V O L U M E 2 6 , NO. 1 1 , N O V E M B E R 1 9 5 4
1759
Table VI. Effect of Excess Silver Nitrate, Sample Size, and pH on Determination of Pure Orthophosphate Theoretical NaOH Deviation PtOs, 1Ig. 100 0 100 0 100 0 100 0 100 0 100 0 149 7 59 88 60 09 250 0 250 0
Excess AgNOa,
yo
50 50 100 100 200 200 280 290 290 100 100
pH at Additiona 11 0 6 5 11 0 6 5 11 0 6 5 11 0 11 0 11 0 11 0 6 5
NnOH Required, All. 10 35 10 35 10 35 10 35 10 35 10 35 15 50 6 20 6 22 25 58 25 58
Actually Used, Ml. 9 94 10 08 9 80 9 89 9 95 9 79 14 57 5 95 5 85 24 68 24 89
from Theory P a r t - ’ion
Absolute average a
-4
1
- 5 ?>
--o
-4 6 -3 9 -5 6 -6 2 -4 0 -6 2 -3 6 -2 8 4.3
Alilirouirllate.
Table YII.
Determination of Mixtures of Ortho-, PJro-, and Tripolyphosphate“
Per C e n t PtOa Pyrophosphate So. Taken Found I 20.0 19.6 I1 25.0 27.5 24.1 I11 20.0 22.3 IV 25.0 24.7 26.0 1. 50.0 53.2 VI 5.0 4.3 7.1 VI1 10 0 10.0 VI11 5.0 5.7 5,7 IX 950 947 1 94 3 3.1 96 9 s 2 0 5 0 980 950 Total PzO, per titration, 0 2660 gram.
sample
Tripolwhosphate Taken Found 50.0 52.8 x o 49.7 62.7 30.0 30.9 25.0 24.5 23.8 25.0 26.7 90.0 88.9 88.7 90.0 90 0 95.0 94.3 94.3 5 0
:;
tuted for silver ions in the orthophosphate analysis. It is not known, hoxever, how well the method norlts with mixed phosphates. Table VI1 shows typical results for the analyses of mist~uiwof ortho-, pyro-, and tripolyphosphates. If rings or long (*hailis are present’ in the mixtures to be analyzed, they must be det,ermined by independent analyses and their presence redures the effectiveness of the method. Even in the absence of long chains or rings, the analysis is very dependent upon the correct determination of the total phosphorus pentoside. Considerable care must be exercised while preparing an aliquot for hydrolysis and in the subsequent titration. T h e tripolyphosphate analysis is dependent only upon the strong- and weak-acid titration and is not influenced by t,he analysis for orthophosphate. The analysis for pyrophosphate is dependent upon the orthophosphate analysis, however. I n general, the constituent present in the largest quantity may lie determined x i t h the greatest accuracy. REFERENCES
( I ) ;Im. ;Issoc. of Cereal Chem., “Cereal Laboratory Methods,” 5th ed.. DD. 2 0 2 4 . 1947. (2) hssoc. 0 6 : Agr. Chemists, “Official Methods of Analysis,” 7th ed., p. 334, 1950. (3) Bell, It. S . ,AXAL.CHEY..19, 97 (1947).
(4)
Orthophosphate Taken Found 30.0 27.3 25.0 22.8 23.2 50.0 47.2 50.0 50 8 50.2 25.0 19.9 5.0 6.8
0 0 0.0 0 0 0 0
0 0 0.0
0 0 0 0
0 0 0 0
Bell, It. N., Wreath. .1.I t . , and Curless, W. T.. Ibid., 24, 1997 (1952).
(5) Dole, l l . , ”Principles of Experimental and Theoretical Electrochemistry,” Xew York, AIcGraw-Hill Book Co., 1935. (6) Gerber, A. B., arid lliles, F.T.. ISD. Esc,. C H m f . , AN.AL.ED., 13, 406-12 (1941). ( 7 ) Graham, Thomas, Phil. Trans., 123, 253-84 (1833). (8) .Jones. L. T., .LN.~L.CHEM.,14, 537 (1942). (9) Kolthoff. I. AI., and Saridell, E. B.. “Texthook of Quantitative Inorganic Analyseb,” p . 551, Sew York. Macmillan Co., 1948.
(10) Madsen, E. It.. and .Jaergard. T.K., dcta Chon. Scand., 7, 735 (1953). (11) Robinson, H. b.,T i a m . Electrockem. SOC.,92, 4 4 5 (1947). (12) Van Waser, J . R., “Encyclopedia of Chemical Technology,” Kirk and Othiner, eds., Vol. X, pp. 403-510, S e w York, Interscience Publishers, 1953. (13) Van Waser, J . R., J . Am.. ( ‘ h e n . SOC.,72, 644-55 (1950). (14) Van Waeer, J. R., and Campanella, D. A , , Ibid., 72, 659 (1950).
