Esso Lamp Method for Sulfur C. C. HALE and
E. R. QUIRAM
Esso Research and Engineering Co., Linden,
N. 1.
J. E. McDANlEL Humble Oil and Refining Co., Baytown, Tex.
R. F. STRINGER Esso Research laboratories, Esso Sfandard Oil Co.,Bafon Rouge, La.
,An integrated and rapid lamp method for determination of total sulfur in petroleum has been developed and cooperatively tested. Modified finishing methods consist of the following: conductometric for nonleaded samples, nephelometric for leaded or nonleaded samples in the range of 1 p.p.m. to 0.06%, and gravimetric which avoids the conventional digestion and ignition steps. The cooperative testing was among four Esso Research and affiliated laboratories and involved 1 2 plant-type samples. The reproducibility for conductometric and gravimetric finishing showed a standard deviation which varied from 0.0008 to 0.015 over the sulfur concentration range of 0.01 to 1.0%. The reproducibility for nephelometric finishing varied from 1.1 to 12 over the range of 5 to 500 p.p.m.
N
UMEROUS variations of the lamp method for determination of sulfur in petroleum products have appeared in the literature. I n general, these methods have emphasized one particular phase, whereas the object of this report is to make available an integrated method. Most of the techniques employed are well known but the task of knitting them together required certain innovations to produce a method that is adaptable to routine testing in a petroleum laboratory. 9 realistic production figure is 20 samples per manday. The use of hydrogen peroxide as an absorbent of the combustion products is curiently a part of an ASTlI method ( I ) as is also the synthetic oxygencarbon dioxide conibustion gas. The unique absorber system and conductivity method of finishing have been described (4). The nephelometric finishing technique is one of relatively long standing ( 7 ) , whereas the use of Kaphtho1 Pellon- S for inducing large particle precipitates has been recently described ( 2 ) .
REAGENTS
Hydrogen Peroxide, acid-free 30% reagent grade. Dilute 1 t o 10 with distilled water just before use. Solution A. Alcohol, Glycerol. Add 3 volumes of redistilled glycerol t o 6 of redistilled 95% ethyl alcohol and 1 of distilled water. Solution B. Alcohol, Glycerol, Acid. Same as Solution A but with 3 N hydrochloric acid substituted for the water. Solution C. Alcohol, Glycerol, Acid, Peroxide. ildd one volume of solution B to 5 of 3% hydrogen peroxide. Barium Chloride. The 20-30 mesh Droduct available from Helliee. Inc.. g e w York, N. Y., as Catdog No: 8042, seems to give the best results. Naphthol Yellow S. Dissolve 0.4 gram of Naphthol Yellow S in 1 liter of distilled water. Dissolve 20 grams of barium chloride dihydrate in 1 liter of dilute hydrochloric acid (25 ml. of concentrated hydrochloric acid per liter of distilled water). Pour the Naphthol Yellow S solution into the acid barium chloride and allow t o stand 24 hr. before using.
Figure 1. Lamp sulfur burner and absorber assembly
Standard Sulfuric Acid. Prepare 0.1249N sulfuric acid. One milliliter of this solution is equivalent t o 2.0 mg. of sulfur. Further dilute for the preparation of additional standard solutions such that 1 ml. of each will contain 0.2, 0.02, and 0.005 mg. of sulfur. APPARATUS
Lamp Assembly. The complete burner and absorber assembly are shown in Figure 1 and are obtainable from the Kontes Glass Co., Vineland, N. J., under the designations indicated. The burner and flask are in accord with ASTM specifications (1) as is also the chimney, with the exception of the substitution of a V 10/30 joint. The carburetion-type burner is procurable as Drawing No. 2881-F (6) and the low volatility burner as Drawing No. 3282-F (6). 4 blast type gas burner is described in the ASTM method (1).
