229
V O L U M E 2 6 , N O . 1, J A N U A R Y 1 9 5 4 pressures involved. The rate of heat transfer in the above experiments in the Emich tubes \vas 0.1T X dT/dt cal. per gram per second. Since d T /dl = 0.320 ( T B - T ) , the rate of heat transfer R as 0.4T X 0.320 X ( T B - 2') cal. per gram per second. If 2 inolesof acetic acid and 1 mole of aniline, totaling213 grams, are placed in capillariep, the rate of heat transfer is 213 X 60 X 0 4i x 0.320 X ( T B - 2') cal. per minute. Thus, for every deglee of difference betaeen the tube contents and the bath, this mixture of acetic acid and aniline can transfer 1920 cal. per minute. The reaction between acetic acid and aniline is most rapid at the very beginning, before the concentrations have diminishcd. With the reaction rate constant equal to 0.392 min.-', it was calculated that a t the beginning of the reaction 0.26 mole of acetanilide was being formed per minute. The heat evolved was therefore 2900 cal. per minute To transfer heat a t this rate, the reaction mixture must be 1.5' hotter than the 200' C. bath. Since the reaction is s l o er ~ a t lower temperatures, the mixture would he0 7" hottrr than the 175'bath and 0.3" hotter than the 150" C. bath. -%q the reaction progresses and becomes slover, the temperature difference would become less. Also, the temperature effect due to the heat of reaction tends to counteract the temperature lag when the cold tuhe is inqerted into the hot oil bath. Examination of Figure 1 indicates that the temperature lags had no appreciable effect on the results of the present investigation. The straight portions of the curves, determined by the method of least quare., point quite direct1:- toward the origin,
a t which the abscissa is zero time and the ordinate is 0.30103. h calculation of the 95% confidence limits (1 ) of the ordinates of the least, squares lines at zero time gives 0.3029 =k 0.0052 a t 150", 0.3038 =t0.0031 a t lis', and 0.304 =t0.0355 at 200' C. Thus, the temperature lags had too small an effect on the course of t,he reaction to be detected by the methods of analysis which were employed. If the effects had been large, they could have been overcome by the use of capillaries with a diameter of 0.5 or 0.1 mm. and by correspondingly more refined micromethods of analysis. ACKNOW LEDGlI ENT
The aut,hor wishes t.o thank Richard J. Turner, Charles R. IVitschonke, Leonard F. Van Eck, and Oliver E. Sundberg for their advice and help in init,iating this investigation, and J. Stuart Patterson for his guidance in the statistical treatment of the results. LITERATURE CITED
( 1 ) Anderson, R. L., and Bancroft, T. h.,"Statistical Theory in Research," pp. 153-63, New York, McGraw-Hill Book Co., 1952. ( 2 ) Goldschmidt, H., and Wachs, C., 2. physih. C h a . , 24,353 (1897). (3) Rider, P. R., "Introduction to Modern Statistical Methods," p. 47, Xew York, John Wiles 8: Sons, 1939. (4) Ibid., p . 93. RECEIVED January 29, 1963. Bccepted October 14,19.53. Presented a t t h e Meeting-in-Niniature of the Philadelphia Section, AXERICAX CHEMMICIL SOCIETY, Philadelphia, Pa., January 29, 1953.
Improved Micro-Dumas Method and Apparatus THOMAS D. PARKS, EDWIN L. BASTIN, ELlGlO 1. AGAZZI, and FRANCIS R. BROOKS Shell Development Co., Emeryville, Calif.
The micro-Dumas method for the determination of nitrogen has been studied for the purpose of developing a reliable method for routine use. A convenient, unitized apparatus has been designed, and a well-defined procedure established. The sample is vaporized in a stream of carbon dioxide and the gases are passed over nickel oxide and nickel at 1OOO"C. to oxidize organic gases, hopcalite at 110"C. to oxidize carbon monoxide, and highly active copper oxide at 700" C. to oxidize traces of methane. The carbonaceous residue formed by pyrolysis of the sample is completely oxidized with oxygen, thus releasing any nitrogen which may be held by the residue. Yitrogen is collected, as usual, in an azotometer over potassium hydroxide solution. The volume of the nitrogen gas is measured by displacing and weighing an equal volume of mercury. The method is widely applicable and avoids certain errors encountered in the commonly used microDumas methods. Results are presented to illustrate the accuracy, precision, and scope of the method.
