United States Environmental Protection Agency Environmental Monitoring and Sup Laboratory Cincinnati OH 45268 Research and Development EPA-600/S4-81-063 Oct. 1981 Project Summary Determination of Phthalates in Industrial and Municipal Wastewaters John W. Rhoades, Richard E. Thomas, Donald E. Johnson, and John B. Tillery This report is one of a series investigating the analytical behavior of selected priority pollutants and suggests a suitable test procedure for their measurement. The specific compounds studied in this effort were: 1. Dimethyl Phthalate (DM P) 2. Diethyl Phthalate (DEP) 3. Dibutyl Phthalate (DBP) 4. Benzyl Butyl Phthalate (BfiP) 6. Diethylhexyl Phthalate (DEHP) 6. Dioctyl Phthalate (DOP) It was desirable that common sample treatment for the various categories be employed, where possi- ble, to minimize cost of analysis of unrelated compounds in any given water sample. The efforts reported under the following performance headings were designed to provide information relative to this common purpose. The study was conducted in two phases. In Phase I, work was conducted with clean water and was intended to provide information which would give direction to Phase II work conducted on actual wastewaters, and to serve as a basis for comparison for the in- formation developed. This Project Summary was developed by EPA's Environmental Monitoring and Support Laboratory, Cincinnati. OH. to announce key findings of the research project that is fully docu- mented in a separate report of the same title (see Project Report ordering information at back). Introduction Literature Search The literature search as conducted yielded over 150 references. Examina- tion of titles, and in many cases, abstracts, drastically reduced the number to five as being of interest to this program. The papers of G. S. Giam and his coworkers at Texas A and M are of particular interest. The paper by Giam, et al., entitled "Sensitive Method for Determination of Phthalate Ester Plasticizers in Open-Ocean Biota Sam- ples" (Anal. Chem., Vol. 47, No. 13, November 1975) was probably the most important product of the literature search. The authors reported several possible laboratory sources of phthalate esters which can/could result in contamination of samples. They also reported the necessity of deactivation of Florisil to prevent loss of DEHP when column chromatography employing Florisil is used in a sample clean-up procedure. Gas Chromatography All six phthalates have been chroma- tographed on two columns. The primary column (Column 1) is 1.8-m x 4-mm ID glass tubing packed with 1.5-percent SP-2250plus 1.95-percent SP-2401 on 100/120 mesh Supelcoport. The sec- ------- ondary column (Column 2) has 3- perce'nt OV-1 as its liquid phase but is otherwise the same as Column 1. Initial investigations with Column 1 indicated that all six phthalates could be resolved at a column temperature of 200°C. However, the retention time for OOP was excessive at 34 minutes and the early eluting phthalates would be difficult to quantitate due to the proximity of the solvent peak. This would be even more critical on extracts of wastewater where the early eluters would be more likely to co-elute with interferences. Therefore, the six phthalates were divided intotwogroups of three for chromatography. The "low" temperature (160°C) group includes DMP (eluting in 1.9 minutes) DEP (2.9 minutes). DBP (12.6 minutes), while the "high" temperature (225°C) group includes BBP (4.1 minutes) DEHP (5.1 minutes), and OOP (9.0 minutes). Investigations with Column 2 gave comparable results, leaving little basis for recommending either column over the other. At the beginning of this work, the electron capture detector was con- sidered to be the primary detector for the analysis of phthalates, and the flame ionization detector the alternate detector, but experimentation confirmed that the electron capture detector is preferred over the flame ionization detector on the bases of the greater sensitivity and selectivity. The response of the electron capture detector was not linear for DMP and DEP, and it was necessary to establish and use calibration curves for these two phthalates and to limit the amounts injected to not more than 1 -2 nanograms. The electron capture response to DBP, BBP, DEHP, and DOP was not linear over several orders of magnitude but was sufficiently linear over a limited range to be used for quantitation purposes. Extraction Study The extraction study was initiated to determine the recoveries of the six phthalates of interest from clean water at pH 2, 7, and 10 using 15 percent dichloromethane (DCM) in hexane and 100 percent DCM as the extracting solvents. The water used in the extraction study was a naturally buffered well water obtained from the Southwest Research Institute supply line prior to chlorination. The water was found to be very low in electron capture sensitive materials as determined thro".gh comparison of an extract of the water with a glassware blank. ,The one liter samples of water were dosed while in