(15) Van Waaer, J. R . , Griffith, E. J., and McCullough, J. F., Ibid., 74, 4977 (1952). (16) Van Waaer, J. R., and Holst, K. A , , I b i d . , 72, 639 (1950). RECEIVED for review 1larcli 4, 1954.
Accepted August 21, 1954
Spectrochemical Determination of Copper in Crankcase Drainings C. R. HODGKINS and JOHN HANSEN Fsso Laboratories, Research Division, Standard O i l Development Co., Linden, The copper content of cranlicase drainings can be rapidly determined by an emission spectrograph method. The addition of hydrocarbon-soluble calcium and lead soaps to the sanlple before ashing serves two purposes: to provide a carrier for the sample ash of nonmetalloadditive lubricants, and to serve as a common matrix to reduce the interelement effect. The method cobers a range of 5 to 500 p.p.m. of copper in the oil and requires about 0.5 man-hour per determination. The results are on the average within +loyo of the amount found by chemical analysis.
T
HE standard or extended Chevrolet L-4 test (CRC L-4-949)
requires t h a t two of the connecting rods be fitted with copperlead bearing inserts, while the other four are high tin Babbitt bearings. T h e determination of the copper-lead bearing weight loss is one of the principal factors of the test. I n some instances,
N. 1.
it is desirable to ascertain the intt:iTinrdiate vaiue of the bearing weight loss during the progress of a test. h correlation between the bearing weight loss of t h e copper content of the crankcase lubricant eliminates the necessity of removing the bearings from the engine for t,he intermediate neighings. The determination of the copper content of the lubricant a t fixed intervals during the test makes i t possible t,o follow the hearing R-eight loss and est,ablish the break point in the loss increase curve, thus enhanring the value of the test in evaluating the lubricant under study. Previous to development of the procedure described, spectrochemical copper determinations in this laboratory were made by a lithium carbonate-graphite coninion matrix technique (4). T h a t method involved quantitatively ashing the sample and determining the per cent copper in the ash, then calculating the copper content of the original blend. T h e number of weighings required in the ashing and subsequent sample preparation, as well as the calculations necessary t.o obtain a result, made the method
1760
ANALYTICAL CHEMISTRY
relatively time-consuming, particularly when applied to the determination of a single element. In addition, i t is necessary to provide a carrier material so t h a t i t is possible to handle the residue obtained in the ashing of nonmetallo-additives or other ashless oils. These disadv:mt,:iges made i t desirable to develop a more rapid method. Earlier, an attempt had Ijeen made to adapt to the determination of copper the method currently used in this laboratory for the determination of iron in used crankcase drainings ( 7 ) . However, this procedure proved inapplicable because erratic results were obtained. Inasmuch as a portion of the copper was known t o be in suspension in some used oils, it was felt t h a t the quenched electrode (3, S), porous cup ( 5 , 61, or rot'ating disk (8) methods of direct analysis would not be applicable to all samples. T h e method described in this paper was developed to provide a rapid method specifically for d e t e r m i n a t i o n of copper in crankcase drainings and resulted in a considerable increase in the number of determinations per nmn-day. The application of the method for the determination of metals other than copper in used lubricants was not investigated. However, there is no apparent reason why the method could not be extended to include a number of elements. APPARATUS, MATERIALS, AND REAGENTS
The following spectrographic equipment was used in the development of this method:
1
MI N
Spectrograph, ARL-Dietert, No. 2060, 1.5-meter grating spectrograph
Excitation, A R L - D ie t e r t , ? i o . 2040, a x . arc unit Densitometer, ARL-Dietert, No. Figure 1. Electrode 2250, projection c o m p a r a t o r densitometer Developing unit, dKL-Dietert temperature-controlled rocking development machine Electrodes, National Carbon special spectrographic graphite, I / d and '/S-inch electrodes
Table I.
