Document v1ZMKn3EozqO08nX7RrMGDxzq

ARX&-0370 SOIL ADSORPTION TEST SUBSTANCE Identity: N-methylperfluorooctane sulfonamldoethanol; may also be referred to as N-MeFOSE Alcohol, FC-790, or FM-3925. (1Octanesulfonamide, N-methyl-1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8heptadecafluoro-N-(2-hydroxyethyl)-, CAS # 24448-09-7) Remarks: Material is an off-white, waxy solid. Sample purity and lot number were not recorded. METHOD Method: Adsorption-desorption studies developed using procedures described by Davidson, 1976 and Hamaker, 1975. GLP (Y/N): No Year (study performed): 1979 Statistical methods: Statistical analysis and plotting of the data was done with the MINITAB package of the 3M TRAC computer service. Temperature: 16-19C during the 24-hours of wrist-action shaker exposure. Stock and test solution preparation: The stock solution used was an aliquot from the 24-hour sample taken during the water solubility study on N-MeFOSE Alcohol. This solution was prepared by the Vieth method and gave a concentration of 2.16 mg/L. Test solutions were made by diluting aliquots of the stock solution. Remarks field: The Brill sandy loam soil was characterized as having 57% sand, 36% silt, 7% clay, 2.5% organic matter, 2.2% organic carbon, with pH 6.5 and cation exchange capacity of 15.3 meq./100 g. Standard solutions of N-MeFOSE alcohol were prepared in deionized water at concentrations of 2.16 mg/L, 1.21 mg/L, 0.691 mg/L, 0.389 mg/L, 0.216 mg/L, and 0.022 mg/L. Forty ml of each solution was shaken with 5 gram samples of the soil in a 50 ml glass centrifuge tubes for 24 hours in duplicate on a wrist shaker at room temperature (16-19C). Desorption extractions were performed with deionized water after the adsorption phase of the experiment. The samples from the adsorption and desorption experiments were centrifuged individually at 3000 rpm for 30 minutes, and each supernatant solution was decanted off into glass sample vials. Supernatant solutions were analyzed by extracting with ethyl acetate and running GC. 006541 RESULTS K: 77 KoC: 3,500* Remarks field: The linear shape of the adsorption isotherm indicated that N-MeFOSE alcohol adsorption on soil would be independent of concentration in solution. * The study report had calculated using the formula: Koc = 100 K/% organic carbon. CONCLUSIONS The study substance is expected to exhibit low mobility in the kind of soil tested. Submitter: 3M Company, Environmental Laboratory, P.O. Box 33331, St. Paul, Minnesota, 55133 DATA QUALITY _________ Reliability: Klimisch ranking 3. Study is using an inaccurate solubility value and the purity of the test substance is not sufficiently characterized. The analytical methodology was not validated, therefore there is no way to evaluate the accuracy of the reported analytical results. It was noted in the report that a high percentage of FM 3925 was adsorbed onto the glass used in the experiment. No attempt was made to correct for this loss of test substance in the calculations of sorption to soil. The Vieth Method of perparing a saturated solution would disproportionately dissolve the more soluble components of N-MeFOSE alcohol which is not a pure material. The study was not performed in duplicate, and the soil was not analyzed to verify the amount remaining. Additionally, the following are summarized comments made by Professor Stephen Boyd, Michigan State University: Use of oven dried soils not recommended. Should be air-dried and characterized for moisture content. Use of deionized water for desorption experiments is not recommended as it causes the soil to disperse. Use dilute CaCl2. Ethyl acetate extraction not validated. Did not establish that the sorption isotherm is linear. 