Environ. Sci. Technol. 1985, 19, 1232-1236
samplers, to Bob Goodrich and Ed Cote for the analytical determination, and to Ted D’Ottavio for suggestions with the modeling. Hunt, C. M. In “BuildingAir Change Rate and Infiltration Measurements”;Hunt, C. M.; King, J. C.; Treschel, H. R., Eds.; American Society for Testing and Materials: Philadelphia, PA, 1980; ASTM STP 719, pp 3-23. “ASTM Standard E 741-80”;ASTM: Philadelphia, 1980. Totzke, D.; Quackenboss, J.; Kaarakka, P.; Flukenger,J. In “Indoor Air: Buildings, Ventilation and Thermal Climate”; Berglund, B.; Lindvall, T.; Sandell, J., Eds.; Swedish Council for Building Research: Stockholm,1984; Vol. 5, pp 459-464. Dietz, R. N.; Cote, E. A. Environ. Int. 1982, 8 , 419-433. Condon,P. E.; Grimsrud, D. T.; Sherman,M. H.; Kameruo, R. C. In “Building Air Change Rate and Infiltration Measurements”;Hunt, C. M.; King, J. C.; Treschel, H. R., Eds.; American Society for Testing and Materials: Philadelphia, PA, 1980; ASTM STP 719, pp 60-72. Grimsrud, D. T.; Sherman, M. H.; Janssen, J. E., Jr.; Pearman, A. N.; Harrje, D. T., ASHRAE Trans. 1980,86, 258-267. Shaw, C. Y. ASHRAE Trans. 1984,2816,212-225. Bassett, M. R.; Shaw, C. Y.; Evans, R. G. ASHRAE Trans. 1981,87, 361-371.
(9) Harrje, D. T.; Hunt, C. M.; Treado, S. J.; Malik, N. J. Center for EnvironmentalStudies,Princeton University,Princeton NJ, Report 13. (10) Dietz, R. N.; Goodrich, R. W.; Cote, E. A.; Wieser, R. F. Brookhaven National Laboratory, 1983,Report BNL 33846. (11) Leaderer,B. P.; Zagraniski, R.-T.;Berwick, M.; Stolwijk, J. A. J., Am. J. Epidemiol. in press. (12) Spengler, J., Harvard School of Public Health, personal communication, 1985. (13) Janssen, J., Honeywell Control Systems, personal communication, 1985. (14) Grimsrud, D., Lawrence Berkeley Laboratory, personal communication, 1985. (15) Dietz, R. N.; Goodrich, R. W.; Cote, E. A.; Wieser, R. F. Brookhaven National Laboratory, 1985, Report BNL 36327. (16) Dietz, R. N.; Goodrich, R. W.; Cote, E. A,; Wieser, R. F. Brookhaven National Laboratory, 1984,Report BNL 35249. (17) Harlos, D., Harvard School of Public Health, personal communication, 1984. (18) Palmes, E. D.; Gunnison, A. F.; DiMattio, J.; Tomczyk, C. Am. Ind. Hyg. Assoc. J. 1976, 37, 570-577. Received f o r review March 25, 1985. Accepted June 27, 1985. This research was supported in part with funds from Grant ES-00354 from the National Institute of Environmental Health Sciences and the Officeo f Buildings and Community Systems of the U S . Department of Energy.