Effect of Lead on Copper-Lead Intensity Ratio (Sample
Synthetic copper standard, 50 p p m ) Ratio Cu 3247 5 4 Cu 3 2 7 4 0 . 4 Lead, 7GAdded Co 3044 0 A Co 3044 0 1 None 2.03 1.14 1.56 0.2 0.88 1.73 0.8 0.98 1.56 2.0 0.90 4.0 1.51 0.89 1.59 6.0 0.92 1.37 8.0 0.82
EXPERIMENTAL
Selection of Carrier-Buff er-In ternal Standard Solution. Cobalt was selected as an added internal standard because of its absence in crankcase drainings, and because it,s excitation characteristics appear to simulate those of copper to an acceptable degree. The response obtained in an exposure time study is shown in Figure 3. The lack of variation in intensity ratio indicates that any arcing time from 30 to 75 seconds would be suit'able. Calcium sulfonate was chosen as a carrier-buffer because its ash is resistant to fusion and its fluffy character lends itself to easy removal from the porcelain crucible. Moreover, calcium :is a component of many lubricating oil additives is likely to be present in the ash of crankcase drainingP in relatively high concentration. By its addition t o each sample, it serves as a common matrix. Experiment shon-ed that an analytical curve prepared by using synthetic copper standards (copper naphthenate in additivefree I m e oil) was not suitable for the analysis of certain crankcase drainings, probably because of the wide variation in lead content of the drsinings. This as shown to be the case by the addition of increments of' lead naphthenate to a lead-free copper standard. These data are presented in Table I. This study showed t h a t lead doe8 lower the copper-caobalt intensity ratio, but that the effect is essentially constant when the concentration of lewd in the blend is between 2 and 6%. As a result of this
T h e sample electrode is prepitred by scoring the '/,-inch rod
at 2-inch intervals and breaking at the score' mark. The electrode is shaped by cutting a crater into the end with a 1/8-incli drill, 1/18 inch in depth, aud the outside wall of the electrode is tapered at it 4.5' angle to give a feather edge at the crater opening. The cutting device consists of a slotted cylindrical tube for shaping the tapered edge and a '/ginch drill for cutt,ing the crater. The sample electrode and cutting tool used are shown in Figures 1 and 2. The counter electrode is prepared by scoring the 'i8-inch rod at 2-inch intervals and breaking at the score mark. The raw surface at the break is used without a n y shaping. T h e following materials and reagents were used iii thr tlevelopment of this procedure. Film, Eastman Kodak SA, S o . 1 Lithium carbonate, spectromopically pure Graphite powder, sprctroscopicallg pure (K:it,ion:tl lyby pipetting the proper aliquot of a xylene solution of the cobalt naphthenate. Dilute these components t o the 300-ml. mark using C.P. xylene and shake to effect solution. This solut,ion must be protected against, undue exposure to the at,mospherc, since such exposure causes it to become viscous and difficult t,o pour. To :tvoid this, add the solutiou to the sample hy use of an indicator dropping bottle. The chemicals used i n this preparation are commercially available and suffirient,ly copper-free t o establish analytical curves without applying a blank correction. Any value read off the curve is the amount of copper above the blank value and represrnts the amount of copper in the sample. Preparation of Calibration Standards. St'andard samples for the preparation of analyt,ical curves can be a series of chemically analyzed samples of crankcase drainings of varying copper content. The standards for the lower concentrations may be prepared by appropriate dilution of a chemically analyzed sample using additive-free hase oil. However, in this work, a series of synthetic standards prepared from copper powder and naphthenic acid was used as primary standards. The analytical curves prepared from the synthetic standards are in agreement with those obtained using chemicalll- analyzed crankcase drainings. A series of synthetic standards is prepared as follows: iVeigh out 0.100 gram of electrolyt,ic copper powder, and quantitatively transfer to a weighed 250-ml. glass-stoppered Erlenmeyer flask. .4dd 5 ml. of distilled naphthenic acids and make u p to 200 gram$ using ttddit,ive-free base oil. Stopper and place in mi ovcn a t 200" f 10" F until visual inspection shows t h a t all t,he copper has react,etl. This reaction proceeds slowly, taking several da!.s to reach completion. Occasional shaking aids in effecting complete reaction. 9 concentrate thus prepared contains 500 p.p.m. of copper and is diluted with base oil to give a series of primary standards covering the range of 5 to 500 p.p.ni. of cwpper. CALIBRATION
Intensity ratios used t o establish the analytical curves are obtained as described: Weigh out, 1.0 gram of the synthet,ic standard into a No. 1 tallform porcelain crucible along with 3.0 grams of the carrierbuffer-internal standard solut,ion. Gently swirl the crucible to mix the contents, place on a hot plate, and ignite using a burner. l h i n t a i n ignition by gradually increasing the heat of the hot plate and finally charring a t full heat. Transfer to a muffle maintaincd a t 1000" to 1200" F. to remove the residual carbon. Remove from the muffle and cool. Grind and mix the ash di-