T
H E nitrogen content of organic materials is generally determined by applying either the Kjeldahl or the Dumas method. While the Kjeldahl method is applicable to many substances and is attractive because of its simplicity, it is unreliable for the determination of nitrogen in certain materials, notably highly nitrated compounds and compounds containing nitrogento-nitrogen single bonds. These limitations of the Kjeldahl Present address, Stanford Researrh Institute. Stanford, Calif.
method have made the Dumas method indispensable in many laboratories. Since the initial development of the micro-Dumas method by Pregl, a number of improvements in the method and apparatus have been described in the literature. The authors have developed a method which embodies many of these improvements and overcomes the major weaknesses of the commonly used microDumas methods (9, I 2)-namely, incomplete oxidation of the methane which forms during sample pyrolysis ( 1 4 ) and incomplete combustion of carbonaceous sample residues which may contain nitrogen ( 2 ) . The apparatus is unitized to increase the convenience of the analysis and to make maintenance of the equipment easier. Use is made of the nickel-nickel oxide tube filling supgested by Kirsten ( 4 ) to replace the conventional coppercopper oxide filling. Combustion of methane is ensured by an auviliary combustion tube filled with highly active copper oxide (8). Pyrolysis of the sample is carried out by a traveling electric furnace ( 3 , 1 0 ) in a stream of carbon dioxide, and any carbonaceous residue is then completely burned in a stream of oxygen as described by Gonick et al. (2). This technique eliminates the necessity for mixing the sample with copper oxide or other oxidation aids when testing refractory compounds ( 2 1 ) . Errors inherent in the measurement of the nitrogen volume in an azotometer filled with strong potassium hydroxide solution ( I S ) are eliminated by use of the mercury-filled 15 eight azotometer described by Koch et al. ( 7 ) . APPARATUS
A photograph of the apparatus is shown in Figure 1 and the apparatus is described schematically in Figure 2. In order to maintain a satisfactorily low blank value it is necessary that the carbon dioxide used a$ a sweep gas contain not more
ANALYTICAL CHEMISTRY
230 t h m 0.01 volume Yoof nitrogen or ot.her inert gases. This requirement is satisfied when carbon dioxide is prepared from the solid, liquefied in a pressure vessel essentially as described hy Gonick et al. (a). The vessel used for this purpose has a capacity of 150 pounds of solid carbon dioxide, which provides a sufficient supply of gas to operate the unit for several years. Oxygen, for the combustion of residues remaining after the pyrolysis of sample, is obtained by the electrolysis of 2.5% potassium hydroxide solution in the all-glass apparatus shown in Figure 3. The generator functions automatically; the direct current, supplied to the electrodes a t 5.7 volts by a suitable rectifier. is turned off when the pressure of the oxygen drives the electrolyte level below the anode and ia turned on when the electrolyte level rises as a result of oxygen withdrawal. Hydrogen, simultaneously evolved, increases the pressure in the system until the mercury level in the by-pass valve drops below the sintered disk. Hydrogen then escapes through this disk until the pressure drops sufficiently to allow the mercury level to rise and reseal the disk.
. .
.