Combustion Gas Metering Assembly. The assembly shown in Figure 2 is suitable for a t least 10 lamp units. The steam-jacketed carbon dioxide heater is satisfactory for maintaining a constant pressure without overheating but is only one of several adaptions that can be devised. Rotameters should be selected to provide a maximum gas volume of 6 cu. feet per hour per lamp, of which approximately 35y0 is oxygen. An auxiliary manifold is shown from which a controlled amount of carbon dioxide can be obtained for mixing.with the combustion gas to each lamp in order t o lean the oxygen content and thus obtain better burning of the more aromatic type samples. Automatic shutoff valves and an alarm are shown as safety features in case of pressure drop from a depleted cylinder. Manifold to Lamp Connections. I n setting up a bank of ten lamps various means can be devised to support them conveniently and permit connections t o be made with the manifolds. The essential connections for a single lamp are shown in Figure 3. Each manifold must be connected to a mater bubbler-type pressure regulator. Eight t o 10 inches of water is sufficient. VOL. 2 9 , NO. 3, MARCH 1957
383
Nephelometer. Use a Coleman Xfodel 7 Photo-Xephelometer FTith an 80-unit Coleman Yephelos standard and filter. This latter item can be made by obtaining an Eastman Kodak S D - 2 (neutral density) photographic filter, all glass type, and mounting it in a Coleman filter holder. Conductance Bridge and Cell. The conductance bridge supplied by Arthur H. Thomas Co., Catalog Xo. 3965, can be used in conjunction with the micro-type conductivity cell, Catalog KO.3997. When ordering it is essential to specify bright platinum electrodes. Glass Fiber Filter Paper. H . Reeve Angel 8t Co., Selv York, N. Y., supplies a glass fiber filter for use in the usual S o . 3 Gooch crucible. The 2.1-cm. size is listed as Catalog KO.X934-BH. Calibration of Nephelometer. Follow the supplier’s directions for use of the instrument by the null method. Insert the 80 Kephelos standard and turn the Bal knob to give a scale reading of 40. Adjust Std. knob to bring the galvanometer to zero. Use this method t o check instrument drift frequently. It is also suggested that the opaque end of the filter holder be inserted in the filter slot in order to darken the photocell for zero adjustment. Accurately pipet suitable amounts of the standard sulfuric acid solutions into the lamp assembly absorber cylinder such that a range of 0.01 t o 0.10 mg. of sulfur is covered for calibration without the filter and 0.10 to 0.50 mg. for calibration with the filter. Add 5 nil. of Solution B, dilute to 30 ml. with distilled water, and mix well. Add by means of a suitable scoop approximately 0.2 gram of the Hellige barium chloride crystals. Close the cylinder with a glass stopper and immediately mix for 1 minute by tilting the cylinder to permit flow from end to end. Allow to stand 3 minutes and then pour into a selected cuvette. Place in the immersion well and read after an elapsed time of exactly 5 minutes from the addition of the barium chloride. Repeat to obtain a blank reading by omitting the standard acid. Subtract the blank reading from the above readings and plot this instrument reading against sulfur concentration. Figure 4 is representative of a typical nephelometric calibration. Calibration of Conductivity Bridge. Operate in accord with supplier’s instructions. Fire polish a heavy ring on the skirt of the conductivity electrode, without restricting the opening, in order to prevent chipping when in use. If the skirt becomes even slightly chipped, it must be recalibrated. Add suitable volumes of the standard sulfuric acid solutions to the absorber cylinders to cover the range of 0.005 to 14.0 mg. of sulfur. Add 2 ml. of 30% hydrogen peroxide and make up to 25 ml. with distilled water. Stopper, shake thoroughly, and place in a constant temperature water bath held a t 1 0 . 1 O C. Khen temperature equilib384
ANALYTICAL CHEMISTRY
VALVE PRESSURE CONTROL
MANIFOLD
Figure 2. Assembly for metering and mixing oxygen-carbon dioxide combustion gas
n
/LAMP
ASSEMBLY
SEGO N DA R Y VALVE PFi 1 M A R Y VALVE
MANIFOLD
Figure 3. Schematic arrangement of manifold to lamp assembly connections
rium has been obtained, insert the conductivity electrode and move it in and out of the solution several times and obtain an approximate reading. Take a final and exact reading immediately after the electrode has again been mored in and out several times. Figure 5 illustrates a representative conductivity calibration curve. Hydrogen peroxide of sufficient purity is available, so a conductivity blank is not necessary. METHOD
The schematic diagram, shown in Figgure 6, provides an over-all description
of the operations involved in the method. The upper part shom the burner types for use with various samples and the lower part indicates the finishing methods and the circumstances under which they are applicable. Burning Operation. Place 20 ml. of the 3% hydrogen peroxide solution in each absorber cylinder. Wick sufficient burners by drawing through two doubled strands of cotton wicking and cut flush with the top of the burner. Place 3 t o 6 grams of sample in each flask and insert the wick and
.3
.2
.I
.4
.5
burner. Immediately weigh, light, and establish in place on the lamp assembly.
