Document zzx3Lba8NRdXDqBr85xzZ491B

Telomer Research Program AR226-1890 Report Title: (14C)-8-2 Telomer B Alcohol: Adsorption/Desorption using a Batch Equilibrium Method Report Author: Sharon Swales, Ph.D., Covance Laboratories Contractor: Covance Laboratories Ltd Otley Road, Harrogate North Yorkshire HG3 1PY ENGLAND RECEIVED OPPT NCIC 2004 DEC 22 AM 11:20 Study Dates: Study Initiation Date (Protocol Signed): 13-March-2003 Study Completion Date (Final Report Issued): 16-July 2004 Study Objective The adsorption/desorption characteristics of (14C)-8-2 TBA were examined in four soil types and one sediment. The study was conducted to meet the requirements of the OECD Guideline 106 (January 2000). The objective of the study was to: determine the adsorption/desorption characteristics of (14C)-8-2 TBA in four different soil types and one sediment. Materials and Methods Test Item The test item (14C)-8-2 TBA (2-perfluorooctylethanol) used in this study had the following structure: *Position of the 14C radiolabel CAS Name: 1-Decanol, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluoroCAS Number: 678-39-7 Does not contain TSCA CBI 1 TRP (Nov 2004) Soils and Sediment Three soils (SK961089, SK566696 and SK179618) and one sediment (Emperor Son's Lake) from sites in the United Kingdom, and one soil (EUROSOIL 5) from Belgium were used for the study. The Land Research Associates (Derby, Derbyshire) and the Institute for Reference Materials and Measurements (Belgium) were the sources for the soils and sediment. The soil and sediment characteristics are summarized in the following table: Experimental Procedure All experiments were conducted in the dark at either 20 2C or 4 1C. Soils were dispensed into pre-weighed glass centrifuge tubes/vials and pre-conditioned by mixing with either 0.01M calcium chloride solution or sterile 0.01M calcium chloride solution overnight before the day of the experiment. Soils and solutions were mixed mechanically using an end-over-end shaker at a speed that ensured efficient mixing. Centrifugation was performed at 2000 rpm (ca 700 g) for a length of time calculated to be sufficient to remove particles larger than 0.2 m from the portion of the solution from which aliquots were taken. Aliquots for liquid scintillation counting (LSC) were removed using a Hamilton SGE syringe (glass syringe with stainless steel needle and piston) that was inserted through the PTFE-lined rubber septum to minimize any volatile losses. A control vial containing ethanol only was used to confirm that the dosing procedure was acceptable. The test was performed over the concentration range of 0.01 g/mL to 0.1 g/mL. Ratio of Soil to Aqueous Phase The ratio of soil to aqueous phase to use in the definitive was determined using the following weights of soil and volumes of 0.01M calcium chloride: 1:1 ratio; 9 g soil to 9 mL calcium chloride solution 1:5 ratio; 3 g soil to 15 mL calcium chloride solution 1:25 ratio; 0.6 g soil to 15 mL calcium chloride solution Does not contain TSCA CBI 2 TRP (Nov 2004) Equilibrium Time Determination and Stability The adsorption equilibrium time was determined in samples of 8-2 TBA (0.1 g/mL) in 0.01M calcium chloride (9 mL) with 9 g soil using 4 of five soils (SK961089, SK566696, Emperor Son's Lake and SK179618). The sample vials were placed on an end-over-end shaker set at a speed sufficient to keep the soils in suspension. At intervals of 3, 6, 24 and 48 hours, duplicate samples of each soil type were removed from the shaker and centrifuged. Aliquots for LSC were removed using a Hamilton SGE syringe that was inserted through the PTFE-lined rubber septum to minimize volatile losses. Once the aliquots for LSC had been taken the lids were removed and the supernatant removed. The 24-hour samples were extracted three times with acetone (10 mL) and the supernatants for each sample pooled. The soil extracts for each sample were quantified by LSC and analyzed by thin layer chromatography (TLC). The extracted soil samples were airdried overnight then ground in a pestle and mortar prior to combustion in oxygen. The desorption equilibrium time for each soil type was determined in samples of 8-2 TBA (0.1 g/mL) in sterile 0.01M calcium chloride (9 mL) with 9 g sterile soil using all five soils. After mixing for the adsorption equilibrium time of 3 hours, samples were centrifuged and the supernatants removed. The supernatants were replaced by equal weights of fresh sterile 0.01M calcium chloride and the samples were placed back on the shaker. At intervals of 1.5, 