006542 There is no evidence for electrostatic forces being involved in soil binding of FM 3925. REFERENCES 3M Technical Report "Adsorption of FM-3925 on Soil." S.K. Welsh and C.H. Schrandt, Project 9970612631 Fate of Fluorochemicals, Report No. 013, March 22, 1979. Review of Technical Report Summary. Adsoprtion of FM 3925 on Soil. Professor Stephen A. Boyd, Michigan State University, May 19, 1993. OTHER Last changed: 5/17/00 006543 Attached are comments on the 3M Technical Report "Adsorption of FM-3925 on Soil. S.K. Welsh and C.H. Schrandt, Project 9970612631 Fate ofFluorochemicals, Report No. 13, Mar. 22, 1979" made by Professor Stephen A. Boyd, Michigan State University, dated May 19, 1993. 006544 Review of Technical Report Summary Adsorption of FM 3925 on Soil Materials and Methods I would not recommend oven drying soils. Use air dried soils and do a separate moisture determination (oven drying) to get the moisture content. Solubility was determined earlier as 2.3 ppm. Desorption experiments should probably use dilute CaCl2 solutions instead of deionized water which will cause the soil to disperse. The extraction procedure described utilizing ethyl acetate needs validation. The percent recoveries of FM 3925 from standard solutions should be reported. The sorption isotherm only extends to an equilibrium concentration of about 0.22 ppm which is 10 times lower than the water solubility (Sw) of FM 3925. The isotherm needs to be extended to 0.5 Swor greater, i.e., equilibrium aqueous concentrations approaching Sw. This is the only way to establish the linearity of the isotherm. I'm again not certain of the meaning of the desorption experiments. I would not draw any major conclusions regarding mobility from those data. There is absolutely no evidence for electrostatic forces being involved in soil binding of FM 3925. This is pure conjecture and almost certainly wrong. The only electrostatic mechanism would be to protonate the N of FM 3925 to create a cationic species that could interact with negatively charged sites in soil clays and soil organic matter. The pKa of FM 3925 would indicate the likelihood of that. The linear isotherms (if they are in fact linear) suggest solute partitioning not adsorption by electrostatic forces. Solute partitioning involves dissolution of FM 3925 in amorphous soil organic matter. The magnitude of the sorption coefficient (K^) depends on the relative solubility of FM 3925 in soil organic matter and water. The K values reported for FM 3925 is 3500 (100 K/% organic carbon = 100 x 330/2.2). The K value reported was 77 so it should be: = 100 x 77/2.2 = 3500. This may be a reasonable value although it would be easier to evaluate if the K^, was known. Gareen and Karickhoff (1990, Pesticides in the Soil Environment, Chapter 4, Sorption Estimates for Modeling, Soil Science Society of America, Madison, WI) give the empirical equation: Log K,* = -0.68 log S Gig/ml) x 4.273 which using the solubility of 2.3 yields a predicted K*. of about 10,000 so its at least close. Equations like this using solubilities of solids that haven't been corrected for melting point, i.e., converted to supercooled liquid solubilities, give pretty rough estimates. I think you could get a better estimate if you knew Kw. 00654 R ecom m endations 1. Measure the octanol water partition coefficient, relate measured S to via Chiou's equation: log K, = -0.862 log Sw + 0.710 remembering Sw of a solid should be converted to supercooled liquid solubility if the melting point is much over 100C. 2. Extend range of equilibrium aqueous concentrations to approach Sw in the sorption isotherm experiments. Test other soils to evaluate 3. Determine the pKa of FM 3925 to evaluate likelihood of electrostatic interactions. V- 006546 Form 6747-11-A TECHNICAL REPORT SUMMARY D a te 3/22/79 TO: TECHNICAL COMMUNICATIONS CENTER - 201-2CN (Important -- If report is printed on both sides o f paper, send two copies to TCC.) D ivision Environmental Laboratory (EE PC) P ro je c t Fate of Fluorochemicals R eport T itle Adsorption of FM-3925 on Soil To A. N. Welter t A u th o r(s ) ....... -- C Stephen K.