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(3) J. W. Farrington, J. M. Teal, G. C. Medeiros, K. A. Burns, E. A. Robinson, J. G. Quinn, and T. L. Wade, Anal. Chem., 48, 1711 (1976). (4) T. L. Wade and J. G. Quinn, submitted for publication in Environ. Pollut. (5) L. R. Hilpert, W. E. May, S. A. Wise, S. N. Chesier, and H. S. Hertz, Anal. Chem., 50, 458 (1978). (6) R. C. Clark, Jr. and D. W. Brown, in "Effects of Petroleum on Arctic and Subarctic Marine Environments and Organisms", D. C. Malins, Ed., Academic Press, New York, N.Y., 1977, pp 1-90, (7) L. R . Snyder, Anal. Chem., 33, 1527 (1961). (8) P. Gearing, J. N. Gearing, T. F. L e , and J. S.Lytle, Geochim. Cosmochim. Acta, 40, 1005 (1976). (9) R. S.Clark and J. S. Finley, "Proceedings of the 1973 Joint Conference on Prevention and Control of Oil Spills", American Petroleum Institute, Washington, D.C., 1973, p 161. (10) L. Hunter, Environ. Sci. Techno/., 9, 241 (1975). (1 1) J. G. Quinn and T. L. Wade, Marine Memorandum Series No. 33, University of Rhode Island, Kingston, R.I., 1974, 8 pp. (12) P. D. Boehm and J. G. Quinn, Estuarine Coastalnlbr. Sci., 6, 471 (1978).
(13) J. W. Farrington, N. M. Frew, P. M.Gschwend, and 6. W. Tripp, Esfuarine Coastal Mar. Sci., in press. (14) P. D. Keizer, J. Dale, and D. C. Gordon. Jr., Geochim. Cosmochim. Acta, 42, 165 (1978). (15) J. W. Farrington and P. A. Meyers, in "Environmental Chemistry", Vol. 1, G. Eglinton, Ed., The Chemical Society, Burlington House, London, 1975. (16) J. W. Farrington and J. G. Quinn, Estuarine Coastalnlbr. Sci., 1, 71 (1973). (17) T. L. Wade, University of Rhode Island, Kingston, R I . , personal communication, 1978. (18) J. W. Farrington and B. W. Tripp, Geochim. Cosmocbim. Acta, 41, 1627 (1977).
RECEIVED for review June 23,1978. Accepted August 14,1978. Work supported by Grant R803902020 of the Environmental Protection Agency.
Determination of Volatile Halogenated Hydrocarbons in Water with XAD-4 Resin Lars Renberg Special Analytical Laboratory. National Swedish Environment Protection Board, Wallenberg Laboratory, University of Stockholm, S- 106 9 1 Stockholm
The determination of trihalomethanes, chloroethenes, and dichloroethane in water was carried out by adsorption on an XAD-4 polystyrene resin, followed by elution with ethanol. The method results in an extract concentrated enough for both chemical determination and small scale biological tests. By using two series-connected columns, the degree of adsorption was studied and the chloroethenes were found lo be more strongly adsorbed than the haloalkanes. The recovery was found to be 60-95% of the substances studied.
the determination of total organic halogen content in water has been described (15). The advantages of using the XAD-4 technique are several. T h e method is simple and allows sampling in situ, thus avoiding changes of water sample composition between time of sampling and time of analysis. T h e procedure involves a concentration step which makes it possible to reach desired detection limits, as these limits may vary with applications. I t also allows the collection of samples large enough for both chemical determination and small scale biological tests such as the Ames' bacterial system for mutagenicity determination (16).