6
I20 IO0 L3
A certain amount of practice will be required before successful lighting can be accomplished. However, if the oxygen to carbon dioxide ratio is first adjusted to give optimum burning of paraffinic samples, most samples can be lighted and established on the bank without smoking. Final adjustments of the gas volumes can then be made. If the top of the flame tends to reach up or shows evidence of smoking, the addition of carbon dioxide from the amiliary manifold m-ill reduce it to normal behavior. However, with pure aromatics it is necessary either to dilute nith a paraffinic hydrocarbon such as isooctane or use the carburetion-type hurner.
P
9
80
(L W
2
w
60
P 3
E 40 z
20 0
.02
MG.
6
4
.IO
.I2
OF SULFUR
Figure 4. Typical calibration curves 2
.OB
.06
.04
nephelometric 8
10
12
14
1000 0 07
E
800
Boo0
600
6000
400
4000
200
2000
>
2
-u i
22 0 0
0
.2
.4
.6 MG.
Figure 5.
OF
.8
1.0
1.2
Typical conductometric calibration curves
BURNING OF SAMPLE PARAFFI NS AROMATICS BY REDUCING RATIO O F O2 TO COP
A S T M B URNER
AROMATICS B Y DILUTION
n
w ‘Ow
VoLATILITY BURNER
1.4
SULFUR
-
FOR WAXES AND GAS OILS
Continue burning until the sample is depleted and the flame is about to go out. This is essential if the sample contains either hydrogen sulfide or elementarytype sulfur. Through the use of sulfur-35 it has been shown that elementary sulfur concentrates a t the tip of the wick but if allowed to burn to dryness recoveries of 90% can be realized. The hydrogen sulfide is flushed out of the sample more rapidly than the sample is consumed. Lower the burner, blow out the remaining flame, and immediately reweigh. Finishing Operation. COXDUCTOMETRIC. Samples not containing tetraethyllead or acid-forming constituents other than sulfur, that are t o be finished conductometrically, must be purged with carbon dioxidefree air for 5 minutes. Partially lift out the absorber tube and rinse down both the inside and outside r i t h an amount of water necessary to bring the volume to 25 ml. It is not necessary to rinse the chimney, since work with sulfur-35 as a radioactive tracer has shown that with nonleaded samples there is a negligible amount of sulfur remaining. Mix well and thermostat. Determine the conductivity. If the measurement indicates the presence of more than 0.1 mg. of sulfur, then it can be used to determine the actual sulfur content of the sample. If the indicated content is more than 10 mg., it is advisable to dilute with sufficient
k==Y FINISHING OF ABSORBER SOLUTION CONDUCTOMETRIC IF 2- 0 I MG. NEPHELO METRI C IF < 0.1 MG.
G RAVI METRI C I F > 3.0 MG.
Figure 6. Schematic diagram of operations in lamp sulfur test
NEPHELOMETRIC I F < 3.0 MG. USE ALIQUOTING TE CHNI Q UE B E T W E E N 0 5 A N D 3 0 MG.
VOL. 29,
NO. 3,
MARCH 1957
385
3% hydrogen peroxide to bring the reading into a more accurate range. NEPHELOMETRIC. If the above absorber solution was found to contain less than 0.1 mg. of sulfur, remove the conductivity cell after freeing it of as much of the solution as poseible. Add 5 ml. of Solution B and mix. Filter completely through a dry No. 42 Whatman filter paper into another clean dry cylinder but do not wash the paper. About 28 ml. will be collected, to which add 0.2 gram of the barium chloride. Complete nephelometrically as was done in the calibration step. The instrument must be adjusted with the Nephelos standard in the same manner as the calibration was made. For all nephelometric work a blank must be determined; this should include the passing of the oxygen-carbon dioxide mixture through the hydrogen peroxide, filtering, etc., as for a sample. A satisfactory blank is of the order of 0.01 mg. of sulfur. NEPHELOMETRICFINISHIKGOF
LEADED SAMPLES. Remove the chimney and rinse down both the inside and outside of the absorber tube with 5 ml. of Solution A. Dissolve the white deposit in the chimney with 2 ml. of 1N hydrochloric acid and add to the absorber. Rinse the chimney with 1-ml. portions of water until the absorber solution is 30 ml. If less than 0.5 mg. of sulfur is known to be in this solution, proceed to filter through No. 42 Whatman and thus continue to complete the nephelometric finishing. If the sulfur content of the filtrate is not known or is known to contain more than 0.5 mg., remove a 5-ml. aliquot and make up to 30 ml. in another absorber with Solution C. Filter through S o . 42 Whatman and complete the nephelometric finishing. If an acceptable reading is not obtained, repeat with a larger aliquot. Thus, if a 5-gram sample containing tetraethyllead is burned, sulfur contents up to 0.01% can be determined nephelo-
Table 1.