one-liter Erlenmeyer flasks, then poured into two-liter separatory funnels for extraction with three 60-mL aliquots of either 15 percent DCM in hexane or 100 percent DCM. Three dosed samples were extracted at pH 2 and 10 with each solvent. At pH 7, four dosed samples were extracted with each solvent. Essentially all the DCM must be removed prior to analysis when the extracting solvent is 100 percent DCM. This was done by taking the extract to a volume of 10 to 15 mL, adding 75 to 100 mL of hexane, and then reconcentrating to the final volume. The DCM extracts usually produced a wider "solvent" peak than those produced by 15 percent DCM' in hexane. This peak broadening was not reduced when the amount of hexane added before reconcentration was increased in amounts up to 200 mL, nor was it a serious problem. The data acquired in the extraction study are presented in Tables 1 and 2. The data have not been corrected for blank extractions. No clear tendency can be detected for one solvent system to produce superior recoveries or for the recoveries to be influenced by the pH of the water. The principal differences occurred when 100 percent DCM was used and a particular pH gave unacceptable results, especially in the cases of DEP and DBP. When 15 percent DCM in hexane was used as the extraction solvent, no differences were detected among the pHs. Another factor in the evaluation is that the 15 percent DCM-hexane solvent system produced more consis- tent results with fewer of the apparent contaminations and none of the low recoveries. It can be concluded, then. Table 1. . PH 2 7 10 Table 2. pH 2 7 10 Extraction Extract 1 2 3 Mean 1 2 3 4 Mean 1 2 3 Mean Extraction Extract 1 2 3 Mean 1 2 3 4 Mean 1 2 3 Mean Study Results DMP 96 125 67 96 135 143 144 115 134 108 119 113 113 Study Results DMP 107 105 100 104 116 111 109 104 110 110 110 113 111 - 100% DEP 89 98 71 86 103 106 103 99 103 100 115 111 109 DCM% DBP 63 81 40 61 97 95 95 94 95 96 00 88 95 Recovery BBP 88 88 90 89 118 110 109 98 109 91 91 90 91 - 15% DCM in Hexane % DEP 104 101 99 101 101 101 103 101 102 104 103 104 1-04 DBP 100 87 87 91 104 — 104 97 102 95 93 95 94 BBP 93 92 84 90 _ 90 85 94 90 98 94 98 97 DEHP 102 92 101 98 104 99 98 98 100 100 99 112 104 Recovery DEHP 99 96 127 107 101 104 98 101 105 102 112 110 DOP 94 90 96 93 99 97 96 94 97 90 95 94 93 DOP 95 95 91 94 91 92 91 93 92 97 96 99 97 — data not available - contamination (?) ------- that 15 percent DCM-hexane should be used for extracting the wastewater and no adjustment of the pK need be made. The mean recoveries obtained with 15 percent DCM-hexane at the three pHs are shown at the bottom of the summary table to indicate the recovery obtained. Preservation Study The preservation study was conducted to determine the effects of a 7 day storage period at various conditions on the recovery of the six phthalate esters of interest from dosed water samples. Each sample consisted of one quart of water dosed with six phthalates, as in the extraction study (see Table 3). Two replicates for each of twelve conditions of pH, temperature, and residual chlorine were prepared as shown in the follow- ing model: 4°C pH2 pH7 pH 10 pH2 pH7 pH 10 0 ppm Cl 2 2 2 2 ppm Cl 2 2 2 24°C 0 ppm Cl 2 2 2 2 ppm Cl 2 2 2 The 2 ppm residual chlorine level was obtained, where required, by adding 160 microliters of Mallinckrodt sodium hydrochlorite analytical reagent (5 percent minimum available Cl). After storage, the samples were extracted with 15 percent DCM-hexane without pH adjustment. Data obtained in the preservation study are presented in Table 3. The results for dimethyl phthalate showed that the best conditions for DMP was storage at neutral conditions with basic conditions clearly unaccept- able. The better temperature for storage was 4°C with an average recovery of 95.8 percent versus 82.2 percent at room temperature. The three pHs produced distinct means for BBP, with storage at pH 2 giving the best results, 93.8 percent recovery, followed by pH 7 and pH 10 (72.8 and 60.3 percent recovery, respectively). Higher results were obtained on average when storage was at 4°C as opposed to room tempera* ture, with mean recoveries of 84.3 k percent and 67.0 percent, respectively. On the basis of the trends shown, the lecommended conditions for storage of Table 3. Results of Preservation Study - DMP, DEP, DBF. BBP. DEHP, (Percent Recovery - 7 - Day Storage Period) Temperature Chlorine pH °C ppm OOP Replicate DMP DEP DBP BBP DEHP OOP 2 4 24 7 4 24 10 4 24 0 2 0 2 0 2 0 2 0 2 0 2 1 2 / 2 1 2 / 2 / 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 * 103 104 104 110 109 116 115 93 92 97 94 112 100 100 94 90 89 87 30 32 26 25 # 97 95 94 103 99 100 103 98 97 100 100 100 98 100 100 97 97 103 85 85 80 78 * 79 89 89 86 90 91 89 85 84 91 88 92 89 105 90 94 95 94 74 81 68 71 105 88 98 93 88 91 85 103 78 67 77 77 73 70 68 79 87 84 79 40 41 37 35 108 91 96 96 101 118 88 104 89 86 88 84 99 85 104 86 92 84 75 89 94 93 94 107 90 99 95 93 91 92 95 94 90 92 90 69 95 91 83 88 83 75 81 89 88 87 * data not