March 15, 1934 (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (26) (26) (27) (28)
(29) (30) (31) (32) (33) (34) (35) (36) (37) (38) (39) (40) (41) (42) (43)
INDUSTRIAL AND ENGINEERING CHEMISTRY
Debray, Bull. soc. chim., 5, 404 (1866). Debray, Compt. rend., 66, 704 (1868). Drechsel, Ber., 20, 1453 (1887). Emioh, Monatsh., 39, 775 (1918); 41, 243 (1920); 46, 261 (1925). Ephraim and Herschfinkel, 2. anorg. allgem. Chem., 65, 237 (1910). Freundler and MBnager, Compt. rend., 182, 1158 (1926). Godeffroy, Ber., 7, 375 (1874). Ibid., 8, 9 (1875). Ibid., 9, 1363 (1876). Gooch and Hart, Am. J. Sci., 131 42, 448 (1891). Gooch and Phinney, Ibid., [3] 44, 392 (1892). Gravestein, Mikrochem., Emich Festschr., 2, 135 (1930). Heller, Haurowitz, and Starry, Ibid., 2, 182 (1930). Hess and Fahey, A m . Mineral., 17, 173 (1932). Hillebrand and Lundell, “Applied Inorganio Analysis,” p. 529, Wiley, 1929. Hillebrand and Lundell, Ibid., p. 39. Huysse, 2. anal. Chem., 3 9 , 9 (1900). Jander and Busch, 2. anorg. allgem. Chem., 187, 165 (1930); 194, 38 (1930). Jander and Faber, Ibid., 179, 321 (1929). Jenzsch, Ann. Physik, 180, 102 (1858). Kehrmann and Bohm, 2. anorg. allgem. Chem., 7, 406, 425 (1894). King, A. S., Astrophys. J., 55, 380 (1922). Klein, Bull. soc. chim., [2] 36, 17 (1881). Marignao, Ann. chim. phys., [4] 3, 5 (1864). Moser and Ritschel, Monatsh., 46, 9 (1925). Moser and Ritsohel, 2. anal. Chem., 70, 184 (1927). Muller, Proc. Am. Phil. Soc., 65, Suppl. 5, 44 (1926). Munroe, J. Analytical and Applied Chem., 2, 241 (1888); Chem. News. 58. 101 (1888). Murmann, E.; Oesterr. ’ChevkZtg., 28, 42 (1925); Chem. Ah., 19, 1827 (1925). Noyes and Bray, “A System of Qualitative Analysis for the Rare Elements,” p. 266, Macmillan, 1927.
111
(44) Papish, J., and O’Leary, W. J., IND. ENG.CHEM.,Anal. Ed., 3, 11 (1931). (45) Parmentier, Compt. rend., 92, 1234 (1881); 94, 213 (1882). (46) PBchard, Ibid., 110, 754 (1890); Ann. chim. phvs., [6] 22, 187 (1891). (47) Pennington, J. Am. Chem. Soc., 18, 56 (1896). (48) Preis, J. prakt. Chem., 103, 410 (1868). (49) Rayman and Preis, Ann., 223, 326 (1884). (50) Reed and Withrow, J. Am. Chem. Soc., 51, 1062 (1929). (51) Robinson, W. O., J. IND. ENQ.CHEIM., 10, 50 (1918). (52) Scheele, Svenska Vet. Akad. Hand., 33, 120 (1771); Mellor, W. J., “Comprehensive Treatise on Inorganic and Theoretical Chemistry,” Vol. 6, p. 947, Longmans, 1925. (53) Schulse, Ann., 109, 177 (1859). (54) Schwarz and Giese, Ber., 63, 2428 (1930). (55) Sharples, Am. J. Sci., [2] 47, 178 (1869). (56) Smith, G. F., and Shead, A. C., J. Am. Chem. Soc., 53, 947 (1931). (57) Snelling, Ibid., 31, 456 (1909). (58) Sonnensohein, J. prakt. Chem., 53, 339 (1851). (59) Stolba, Dinglers polytech. J., 198, 225 (1870). (60) Strecker and Dias, 2. anal. Chem., 67, 321 (1925). (61) Svanberg and Struve, J. prakt. Chem., 44, 291 (1848). (62) Tananaeff. 2. anal. Chem.. 88.343 (1932). (63j Tananaeff’and Harmasch, Idid., 89, 256 (1932). (64) Vogel, Monatsh., 46, 265 (1925). (65) Wells, Am. J. Sci., [3] 45, 121 (1893); [3] 46, 186 (1893); 2. anora. allgem. Chem., 45, 121 (1893). (66) Wells a n d Fooie, Am. J. Sci., [413, 461‘(1897). (67) Wernadski, Bull. soc. franc. mindral., 36, 258 (1913). (68) Winokler, J. prakt. Chem., 121, 36, 177 (1887). (69) Wyrouboff, Bull. soc. franc. minbral., 19, 219 (1896). (70) Yajnik and Tandon, J.Indian Chem. Soc., 7,287 (1930); Chem. Ahs., 24,4236 (1930).
