equivocal identification of vinyl chloride. Samples containing vinyl chloride can be stored a t least four days in completely filled, glass-stoppered bottles without significant losses. Losses between 10 and 20%/h can be expected from unconfined samples or samples containing a sealed headspace.
Literature Cited (1) “Recommended Occupational Health Standard for the Manu-
facture of Synthetic Polymer from .Vinyl Chloride”, USHEW, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, Cincinnati, Ohio, March 11, 1974. (2) Sugar, J. S., Conway, R. A,, J. WaterPollut.Control Fed., 40,1622 (1968). (3) ASTM D-2908-74, “Standard Recommended Practice for Measuring Volatile Organic Matter in Water by Aqueous Injection Gas Chromatography,” Annual Book of Standards, Part 31, Water, 1974.
(4) Harris, L. E., Budde, W. L., Eichelberger, J. W., Anal. Chem., 46, 1912 (1974). ( 5 ) “Method for Organochlorine Solvents in Industrial Effluents”, Methods Development and Quality Assurance Research Laboratory, National Environmental Research Center, EPA, Cincinnati, Ohio, 1973. (6) “Determination of Vinyl Chloride Monomer in Aquatic Effluents”, Analytical Chemistry Branch, Southeast Environmental Research Laboratory, EPA, Athens, Ga., 1974. (7) Bellar, T. A., Lichtenberg, J. J.,J . Am. Water Works Assoc., 66, 739 (1974). (8) Bellar, T. A., Lichtenberg, J. J., Kroner, R. C., ibid., p 703. (9) Stenhagen, E., Abrahamsson, S., McLafferty, F. W., “Atlas of Mass Spectral Data”, Vol 1,Interscience, New York; N.Y., 1969. (10) McLafferty, F. W., “Mass Spectral Correlations”, Advances in Chemistry Series, No. 40, American Chemical Society, Washington, D.C., 1963. (11) Smith, B., Ohlson, R., Acta Chem. Scand., 16,351 (1962). Receiued for review M a y 23, 1975. Accepted April 6, 1976.
NOTES
Determination of Micro-Quantities of Chrysotile Asbestos by Dye Adsorption M. Clare Markham” and Karen Wosczyna Chemistry Department, St. Joseph College, West Hartford, Conn. 061 17
A method of analysis for airborne asbestos is developed by a differential dye adsorption technique. Estimation of quantities of chrysotile asbestos is possible down to the 1OO-wglevel and requires only a differential-reading spectrophotometer. This method is also applicable to crocidolite. For applications in industrial areas where chrysotile asbestos constitutes over 95% of the asbestos used in this country, the asbestos samples must first be separated from interfering minerals by a density flotation process. The development of a density gradient method for separating asbestos from minerals that interfere with its analysis ( I ) , on the basis of research carried out in our laboratories, opened up new possibilities for quantitative estimation of isolated asbestos. Bagioni ( I ) applied an infrared method which was sensitive to fractions of a milligram and could differentiate chrysotile (carcinogenic) from amphibole types of asbestos. The present research describes a method based on adsorption of the ammonium salt of aurin tricarboxylic acid which facilitates estimation of chrysotile asbestos with sensitivity down to the 1OO-wg range and requires only a good spectrophotometer for application. This method constitutes a significant improvement over expensive and time-consuming analysis by electron microscopy for monitoring dangerous forms of asbestos in ambient air. The density gradient method of separating chrysotile asbestos from interfering minerals can cause difficulties in subsequent infrared analysis in that residues of the 1,1,2,2tetrabromoethane used in the gravity flotation process may also absorb around 2.72 y which is the wavelength used for identifying chrysotile asbestos. Therefore, it is imperative that complete removal of the difficultly volatile 1,1,2,2-tetrabromoethane is accomplished for accurate infrared analysis. Our quantitative dye technique is not affected by such residues of solvent nor of serpentine, since a different spectral region is used. The applications of a dye adsorption method of analysis are quite valuable in detecting one of the most common forms of asbestos, chrysotile, above allowable limits for both industry 930
Environmental Science & Technology
and ambient air samples. Present electron microscopy and x-ray methods of analysis are dependent on the structure of the asbestos and employ costly and time-consuming methods that curtail regular monitoring of such areas. Proper control of asbestos as a pollutant is dependent on its detection, and the method outlined below is one that is readily applicable, inexpensive, and easy to use.