T h e presence of volatile halogenated hydrocarbons such as trihalomethanes and chloroethenes in water has been established in water samples from several sources. T h e trihalomethanes have been shown to be formed during the chlorination process, used in water treatment plants, and the average levels of chloroform, bromodichloromethane, and chlorodibromomethane in drinking water samples from 80 cities in the U.S.A. were found to be 21, 6, and 1.2 Fg/L, respectively (I). Also the incoming water to a water treatment plant has been shown to contain several halogenated compounds such as the commonly used solvents 1,2-dichloroethane, trichloroethene, and tetrachloroethene (2). The main interest in these types of compounds is focused on possible toxic effects, particularly carcinogenicity. Using bacterial systems, bromodichloromethane, chlorodibromomethane, trichloroethene, and 1,2-dichloroethane have been shown to possess mutagenic properties (3, 4 ) . T h e need for determination of volatile hydrocarbons in water samples has resulted in several methods such as solvent extraction ( 5 ,6), gas stripping ( 7 ) ,head space (8),and direct injection techniques (9). I n this paper, a method is described which involves the adsorption of volatile halogenated hydrocarbons on an Amberlite XAD-4 resin followed by elution with ethanol. The use of XAD-2 or XAD-4 resins for the determination of less volatile substances has been described earlier (10-1.2), and adsorption of haloforms on acetylated XAD-2, followed by elution with pyridine ( I 3 ) ,and on non-acetylated XAD-'2 (14) has also been reported. Recently, the use of XAD-resins for 0003-2700/78/0350-1836$01.OO/O
EXPERIMENTAL Materials. Amberlite XAD-4 (Rohm and Haas Company), acetone (pesticide grade), methanol and ethanol (spectroscopic grade) were used. The purity of the methanol and ethanol was checked by the gas chromatographic system described below. Polymeric Resin Cleanup. Amberlite XAD-4 was placed in a column with a glass filter. Five bed volumes of acetone were passed through the column with a flow rate about 0.1 bed volume/min. Then water was passed upflow through the column at a rate sufficient to expand the bed by about 50% to remove the smallest particles. The resin was then extracted by means of a Soxhlet apparatus with methanol for at least 6 h, then replaced into the column and eluted with 20 bed volumes of purified water and finally stored under purified water. The purity of the resin was checked in a blank procedure. Purified Water. Deionized water was distilled through an all glass apparatus. The first 1070 of the distillate was discarded and the 1G-5070portion was passed through a column containing 10 mL XAD-4 at a flow rate of about 30 mL/min. If the resin was taken directly from the Soxhlet extraction and thus containing methanol, the first 200 mL of the eluate was discarded. Adsorption and Desorption Steps. Two glass columns, 15 X 1.1(id.) cm, with Teflon stopcocks, were each filled with 5 mL of XAD-4. Purified water was added to the top of the columns and the beds were stirred t o release air bubbles. The columns were connected in a series and the water sample was allowed to pass through the columns at a flow rate of 30 mL/min. The columns were allowed to run dry and disconnected. To each column, ethanol (3 mL) was added, the beds were stirred, and the resins were allowed to swell for at least 20 min. The beds were stirred once more t o release air bubbles and the columns C 1978 American Chemical Society
ANALYTICAL CHEMISTRY, VOL. 50, NO. 13, NOVEMBER 1978
Table I . Results of Recovery Experiments from Five Spiked Samples re coveri esa amount of mean spiked value (%) substance, i re1 std ratio a , / a , b substance ~ g / 2 5 0 u L dev i std dev chloroform 2.9 8 5 i 4.1 0.27 i 0.03 86 i 9.6 0.22 * 0.08 bromodichloro0.63 methane 0.12 i 0.03 1.3 91 i 6.7 chlorodi bromomethane 95 i 9.0 0.44 i 0.09 1,2-dichloroethane 120 trichloroethene 2.5 74 i 3.6 0.07 + 0.03 60 i 4.5 0.06 i 0.02 tetrachloroethene 1.4 Sum of the amounts found in the two series-connected columns ( a , + a 2 ) . Ratio of the amounts found in the second and the first column, respectively. were eluted separately with ethanol (flow rate 1 mL/min) until 20 mL of eluate were collected. The eluates were then analyzed by gas chromatography. Recovery Experiments. Purified water (250 mL) was transferred to a 250-mL separatory funnel and 250 WLof an ethanol solution containing chloroform, bromodichloromethane, chlorodibromomethane, 1,2-dichloroethane,and tri- and tetrachloroethene was added. The funnel was shaken and the spiked water allowed to pass the columns. The flow was stopped when the level just reached the top of the upper bed. In order to rinse the glass walls from substances adsorbed, additional water (3 X 250 mL) was passed through the funnel columns and the columns were eluted as described. The separatory funnel was shaken with ethanol (25 mL) for the determination of substances adsorbed on the glass walls. Five spiked and two blank samples were analyzed. Gas Chromatographic System. A Varian 3700 gas chromatograph equipped with an electron capture detector was used. Injector and detector temperatures were 250 "C. The ethanol extracts were injected into a 170 X 0.18 (id.) cm glass column, packed with Chromosorb 101 80/100mesh which was kept at 145 "C. Alternatively, ethanol extract (1 mL) was shaken with purified water ( 5 mL) and hexane or pentane (1 mL). The organic phase was, after centrifugation, injected into a 50-m OV-17 capillary column at a split ratio of 1 : l O . After injection, the column was held 5 min at 80 "C, then programmed at a rate of 2 "C/min until 120 "C was reached.