rectly in the crucible using a stainlees steel spatula (No. 9007, Style B, Arthur H. Thomas Co.) taking care to scrape down the sides and bottom of the crucible. Measure out 1 part of the pulverized ash into a small mullite mortar and add 9 parts of the lithium carbonate-graphite mixture using a special Lucite measuring spoon. Then, mix and grind the measured portions intimately. The measuring spoon is shaped from a I/(-inch-square Lucite rod about 3 inches long. At each end, a cavity is shaped, one having the capacity of approximately 10 mg. of pulverized ash, and the other approximately 90 mg. of matrix mixture. Amounts delivered by the spoon are not critical since the ash-matrix mixture ratio can vary over a considerable range without undue effect on the copper-cobalt intensity ratio. Fill the small cavity of the Lucite spoon with ash directly from the crucible, pack by gently tapping, and scrape level using a small straight-edged spatula. Measure the matrix mixture in :I similar fashion using the large cavity. Pack (tn-o or more) electrodes with the ash-matrix mixture obtained from each of the synthetic standards. Place the prepared sample electrode in the lower electrode holder of the arcX 2-inch counter electrode to a spark stand and adjust the 5-mm gap with the optical axis a t the midpoint of the gap. Excite for 75 seconds in the alternating rurrent arc a t 5 kilovolts n-ith a 2-amprrr current using a 50-p slit width. I n order that the analytical lines may be read a t the optimum transmittance, the energies passed bv the 25, 50, and 100% steps of the fourstepped sector are photographed. I n order to save film and time, a mask is inserted in front of the film a t the camera so t h a t only the spectrum from 3000 to 3300 A. is rrcorded. By storing the exposed portion of the film in the transfer rase and moving the film just enough to bring unexposed film in front of the mask opening, 24 exposures are recorded on a single length of film.
0.2
I
I
Figure 4.
I
I
I
I
I
I
I
I
Analytical Curve for Copper
The details of the photographic processing procedure are shown below : Developer, Eastman Kodak D19 Developer, 5 minutes, 68" F. Shortstop, 5 ml. of glacial acetic acid in 400 ml. of water, 15 seconds Fixer, General Electric x-ray fixer, 1 minute Water n-ash, 2 minutes Drying, rlRL film dryer, 2 minutes After the film is processed, measure the transmittances of the 3044.0 A. internal standard line, and the 3247.5 and 3274.0 A. copper lines. Adjust the densitometer to 100% transmittance for the background adjacent to each line. Determine the intensity ratios for each conrentration by applying the transmittance readings to an emulsion calibration curve prepared for the region of 3000 to 3300 -4. Average two or more ratios for each concentration and plot parts per million of copper us. average intensity ratio for each concentration as illustrated in Figure 4. Samples to he analyzed are treated in the same manner and excited under the same conditions as those used to establish the analytical curves. A mechanical shaker should be used to assure homogeneity of the sample prior to taking portion for analysis. PRECISION AND ACCURACY
I n order to ascertain the precision and accuracy obtainable using this method of analysis, replicate determinations were made
ANALYTICAL CHEMISTRY
1762 on two chenlically analyzed samples of engine drainings. Sample 1 was run in a parallel manner while the data presented for sample 2 were obtained on consecutive days and represent the results that can be expected on a day-after-day basis. These data are presented in Table 11.
Table 11.
~-
Table 111. Analysis of Successive Dilutions of Used Oil Sample
Replicate Study of Copper Determination
Copper, P . P . M . Sample 1, Parallel Detn. Sample 2, Successive Detn. Detn. Cu Line Cu Line No. 3247.5 A. 3271.0 A. Average 3247.5 A. 3274.0 A. .4verage 1 25.8 25.3 25.6 110 113 114 2 22.6 23.1 23.6 110 113 112 3 26.4 26.5 108 26.5 116 112 4 29.2 30.0 29.6 112 113 113 5 124 30.3 32.0 31.2 123 124 6 23.0 21.6 22.3 124 128 126 7 24.3 25.2 26.0 106 107 107 8 21.9 25.7 106 26.5 109 112 9 24.7 25.5 23.8 100 102 101 10 25.3 26.4 24.3 ... ... ... 11 24.2 24.0 24.3 ... ... -47.. 25.8 113 Std. dev., S 2.6 7.8 Chemical analysis 25.3 103
To check further the validity of the analytical curves prepared from synthetic standards, a series of drainings of known copper content was analyzed. The gamut of concentrations was covered by making SUccessive dilutions O f drainings having a reIativelY high copper content. These data are shown in Table 111.
a
Copper, P.P.M. Dilution Ratio Calculated value Spectrochemical 0 203a 218 2 102 102 4 50.8 45 8 25.4 23 16 12.7 12 R .3 6.4 32 _. By chemical analysis ( I ) ,Cu p . p . m 209, 196, 203.