Experimental Preliminary search for a dye that would be selective for asbestos and whose decrease in absorbance would be sensitive enough for detection in a spectrophotometer resulted in the selection of Aluminon which dyed several types of asbestos a purple-rose color. Most dyes tested were pH dependent, and a range from 4.5 to 5.0 gave optimum adsorption of Aluminon on asbestos. The buffer solution used was prepared from potassium hydrogen phthalate and sodium hydroxide as directed in the “Handbook of Chemistry and Physics” and did not interfere with the analysis. The concentration of dye that would be sure to saturate 1 mg of asbestos was found by using 1 mg of chrysotile asbestos in varying concentrations of the dye and then measuring differences in absorbancy of the supernatant and the original dye solution. A concentration of 0.1 g dye per 500 ml of buffer solution was used and assured maximum adsorption on amounts of asbestos less than 1mg. Types of asbestos tested, other than chrysotile and amphibole, were supplied by Raybestos Co., Stratford, Conn. The procedure for the routine analysis by this method consists of suspending the asbestos residue in 3.5 ml of the prepared dye solution and heating in a beaker of water a t 50-60 “C for 1 h until the asbestos fibers swell and are dyed a purple-rose color. It is then centrifuged, and the supernatant is pipetted off. Necessary water is added to the supernatant to replace that which has evaporated. The supernatant is then read at 525 nm on the DK-2 spectrophotometer vs. a reference of the original dye solution. A scale of 0-200% transmittance was used. With amounts of asbestos less than 1 mg, more sensitive scale expansions can be used on the spectrophotometer allowing detection to 100 fi or less. If a spectrophotometer is not available with such sensitive scale expansions, a cell with a smaller path length would suffice and give equal
detection limits. The resulting readings can be plotted vs. the amount of asbestos used to construct a calibration curve to be used for unknown amounts of chrysotile asbestos samples. This graph relates decreases in adsorption to micrograms of asbestos (Figure 1).
Results and Discussion Heating is important to the dye adsorption to obtain reproducible results and tends to physically alter the asbestos fibers so as to increase the adsorption rate. The graph in Figure 1relates the amount of asbestos to the percent decrease in transmittance of dye and can easily be used as a calibration curve for further quantitative estimations. Different types of asbestos were used as samples for this dye adsorption method, and both chrysotile and crocidolite forms gave good adsorption data. Amphibole and amosite asbestos did not adsorb the dye to any significant amount, and antrophyllite asbestos had minimal dye adsorption levels. Since chrysotile asbestos is the principal variety of asbestos used in industry, larger than 95%,this method would be valuable due to chrysotile’s consistent and high adsorption data (2).The surface area of the asbestos fiber would also be related to its adsorption of dye and possibly to the carcinogenicity of the inhaled fibers. Independent surface area measurements were not taken, but such an investigation might yield interesting data. The dye adsorption method presented here would lend itself readily to monitoring air on the premises of manufacturing processes using asbestos, where asbestos emission to ambient air may not exceed 25 pg/m3. To meet general ambient air quality standards of 30 ng/m3, it would be helpful to have a method with still greater sensitivity ( 3 ) . The dye adsorption method should be readily adaptable to adsorption of a fluorescent substance which might offer this possibility. However, several dichlorofluorescein dyes have been tried, and a reproducible method has not yet been perfected.
241
$: 4 rei
0 1
c’
7
80
0126
d.6 miiligrama
d.76
1.0
’
aibeat08
Figure 1. Relationship between amounts of chrysotile asbestos and percent decrease in transmission at 525 nm of Aluminon dye (0.1 g/500 ml) due to adsorption on surface of asbestos fibers
Literature Cited (1) Bagioni, R., Enuiron. Sci. Technol., 9 (31, 262-3 (March 1975). (2) Bruckman,L., Rubino, A., “Rationale behind a Proposed Asbestos Air Quality Standard”, independent study for Connecticut Dept. of Environmental Protection, Hartford, Conn., 1975. (3) “Air Regulations: Hazardous Material Air Pollutants”, proposed by the State of Connecticut Dept. of Environmental Protection,
1975.
Received for review J u n e 23,1975. Accepted March 25, 1976.
Capture of Hg2+ Ions from Effluent Stream by Cellulose Derivatives Francesco Gasparrini, Gianni Palmieri, and Giovanna Cancelliere Cattedra di Chimica Organica, Facolta di Farmacia, Universita di Roma, Roma, Italy
Mauro Ghedini” and Giuliano Dolcetti Dipartimento di Chimica, Universita della Calabria, 87030 Arcavacata (Cs), Italy
The ability of cellulose derivatives with 10-undecylenic acid supported on celyte and with o-aminothiophenol to capture Hg2+ions from aqueous solutions is tested. These systems are useful tools for removal of Hg2+ ions from low concentration (0.5 mg Hg/ml aqueous solutions and can lower them A practo a safe concentration of about 0.05 mg Hg/ml tical operational scheme is proposed which involves the sequential elution of a Hg2+-containing solution through a column filled with cellulose 10-undecylenate support followed by elution through a column filled with o-aminothiophenol cellulose derivative. Methyl mercury and homologous short chain compounds exhibit effects in man which differ from those effects produced by other mercury-containing compounds. These phenomena involve the nervous system with loss in limb sensitivity, gait
coordination, sight, and hair (1).Mercury removal from water may be achieved by precipitation with sulfide ( 2 ) ,by use of ion exchange (3-6), by reduction and separation with metallic mercury (7),and by sorption on protein such as wool (8)or on nitrogen-containing chemically modified cellulose (9). The system reported here is based on the use of cellulose derivatives functionalized with alkenes. These substrates were selected because of low reagent price and reaction reversibility which allows mercury recovery and subsequent possible substrate neutralization in the purification cycle. Mercury salts form adducts with alkenes in rather mild conditions according to the following reaction ( 1 0 ) : \C = E
I a2
,
.
=3
a 4
HsX2lOH-
i’ 7’
R2-0-C
H-
- R 4
I
HgX
I
OH
This reaction is reversible, relatively fast, and quantitative Volume 10, Number 9, September 1976
931