RESULTS AND DISCUSSIONS Among several possible adsorbents, XAD-4 was judged to be the most suitable. Pilot experiments showed that the substances tested were less strongly adsorbed on the polyacrylic ester resin XAD-7. As the average pore diameters for XAD-4 and XAD-2 (50 and 90 A) were both sufficiently large for the substances tested, the X.4D-4 resin was also preferred when compared to the chemically similar XAD-2, because of a larger surface area (750 and 330 m2/g, respectively). T h e results of recovery experiments for different volatile organohalogens are summarized in Table I. Recovery experiments have also been made with spiked drinking water with similar results. It should be pointed out that the flow rates used here for both the adsorption and the desorption step (360 bed vol/h and 12 bed vol/h, respectively) are much higher than those recommended by the manufacturer (4-16 bed vol/h and 1-4 bed vol/h, respectively) (17). Such high flow rates speed up the time of analyses while still maintaining high recoveries. T h e method described, however, is intended to be used not only for the volatile organohalogens tested in this paper, but also for other unpolar substances, which can be found in different types of waters (including wastewater). T h e main reason for choosing an enrichment method, instead of the above referred techniques (5-9), is the fact that the present
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Figure 1. Elution curves of some volatile halogenated hydrocarbons (5 mL XAD-4 column). (1) Chloroform, (2) 1,2-dichloroethane, (3) tetrachloroethene, (4) bromodichloromethane, (5) chbrodibrommethane, (6) trichloroethene
method results in an extract, sufficiently concentrated to be used both for chemical determination, e.g., gas chromatography/mass spectrometry, and also in biological tests. Consequently, the solvent used for the elution of the adsorbent should, besides a good eluting ability, also possess a low toxicity, which restricts the choice of solvent to, for instance, acetone or ethanol. T h e latter solvent was chosen because of the difficulties in obtaining sufficiently pure acetone compared to ethanol. If desired, the unpolar components in the ethanol extract can be transferred into a hexane solution, by adding water to the ethanol extract, followed by extraction with hexane. Activated carbon was excluded as a possible adsorbent, because of the high toxicity of eluting solvents, commonly used for activated carbon, e.g., benzene, toluene, or carbon disulfide. T o study the adsorption character of substances described here, as well as other compounds, two columns were connected in a series and after the passage of the water sample the columns were eluted separately. The recovery of the substances of the second column, compared to those of the first one, will indicate the leakage of substances which is dependent on, e.g., water flow rate and polarity of the substances. T h e ratio (az/a,) of the amounts found in the second ( a z ) and the first columns (al), respectively, will predict the degree of adsorption, which can be regarded as a measurement of the lipophilicity of the substances studied. The values of the ratios found in the recovery experiments, shown in Table I, indicate
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character of the chloroethenes, but may also depend on interference of the n-electrons with the polystqTene matrix. The recoveries of the chloroethenes are increased if either a larger elution volume or shorter columns are used. However, the technique described is a compromise between relatively small elution volumes and satisfactory recoveries for compounds with quite different water solubilities. The method has been applied to incoming and outgoing water from a water treatment plant (see Figure 2) and on wastewater from a poly(viny1 chloride) plant for the determination of trihalomethanes and 1,2-dichloroethane. Furthermore, the ethanol extract of wastewater from poly(viny1 chloride) production was found to possess mutagenic properties, using the Ames' bacterial system (M. Moller and L. Renberg, unpublished work).
ACKNOWLEDGMENT ii
The author is indepted to Karin Sund-Nygird for skillful technical assistance and to the staff of the laboratory for valuable discussions.
LITERATURE CITED Figure 2. G a s chromatogram of water extracts from a water treatment plant (OV-17 capillary column). (A) Incoming water, (B) outgoing water. (1) Chloroform, 5.0 kg/L; ( 2 ) bromodichloromethane, 2.5 kg/L; (3) chlorodibromomethane, 0.54 kg/L
tetrachloroethene and 1,2-dichloroethaneas the most and the least lipophilic of the substances tested. As long as the desorption step is carried out quantitatively, an approximation of the original concentration can be calculated, using the values from the two individual columns as the first two terms in an infinite geometrical series, giving a finite sum (s) as long as u 2 / a 1
