Tapped holes for stop screws X, X'. Lever bearing pins Y . Hole for intermittent siphon N
duration of t h e escapement cycle was found to have been 618.5 seconds, with a
As the present apparatus has 72 stations, it will operate for 12 hours without attention if set for a 10-minute operating cycle. Bn 18-liter Mariotte bottle provides sufficient mater for more t,han 160 operations, and in case of a protracted fractionation the water bottle can be changed without seriously affecting the accuracy of the over-all process. The total cost of materials for construction of this fraction collector is estimated a t not more than $20. The writer spent approximately 40 hours in building the apparatus; it is probable that its duplication would require less time.
Remotely Operated Filter Photometer M. T. Kelley, E. B. Wagner, Health Physics Division, and W. 1. Maddox, H. C. Jones, and D. J. Fisher, Analytical Chemistry Division, O a k Ridge National laboratory, Union Carbide Nuclear Co., O a k Ridge, Tenn.
C
unstable pori-er lines. The relative standard deviation of routine remote colorimetric analysis is about 5% (2). It may also be operated nonremotely.
analyses of radioactive samples are done remotely within cells in the High Radiation Level Analytical Facility ( I ) a t Oak Ridge Sational Laboratory. Manipulations of the sample and instrument are done with a pair of Argonne llIodel 8 master slave manipulators. The instrument described was specially designed for master slave manipulation. Only the compact sensing unit is within the cell. This separation of components reduces slave movements to a minimum, saves valuable cell space, and simplifies maintenance problems. Where practical, commercial components were utilized as instrumental building blocks. This photometer is reliable and stable. The instrument is operated from a Sola constant voltage transformer when it is installed on OLORIMETRIC
,LIGI-T
DESCRIPTION OF INSTRUMENT
Figure 1 is a block diagram of the photometer. The power supply for the light source and the Densichron amplifier are located outside the cell, in the instrument chase below the cell window. These components are connected by electrical cables to the sensing unit located remotely within the cell. The sensing unit consists of a light source, heat filter, absorption cell holder, filter, holder, and light detector. This instrument is a single-beam photoelectric colorimeter that utilizes interference filters. The absorption cell holder provides for two absorption
SOURCE O N - C F F S W ' T C H
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Figure 1.
Remotely operated filter photometer
cells. Eithcr mag be positioned in the light path by a slave-operated slide rod. Light from an incandescent lamp is condensed by a mirror, passed through a heat filter, and beamed through the solution whose transmittancy is being measured. The light then passes through a plug-in interference filter and finally into the photocell. The output of the photocell is fed through a cable to the Densichron amplifier unit where the absorbance and the per cent transmittancy are indicated by a meter. DISCUSSION OF INSTRUMENT COMPONENTS
Constructional details of this photometer are available in a set of niechanical drawings ( 3 ) . The light source power supply is a Sola Catalog KO. 30882 constant voltage transformer which has an output of 6.3 volts. A Beckman Model No. 3300 lamp house assembly is used as a light source, The Beckman tungsten lamp backplate is included in the assembly. To this unit is added a G.A.B. interference type heat filter obtained from Photovolt Corp. ( 4 ) . The cell holder is designed t o accommodate either round culture tubes 16 mm. in diameter or square absorption cells (Coleman Instruments, Inc., KO. 14-306). Cells of this size were chosen rather than small ones because they are more easily filled and handled remotely by the master slave manipulators. The square cells provide better precision in a colorimetric analysis, but the round cells are much cheaper and are adequate for some work. Cell cleanliness and VOL. 30, NO. 10, OCTOBER 1958
1711
filling are difficult but possible in remote slave-manipulated determinations. Several G.A.B. interference filters that cover the required spectral range are used with this instrument (4). Separate holders which fit into a slot in the photometer sensing unit are provided for each filter. These housings protect the filters and allow the filter to be changed readily by the master slave manipulators. The width of the spectral band isolated by each filter is 12 to 14 mp a t the half-peak position, about 50% of the incident light of the band isolated is passed, and each filter has a colored backing filter as an integral part.
The light detector is a Densichron probe unit (IT. AI. Welch hlfg. Co.). It consists of a phototube and a magnetic modulation system. For most work with this photometer a blue probe having maximum response a t 400 mp is used. A Welch Densichron amplifier unit is installed outside the cell. It has proved very stable. OPERATIONAL PROCEDURE
A detailed operating procedure has been written for these photometers (6). Calibration curves and analyses are made in a conventional manner,
except that the determination is carried out remotely. LITERATURE CITED
(1) Frederick, E. J., .Vuc/eonics 12, 36
(1954).
(2) Lamb, C. E., Oak Ridge Sational
Laboratory, Oak Ridge, Tenn., private communication. AUK 1. 1957. (3) Oak Ridge ’ Sa3onal Laboratory, Oak Ridge, Tenn., ORNL-LR-Dwg. NO. 13584; ORNL-LR-Dw~. - NO. 13584, Parts 1-3. (4) Photovolt Corp., New York, N. Y., Bull, 180, “G.A.B. Interference Filters.” (5) Wagner, E. B., “Filter Photometer, ORNL Model Q-1734,” ORNL Master Analytical Manual, Method Nos. 1 003090,9 003090.
