Manganous ESR Signal in Air-Particulate Samples Richard H. Wiley and Henning Proelss Hunter College of the City University of New York, 695 Park Ave., New York 10021
Manganous ion has been identified as a constituent of air pollution particulates.
T
he authors wish to record their observation of an electric spin resonance signal characteristic of the manganous ion in samples of particulates collected in New York City. The samples were collected on asbestos fibers in a standard quartz 5-mm. ESR sample tube through which air was drawn for a period of 1 to 3 days at a rate of about 1 liter per minute at the 14th floor level in residential mid-Manhattan. The spectra were recorded with a Varian 4502-15 EPR spectrometer with dual cavity and with the settings stated in the legend for the figures. Sample I (Figure 1) was collected about September 10, 1967. Sample I1 (Figure 2) was collected
Figure 1. FSR spectrum of asbestos-filtered air particulate sample Sweep time 10 minutes, sweep range lo00 gauss, chart speed 1 inch per minute, Glter time constant 0.1 second, microwave power 6 db., modulation amplitude 1o00, scale division 100 gauss, room temp.
Figure 3. ESR spectrum of a s b e s t d t e r e d air particulate sample (lower line) and reference trace for MnO/CaO (1/100) (upper line) Sweep time 10 minutes, sweep range lo00 gam, chart speed 1 inch per minute, filter time constant 0.1 second, microwave power 6 db., modulation amplitude 500, reOm temp., d e division 100 gauss. Particulate sample at 100 kc., signal level 100. Reference sample at 400 c., signal level 50
on October 9, 1967. Sample 111 (Figure 3) was collected on November 21 (22 hours, 1350 liters flow). Figures 2 and 3 show superimposed traces for a manganous oxide (1 part) on calcium oxide (100 parts) reference sample in the dual cavity. The six-line spectrum characteristic of the manganous ion is apparent in the three figures. The signal occurs at 3100 to 3650 gauss and shows the hyperfine splitting about 90 OE, characteristic of the manganous ion (Borg and Elmore, 1967; Carrington and McLachlan, 1967; Pake, 1962; Title, 1963). There are additional structural features in the spectra which are being further investigated. One is the appearance of intermediate maxima of lesser intensity which may be related to the silicate (asbestos) lattice. The other is the relatively weak carbon radical signal which should appear in the center of this field region. The last is noted because it seems otherwise reasonable to attribute the manganous signal to the organic ash character of the sample which presumably originates from local heating or incinerator operations. Manganous signals have been observed previously in ashed organic materials, and manganese is a known (Bowen, 1966) constituent of industrial smoke. The presence of manganous ions in air pollution particulates is probably attributable to the presence of oxidizable carbon and nitrogen compounds. It may be stabilized on the porous particulates as are organic radicals on porous glass (Turkevich and Fujita, 1966). Possible health hazards associated with this material have apparently not been evaluated. It has been reported (Merck, 1960) that inhalation of fumes containing over 6 mg. per cu. meter produces toxic symptoms. Literature Cited
Figure 2. ESR spectrum of asbestos-filtered air particulate sample (lower line) and reference trace for MnO/CaO (1jlOO) (upper line)
Borg, D. C., Elmore, J. J., Jr., “Atlas of Electron Spin Resonance,” H. J. Bielski and J. M. Gebricki, Eds., p. 319, Academic Press, New York, 1967. Bowen, H. J. M., “Trace Elements in Biochemistry,” p. 161, Academic Press, New York, 1966. Carrington, A., McLachlan, A. D., “Introduction to Magnetic Resonance,” p. 169, Harper and Row, New York, 1967. Merck Index, p. 634, Merck and Co., Rahway. N. J., 1960. Pake, G. E., “Paramagnetic Resonance,” pp. 76. 183, W. A. Benjamin, New York, 1962. Title, R., Phys. Rec. 131,623 (1963). Turkevich, J., Fujita, Y., Science 152, 1619 (1966).
Sweep time 10 minutes, sweep range 500 gauss, filter time constant 0.1 second, microwave power 6 db., modulation amplitude 500, room temp., scale division 100 gauss. Particulate sample at 100 kc., signal level 1250. Reference sample at 400 c., signal level 40
Receiuedfor reciew February 21, 1968. Accepied J u l ~18, 1968. Research was supported in part under PHS Grant 00478-02 between Hunter College of‘ the City Unicersity of New York and the Bureau of State Sercices of the Public Health Sercice, (1. S . Department of Health, Education, and Welfare. Volume 2, Number 9, September 1968 705