available - contamination (?) phthalate esters as a class would specify an adjustment of the water to acidic conditions, and storage at a temperature of 4°C. Under these conditions, no interference can be expected from residual chlorine up to the 2 ppm level. Adjustment of wastewater samples to pH 2 may not be practical under field conditions and may be avoided with minimal effect on the determination of phthalate esters, provided the samples are stored at 4°C. Liquid-Solid Column Chromatography Two column chromatographic ap- proaches were developed to clean up extracts for phthalate analysis. Deacti- vated Florisil and alumina were both examined for their ability to quantita- tively elute the six phthalate esters. The clean-up procedures using Florisil and alumina were evaluated as to the recoveries that could be obtained when doses of the six phthalates were applied to columns of these adsorbents. The recoveries for all six test phthalates from both materials appear to be very good, averaging 90 percent or better. Wastewater Application With the assistance and approval of the project officer, five wastewaters were procured and analyzed. All sam- ples were put in clean, one gallon bottles and shipped unrefrigerated via air to Southwest Research Institute laboratories. All of the wastewater from a particular source with the exception of Wastewater 2, were pooled, adjusted to pH 5-7 if necessary, returned to the bottles in which they were shipped, and stored in the dark at 4°C until used. Due to the high acid content of Wastewater 2 which required approximately 48 g/L NaOH to neutralize, it was stored at4°C as received. In order to develop method improve- ments and to provide base data for ------- dosing and recovery experiments and for the accuracy and precision evalua- tions to follow, each wastewater was analyzed in triplicate for each substance of interest in this program. One liter of wastewaters was extracted three times using 60 ml DCM for each extraction. The combined extract was dried with Na2S04 and placed in a Kuderna-Danish (K-D) evaporator. The DCM extract was concentrated to 5-10 ml, 90 ml of hexane was added, and the extract was concentrated to slightly less than 10 ml in the K-D. The sample was then transferred to a small vial and concentrated to 2 ml. This 2 mL concentrated extract was then sub- jected to the Florisil clean-up procedure as previously described. One procedural change, used only with Wastewaters 3, 4, and 5, was attempted and with some success. In the Florisil clean-up proce- dure, instead of collecting a single fraction of TOO mL of eluting solvent containing all the phthalate esters of interest, a two-fraction collection was made. Fraction 1, which consisted of the first 60 mL contained nearly all of the OOP and DEHP, most of the DBP and BBP and, in some instances, much of the early GC-eluting material. Fraction 2, the next 40 mL, contained all the DMP, most of the DEP, some DEP and BBP and, in some instances, reduced amounts of early GC-eluting material(s) which otherwise interfere with detection of the DMP and DEP. Accuracy and Precision Approach The accuracy and precision assess- ment for the method was of a limited nature due to the number and types of analytical results obtained. According to the design of the program three repli- cates of each of five wastewaters were to be dosed for the compounds of interest and analyzed, both at a zero time and after seven days storage at 4°C. Results Wastewater 1 Neither the DMP nor the DEP was dosed into Wastewater 1, either at time zero or after storagedue to interferences. Consistent results were obtained for the other four compounds studied, however, with recoveries from 70 percent for DEHP to 81 percent for DBP. In each of these cases, the precision of the analyses was good, with ranges of 2,0, 4, and 2 percent recovery for DBP, BBP, DEHP, and OOP, respectively. The preservation recoveries were generally good for the four higher- boiling phthalates, but more variable than the zero day analyses. The re- coveries were from a low of 94 percent to a high of 106, with ranges of 6, 7, 9, and 18. The 106 average for DBP'was influenced by a single value of 118, and the indication is that recovery for these compounds was not affected by the storage conditions in this wastewater. Wastewater 2 Wastewater 2 was a particularly difficult sample. The pH of this sample was not adjusted at the time of samp- ling. The initial analysis of this waste- water indicated large interferences making qualitative estimations almost impossible. Upon further storage in the cold room, the sample darkened and considerable black precipitate was formed. Considering the problems en- countered, no attempt was made to establish recovery or preservation data on Wastewater 2. Very likely Waste- water 2 was a process water and the clean-up procedure was inadequate. Wastewater 3 The analyses on this wastewater produced results which ranged from low to very good, depending upon the particular compound. Results for both DMP and