F l a Rata
Table I.
Precision of Automated Peroxide Method No. of
Concri. 5 p.p.b. 100 p.p.b. 1 p.p.ni. 4 p.p.111.
Rel. std. dev., Yo 2.3 2.4 0.7 1.6
measurementa 15 20 20 13
Conditions for 5 p.p.b. to 8 p.p.m. H202
Table II.
Light path, mm. 15 15 10
Concwitration 5-10 P.P.b. 10-600 P.P.b. 50 p.p.t).-8 p.p.m.
Range expansion 10 4 1
Concentrations from 5 p.p.b. t o 8 p.p.ni. were determined simply by ch:inging the range expansion and path Icngth of the absorption cell. Con-
Phcmlphthalein
(0.012M)
Figure 1 .
0.32:
-Rnp
Flow diagram of automated peroxide method
centrations higher than 8 p.p.m. required dilution or manifold changes. Proper conditions for concentrations between 5 p.p.b. and 8 p.p.m. are shown in Table 11. Scouting tests showed that the method is applicable in heavy water with very little loss of sensitivity. Strong oxidants and complexing agents for peroxide would be expected to interfere.
(3) Collins, P. F., Diehl, H., Smith, L. F., Ibid., 31, 1862-7 (1959). ( 4 ) Ferrari, A , , Russo-Alesi, F. M., Kelley, J. M.,Ibid., pp. 1710-17. (5) “Handbuch der Analytischen Chemie,” R. Fresenius. G. Jonder. eds.. Vol. VIa. p. 333, Springer, Berlin, ’1940: (6) Lundgren, D. P., ANAL. CHEM.32, 824-8 (1960). (7) Skeggs, L. T., Am. J . Clin. Path. 2 8 , 114 (1957).
E. K . DUKES M. L. HYDER
( 1 ) Ann. N . Y . Acad. Sci. 87, 609-51
Savannah River Laboratory E. I. du Pont de Semours & Co. Aiken, S.c.
(1960). (2) Britt, R. D., Jr., ANAL. CHEM.34, 1728-31 (1962).
WORK under contract AT(07-2)-1 with the LT. S. Atomic Energy Commission.
LITERATURE CITED
Spectrophotometric Method for Determination ot Tetranitromethane in Solution and in Air SIR: The analytical procedure reported recently ‘ ( 8 ) for trinitromethyl compounds yielded only 90 to 95% of nitroform from tetranitromethane (TKM). This mas wrprising, for this is the isolable yield in the preparation of potassium nitroform from T N M with hydrogen peroxide and pota.;sium hydroxide. Apparently, in methanol, hydroperoxide ion attack5 both a nitro group and the carbon atom to give nitroform ion and carbonate ion a9 in water does hydioxide ion only ( 5 ):
+
C ( N O P ) ~ OOH- .--t [C(S02)3 . . . NO2 . C(NOz)3NOzC(N02)4
. . OOHI-
-+
+ Oz + H +
+
(1)
+ 600HcO3-’ + 4NOz-+
f 3Hz0 f 302
+
+ +
1690
+
(2)
+
ANALYTICAL CHEMISTRY
EXPERIMENTAL
T N M in Solution. Apparatus. All
T N M has been determined colorimetricrtlly by its reaction with benzidine (6), and by titrating the iodine liberated w h ~ nTKhf reacts with iodide ion ( 3 ) . lhillic, JLI:tc.hrth, and Maxwell ( I ) rc1l)oi.t a quantitative gasometric determination of ‘1’554in which the nitrogen ~~ro(luc.cd by the reaction with hydraz i i i v i< incawred: 2 (’(XO?)4 S2HI 4KOH 21