Determination of Alkylethoxylated Sulfates in Wastewaters and Surface Waters Thomas A. Neubecker* Environmental Safety Department, The Procter & Gamble Company, Cincinnati, Ohio 452 17
A novel method was develoved for the determination of parts per billion levels of alkyiethoxylated sulfates (AES) in wastewaters and surface waters. The analysis scheme involves concentration of the AES on an anion-exchange resin, elution off the resin with methanolic HCl, hydrolysis of the AES to alkylethoxylate (AE), extraction of the AE from the remaining ionic species, derivatization to the corresponding alkyl bromides, and analysis of the alkyl bromides by gas chromatography. Recovery of several AES homologues through this scheme ranged from 68 to 78% with an estimated sensitivity of -1 ppb for each alkyl-chain homologue of AES. AES levels were measured in several wastewater and surface water samples by using this method and the nonspecific methylene blue active substance (MBAS) method. Results indicate that only about 10% of the total MBAS response arises from AES. Introduction Alkylethoxylated sulfates (AES) are a major class of anionic surfactants used in consumer cleaning products. They are components of light-duty dishwashing liquids, shampoos, and other household specialty products. In the United States, production of AES exceeds 128 million pounds/year (1). The structure of AES consists of a long-chain alkyl group (normally C12-C18) bound to a variable length ethoxylate chain (normally E1-E12)and terminated by a sulfate group. Its general formula is represented by *Address correspondence to this author at the Miami Valley Laboratories, Human Safety Department, The Procter & Gamble Co., Cincinnati, OH 45247. 1232
Environ. Sci. Technol., Vol. 19,No. 12, 1985
CH3(CH2)x(OCH2CH2)yOS03Commercial materials are often supplied as either the NH4+or Na+ salts and are sold under trade names such as Alfonic (Conoco), Neodol (Shell), and Polystep (Stephan) . AES occurs in domestic wastewater and is extensively removed from sewage by wastewater treatment (85-100% removal; see ref 2). Thus, in wastewater effluents or surface waters, only parts per billion (ppb) levels are anticipated. To date, analysis of AES in wastewater or surface waters was conducted by nonspecific anionic surfactant analyses (3, 4), the most common method being the MBAS (methylene blue active substance) procedure (5). The MBAS method measures AES, other anionic surfactants such as LAS (linear alkylbenzenesulfonate) and alkyl sulfates, and some naturally occurring anionic materials. Thus, any value for AES obtained by this nonspecific method is exaggerated. The method presented here offers considerable improvement in terms of selectivity and sensitivity. It takes advantage of the selective cleavage of the sulfate functionality and the conversion of the anionic surfactant into a nonionic material. After this conversion, a specific analysis for the nonionic species is obtained by hydrolysis to an alkyl bromide followed by gas chromatographic measurement.
Experimental Section Materials. The alkylethoxylated sulfate was prepared by Procter & Gamble via sulfonation of the corresponding alkylethoxylates. Shell Neodol 23-12 (a C12-13E12 alkylethoxylate) was the starting material. The C12-13E12S
0013-936X/85/0919-1232$01.50/0
0 1985 American Chemical Society
produced had a 40/60 distribution of C12/C13 alkyl groups with an average ethoxylate length of 12. These distributions were determined by gas chromatography (GC) analysis of the HBr cleavage products (6). Standards of the c12-clS bromides were obtained from the following sources: C12Brand C14Brfrom J. T. Baker (Phillipsburg, NJ), C13Brfrom Aldrich (Milwaukee, WI), CISBr,C16Br,and ClsBr from Eastman Organic Chemicals (Rochester, NY), and C17Brfrom Fluka (Hauppauge, NY). Anion-exchange resin (AG1-X2) was obtained from BioRad (Richmond,CA). For MBAS analysis, methylene blue reagent was obtained from MCB Chemicals (Gibbstown, NJ). All other materials were of reagent-grade quality unless otherwise noted. Apparatus. Chromatographic analysis of the alkyl bromides was performed on a Hewlett-Packard Model 5840A gas chromatograph equipped with an integrator and flame ionization detector. The column was a 6-ft, stainless steel column packed with 10% OV-17 on Chromosorb W from Hewlett-Packard. The GC response was calibrated by injection of c12-clS bromide standards using C17Bras the internal standard. MBAS colorimetric analyses were performed on a Beckman Model 25 recording spectrophotometer. Sample Collection. Wastewater influent and effluent samples were collected from the Colerain Heights wastewater treatment plant in Cincinnati, OH. This is a small, extended-aeration plant that receives primarily domestic wastewater. The influent was collected after comminution and effluent samples before chlorination. The river water was collected from the Ohio River at Anderson Ferry and a t Sayler Park, OH. These points are above and below Cincinnati's Muddy Creek wastewater treatment plant outflow, respectively. All samples were preserved after collection by addition of formalin to a level of 1% to prevent biodegradation of the surfactants. Sample sizes used in the analysis depended on the anticipated levels of AES in the sample. For wastewater influent a 50-mL sample was sufficient, while for wastewater effluent a 200-mL sample or larger was desirable. For river waters, 1L or more of sample was used for analysis. Recovery measurements with radiolabeled material showed particulate matter does not interfere, so in all cases the samples were used without filtration.
Analysis Procedure Concentration and Hydrolysis. An appropriate volume of unfiltered sample was passed through an ionexchange column containing -6 g of AGl-X2 anion-exchange resin at a rate of 1drop/s. The column was next washed with 50 mL of methanol to elute hydrophobically adsorbed materials. This methanol was discarded. Next, four 25-mL aliquots of 10% HC1 in methanol were passed through the column and collected. This quantitatively eluted the AES as well as other adsorbed anionic materials. This eluant was then evaporated on a steam bath to