DEP were very good, with triplicate analyses indicating 100 percent recovery of the spike. The recovery of J3BP was 91 percent, on average, bufwith a range of 10 percent recovery. The results for the remaining phthalates were not good in this wastewater, however. The average recovery of BBP was 104 percent, but the individual recoveries had a range of 27 percent (93-120). DEHP and DOP were recovered at 65 and 66 percent, respectively, of the dose level with ranges of 16 and 20 percent recovery. The preservation data were also inconsistent from one compound to the next. For the six compounds studied, the average recovery relative to the zero day analyses went from 68 percent for DBP to 109 percent for DEHP. These analyses were more variable than the zero day analyses in the cases of DMP and DBP, equivalent for DEP, and considerably less variable for the remainder. The ranges of the triplicate analyses at zero time were 27, 16, and 20 for DBP, DEHP, and DOP, respectively, at the i n itia I a na lyses compa red to 9, 6, a nd 1 0 for these compounds after seven days' storage. Wastewater 4 The analysis on Wastewater 4 for DMP and DEP produced good recovery, '88 and 82 percent, respectively, with ranges of 3 and 2 percent. Recovery of 91 percent on average was noted for DBP but more variability was also noted with a range of 10 percent recovery. Lower recoveries were obtained for the remaining three phthalates, with av- erage percent recoveries of 76, 50, and 50 for BBP, DEHP, and DOP, respectively with ranges of 10, 9, and 8. The preservation data were good for the first four compounds, going from 96 to 107 percent recovery. For the DEHP and DOP analyses, however, the average recoveries were 140 and 139 percent with ranges of 9 and 1 1 , respectively. These recoveries are comparable to 70 and 69 percent, respectively, of the original dosed amount and indicate a problem with the initial analyses. Wastewater 5 The results for both DMP and DEP were good in this wastewater, with 4 average recoveries of 97 and 921 percent, respectively, and ranges of 6 and 4 percent recovery. The DBP and BBP results were low and variable, with average recoveries of 41 and 63 and ranges of 1 6 and 1 3 percent recovery, respectively. The DEHP and DOP values were consistent but only 71 percent of the dose was recovered on the DEHP, while 93 percent was recovered on the DOP. For both of these compounds there was a zero range, with all three analyses showing the same recovery. The preservation recoveries were fairly consistent for all of the compounds, with ranges of recovery of 0 to 9 percent. However, the level of recovery could be broken down into three groups: DMP-DEP, DBP-BBP, DEHP-DOP. The recovery after storage was 95 to 1 00 for the first pair, 61 to 65 for the second, and 78 to 79 for the third. The 61 percent recovery represents only 25 percent of the initial dosed amount remaining after seven days and indicates that storage in this wastewater would not be recommended for these analyses. Summary The accuracy and precision evalua- tions on phthalate esters in wastewater lead to the following conclusions Acceptable recovery was obtained ------- phthalate esters using this methodology when the background of electron capture sensitive materials was low. When interferences were present, as in the case of Wastewater 1 in the DMP and DEP region, the clean-up procedures did not remove them sufficiently to allow these substances to be quantitated in fjg/\ concentrations. In the case of Wastewater 2, believed to be a process wastewater as opposed to a final treated effluent, excessive interferences could not be removed by the clean-up pro- cedures to allow quantitative estimation of the analytes of interest. The re- coveries that can be expected for the compounds studied ranged from 40 to 100 percent, depending upon the compound and the wastewater studied. In general, the precision of the analyses was acceptable to good, with ranges of less than 10 percent recovery common. The overriding conclusion is that the recovery and the ability to store the water for later analysis are a function of the westewater. Storage frequently resulted in significant losses of the study materials and in less precise determinations. Therefore, storage cannot be recommended as a general rule. it US. GOVERNMENT PRINTING OFFICE; 1981 - 559-017/7372 John W. Rhoades, Richard E, Thomas, Donald E. Johnson, and John B. Tilleryare with the Southwest Research Institute, San Antonio, TX 78283. James E. Longbottom is the EPA Project Officer (see below). The complete report, entitled "Determination of Phthalates in Industrial and Municipal Waste waters," (Order No. PB 81 -232 167; Cost: $9.50, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Environmental Monitoring and Support Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 ------- ------- United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 Postage and Fees Paid Environmental Protection Agency EPA 335 Official Business Penalty for Private Use $300 PS jECT10N ------- |