F i g u r e 1. Unitized Micro-Dumas A p p a r a t u s
Pack the high temperature tube a8 shown, omitting the hopcalite. Hold the tube in a horizontal position and tap i t to form a channel along the top of the nickel powder. Insert the tube into the furnaces as shown in Figure 2 and attach the inlet and tube closure fitting, which is made of stainless &eel and is equipped with a screw cap to allow insertion of the sample. Adjust the temperature of the main furnace to 5W"C. and that of the bopcalite furnace to 110" C. Pass carhon dioxide through stopcocks G, F, E, and D to remove air from the gas manifold, then turn stopcock G so that carbon dioxide flows through the tube. Attach stopcock F to a muree of hydrogen, by means of rubber tubing, and pass a smdl amount of hydrogen through F , E, and D to flush the connecting tubing free of air. Turn o f f the carbon dioxide flow and pass hydrogen, a t a rate of 10 to 20 ml. per minute, into the tube through stopcocks F and G until any nickel oxide is completely reduced. Sweep the hydrogen from the tube and manifold with carbon dioxide and, without removing the tube from the furnace, pack the exit end of the tube with hopcdite as shown in Figure 4. Insert the ituxilirrry tube, packed with precipitated copper oxide containing 1%iron oxide, into its furnace and adjust the temperature of the furnace to 300' C. Connect the tube containing the nickel to the auxiliary tube by means of a section of 2-mm. bore capillary tubing equipped with ball joints a t each end. Connect the exit end of the auxiliary tube to stopcock E by means of stainless steel hypodermic tubing fitted with metal hall joints. Seal the joints with sealing wax. Disconnect stopcock F from the hydrogen source and sweep the hydrogen from the rubber tubing by introducing carbon dioxide through stopcocks G and F. Sweep hydrogen from the absorption tower by passing carbon dioxide through stopcocks G, F, E, a n d D. At.bch the rubber tubing t o a source of cylinder oxygen; cylinder oxygen is used for oxidation of the tube packing because of the relatively small capacity of the electrolytic oxygen generator. Remove the cap from the fitting on the entrance end of the cornbustion tube and turn stopcocks F and E so that oxygen can be introduced into the combustion tube through the auxiliary furnace. Adjust the flow of oxygen to 10 ml. per minute and 0x1dize the nickel for a distance of 90 mm. Recap the front end of the tube and turn stopcocks P , G, and E so that oxygen flows into the entrance end of the combustion tube and into the absorption tower; leave stopcock D open t o the atmosphere. Oxidize a 70-mm. section of the nickel, then slowly (to prevent surface oxidation of the nickel) sweep the tube with carbon dioxide. Disconnect the tubing from F and adjust the temperature of t h e main furnace to 1000' C. and that of the auxiliary furnace to 700" W&I pot in us!, keep~ the filled with carbon I . system ~ di, '
9.
~~
~
~~~
'
~
~
~ . ~ . ~
a 2-holed rubber st&& carrhng two glass tubes. one of which extends to the hattamof the &a& Connect the glass tube which extends to the bottom of the flask to the exit line on the top of
the 100-mI. oxygen bulb of the generator. Apply pressure to the solution in the flask through the other glass tube. sunuort the generrttor in a horizontal posiGon with the mercury byfa& valve upward, and completely fill the generator with the caustic solution. Cap the open end and the sintered-glass plate of the mercury bypass line with rubber policemen, return the generator t o an uurieht Dosition. and release the uressure on the Erlenmeyer .~ ~~~~~
~
~~
to where it is even with the &phf the small bulb. -Cap the e& line of the oxygen bulb with a ball joint plug and remove the ruhher policemenfrom the mercury bypa& line. Add mercury to tbe mercury bypass line until the mercury level in the arm open to the atmosphere is approximately 5 ern. above the sintered disk. Connect the oxygen outlet to the apparatus and seal the spherical joint connection with sealing wax. Remove the liquid in the open arm of the bypass vdve using an eyedropper. Determine the purity of the generated oxygen by correcting the blank value (determination described suhsequently) for the amount of nitrogen derived from the csrbm dioxide. Less than 0.05 gram of mercury (0.01 volume % inert gases) should be obtained. If a higher value is obtained, draw oxygen from the generator by venting the gas to the atmosphere through stopcock F (Figure 2). To avoid any diffusion of air through F , close the stopcock when the pressure differential in the mercury bypass valve drops to 15 mm. above atmospheric. Permit oxygen t o accumulate until the generator ceases to generate gas and,redetermine the purity of the oxygen as before. Repeat until a ,&isfactory product is obtained. Combustion Tube. The cornbustion tubes and fillings are described in Figure 4.