^ Weight 8 C N otebook Reference , Schrandt #51050 Oept. N um ber 0535 P roject N um ber 9970612631 Report N um ber 013 Em ployee Num ber(s) 073583, 113152 N o. o f Pages In c lu d in g C oversheet 11 SECURITY ^ Open (Company Confidential) lvJ Closed (Special Authorization) 3M CHEMICAL REGISTRY w New Chemicals Reported Yes S No KEYWORDS: (Select terms from 3M Thesaurus. Suggest other applicable terms.) EE PC FIuorochemical CURRENT OBJECTIVE: To obtain an indication of FM-3925 mobility in a sandy loam soil, REPORT ABSTRACT: (200-250 words) This abstract information is distributed by the Technical Communications Center to alert 3M`ers to Company R&D. It is Company confidential material. To obtain an indication of mobility of FM-3925 in a sandy loam soil, adsorption/desorption experiments similar to those of Davidson, 1976, and of Hamaker, 1975, were conducted. FM-3925 wars judged to v be immobile based on an adsorption coefficient of 77; less, than 15% desorption with three desorption extractions; and water solubility of only 2.16 mg/1. Information Liaison Initials: 006547 FM-3925/ -2- 3/22/79 CONCLUSIONS The adsorption coefficient for FM-3925 was 77. Considering the adsorption coefficient, desorption characteristics, and water solubility, FM-3925 would be judged immobile in the sandy loam soil used in this study. INTRODUCTION As a part of the Fate of Fluorochemicals Project, an indication of mobility of FM-3925 in sandy loam soil was desired. Adsorption-desorption experiments (after Davidson, 1976 and Hamaker, 1975) along with water solubility data can provide this indication of mobility. This approach is used by the USEPA in pesticide registration requirements. MATERIALS AND METHODS Duplicate 5-g samples of oven-dried (103 C.) Brill sandy loam soil (57% sand, 36% silt, and 7% clay, with 2.5% organic matter, 2.2% organic carbon, with pH 6.5 and CEC of 15.3 meg/100 g) were shaken with 40 ml of solution in 50 ml glass centrifuge tubes for 24 hours on a wrist-action shaker at room temperature (16-19 C.). Glass tubes were used because it was believed, based on prior experience, that glass would adsorb less FM-3925 than polypropylene or polyethylene tubes. Solutions were made by diluting a stock solution of the chemical. The stock solution was the 24-hour sample from the second Vieth study of water solubility (46269-53 and 48277^8). Concentrations of FM-3925 were 2.16 mg/1, 1.21 mg/1, 0.691 mg/1, 0.389 mg/1, 0.216 mg/1, and 0.022 mg/1 (100%, 56%, 32%, 18%, 10%, and 1% of stock). v> After shaking-the initial solutions, as well as the three desorption extractions with deionized water, the samples were centrifuged at 3000 rpm for 30 minutes, and each supernatant solution was decanted off into glass sample vials. * After removing the 40 ml of initial solution for analysis, 40 ml of DI water was put into the tubes for the first desorption extraction. Similarly, the second and third desorption extractions were conducted. The samples, now in glass sample vials, were analyzed by first adding 5 ml of Burdick and Jackson distilled in glass ethyl acetate to each vial, mixing on a .Genie Vortex Mixer at maximum speed for 30 seconds, and centrifuging at 2500 rpm for 10 minutes. The ethyl acetate layer (about 1 ml) was then drawn off with a transfer pipet to a clean vial, and