State of Quality Control of Various Laboratories on Practice Samples fSampleafor conductometric finishing. Theoretical S concn., 0.103% x o . of 95% Confidence Laboratory Tests Average High Low Level .4 37 0.101 0.105 0.098 10.0035 R 28 0.104 0.105 0,099 10.0032 0,096 i0.0044 C 15 0.099 0.103 D 19 0.102 0.107 0.098 1 0 ,0044
0
Sampleo for Nephelometric Finishing. Theoretical S concn., 12 P.P.M. 10 12.0 10 11.7 8 *3.4 10 12.6 Iso-octane plus thiophene.
Table II.
Sample
SO.
Nephelometric*
Lab A
metrically rithout aliquoting and up to 0.06% with aliquoting. Such nephelometric finishing is relatively fast. GRAVIMETRIC. If the 5-ml. aliquot described above contains more sulfur than can be determined nephelometrically, the sample can still be salvaged for gravimetric finishing by adding all the portions, including washings of the filter paper, to a 600-ml. beaker. If gravimetric finishing is contemplated from the start, i t is preferable to burn a t least a 6-gram sample. Rinse the contents of the absorber into a 600ml. beaker. Dissolve the white deposit in the chimney with 5 t o 10 ml. of IN hydrochloric acid and add the acid and subsequent rinsings to the beaker. Dilute to 200 ml. and filter if it appears necessary. Heat the solution to boiling and add 100 ml. of the Naphthol Yellow S-barium chloride solution. Permit the solution to stand until it reaches room temperature. Prepare a filter by placing two glass fiber filter pads in a clean dry Gooch crucible. Best results are obtained by heating for 30 minutes in a 230" F. oven. Cool and weigh. With gentle suction (about 7 inches of mercury below atmospheric) filter the contents of the beaker and wash until free of chloride. Heat a t 230' F. to constant weight. All calculations are obvious and have been omitted. Likewise, the application of the method to liquefied gases, gaseous and low volatility samples is not described. Wax samples are easily burned with the low volatility burner, if the assembly is heated with an infrared lamp ( 5 ) . COOPERATIVE TESTING
Four Esso Research and affiliated laboratories participated in the coop-
Cooperative Test Results
Lab B
Lab C Sulfur, P.P.M.
Lab D
Average
211 221 215 215 212 211 208 215 203 196 196 193 1 3 2 2 3 1 1 3 3 1 Hydroformate 4 4 475 467 475 501 503 477 479 505 480 497 486 Leaded motor gasolinec 486 25 27 Aviation gasoline 28 28 24 28 32 31 27 24 30 31 Heavy virgin naphtha 51 49 50 46 44 48 48 49 49 50 45 47 45 p.p.m. S added Conductometric Sulfur, Wt. yo 6 Virgin naphtha 0.0110 0.0120 0.0120 0.0107 0.0101 0.0102 0.0098 0.0103 0.0102 0.0113 0.0105 0.0104 7 Commercial kerosine 0,0270 0.0330 0.0280 0.0284 0.0276 0.0294 0.0264 0.0282 0.0271 0.0286 0,0274 0.0276 8 Iso-octane 4-0.1934% S added 0.191 0.187 0.186 0.1962 0.1885 0.1908 0.184 0.189 0.188 0.189 0.195 0.187 9 Coker naphtha 0.129 0.125 0.128 0.1258 0.1291 0.1240 0.124 0.131 0.134 0,139 0.135 0.135 10 Heavy cat. naphthac 0.321 0.326 0.311 0.306 0.300 0.314 0.297 0.316 0.321 0.313 0.307 0.300 11 Coker naphtha" 0.905 0.910 0.916 0.900 0.912 0.907 0.900 0.910 0.940 0.926 0.919 0.895 Gravimetric 12 Iso-octane 0.072f70 0.066 0.064 0.068 0.0686 0.0695 0.0709 0.0664 0.0615 0.0660 0.068 0.068 0.069 S added 13 Leaded motor gasolinec 0.043 0.040 0,042 0.0437 0.0436 0.0489 0.0415 0.0371 0,040 0.042 0.044 0.043 14 Heavy cat. naphthac 0.303= 0.313 0.317 0.319 0.322 0.317 0.304 0.309 0.307 0.300 0.298 0.302 0.910 0.932 0.931 0.927 0.895 0.915 0,913 0,918 0.911 0.929 0,922 0.927 15 Coker naphthac 4 Value corrected to 0.3157, S on basis of Dixon's test. * Nephelometric portion of program was repeated. c Samples 3 and 13, 10 and 14, 11 and 15 are the same. 1 Heavy cat. naphtha
2 3 4 5
+
+
386
ANALYTICAL CHEMISTRY
208 2.3 485 28 48 0.01G7 0.0280 0.1893 0.1299 0.311 0.912
0.0672 0.0422 0.310 0.919
Table 111.