ACKNOWLEDGMENT
The authors wish to express appreciation to G. W, Brown, Jr., and G. F. Treacy for performing many of the analyses included in this paper. LITERATURE CITED
(1) Akm.SOC. Testing Materials, D810-48.
(2) Calkins, L. E., and White, 11. AI., .VutZ. Petroleum News, Tech. Sec., 28, R-519 (1946). (3) Clark, R. o.,et ul.. A N A L . CHEM.. 23. 1348 (1951).
(4) Dyroff, G. V., Hansen, John, and Hodgkins, C. R., I b i d . , 25, 1898 (1953). (5) Feldman, Cyrus, Ibid., 21, 1041 (1949). (6) Gassman, A. G., and O'iTeill, W. R., I b i d . , 21, 417 (1949). (7) Hansen, John, Skiba, Paul, and Hodgkins, C. R., Zbid., 23, 1382 (1951). (8) Pagliassotti, J. P., and Porsche, F. W., I b i d . , 23, 198 (1951). RECEIVED for review xfay 26, 1 9 s Accepted August io, 1954 Presented before the Meeting of American Petroleum Instltute. Houston. Tex , 1954
Infrared and Raman Spectra of a Series of Deuterated Alcohols JAMES R. QUINAN and STEPHEN E. WIBERLEY Department o f Chemistry, Rensselaer Polytechnic Institute, Troy,
.4review of the literature revealed disagreement about the assignment of the OH deformation frequency in alcohols in which the H atom moves in the COH plane and perpendicular to the OH bond. The purpose of this investigation was to assign this hydroxyl deformation frequency and at the same time to obtain information about the OD stretching and bending frequencies in higher alcohols. The OH deformation frequency in the liquid state is assigned to the region of 1010 to 1035 cm.-'by comparison of the infrared and Raman spectra of a series of alcohols with their corresponding OD compounds. The OD deformation frequency appears at 915 to 949 cm.-' in the liquid state. The OH stretching frequency in the associated state gives rise to a broad band at 3330 cm.-' which shifts to a weak band at 3682 cm.-' in the vapor state. The corresponding OD stretching frequency appears as a broad band at 2476 cm.-'in the liquid state and shifts to 2726 cm.-' upon vaporization. The regularity of the OD stretching frequency indicates its value as a group frequency, and the presence of either the free or associated OD stretching frequency can be used to indicate the presence or absence of hydrogen bonding in complex molecules.
T
HE purpose of this investigation was to characterize the
OH bending frequency. I t was hoped that this characterization would be helpful in distinguishing between an OH group and a XH group in cases where hydrogen bonding occurs; both groups give rise to a stretching vibration in the region of 2900 em.-' t o 3500 cm.-' However, this investigation subsequently
N. Y.
points out that the use of these deformation bands is very limited as a group frequency. The parallel bending deformation frequency of the S H group has been assigned recently to the region from 1406 to I460 cm.-' (11). The vibrational assignment of the O H deformation frequency of alcohols, in which the hydrogen moves perpendicular to the OH bond and out of the C-OH plane, recently was assigned by Stuart and Sutherland (19) to a broad band in the liquid starting a t 800 cm.-l, reaching a maximum near 670 cm. -1 and extending beyond 500 em.-' I n deuterated methanol this was found to shift to 475 em.-' Koehler and Dennison (9) assign a broad band with a maximum a t about 270 cm.-l for this vibration in methanol vapor. The assignment of the in-plane h y d r o u l deformation vibration was recently made by the authors in a brief letter ( l j ) , and this paper represents a more complete report. The purpose of this investigation, therefore, is to characterize the in-plane or parallel deformation frequency of the OH and OD groups. The position of the OH stretching frequency is well established. Errera ( 6 ) , after studying the infrared spectra of a series of aliphatic alcohols a t various dilutions, was the first to assign a value of 3640 em.-' to the free OH stretching, and a value of 3350 cm. -l to this vibration when the molecules are associated because of hydrogen bonding. I n a more recent study, Smith and Creitz ( 1 7 ) resolved the broad association band a t 3350 cm.-I into components attributed t o the dimeric and polymeric forms. The free OH in the vapor has been reported a t slightly higher frequencies of 3650 and 3687 em.-' (2, 14). The only deuterated alcohols reported in the literature to date were methyl and ethyl alcohols ( 2 , 3,I S ) . Halford, Ander-