RECEIVED August 29,1933. Extract from a theeis submitted to the faculty of the Graduate Sohool of Cornell University by Wm. J. O’Leary in partial fulfilment of the requirements for the degree of Dootor of Philosophy.
Retention of Dichromate by Glassware After Exposure to Potassium Dichromate Cleaning Solution EDWINP. LAUG,Chemical Room, Marine Biological Laboratory, Woods Hole, Mass.
I
T HAS perhaps not been generally realized that the use of cleaning solution (HzS04.KzCr207 mixtures) may be a source of trouble in biology, chiefly through contamination of media kept in contact with glassware cleaned by this method. Some workers, suspicious of cleaning solution, have regarded the ordinary rinsing with tap water and distilled water as inadequate] and have resorted to longer periods of washing, the assumption apparently being, that whereas rinsing removed the cleaning solution on the surface of the glass, it did not extract that which had penetrated into the glass. As far as can be gathered from the literature, no systematic biological or chemical assay has ever been attempted to determine the adequacy of rinsing and washing procedures in ridding glassware of cleaning solution. a,6-Diphenylcarbohydrazide (C6HsNHNH)2C0 has been known for a long time. I n 1900 Cazeneuve (2) suggested i t as an extremely sensitive reagent for detecting potassium chromate. It was subsequently used by Barnebey and Wilson (1) as an indicator for the dichromate titration of iron. Chromate or dichromate oxidizes a, d-diphenylcarbohydrazide to diphenylcarbazone (NH2NHCON:NH), a reaction which gives a well-defined pink coloration to the solution and is so delicate that 0.0001 mg. ( 0 . 1 ~ )can be easily detected. Moreover, in somewhat greater concentration, the color value is adaptable for a colorimetric determination.
PROCEDURE ,+Diphenylcarbohydrmide was prepared by dissolving 0.5 gram of the dry powder in 70 ml. o 95 per cent alcohol and 25 ml. of glacial acetic acid and making the solution up to 100 ml. with distilled water in a volumetric flask. The reagent keeps about 3 hours at room temperature, after which a pink color develops, presumably due to an oxidation similar t o that effected by the chromate. The standards were prepared so as t o contain respective1 5.0, 4.0, 3.0, 2.0, 1.0, 0.57 of potassium dichromate per 5 m l To each of these tubes 1 ml. of the oc,&diphenylcarbohydrazide reagent was added. It required about 10 minutes at room temperature for the full pink color t o develop. After about 45 minutes the color gradually began to fade, so that it was necessary to make all comparisons at least within 0.5 hour after the standards and unknowns had been prepared. For the comparison a Klett colorimeter was used with 5-ml. cum. Concentrations below 0.57 were not adaptable for measurement in the colorimeter because of low color value, but were simply roughly estimated. In general, anything less than 0.27 was considered a trace.
It was assumed that ten rinsings with water, seven of tap and three of distilled] constituted adequate removal of all potassium dichromate from the surface of the glass. This was borne out by tests. However, any potassium dichromate which hard in some manner been retained within the glass might not be so quickly removed by rinsing. Hence all the tests reported were done on wash waters which had been in contact with the glass for various lengths of time. These extractions with water were sometimes repeated twice in
112
ANALYTICAL EDITION
order to gain some idea of the rate of diffusion of potassium dichromate out of the glass. In spite of the delicacy of the reaction, it was found necessary to concentrate all wash waters by heat evaporation before applying the test. This was always done in a container other than the one used in the test. I n one series of tests, the wash water was kept hot during the extraction period in order to see whether hot water would effect a more speedy removal of the retained potassium dichromate than cold water.
TABLEI.
