servative in LPE I1 bottles. Such compounds, which are atypical of commonly used protective additives, may have been deliberately or accidentally added to the plastic during some stage of the manufacturing process. Because of its inherently high solubility in water, a polyhydroxy compound could interact readily with the acidic aqueous dichromate solutions. The ability of acidic pichromate to oxidize alcohols is well known (15),and the acidic dichromate preservative is quickly reduced by small quantities of low molecular weight alcohols and polyols. As an example, 0.34 mmol of glycerol completely reduces 50 mL (0.085 mmol) of the dichromate preservative in less than 9 h. The reasons for the relatively poor stability of Hg(I1) in LPE I bottles are not yet known, but factors such as the additives, surface oxidation products, or residual terminal unsaturation of the polyethylene may contribute to the loss of Hg(I1). The LPE I plastic contains significant quantities of an HAP, and Koirtyohann and Khalil(16) have shown that 2,6-di-tert-buty1-4-methylphenol,a representative HAP, rapidly reduces Hg(I1) to the elemental state. Elemental mercury so formed might be removed from solution by diffusion into the plastic. The dialkylthiodipropionate additive, being an alkyl sulfide is expected to bind Hg(I1) strongly (17) and could thereby remove Hg(I1) from solution. Functional groups formed by oxidation of the additives or the polyethylene surface itself might also bind Hg(I1) effectively and remove it from solution. The LPE I plastic exhibits a significant degree of unsaturation, and the well known interaction of Hg(I1) with double bonds to form organomercury adducts (18, 19) could also contribute to the loss of Hg(I1) from solution. We do not know the frequency with which composition differences of the type described or other composition differences occur in commercial linear polyethylene bottles. Those who use such bottles to store samples for trace analysis should periodically verify the suitability of the bottles for storage of their samples.
LITERATURE CITED (1) C. Feldman, Anal. Chem., 46, 99 (1974). (2)J. F. Kopp, M. C. Longbottom, and L. B. Lobring, J. Am. Water Works Assoc., 64, 20 (1973). (3)D. 0.Hummel and F. K. Scholl, "Infrared Analysis of Polymers, Resins and Additives", Vol. I, Part 2,Wiley-lnterscience, New York, N.Y., 1971. (4)J. P. Luongo, J. Appl. folym. Sci., 3, 302 (1960). (5) D. 0.Hummel and F. K. Scholl, "Infrared Analysis of Polymers, Resins and Additives", Vol. I, Part 1, Wiley-lnterscience, New York, N.Y., 1971,p 13A
R. M. Bly, P. E. Kiener, and B. A. Fries, Anal. Chem., 38, 217 (1966). T. Gossl, Makromol. Chem., 42, l(1960). C. E. Day and J. Mitchell, Jr., personal communication, ExperlmentalStation, E.I. du Pont de Nemours and Co., Wilmington, Del., August 4, 1976. "1975 Annual Book of ASTM Standards", Standard D 1248-74,Vol. 34, American Society for Testing and Materials, Philadelphia, Pa., 1975, p
20. (10)B. Ke, J. folym. Sci., 42, 15 (1960). (11) D. 0.Hummel and F. K. Scholl, "Infrared Analysis of Polymers, Resins and Additives", Vol. II, Carl Hanser, Munich, 1973,663 pp. (12)G.Scott, "Atmospheric Oxidation and Antioxidants", Elsevier. New York. N.Y., 1965,p 299. (13) "The Sadtler Standard Spectra", Sadtler Research Laboratories, Philadelphia, Pa., Ultraviolet Spectra 10, 7923, 7924, 7925, 7926, 2927, 18543. (14) P. A,de Paolo and H. P. Smith, "New Phenolic Phosphite Stabilizers for Polypropylene", Adv. Chem. Ser., 85, 203 (1968). (15) R. T. Morrison and R. N. Boyd, "Organic Chemistry", 3rd ed., Allyn and Bacon, Boston, Mass., 1973,Chap. 16,pp 518-540. (16)S. R. Koirtyohann and M. Khalil, Anal. Chem., 48, 217 (1976). (17) E. E. Reid, "Organic Chemistry of Bivalent Sulfur", Vol. 11, Chemical Publishing Co., New York, N.Y., 1960,pp 52-54 (18)K. Hoffman and J. Sand, Chem. Ber., 33, 1340,2692 (1900). (19)J. Chatt, Chem. Rev., 48, 7 (1951).