Determination of Combining Weight of Sulfonates C. M. Gardner, C. H. Hale, E. A. Setzkorn, and W. C. Woelfel, Development and Research Department, Continental Oil Co., Ponca City, Okla.
average combining weights of T comniercially available sulfonates are important because they are related HE
to the useful properties of the products. They are also needed in the calculation of active content from rapid titration data. The standard method for determining the combining weight of a sulfonic acid or sulfonate is to convert a weighed portion of the purified sulfonate (as its sodium salt) into sodium sulfate by a sulfated ash procedure ( 1 ) . This takes considerable time and requires careful correction for the presence of sodium carbonate, as combining weight is determined on the amount of sodium present. Another procedure is to run a p toluidine titration on a weighed portion of the purified sodium sulfonate (4). This is fairly satisfactory for the sulfonates of higher molecular weight, but fractionation may occur in the case of sulfonates of molecular weight lower than that of dodecylbenzene sulfonate. The reaction involved is not stoichiometric, as the alkali equivalent per gram of sample varies 11-ith the concentration of p-toluidine hydrochloride in the reagent. The sulfur content of a sulfonate can be used as a basis for calculating combining weight, but determination of sulfur by the classical gravimetric barium sulfate procedure would be too time-consuming. Recently, ASTAI Committee D-2 published a rapid combustion method for sulfur in petroleum products ( 8 ) . The sample is burned in a stream of oxygen by a high frequency furnace a t a temperature high enough to decompose practically any compound of sulfur and to liberate the sulfur as its oxides. Under the operating conditions employed, 93 to 95% of the sulfur evolved is absorbed as sulfur dioxide and titrated iodometri1712
ANALYTICAL CHEMISTRY
cally. The proportion of total sulfur liberated as sulfur dioxide appears to be constant for any given furnace operated under standardized conditions; this proportion is determined by ignition of potassium alum as a standard and is expressed as the “furnace constant.” Combustion and titration of a sample and calculation of its sulfur content from titer and furnace constant require only about 15 minutes. PREPARATION OF PURIFIED SULFONATE
of water and titrate with 0.1S acid. using phenolphthalein as indicator, Use hydrochloric acid if the combining weight is to be based on the sulfur content of the sulfonate; use sulfuric acid when the sulfated ash procedure for combining weight is to follow (1). At the phenolphthalein end point the sodium carbonate will be half neutralized. Add a volume of standard acid equal to the titration value, to neutralize the carbonate completely. Evaporate the solution to dryness on a steam bath, then finally dry in a vacuum oven for 3 hours at 100” C., cool in a desiccator, and weigh. Calculate the percentage of sodium chloride or sodium sulfate in the purified sample.
The sample of sulfonate must first be purified. Sodium sulfonate may contain unsulfonated hydrocarbon, sulfones, sodium sulfate from neutralization of excess sulfonating acid, water of solution and neutralization, plus other impurities. These are removed by a purification procedure, similar to the ASTM method ( I ) .
To purify a barium or calcium sulfonate, it is first necessary to convert it to the sodium salt, so that the oil can be extracted from the sample. The procedure used is essentially that of Brooks, Peters, and Lykken ( 3 ) .
Dissolve 2 to 3 grams of the sample in 100 ml. of 1 to 1 isopropyl alcoholwater solution. Transfer to a 500-ml. separatory funnel, using 50 ml. of 1 to 1 isopropyl alcohol-water solution to aid in the transfer. Extract with 50 ml. of hexane, and repeat the extraction n i t h two 25-ml. portions of hexane. Draw the aqueous alcoholic solution containing the sulfonate into a 250-ml. glass-stoppered graduated cylinder. Combine the hexane extracts and wash n i t h 25 ml. of 1 to 1 isopropyl alcoholwater solution, adding the washing to the cylinder. Place the cylinder in a water bath a t 60” to 70’ C. for 20 minutes. Remove and add small portions of solid sodium carbonate to the solution in order to saturate and cause the separation of an alcoholic layer. Allow the two-phase system to stand a t least 2 hours. By means of a pipet transfer approximately 50 ml. of the alcoholic solution of sulfonate to a 150-ml. beaker and evaporate to about 10 ml. Add 15 nil.
Transfer 3 to 5 grams of the sulfonate to a 250-ml. beaker and add 50 ml. of chloroform to dissolve the sample. Add 50 nil. of 1 to 1 hydrochloric acid and mix the two phases, stirring with a glass rod while warming for 5 to 10 minutes on a steam bath. Transfer the solution to a 500-ml. separatory funnel, using 25 ml. of chloroform, 10 ml. of kvater, and 100 ml. of acetone to aid in the transfer. Shake the mixture vigor ously and, after the phase separation, draw off the lower chloroform-acetone phase into a 150-ml. beaker. Make two more extractions, each with 25 ml. of chloroform. Combine the three extracts and evaporate to dryness on a steam bath. The residue consists of sulfonic acid plus oil. Wash this residue into a separatory funnel, using a total of 75 ml. of isopropyl alcohol in making the transfer. Add 75 ml. of water and neutralize the sample with 25% sodium hydroxide. Proceed with the purification, extracting the oil with hexane as described for sodium sulfonate.
