coagulative activities which yield large particles by growth processes from smaller particles, however other factors may have an influence. With emission aerosols in Ankara, large newly formed particles are injected into the air from the incomplete combustion of lignite fuel, whereas the smaller particles with a lower settling velocity have a comparatively longer residence time. Further, the almost continuous inversion conditions which exist in Ankara can also contribute to a wide range of particle sizes by growth processes. Comparisons of the particle size distiibution of suspended particulate matter in Ankara with urban areas in the U S . and Great Britain reveal the uniqueness of the aerosol in Ankara air. The large average particle size appears to be characteristic of aerosols emitted from the combustion of poorquality lignite fuels since this is the only major difference between Ankara and the other urban areas sampled. Although the aerosol concentration in Ankara is higher than those found at the U.S. and British urban sites, the respirable frac-
tion is low for equivalent concentrations. Hatch and Gross (1964) concluded that the percentage penetration of particles into the pulmonary air spaces rises from essentially zero at 10 p to a maximum at and below about 1 p. An average aerosol in Ankara less than or equal to 1 p diam is 37% while, by comparison, the average yearly values for 1970 in six U S . cities (Chicago, Cincinnati, Philadelphia, St. Louis, Washington, D.C., and Denver) ranged from 54 t o 68 % (Lee and Goranson, 1971). Further measurements need to be made to characterize the chemical composition of the various size fractions in urban areas which use low-quality fuel, especially in view of the possible presence of polynuclear hydrocarbons. However, the results reported here indicate that the inhalation hazard of the total particulate matter may not be as great as equivalent concentrations in U.S. and British cities.
Table I. Particle Size Distribution Parameters Measured in Ankara Air Geometric Concn, MMD, std Part. Part. Date I* dev I 1 I* I 2 P 57 1.44 7.00 43 4-26-71 104.2 55 1.64 5.79 39 4-27-71 119.2 61 6.38 46 107.9 1.21 4-28-71 49 2.09 5.24 33 4-29-71 104.8 59 1.33 6.32 44 68.4 4-30-71 53 1 82 5.14 36 90.8 5-1-71 51 1.99 5.21 34 121.3 5-2-71 54 4.19 35 132.8 1.79 5-3-71 48 2.19 4.61 31 163.0 5-4-71 50 2.03 4.25 32 5-5-71 146.5 53 Composite 115.9 1.79 5.20 37
Literature Cited Hatch, T. F., Gross, P., “Pulmonary Deposition and Retention of Inhaled Aerosols,” p 67, Academic Press, New York, N.Y., 1964. Lee, R. E., Caldwell, J. S., Morgan, G. B., “The Evaluation of Methods for Measuring Suspended Particulates in Air,” presented at 162nd meeting, American Chemical Society, Washington. . D.C.. SeDtember 12-17.1971 : A m o s . Enciron.. in press, 1972. Lee, R. E., Flesch, J. P., “A Gravimetric Method for Determining the Size Distribution of Particulates Sumended in Air,” presented at annual meeting, Air Pollution Control Association, New York, N.Y., June 22-26, 1969. Lee, R. E., Goranson, S., “The NASN Cascade Impactor Network: First Year Operation,” presented at the National Meeting of the American Chemical Society, Washington, D.C., September 12-17, 1971. TBTAK,unpublished report, Engineering Investigation Group (MAG),TBTAK,a research institute in Ankara, Turkey, 1970. Receiced for reciew February 18, 1972. AcceptedJune 14,1972.
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Acknowledgment The authors thank Marilyn Hawkins for performing the gravimetric analysis and Stephen Goranson for the computer services.
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Determination of Bis-Chloromethyl Ether at the Ppb Level in Air Samples by High-Resolution Mass Spectroscopy Ledelle Collier Rohm and Haas Co., 5000 Richmond St., Philadelphia, Pa. 19137
Bis-chloromethyl ether vapor has recently been shown t o be extremely toxic. A high-resolution mass spectral procedure with the capability of measuring bis-chloromethyl ether at the 0.1-ppb level in air containing other organic compounds has been developed. This procedure utilizes a n enriching adsorber of Porapak Q, a high-surface-area aromatic copolymer in bead form, to adsorb the organic compounds from a volume of air. The adsorbed communds are then therrnallv eluted into the reservoir of the mass spectrometer. The intensity of the ions at m,/e 78.9950 (C[CH2-o-cH2+-) is measured with a resolution of 1/3500. 930 Environmental Science & Technology
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hloromethyl ether (CME,CH3-O-CH2CI) is a commercial chloromethylating reagent widely used in the production of anion exchange resins, membranes, and other aromatic products. Typically CME contains several percent of bis-chloromethyl ether (BCME,CH2CI-O-CH2C1) as an impurity. Laskin et al. (1971) have shown that vapor samples of BCME are extremely toxic. Recent results (Collier, 1971) in our laboratory have shown that BCME is stable at 10 and 100 ppm in 70% r.h. air for at least 18 hr. CME hydrolyzes rapidly under similar conditions. An extremely selective method for the determination of BCME at the ppb level in air samples utilizing high-resolution mass spectroscopy will be reported.
The mass spectrum consists chiefly of ions produced by two distinct bond cleavages. These cleavages are ClCH2&OCHpCl and C1CH~-O-CH2+Cl. The diagnostic ions are observed at m,'e's 49 and 51, and 79 and 81 (produced in pairs because of the Wl and 37Clisotope ratio), respectively. The mje 79 is the most abundant ion in the spectrum, thus making it the most sensitive choice for detecting BCME at very low levels. The mass spectrometer is not sufficiently sensitive to detect BCME at the levels desired via direct introduction of an air sample. We therefore sought a means of concentrating the BCME by a factor of about 15,000. Porapak Q (Waters Associates, Inc., Framingham, Mass.) proved an ideal adsorber because water is not collected, BCME is efficiently adsorbed, and BCME is readily recovered from the column by thermal elution. Other advantages of porous polymer adsorbents have been cited (Williams and Umstead, 1968; Dravnieks et al., 1971). Porapak Q has a high affinity for many organic compounds in air. Some of these compounds may produce ions at m,'e 79 and/or ni!e 81. The additional ions at ml'e 79 and 81 consequently prevent the use of these peaks for measuring the quantities of BCME collected. High-resolution mass spectroscopy of the mje 79 and m!e 81 peaks separates the diagnostic ions from the other ions, thus making it possible to make an accurate measurement for BCME. Experimental Enriching Columns. The enriching columns are 7-cm lengths of 5 mm 0.d. glass tubing filled with 170 mg of Porapak Q SOjlOO mesh resin. The ends of the glass tubes are partially constricted and packed with approximately 0.5-cm plugs of Pyrex wool to retain the beads. Before the beads are placed into the glass columns, they are cleaned by extracting with ethylene dichloride (EDC)in a Soxhlet extractor for a period of at least 6 hr at a rate of 6 cycles 'hr. After the extraction is complete, the excess EDC is removed from the surface of the beads by placing them in a large beaker and flowing a gentle nitrogen stream over them with periodic stirring. After the glass columns are packed with the partially dried beads, they are heated at 200°C in a glass-lined vacuum oven for 2 hr under a pressure of
