I n the sulfuric acid digestion for the elemental group test, 30% hydrogen peroxide may be substituted for the perchloric acid if desired, using 3 drops of the peroxide for each addition and repeating the cooling- and digestion until clear, colorless solutions are obtained. However, this increases the
digestion time t o approximately 15 minutes. The perchloric acid is more effective for rapid digestion and is nonhazardous under the test conditions described. The use of perchloric with sulfuric acid for quantitative microdetermination of nitrogen has been reported ( 2 ) .
LITERATURE CITED
o,,
(1) ~ ~ l i jyu, ~ ,H.,
J.
~
~ Chern. ~ 38, 1 ,
89 (1919). (2) Pepkowit,z, L. P., Shine, J . W., IND. ENQ.CHEM., ASAL. ED. 14, 914 (1942). R~~~~~~~ for review hTay 24, 1957, Accepted July 30, 1957.
Detection of Pyrene, Benzo[a] pyrene, and Other Polynuclear Hydrocarbons EUGENE SAWlCKl and ROBERT R. MILLER Robert A. Tuft Sanitary Engineering Center, Public Health Service, Cincinnati 26, Ohio
b A new color test has been developed for the detection of polynuclear compounds. A brilliant dark blue color was obtained with pyrene and benzo[ a ] pyrene. Some eight compounds gave red to violet colors. About 15 other hydrocarbons gave an essentially negative reaction.
T
polynuclear compounds found in the atmosphere include anthracene (I, 2 ) , fluoranthene ( I , 2, 1 4 , pj-rene (I, 2, 7, 121, alkylpyrene (?) (I), chrysene (7, I W ) , benz[a]anthracene (la),perylene ( I ) , benzo [n]p~-rene(1, 2, 7 ) , benzo [elpyrene (I, 7 ) . benzo [ghilperylene (1, 2, 7 ) ,and anthanthrene ( I ) . Many of these compounds, as well as coronene, have been found in gasoline engine exhausts (8). Anthracene (S), acenaphthylene (S), pyrene (3, I O ) , benzo [alpyrene (3, I O ) , benzIalanthracene (Q), azulene (IO), benzo(e)pyrene (QJO), and a probable alkyl benzo[a]pyrene (IO) are stated to be present in tobacco smoke. A few of these coinpounds or their methyl derivatives cause cancer in mammals (4). The accelerating growth of industry is linked rTith increased air pollution, Increasing pollution of the air with cancer-causing chemicals is believed to be one of the dominant agents etiologically associated with the rise in lung cancel deaths (6, I S ) . Thus, detection of carcinogens in the air is of extreme importance. HE
Department o f Health, Educafion and Welfare,
y of the hydrocarbon, fluorenone or quinone in chloroform was evaporated to dryness in a 1-ml. test tube, and 0.1 ml. of fuming nitric acid (density 1.5)acetic acid (1 t o 1) was added. The mixture was heated in a steam bath for 5 minutes and then evaporated to dryness under a vacuum in the steam bath. The residue was dissolved in 0.5 ml. of dimethylformamide, allowed to stand for 30 minutes. and then treated with 0.005 ml. of lOy0 aqueous tetraethylammonium hydroxide (Table I). For larger quantities of fluorenone or quinone, the volumes of reagents were proportionally increased. In all cases blank solutions containing evaporated chloroform treated with nitric-acetic acid gave negative color reactions with the test procedure.
SPECIAL REAGENTS
Dimethylformamide. Tetraethylammonium hydroxide, 10% aqueous solution. EXPERIMENTAL
Color Test Procedure. A drop of the test solution containing 5 to 100
U. S.
a
DISCUSSION
Color Test. Proof of structure of t h e hydrocarbons found in the air is based on the similarity of the ultraviolet absorption spectra and/or the fluorescence spectra of the chromatographically separated unknowns t o the analogous spectra of known hgdrocarbons. As this proof of structure is not unequivocal, other methods need to be developed as supplementary tools for the identification of polynuclear compounds. Xitrated polynuclear compounds form colored salts containing a resonating negative charge in alkaline solution. I n most cases the color involves an an-
Table I. Color Reaction of Some Polynuclear Compounds Compound Color Amax, 1111 Benzo [alpyrene Dark blue 622 Pprene Dark blue 627 Fluorene Red 515 9-Fluorenone Violet 530 520 11H-Benzo [blfluorene S'iolet Triphenylene Brown-red 500 Benzene Pink 510 Biphenyl Light violet 540 ,j2