then two more extractions were conducted with 2 ml of ethyl acetate each followed by mixing and centrifug ing as above, and the ethyl acetate layers from each successive extraction were combined in the same clean vial. Then, 15 ml of ethyl acetate was added, and the extracts were evaporated to near dryness under nitrogen and then trans ferred to 4-mi concentrator tubes and brought up to 1 ml with ethyl acetate. After transferring to automatic sanqpler vials, gas chromatograms were run on duplicate 5-pl injections of the extracts. GC equipment and conditions included: 006548 FM-3925 -3- 3/22/79 Column - 6' x 1/8" O.D. stainless steel, 10% Carbowax 20M on 60/80 mesh Chromasorb W-AW; Chromatograph-HP 5713, Ni 63 Detector; Conditions - Inject Port 200 C., Detector 300 C., Flow 35 cc/min. Ar/CH. 95/5, Oven temp. 175 for 16 min., then up to 230 C. at 32/min. for 4 min. Statistical analysis and plotting of the data was done with the MINITAB package of the 3M TRAC computer service. RESULTS AND DISCUSSION Adsorption data for FM-3925 are given in TABLE I. The amount of FM-3925 removed from solution by the soil (Column C) was 83-90% of the initial amount at the various starting (initial) concentrations. Equilibrium concentrations in solution (C) in mg/1 are shown in Column B, and amounts adsorbed on the soil (x/m) in yg FM-3925 per gram soil are shown in Column F. The regression equation of the adsorption isotherm shown in FIGURE 1 was x/m = -1.7 + 77C, so that the adsorption coefficient, K, was 77. The linear shape of the adsorption isotherm indicated that FM-3925 adsorption on soil would be independent of concentration in solution. The high percentage adsorbed and the relatively high adsorption coefficient indicated that FM-3925 would be immobile in this sandy loam soil. Desorption data are given in TABLE II, and the desorption isotherms are shown in FIGURE 1. Of the amounts initially adsorbed on the soil, less than 15% was removed by the three desorption extractions with water (TABLE II, Column I). This small amount of desorption is also shown by the fairly horizontal slopes of the desorption isotherms compared with the slope of the adsorption isotherm. This very small amount of desorption was another indication of the immobility of FM-3925. The large amount adsorbed and the small amount desorbed suggests strong binding of FM-3925 to soil particles by intermolecular interactions involving electro static forces. The adsorption coefficient based on soil organic carbon, K , for FM-3925 would be 3,500 (100 K/% organic carbon = 100x330/2.2). Comparedwith K values for a selected group of pesticides and other fluorochemicals (TABLE I?f), 3,500 is quite high and is another indication of low mobility of FM-3925. These adsorption and desorption data, along with the low water solubility of FM-3925 (2.16 mg/1), provide good evidence that FM-3925 would have very low mobility in the sandy loam soil used in this study. In a 'Jcontrol" using the full-strength stock solution and no soil, it was found that 53% of the FM-3925 was -removed'from solution (100 x (2.16-1.007)/2.16), being adsorbed on the glass tubes (TABLE I V ) . Of the amount adsorbed, 20% (100 x (46.1-37.1)/46.1) was subsequently desorbed in three desorption extrac tions with DI water (the desorption isotherm is shown in FIGURE 2). 