Fi
LtUS
__
._ ~ ~--~-.iersr . lllllll.J "_ I._____1_ _._- ._.~ ture combustion tube. This is accomplished by determining t h e nitrogen content of acetanilide, as described below, until a value is obtained which deviates from the true value by 0.1% nitrogen or less. Usudly a satisfactory value is obtamed after three or four analyses. A quartz rad, approximately 5 cm. long and of such diameter as to fit into the comhustion tube with a clearance of about 0.5 mm., is inserted into the tube behind the boat t o pfevent sample vapors from backing up and provide some eonductlon of heat to the boat in the early stages of pyrolysis. A loop drawn a t one end of the quartz rod facilitates its removal from the combustion tube. A hook made from small-diameter brass rod is used to re-. move the boat and quartz plug from the tube. Combustion Burnaces. The nickel-nickel oxide section of t h e high temperature combustion tube is heated to 1000° C. by means of a 23-cm. furnace wpund with Kanthal (C. 0. Jelliff Mfg. Co., Southport, Cann.) resistance wlre. The furnace IS controlled b y _I
I__
~~~~~~
231
V O L U M E 26, N O . 1, J A N U A R Y 1 9 5 4 means of a variable autotransformer and its temperature is indicated by a pyrometer. The hopcalite is heated by a furnace consisting of an insulated aluminum cylinder, 11 cm. in length, and drilled to accommodate three cartridge-type heaters, the tube and a thermo-switch set to maintain the temperature a t l l O o JC. The auxiliary tube containing precipitated copper oxide is maintained a t 700 O C. by a 13-cm. furnace wound with Chrome1 resistance wire and controlled by a variable autotransformer. The traveling furnace that is employed for vaporization of the sample consists of a 6-cm. length of Alundum tubing wound with platinum-10% rhodium resistance wire and is maintained at approximately 1000' C. during operation. The rate of travel of this furnace is determined by the voltage that is applied to the drive motor through a variable autotransformer.
Cylindrical pla*inu electrodes w i l h 16
crn or s u r r a c on one side. lheig LO. diamelar-25! 5q.
minutes a t a rate of 5 ml. per minute. Follow with carbon dioxide a t a rate of 5 ml. per minute for 4 minutes. Increase the rate of flow of carbon dioxide to 10 ml. per minute and maintain this flow for 5 minutes. Open stopcocks A and B to the atmosphere for a few seconds and determine the residual gas volume by displacing mercury as above. Less than 0.2 gram of mercury should be displaced. Analysis of Sample. Bring the level of potassium hydroxide solution to the mark, close stopcock D, and lower the leveling bulb. Accurately lseigh sufficient sample to yield 0.5 to 2.0 mg. of nitrogen, but do not take more than 25 mg. in any case. Weigh solids and nonvolatile liquids in platinum boats. Keigh hygroscopic samples in boats enclosed in glass piggies. Draw volatile samples into weighed glass capillary tubes with a bulb in the middle (1). Seal one end of the sample tube, weigh the capillary plus sample, and quickly dip the open end into melted paraffin. Place the capillary on a platinum tray before putting it into the combustion tube. Place a quantity of solid carbon dioxide over that section of the combustion tube which contains the sample. Open the front end of the combustion tube and pass carbon dioxide through stopcocks G, F , and E and out the front end of the combustion tube a t the rate of 40 ml. per minute. Insert the sample and push the sample to within 5 or 6 cm. of the high temperature furnace with the hook. Insert the quartz plug so that it touches the boat and replace the cap on the front end of the combustion tube; screw the cap on firmly. Quickly turn stopcockq G and E so that carbon dioxide flows through the combustion tubes and into the absorption tower. Reduce the flow of carbon dioxide to 10 ml. per minute and maintain this flow for 6 minutep. Open stopcock D to the atmosphere and allow the potassium hydroxide solution to flow into the leveling bulb. Bring the level of potassium hydroxide to the mark on the capillary as before. Close stopcock D and pass 60 ml. of carbon dioxide through the tube and measure the residual gas as described; repeat if more than 0.1 gram of mercury is obtained. Continued high values indicate that the sample is vaporizing or the system ic: leaking. High T e m p e r a t u r e Combustion Tube
Hydrogen
Figure 3.