R. W. Heiden D. A. Aikens* Department of Chemistry Rensselaer Polytechnic Institute Troy, N.Y. 12181
RECEIVEDfor review September 29,1976.Accepted January 10,1977. Supported in part by a Grant-in-Aid from Allied Chemical Corporation. Presented a t 7th Northeast Regional Meeting, American Chemical Society, Albany, N.Y., August 8-11,1976.
AIDS FOR ANALYTICAL CHEMISTS Potential Hazard Associated with Removal of Needles from Septa in Injection Ports of a Gas Chromatograph Eric B. Sansone" NCI Frederick Cancer Research Center, Frederick, Md. 2 170 1
Hiram Wolochow and Mark A. Chatigny Naval Bioscience Laboratories, University of California, Naval Supply Center, Oakland, Calif. 94625
The use of various chromatographic techniques to effect a separation among several components of a mixture has become quite common. It is obvious that when working with hazardous materials, regardless of the degree of separation realized, these materials will be introduced into the laboratory environment if they are not destroyed by the detector. (In fact, there is a possibility that hazardous materials may be produced by pyrolysis in a flame ionization detector.) The remedy is to provide an air exhaust in the immediate vicinity of the detector, so the hazardous materials can be carried away by 670
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the flow of air and captured by suitable means. In addition to this source of contamination, observations reported in connection with the use of syringes (1-5) suggest that withdrawal of a needle from a septum could produce an aerosol. The experimental work described below was undertaken to test this hypothesis.
EXPERIMENTAL An o n - c o l u m n i n l e t ( H a m i l t o n Co., Reno, Nev.) was connected to a cylinder of compressed nitrogen. T h e nitrogen pressure was reduced
to 40 psig; the flow rate was measured with a calibrated flowmeter and was maintained at about 40 cm3/min by a metering valve connected to a length of stainless steel tubing (%-in.o.d., %-inchid.) which served as a column. A 100-W heater connected to a variable transformer was used to establish inlet temperatures of 150 and 250 "C. Temperatures were measured with an iron-constantan thermocouple and a calibrated, compensated pyrometer. Two types of septa were used: Microsep F-138 and Hamilton 760. Two-inch, 26s gauge, stainless steel Luer needles with 90" and 22" points were used with syringes to deliver up to 200 gl of material. The materiai injected was either an aqueous suspension (0.3% solids) or the chloroform soluble fraction (about 5 mg/ml) of Calcofluor white BGT (American Cyanamid Co., Bound Brook, N.J.). Calcofluor white BGT contains a nonvolatile fluorescent material with excitation wavelength = 365 nm and emission wavelength = 440-445 nm. To detect any particles released by the operation simulated, a microaerofluorometer was used. This is an electrooptical device which senses fluorescent particles (6). A 1-cm diameter exhaust opening, which was connected to the microaerofluorometer,was located within 1 cm of the center of the septum. At a sampling rate of 12 l/min, the air velocity at the exhaust opening was about 2.5 m/s. Pulse height discriminators were adjusted so that the number of particles between approximately 1-and 10-gm diameter was printed out every 5 s (after each liter of air sampled). Particles in this size range are generally considered to be of respirable size (7);Le., able to be deposited in the gas exchange space of the lungs. To determine whether volatile materials would be released into the laboratory environment under similar circumstances, another experiment was performed. With an injection port temperature of 250 "C and carrier gas flow rate of 20 cm3/min, 1- to 2-111 portions of chloroform were injected through a Supelco Teflon coated septum using a Hamilton 701 syringe. To detect any escaping materials, a halogen leak detector (General Electric Co., West Lynn, Mass.) was used. This device measures the markedly increased emission of positive ions from a heated platinum filament caused by the presence of halogens. Leakage rates (of pure halogen-containing material) as small as 2 X cm3/s can be detected. In use, the tip of the leak detector was located within l cm of the center of the septum.