3, 6 and 24 hours, duplicate samples of each soil type were removed from the shaker and centrifuged. Aliquots for LSC were removed using a Hamilton SGE syringe that was inserted through the PTFE-lined rubber septum to minimise volatile losses. Adsorption Isotherms Duplicate samples at five concentrations of 8-2 TBA in sterile 0.01M calcium chloride (9 mL) with 9 g sterile soil were prepared. The sample vials were placed on an end-over-end shaker in an incubator at 4 1C. After mixing for the adsorption equilibrium time of 3 hours, the phases were separated by centrifugation. Aliquots (ca 1 mL or 1.5 mL) for LSC were removed using a Hamilton SGE syringe that was inserted through the PTFE-lined rubber septum to minimize potential volatile losses. Once the aliquots for LSC had been taken, as much of the adsorption supernatant as possible was removed. Desorption Isotherms Samples at the highest concentration of 8-2 TBA added in determining the adsorption isotherm were used in the desorption isotherm study (0.125 g/mL). The volume of adsorption supernatant removed was replaced by an equivalent weighed portion of fresh 0.01M calcium chloride. The samples were shaken vigorously to break up the soil packed at the bottom of the tube and then mixed end-over-end for the desorption equilibrium time of 3 hours at 4 1C. After this time, each sample was centrifuged and the supernatant quantified by LSC. The remaining soil samples were extracted three times with acetone (10 mL) and the supernatants for each sample pooled. The soil extract for each sample was quantified by LSC. The extracted soil samples were air-dried then ground in a pestle and mortar prior to combustion in oxygen and quantification by LSC. The PTFE-lined lids used for each sample were soaked in acetone prior to quantification by LSC. Does not contain TSCA CBI 3 TRP (Nov 2004) Analytical Methods and Measurements High Performance Liquid Chromatography (HPLC) Radiochemical purity determinations of the test item were performed using an HPLC method. Samples were co-injected with non-radiolabelled 8-2 TBA. Chromatograms were evaluated using Laura (version 1.4a) software (LabLogic). Thin Layer Chromatography (TLC) A TLC system was used for determination of radiochemical purity and analysis of selected sample extracts. Following chromatography, non-radiolabelled 8-2 TBA was visualized by spraying the plate with a 2% potassium permanganate solution. (14C)-8-2 TBA was detected by preparation of a radioluminogram of the TLC plate using a Fuji BAS 1500 Bio-image analyzer. Chromatograms were evaluated from the radioluminograms using the associated Tina software (version 2.09g). Radioactivity Radioactivity was measured using a Packard Tricarb model 1900TR liquid scintillation counter (LSC) with facilities for computing quench corrected disintegrations per minute (dpm). Efficiency correlation curves were routinely checked by the use of commercially available quenched standards (Perkin Elmer) quenched over the range observed in test samples. The limit of detection was taken as 1.5 times the background radioactivity, determined by counting vials containing scintillant only in the same batch as the samples. The radioactivity in liquid samples was determined by calculating the total sample weight and assaying duplicate weighed aliquots by LSC, after mixing with liquid scintillant (ca 5 mL). The density of calcium chloride solutions and supernatants was assumed to be 1.00 g/mL so concentrations per g are equivalent to concentrations per mL. The radioactivity in solid residues was determined, after air-drying and grinding using a pestle and mortar, by combustion of triplicate weighed aliquots in oxygen using a Harvey OX-500 biological oxidizer. The combusted products were absorbed in scintillation cocktail and the radioactivity absorbed assayed by LSC. Carbon-14 standards were combusted at the beginning and at regular intervals throughout the day to check the carryover between samples and the efficiency of the combustion process. Combustion efficiencies were 99 4%; therefore, no correction factors were applied to the data. Findings Preliminary Tests Preliminary tests were performed to assess the solubility and adsorption to containers. These tests demonstrated that in a sealed vial with minimal headspace 8-2 TBA may not exist fully in solution over a concentration range of 0.01 to 0.1 g/mL. Loss of radioactivity occurred when the vials were opened, thereby confirming the volatile nature of 8-2 TBA. No definitive conclusions could be drawn