I
AII ~ l m e n i m nt n~ ~n
-
p35-15-k35J,
Electrolytic Oxygen Generator
Gas-Measuring System. The gas-measuring system consists of an ungraduated absorption tower filled with 307, potassium hydroxide solution and a weight azotometer filled with mercury. Sufficient mercury is placed in the bottom of the absorption tower to form a column extending 3 to 5 mm. above the inlet side arm; this prevents the caustic from draining out through the side arm. The combustion products are swept into the absorption tower by a stream of carbon dioxide. The caustic solution absorbs the carbon dioxide and the residual gas volume is measured by displacing and weighing an equal volume of mercury as described by Koch et al. (7). PROCEDURE
Before making the first analysis of the day, purge the carbon dioxide and oxygen lines by venting the gases to the atmosphere through stopcock F. Determine whether any air is entering the apparatus as follows: Open stopcock D to the atmosphere and raise the leveling bulb until the potassium hydroxide solution rises to the mark etched on the capillar portion of the absorption tower. Mark the position of the IeveLg bulb so that it can be returned to this position. Close stopcock D and lower the leveling bulb. Pass 60 ml. of carbon dioxide a t a rate of 10 ml. per minute through stopcock G, the combustion tubes, stopcock E,and into the absorption tower. Open stockcock D to the atmosphere and return the level of potassium hydroxide solution to the mark. Close stopcock D, lower the leveling bulb, and again pass 60 ml. of carbon dioxide into the absorption tower a t a rate of 10 ml. per minute. Close sto cocks A , B, and E and raise the leveling bulb to the previously L e d upper position. Turn stopcock D to connect the absorption tower to the weight azotometer and, by means of stopcock C, drain mercury into a small weighed weighing bottle until the level of potassium hydroxide solution returns to the mark. Weigh the mercury; the amount displaced should be less than 0.1 gram. Blank Determination. Open stopcock D to the atmosphere and bring the level of otassium hydroxide solution to the mark. Close sto cock D an: turn E to communicate the absorption tower to tge combustion tubes. Lower the leveling bulb and pass carbon dioxide through the apparatus and into the absorption tower for 17 minutes at a rate of 3 ml. per minute. Change the gas flow to oxygen and pass oxygen through the tube for 6
r I1
lo I 2
O.D.Quartz Tubing I Q I O
i Auxiliary Combustion Tube IOmrn. 0 . D. Quarlz Tubing
r Figure 4.
Quartz Combustion Tubes and Packing0
A.
60-mesh nickel gauze
E. F.
40-mesh copper gauze Hopcalite
B. 150-mesh oxidized nickel powder C. 150-mesh nickel powder D . Quartzwool
G . Glasswool
H. Preeipitated copper oxide plus iron oxide All dimensions in millimeters
Open stopcock D and return the level of thepotasium hydroxide solution to the mark. Close stopcock D, lower the leveling bulb, turn on the carbon dioxide, and adjust the flow of carbon dioxide to 3 ml. per minute. Remove the solid carbon dioxide from around the combustion tube and turn on the heater of the traveling furnace. Move the furnace to R-ithin 1 to 2 cm. of the sample and allow i t to warm up for about 2 minutes. Start the furnace traveling by increasing the drive motor voltage with the variable autotransformer. Adjust the rate of travel so that the sample is burned slowly and a t a uniform rate, as indicated by the rate of formation and size of the gas bubbles in the absorption tower. Conduct the combustion a t such a rate that the traveling furnace reaches the high temperature furnace in less than 17 minutes. When a total of 17 minutes has elapsed from the time the travel of the furnace was started, return the traveling furnace to a position directly over the sample. Turn off the carbon dioxide, turn on the oxygen, and adjust its flow to 5 ml. per minute. After 2
232
ANALYTICAL CHEMISTRY
minutes has elapsed, start the furnace traveling a t such a rate that it will reach the high temperature furnace in 4 minutes. Turn off the oxygen and pass carbon dioxide through the tube for 4 minutes a t a rate of 5 ml. per minute, then for 5 minutes at a rate of 10 ml. per minute. Turn off the carbon dioxide and the heater of the traveling furnace and close stopcock E. hlomentarily open stopcocks A and B to the atmosphere, place the leveling bulb in its upper position and open stopcock D to the weight azotometer. Displace mercury into the weighing bottle t h o u h stopcock C until the level of the caustic solution returns to t i e mark on the capillary. Weigh the mercury to the nearest 0.005 gram.