1 2 3
4
5
7
8
~
10
0.6 11
0.5
so+
OF POTAS6IUM DICHROMATE FROM TABLE11. RECOVERY GLASSWARE BY HOTAND COLD WASH WATER
c '-
(Pyrex beakers, 250 ml. capacity, exposed to oleaninn solution for 15 hours) KLhOla KeCrzOib EXPERIMENT RECOVERED RECOVERBD
0.1
u
Y
$
OF
WIPE
CLEANINQ WASH WASH KzCraOi SOLUTIONWATER WATER RECOVERED Hours Hours M1. 7 Small finger bowl, ljme glass 17.5 12.5, 140 1.8 Bma.11finger bowl, lime glass 6 145 16.33 5.3 60-ml.flask Pyrex 6 50 16.5 0.8 Test tube Pyrex 6.25 20 15.75 Trace Test tub; lime glass 20 6.75 15.75 Trace 100-ml. biaker Pyrex 0.75 95 5.75 2.0 60-ml. beaker gyrex 17 0.5 45 1.6 60-ml. beaker' Pyrex 17 0.5 45 1.2 Black elass d&ression block, lime glass 6.5 16.5 75 0.6 Clear glass depression block, lime glass 6.5 16.5 75 0.7 nna - -." Large beaker, Pyrex month 3.25 85 5.0 GLASSWARE
MENT
g
C
WITH
EXPERI-
0.8
I-
RECOVERY OF POTASSIUM DICHROMATE IN WASH WATER (Miscellaneous glasswah) CONTACTCONTACT VOLUME
6
0.7
Vol. 6, No. 2
0.2 1
0.1
2 3
FIGURE 1. RATEOF DIFFUSION OF DICHROMATE FROM GLASSWARE EXPOSED TO CLEANING SOLUTION
Glassware for the tests was taken a t random from the shelves of the Chemical Room, no attempt being made to trace its history. The tests were concentrated, however, on two types of glass: Pyrex, consisting of beakers, flasks, test tubes, and other miscellaneous pieces; and lime glass, consisting mostly of finger bowls, which are so largely used in the Marine Biological Laboratory. The largest amounts of dichromate recovered from glass were of the order of 5y or 0.005 mg., a concentration of 5 parts per million in a 1gram sample. Such concentrations, while of no importance in the ordinary chemical procedures, are presumably significant when the glass is used for storage of biological specimens. RESULTS Table I presents experiments done on miscellaneous glassware selected a t random, exposed to cleaning solution and wash water for varied lengths of time. Examination of the data reveals that short or long exposure to cleaning solution (within the limits of 6 to 18 hours) does not seem to influence the amount of potassium dichromate recovered from the wash waters, Thus, in the case of experiments 1 and 2, it might be expected that the glass exposed longer should retain the larger amount of potassium dichromate, the extraction periods being roughly equal, but the reverse is true. However, since none of the glassware was new and its history was unknown, differences might occur in the nature of the glass surface exposed which would influence the rate of penetration of potassium dichromate. Furthermore, there is reason for believing that the rate of penetration of potassium dichromate into the glass is initially large but decreases rapidly with time, so that glass exposed 10 hours might not contain much more potassium dichromate than glass exposed 1 hour. Referring to Table 11,it can be seen that the use of hot water is very effective in increasing the rate of removal of dichromate from glass. Thus, during the first half-hour extraction period, the hot water removed 0 . 7 ~and cold water only 0.27. Additional proof of this action is seen in the second and longer extraction period. Here comparison of the wash waters (both cold) shows that the glass initially extracted hot gave blank tests, while that extracted cold continued to show traces of dichromate.
a
b
Y
Cold water Trace Faint trace Trace Cold water Blank Blank Blank
0.2 0.2
Hot water 0.7
4 5 6
Time in Hours
7
Cold water 0.2
0.7
0.7
30-min. contact with wash water. 2-hour contact with wash water.
Table I11 presents data obtained from a series of finger bowls and Pyrex beakers of nearly the same capacity. It is seen from Tables I and I11 that there is no well-defined difference between Pyrex and lime glass in regard to retention of potassium dichromate. The point to be particularly stressed is that, without exception, the rate of diffusion of potassium dichromate out of the glass and into wash water is not a linear function of time. This is clearly shown in Figure 1. An extremely rapid initial rate of diffusion of potassium dichromate out of the glass results in approximately 50 per cent removal in the first 30 minutes and 80 per cent in 2 hours. Even prolonged third extractions with wash water may contain traces of dichromate, indicating that residual amounts of dichromate leave the glass extremely slowly. TABLE 111. RECOVERY OF POTASSIUM DICHROMATE FROM GLASSWASH WATERDURING SUCCESSIVE PERIODS OF Ex-
WARE BY
TRACTION
PERIOD 1 PERIOD 2 PERIOD3 Contact Contact CONTACTContact with KzCraOi with KaCrgOi with K z C r O WITH wash rewash reEXPERI-CLEANINQwash rewater covered MENT SOLN. water covered water covered Hrs. Hrs. y Hrs. 7 Hrs. Y FOUR-INCE LIMB-QLASS FINQER BOWLS. a70 ML. CAPACITY
1 2 3 4 5 6
3.5 3.5 3 3 35 35
0.5 1.66 0.5 1.66 0.5 1.5
0.8 0.2 0.8 0.75 1.4 5.5
1.33
11
1.33
11 1
11
0.5 0.3
Trace Trace Trace Trace
11
0.3
11
.. ..
Tr&e
11
Track
6 6
Blank Blank
6
Blank
..
...
PYREX BEAKERS, 260 ML. CAPACITY
1
2 3 4 6
1 4
4 8 8
0.5 0.5 2 0.5 ~
0.7 0.75 0.9 0.5
0 2. 6
2 2
.,. 2 ...
0.6 0.25
Blank
..
..
..
...
The safest and quickest method of disposing of the dichromate retained in the glass seems, therefore, to boil it out with several successive changes of boiling water, allowing a t least 15 minutes for each treatment. Running cold water can also be used, but would probably require much longer. LITERATURE CITED (1) Barnebey and Wilson, J. Am. Chem. Soc., 35, 156 (1913). (2) Caaeneuve, Bull. sac. chiwz., 23,592,701,769 (1900). RECEIVED October 27, 1933.