RESULTS AND DISCUSSION The results obtained with the microaerofluorometer showed that thousands of particles were usually released when the needle was removed from the septum after injection, even after leaving the needle in the septum for as much as 30 s. Particle production was highly variable; of more than 150 injections, 10% yielded fewer than 100 particles, 22% yielded 100-1000, 52% yielded 1000-10 000, and 16% yielded more than 10 000 particles. Variations in injection port temperature, needle type, volume injected, or injection technique demonstrated no reproducible effect on particle production. Particles may be produced by evaporation of liquid or condensation of vapor of the material injected through the septum.
The results obtained using the halogen leak detector showed that materials containing chlorine were released when the needle was removed from the septum after injection. This was observed even after leaving the needle in the septum for as much as 30 s after injection. The principle of operation of the halogen leak detector does not allow one to distinguish between halogen-containing vapors or particles, but it is clear that volatile materials can be released into the laboratory environment on removal of a needle from a septum. On one occasion, after about 20 injections, the septum was so damaged that fluorescent particles were emitted continuously for a period of minutes. It was also observed that following injection of test material, injection of a nonfluorescent material with a fresh syringe and needle produced particles of fluorescent material. (A similar observation was made when a fresh syringe and needle were used following injection of chloroform.) This suggests that injection of potentially hazardous materials may establish a reservoir of such material within the injection port, portions of which may, for undetermined periods of time, be released into the laboratory environment after subsequent injections. It is recommended that injection ports, through which potentially hazardous materials are injected, be equipped with a suction opening sufficiently near the source of contamination and with air-moving capability sufficient to carry materials generated in the fashion described to a suitable collection device. For injection ports on vertical surfaces of equipment, the suction opening should be directly above the port.
LITERATURE CITED (1) R. E. Anderson, L. Stein, M. L. Moss, and N. H. Gross, J. Bacteriol., 64, 473-481 (1952). (2) A. G. Wedum, Am. J. Public Health, 43, 1428-1437 (1953). (3) M. Reitman, M. L. Moss, J. B. Harstad, R. L. Alg, and N. H. Gross, J. Bacferiol., 68, 545-548 (1954). (4) M. Reitman, R. L. Alg, W. S. Miller, and N. H. Gross, J. Bacteriob, 68,549-554 (1954). (5) E. Hanel, Jr., and R. L. Alg, Am. J. Med. Techno/, 21, 343-346 (1955). (6) L. J. Goldberg, J. Appl. Mefeorol., 7, 68-72 (1968). (7) T. F. Hatch and P. Gross, "Pulmonary Deposltion and Retentlon of Inhaled Aerosols", Academic Press, New York, 1964.
RECEIVEDfor review August 31, 1976. Accepted December 7,1976. Research sponsored by the National Cancer Institute under contract No. N01-CO-25423, with Litton Bionetics, Inc., and by the Office of Naval Research through NCI-SVCP Biohazards Contract No. YO1 CP 40200 with the University of California.
Direct Transfer of Thin-Layer Chromatographic Fractions into Vials Benjamin Preiss Department of Biochemistry, University of Sherbrooke, Sherbrooke, Que., Canada J 1H 5N4
The purpose of a chromatographic separation may be preparative or analytical. In the special case of an analytical procedure involving the separation of radioactive compounds by thin-layer chromatography (TLC), an efficient procedure for counting the separated material is desirable. A number of devices have been described for the collection of zones or spots from TLC plates. In the design of Goldrick and Hirsch ( I ) ,the powder scraped from the plate is collected by suction on the surface of a sintered glass filter inside a glass container (aspirator) from which the separated material can be eluted. A separate glass aspirator is needed for the collection of each sample. The design of Ritter and Meyer (2) and
a commercially available model (Desaga, Heidelberg, Germany) permit the collection of samples by suction into an interchangeable soxhlet thimble attached to a single collection device. A more complicated design, using interchangeable receptacles and a scraping device, was described by Sudilovsky and Hinderaker ( 3 ) .The use of these devices is limited to compounds which are easily eluted from the solid support. The device described here is incorporated into a screw cap for standard size scintillation counting vials. A sintered glass filter is used to exclude the collected powder from the vacuum line, keeping it inside the vials. The present design permits collection and direct counting ANALYTICAL CHEMISTRY, VOL. 49, NO. 4, APRIL 1977
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