Table I. .4pplication of Micro-Dumas Method to Various .Materials
Material .4cetanilide Acridine Azobenzene
DISCUSSION
The method descnbed has been routinely applied to a wide variety of materials over a period of several years. The method permits an operator to complete five or six analyses per 8-hour working day and the compact, rugged design of the apparatus minimizes the maintenance work that is required. Results typical of those obtained are shown in Table I. The pooled standard deviation of replicate tests from their average is 0.05%. Appropriate statistical tests failed to shoiv the presence of systematic errors, thus indicating that the results are not significantly influenced by the type of nitrogen compound tested. Single results should not differ from the theoretical value by more than 0.11% for more than one time in 20. If duplicate tests are made, the average should not differ from the theoretical value by more than 0.0870 for more than one time in 20. The practice in this laboratory at one time was to use a combustion tube packed with copper and copper oxide in a manner similar to that described by Pregl; both copper gauze and wireform copper oxide were used. The temperature of the first oxidized portion of the 6lling a a s maintained at 900" C., since a t this temperature it was found that methane \vas quantitatively oxidized with a contact time of approximately 15 seconds. .4t lower temperatures such as are commonly used in micro-Dumas combustions, a much longer contact time v a s required. However, it was found that the copper-copper oxide filling was not completely adequate for dinitro compounds; such compounds gave nitrogen values which generally were about O.5Y0 low. -4 solution to this problem was presented by Kirsten ( 4 ) , who obtained excellent results for such materials by employing a nickelnickel oxide filling maintained at 1000" C. At this temperature some carbon dioxide dissociated to form carbon monoxide, causing positive errors, so part of the tube was packed with hopcalite to reoxidize the carbon monoxide. Kirsten used nickelous oxide and nickel for the tube filling. He prepared the nickel by reducing the oxide with hydrogen at an unstated temperature. In attempting to repeat his work, nickelous oxide was reduced with hydrogen at 800" C. in the combustion tube, but the filling fused into a mass of hard lumps. At 550" to 600" C. reduction was effected without this difficulty; hoviever, a shrinkage of about 500/0 took place during reduction. Further tests showed that the use of 150mesh nickel powdef (A. D. Mackay, 198 Broadyay,.New York 7 , N. Y.) as the starting material circumvented this dficulty; this material also proved to be more convenient to handle. Theoretical nitrogen results were obtained when the nickelnickel oxide packing was used for the analysis of a variety of materials; however, petroleum fractions consistently yielded resulte which were high by as much as 1% nitrogen. This was attributed to the formation and incomplete combustion of methane. The difficulty was overcome by passing the gases from the combustion tube through an auxiliary tube maintained a t 700" C. and packed with precipitated copper oxide containing 1% fernc oxide (8). This modification resulted in a marked improyement; however, the low but consistently positive values obtamed for nitrogen-free hydrocarbons (Table I ) may be the result of incomplete oxidation of methane, The simpler expedient of Kirsten ( 5 ) , who employed a tube with an enlarged nickel-nickel oxide catalyst zone, proved to be inadequate in the authors' hands. Possibly the nickel oxide was not so active as that prepared by Kirsten. It seemed that the apparatus could be simplified by using the precipitated copper oxide containing iron oxide to oxidize both methane and carbon monoxide, thus eliminating the hopcalite packing and furnace. However, tests showed that incomplete combuetion of the carbon monoxide was obtained with this catalyst under the conditions employed. Kirsten (6) points out that nitrogen oxides are retained by nickel oxide when free oxygen is present in the combustion tube. On the basis of this observation the use of oxygen to burn carbonaceous residues would appear to offer a source of error. However, since oxygen is introduced after the sample has been pyrolyzed, the chance of oxides of nitrogen and oxygen being present together in the combuetion tube is small.