Summary
of Statistical Evaluation of l a m p Sulfur Cooperative Program Sulfur, P.P.M.
Sample Xephelometric Heavy catalytic naphtha Hydroformate Leaded motor gasoline hviation gasoline Desulfurized virgin naphtha p.p.m. S
208 2.3 485
+ 45
+10
28
=!=3 1.2 14 2.7
48
2.3
2.3
0.0107 0.028 0.1893 0.1299 0.311 0.912
0.00043 0.0017 0.0035
0.0008
0.06T2 0.042 0.310 0 919
0.0026 0.0023 0.0023 0.011
1.2 14 2.7
Kt. c
w 0 0 P
a
0
2
0.002
v)
0.001
t
I
I
I
0 0005 001
I
01 02 SULFUR LEVEL-%
005
002
,
I
05
l
l
,
I
Figure 7. Reproducibility when conductometrically and gravimetrically finished
20 10
z
5
0
+ 5 2
0 0
2
a
a 1 0
z a
0.5
1
Figure 8.
2
5
20 50 100 SULFUR LEVEL RRM.
IO
200
500
1000
Reproducibility when nephelometrically finished
erative testing of the lamp sulfur method described above. However, before these laboratories undertook the actual testing, each demonstrated that it was in a satisfactory state of quality control by applying the method to known practice samples. The data shown in Table I were so obtained. I n addition to determining the fitness of each laboratory, the work also demonstrated the variation from the true sulfur content which the method n-ould give when ideal samples were tested in different laboratories. Thus for conductometric finishing a t the 0.103% sulfur level, the average of all four laboratories showed a bias of -0.0014 and for nephelometric finishing a t the 12 p.p.m. level the bias was -0.6 p.p.m. Following this demonstration, 15 plant-type samples were supplied to the laboratories. Each sample n a s submitted in three bottles. These bottles were identified n-ith an unrelated number and the finishing method that should be applied. The laboratory supervisor &-as informed which numbers to test in a single day, so that each sample would be tested singly on three different days. Contents of each of the 45 bottles were tested once. Table I1 describes the samples. m-ith the results reported by the four laboratories. These data have been statistically evaluated by a method essentially the same as one developed in the Esso Laboratories (3) and are shown on Table 111. The standard deviation of the reproducibility results for gravimetric and conductometric finishing have been plotted against the sulfur level in Figure 7 . From this curve the following sulfur levels and corresponding expected reproducibility values have been taken: Sulfur Level, Standard Deviation n /G of Reproducibility 3 t O 0008 0 010 0 050 0 0022 0 100 0 0035 0 500 0 0098 1 000 0 015 To translate these figures into a practical application, the 0.100% level may be considered, IThich is a comnion specification limit for sulfur in motor gasoline. The data indicate that a refinery must maintain a 0.093y0 test limit in order to be 95% confident that any given shipment will not exceed 0.100% sulfur. For nephelometric finishing the reproducibility results have been plotted against the sulfur level in Figure 8. These data do not conform to a straight-line relationship as well as those of Figure 7 . However, in the lower sulfur ranges more scattering would be expected. From this curve the following sulfur levels and expected nephelometric reproducibility values have been taken. VOL. 29, NO. 3, MARCH 1957
387
Sulfur Level, P.P.N.
Standard Deviation of Reproducibility
5
A 1.1
10
1 6 3 7 5.3 12.0
50
100 500
To extend the abore data further it is _. . found that a t the 10 13,p.m. level a re“It in the range Of 6‘8 to 13‘2 can be expected 95% of the time. Four of the five samples finished nephelo-
metrically and eight of the ten samples finished conductometrica]ly or gravimetrically have the same deviation for both repeatability and reproducibility. LITERATURE CITED
(1) Am. Soc. Testing Materials, “hSTM Standards on Petroleum Products and Lubricants.’, D 1266-55T. (2) Fischer, R. B., Rhinehammer, T. B., h . 4 ~ .CHEV.2 6 , 244-6 (1954). (3) RlcArthur, D. A., Baldeschweiler, E. L., White, IT. H., .4nderson, J. S., Ibid., 2 6 , 1012-18 (1954).