from the preliminary solubility test due to the volatile nature of the compound. The amount of 8-2 TBA adsorbed to the test vessels from aqueous solution as 2% of the applied radioactivity. The concentrations used for the remainder of the study were selected Does not contain TSCA CBI 4 TRP (Nov 2004) such that they were below the stated water solubility (0.14 mg/L), but were high enough to ensure that the radioactivity could be detected throughout each stage of the study. Further preliminary tests demonstrated that: The percentage adsorption of 8-2 TBA to the test soils (not including Eurosoil 5) was >80% at ratios of soil to solution of 1:1 w/v and 1:5 w/v. For a soil:solution ratio of 1:25 the percentage adsorption of 8-2 TBA to the test soils was >60%. The recovery of applied radioactivity from the samples was dependent on the proportion of soil present with >90% being recovered at a soil:solution ratio of 1:1 w/v. The 1:1 ratio was, therefore, selected for the remainder of the study (Fig. 1). Three hours was a suitable adsorption and desorption equilibrium time for the study (Fig. 2). The 8-2 TBA was not stable in the test system at 20C (Fig. 3). The 8-2 TBA was stable in the sterile test system at 4C; therefore, the isotherms test was conducted using sterile soil, sterile 0.01M calcium chloride and at a reduced temperature of 4 1C (Fig. 4). Figure 1. Ratio of soil to aqueous phase and mass balance following treatment at 0.025 g 8-2 TBA/mL. Applied Radioactivity, % 100 90 80 70 60 50 40 30 20 10 0 Soil: Solution Soil extract Residue Supernatant Lid Wash 1:1 1:5 1:25 SK961089 1:1 1:5 1:25 SK566696 1:1 1:5 1:25 Emperor Son's Lake 1:1 1:5 1:25 SK179618 Does not contain TSCA CBI 5 TRP (Nov 2004) Figure 2. Adsorption equilibrium time data for three soils and one sediment following treatment with 8-2 TBA. Adsorption graph for Soil A (SK961089) Percent adsorption to soil 100 90 80 70 60 50 40 30 20 10 0 0 12 24 36 48 Adsorption Tim e (hours) Soil A Adsorption graph for Soil B (SK566696) Percent adsorption to soil 100 90 80 70 60 50 40 30 20 10 0 0 12 24 36 48 Adsorption Tim e (hours ) Soil B Adsorption graph for Soil C (Emperor Son's Lake) 100 90 Percent adsorption to soil 80 70 60 50 40 30 20 10 0 0 12 24 36 Adsorption Tim e (hours) Soil C Adsorption graph for Soil D (SK179618) 100 90 Percent adsorption to soil 80 70 60 50 40 30 20 10 0 48 0 12 24 36 48 Adsorption Tim e (hours) Soil D Does not contain TSCA CBI 6 TRP (Nov 2004) Figure 3. Stability of 8-2 TBA in the soil extract of non-sterile SK179618 soil following adsorption for 24 h at 20C determined by TLC. Figure 4. Stability of 8-2 TBA in the soil extract of sterile SK179618 soil following adsorption for 3 h at 4C determined by TLC Does not contain TSCA CBI 7 TRP (Nov 2004) Conclusions The Freundlich adsorption constants (Kf) were calculated by linear regression analysis and the results were as follows: Soil Freundlich constant (Kf) SK961089 (clay loam) 35 SK566696 (loamy sand) 40 Emperor Son's lake sediment (sandy loam) 20 SK 179618 (loam) 130 Eurosoil 5 (loamy sand) 38 The Freundlich adsorption constants related to organic carbon content (Koc) as shown below: Soil SK961089 (clay loam) SK566696 (loamy sand) Emperor Son's lake sediment (sandy loam) SK 179618 (loam) Eurosoil 5 (loamy sand) Koc 765 4941 1667 3414 572 Mass balance for the four soils and one sediment range 86 to 96%. The adsorption and desorption isotherm showed a strong positive monotonic relationship between log Ce (Ce = concentration of test article in adsorption supernatant) and log X/m (X = quantity of test substance adsorbed; m = dry weight of soil), indicated by the correlation coefficients being close to 1. These values characterize 8-2 TBA as slightly mobile (Koc 500 to 4000) to non-mobile (Koc > 4000) in the four soils and one sediment used in this study. Publications / Presentations Publication planned in peer-reviewed journal, such as Environmental Toxicology & Chemistry. William R. Berti, Robert C. Buck, Hiroyuki Iwai, Volker Koch, Seiji Shinya, Bogden Szostek, Ning Wang, Robert Waterland. 2004. Soil-Water Partitioning of a Fluorotelomer Intermediate used to Manufacture Fluorotelomer-based Polymers. Poster at Annual Meeting 2004 SETAC Europe Prague, 18-22 April 2004. Hollis, J M (1991). Mapping the vulnerability of aquifers and surface water to pesticide contamination at the national/regional scale. Pesticides in Soil and Water: Current Perspectives (A Walker Ed), BCPC Monograph 47, pp 169 to 174. Does not contain TSCA CBI 8 TRP (Nov 2004)