Approximate Sample Wt., Mg.
Nitrogen, Found
Dev. from theory
7 5 6.6
10.36
10.36 10.32
0.00 -0.04
6.6 6 2
7.82
7.80 7.83
+0.01
10 7 7 9 8 4
15 3 8
7 1
...
...
... ...
...
s-Benzylisothiourea hydrochloride
7 6 7 8
0 7 9 2
l3:82
p-Chloroacetanilide
8 3 8 7
8.26
8 6
11 66
Cystine
2,4-Dinitropheno
7%
Theory
7 3 8.7
... ... ... , . .
...
-0.02
-0 09
15 29
I5 48 15 39 15 37
+ O 10 + O 01
13.78 13.69 13,81 13.67 8.24 8 21
-0.04 -0.13 -0.01 -0,15
11.55 11.60 11.57
-0.11 -0.06 -0.09
-0 01
-0.02 -0.05
9.9 7.3 !. 1
15.22
15.30 15.30 15.20 15.26
+0.08 +0.08 -0.02 +0.04
Gasoline
8 4 13 I
0.00
0.06 0.04
+0.06 +O.M
n-Heptane
11.7
0.00
0.06
+0.06
p-Iodoacetanilide
12 7
5.37
5.40 5.45 5.49 5.44 11.37 11.40
4-0.03 +0.08 fO.12 +0.07
10.08 10.14 9.98 10.05
+0.01 f0.07 -0.09
0.08 0.03 0.01 0.10 0.05 5.39 5.30
+0.08
, 4
9 2
Xicotinic acid p-Nitrophenol
K h i t e oil
n,n-Diisopropyl bibutane phosphinic amide Quinoline
... ... ...
...
...
...
9 1 11.6
...
9 6
11.38
8 5
...
7 2 9 1
10.07
...
9 9 10 8
... ...
16.3 12.2 14.1 14.4, 11 I 9.9 10.2
0.00
13 0 14 2
... ...
... . . 5.36
...
10.85
...
10.85 10.91
-0.01 +0.02
-0.02
+0.03
+0.01
+O.lO
f0.05 +0.03 -0.06
0.00 +0.06
ACKSOWLEDGMENT
The authors wish to acknowledge the contributions of A. B. Bullock, Louis Lykken, and K. R. Fitzsimmons in the early stages of the development work. LITERATURE CITED
(1) Campanile, V. A., Badley, J. H., Peters, E. D., Agazzi, E. J., and Brooks, F. R., ANAL.CHEM., 23,1421 (1951). (2) Gonick, H., Tunnicliff, D. D., Peters, E. D., Lykken, L., and Zahn, V., IND. ENG.CHEY.,ANAL.ED.,17, 677 (1945). (3) Hallett, L. T., I b i d . , 10, 101 (1938). (4) Kirsten, W., ANAL.CHEY.,19, 925 (1947). (5) Ibid., 22,358 (1950). (6) Kirsten, W., Mikrochemie per. Mikrochim. Acta, 40,121 (1952) (7) Koch, C. W., Simonson, T. R., and Tashinian, V. H., Ibid., 21, 1133 (1949). (8) Murdock, R. E., Brooks, F. R., and Zahn, V., AXAL. CKEM, 20, 65 (1948). (9) Roth, H., "F. Pregl Quantitative Organische Mikroanalyse." 5th Auflage, Berlin, Springer-Verlag, 1947.
(10) Royer, G. L., Norton, A. R., and Foster, F. J., IND.ENG. CHEM.,AIVAL. ED.,14, 79 (1942). (11) Sternglanz, P. D., Thompson, R. C., and Savell, w.L., A N A L .
CHEM., 23, 1027 (1951). (12) Steyermark, A., "Quantitative Organic Microanalysis," Philadelphia, Blakiston CO., 1951. (13) Trautz, 0. R., Mikrochemie, 3, 300 (1931). (14) Van hfeter, R., Bailey, C. W., and Brodie, E. C.,ANAL.CHEM , 23, 1638 (1951). RECEIVED for review August 10, 1953. -4ccepted October 6 , 1953.