(4) Quiram, E. R., Ibid., 27,274-7 (1955). ( 5 ) Tighe, J. J., McNulty, J. S.,Center, E. J., Ibid., 23, 669-70 (1951). (6) \vear,G, E. c., Quiram, E. R,, I b i d , , 21,721-5 (1949). (7) Zahn, V., ISD. ENG. CHEM.,ASAL. ED.9,543-7 (1937).
RECEIVEDfor review July 30, 1956. Acceoted Kovember 8. 1956. Division of Petroleum Chemistry, 129th hleeting, ACS, Dallas, Teu., April 1956. Seventh annual Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Pittsburgh, Pa., February 1956.
Remote Control Determination of Corrosion Products
and Additives in Homogeneous Reactor Fuel Application of Ion Exchange A. D. HORTON,
P. F.
THOMASON, and M. T. KELLEY
Oak Ridge National laboratory, Oak Ridge, Tenn.
b Ion exchange techniques have been applied to remote control separation of the most important metal corrosion products from uranyl sulfate solution in homogeneous reactor fuel. In most cases, the metal in the effluent from the column is collected in a calibrated polarographic cell sample holder, in which the effluent can be evaporated to dryness, redissolved, and diluted to volume with the proper supporting electrolyte. Adsorption characteristics of the corrosion products with respect to anion and cation exchange resins, and procedure outlines for determination of aluminum, nickel, cobalt, chromium, iron, manganese, copper, and zirconium are given in tabular form.
D
operation of the homogeneous reactor, uranyl sulfate solution a t high temperature and pressure is in contact with stainless steel, zirconium alloy, and other alloys which are integral parts of the reactor. Because of high temperature, radiation, and the acidic nature of the fuel, a certain amount of corrosion takes place. Initially, the fuel consists of 0.005M copper sulfate solution that contains 10 grams of uranium, as uranyl sulfate. per liter. Copper is used to catalyze the recombination of hydrogen and oxygen produced by decomposition of water in the fuel during operation of the reactor. As corrosion takes place, nickel, manganese. cobalt, iron, chro-
388
URIXG
ANALYTICAL CHEMISTRY
mium, zirconium, aluminum, and other metals may enter the solution. Analytical determination of the corrosion products gives an indication of the stability of the metallic components of the reactor. Many of the methods now in use for the determination of these elements require separation techniques involving multiple solvent extractions or precipitations. Although these methods are effective for a particular element, they are impractical where remote control manipulation is required. There are several prerequisites to the development of analytical methods for use in remote control analytical facilities. The methods must be siniplified as much as possible, in order to minimize the handling of equipment by the master-slave type manipulator or by remotely controlled electrical and mechanical devices. It is desirable to combine as many steps as possible by constructing unitized separation and analytical apparatus, whereby coniplete determinations may be carried out with three or four simple manipulations. An ion exchange column is particularly well suited to remote control analytical methods, as it requires no shaking or stirring. Simple attachments to the outlet of the column make possible the collection of effluents 01 eluates in the vessel that is to be used in the final step of the determination, thereby eliminating or minimizing transfers of solutions. For example, trans-
fer of a solution from a narrow-necked volumetric flask to a polarographic cell requires expert handling of the niasterslave manipulator. This step in a given polarographic analysis niay be eliminated by collecting the effluent from the column directly in a polarographic cell, reducing the volume by placing the cell in a cylindrical heater, then adding reagents to the cell to provide a supporting electrolyte for polarographic determination. This principle is illustrated in Figure 1. The ion exchange column may be prepared outside the remote facility and admitted to the facility by means of an access port. The amount of ion exchange resin required for an analysis can be predetermined from experience n ith nonradioactive test-loop samples. The amount of sample taken from the reactor is alwiys the same, and the amount required for the indil-idual determination is easily estimated. Kraus and Kelson ( 3 ) have deteimined the adsoiption coefficients of all the ions considered herein from equilibration studies of radioactive tracer solutions with various ion exchange resins. The adsorption characteristics of the corrosion products n ith respect to anion and cation resins are given in Table I. The ion exchange column is discussed with respect to column size, resin volume, flow rates, and other factors in an earlier papei ( 2 ) . REAGENTS A N D APPARATUS
10s EXCHAXGE RESINS. Domex 1