006549 FM-3925 -4- 3/22/79 This control experiment indicated that a considerable portion of the FM-3925 removed from solution (TABLE I, Column C) was being adsorbed on the glass rather than on the soil. In order to correct for this in the calculations, it would be necessary to conduct such controls at each of the initial con centrations. While such a correction would make it truly a "soil adsorption" experiment, it probably wouldn't change the conclusions. The % removed "by soil" would be lower, and the amounts on the soil (TABLE I, Column F) would be lower moving the adsorption isotherm down, but the adsorption coefficient (the slope of the isotherm) may not change. Likewise, the desorption isotherms may be shifted down without changing the desorption coefficients. Also, since there is no carbon in the glass, the adsorption coefficient based on organic carbon content of the soil, Koc , should remain the same. TERMS C - Concentration of chemical in solution atequilibrium x/m - Concentration of chemical adsorbed on soil at equilibrium R2 - Coefficient of determination K - Adsorption coefficient K - Adsorption coefficient based on soil organic carbon content REFERENCES Davidson, J. M., et al, 1975, Use of Soil Parameters for Describing Pesticide Movement Through Soils, USEPA, EPA-660-2/75-009. Davidson, J. M., 1976, "Vertical Movement and Distribution of Organics in Soils," Presented at Symposium on Nonbiological Transport and Trans formation of Pollutants on Land and Water, at National Bureau of Standards, Gaithersburg, MD, May 11-13, 1976. Hamaker, J. W., 1975, "Interpretation of Soil Leaching Experiments," in Chemicals, Human Health and the Environment, A Collection of Dow Scientific Papers, Vol. 1, Dow Chemical USA, Midland, MI 48640. Hamaker, J. W. and J. M. Thompson, 1972. "Adsorption" in Organic Chemicals in the Soil Environment. C, A. I. Goring and J. W. Hamaker TJeds.) Marcel Dekker, Inc., NY. SKW/CHS/cen 006550 TABLE I FM-3925 ADSORPTION DATA A Initial FM 3925 Cone., mg/1 2.160 (100%) 1.210 (56%) 0.691 (32%) 0.389 (18%) 0.216 (10%) 0.022 (1%) B Equil. Cone., C, mg/1 0.2135 + 0.0516 0.1455 +_ 0.0106 0.0940+0.0156 0.0490 +_ 0.0042 0.0370 +_ 0.0028 * C % Removed by Soil Glass Tubes J kAJ L x 100 90 88 86 87 83 D Total FM 3925 In Initial S o l 'n, mg (A x 0.04 liters) 0.0864 0.0484 0.0276 0.0156 0.0086 E Total FM 3925 In S o l 'n at Equil., mg (B x 0.04 liters) 0.00854 0.00582 0.00376 0.00196 0.00148 F FM 3925 Adsorbed on Soil, x/m, y g/g (D-E l(?/5g) 15.57 8.52 " 4.78 2.72 1.43 *A11 samples at the 1% initial concentration were below the detectable limit, and these were not included in the calculations. 006551 TABLE II FM-3925 DESORPTION ISOTHERM DATA A Equil. Cone, in Solution, C, mg/1 (Table 1, Column B) 0.2135 +_ 0.0516 0.1455 +_ 0.0106 0.0940 + 0.0156 0.0490+0.0042 0.0370 + 0.0028 B Equil. Cone, in First Desorption mg/1 0.1160 +_ 0.0057 0.0585 +_ 0.0035 0.0310 +_ 0.0057 0.0165+0.0007 0.0050 +_ 0.0057 C Equil. Cone, in Second Desorption mg/1 0.0605 +_0.0021 0.0410 * 0.0130 +_ 0.0028 0.0100 * 0.0010 +_ 0.0 D Equil. Cone, in Third Desorption mg/1 0.0525 + 0.0134 0.0260 * 0.0080 + 0.0099 0.0080 + 0 . 0 0.0035 +_ 0.0035 E Amount Adsorbed on Soil, x/m yg/g (Table 1, Column F) 15.57 8.52 4.78 2.72 1.43 F Amount on Soil After First Desorption, yg/g 14.64 8.05 4.53 2.59' 1.39 G Amount on Soil After Second Desorption, yg/g 14.16 7.72 4.43 2.51 1.38 H Amount on Soil After Third Desorption, yg/g 13.74 7.52 4.36 2.44 1.35 I Percent Desorbed CEE;H) 100 12 12 9 10 5 006552 TABLE III COMPARISON OF ADSORPTION COEFFICIENTS FOR A SELECTED GROUP OF PESTICIDES (Hamaker and Thompson, 1972) (mobile) (immobile) Chemical Koc Chloramben 12.8 (FC-143 ------------- ......... 17) 2,4-D 32 (FC-95 ............. ----------- 45) Propham 51 Bromacil 71 Monuron ' 83 Simazine 135 Propazine 152 Dichlobenil 164 Atrazine 172 Chloropropham 245 Prometone 300 Ametryn 380 Diuron 485 Prometryne 513 (FM 3925 ----------- ------- 3,500) Chloroxuron 4,986 (FM 3422 - - ------- ------- 15,000) Paraquat 20,000 DDT 243,000 006553 Amount on Soil, x/m, yg/g Soil 14. 0+ 12. CH- 1 0 . 0+ x/m = -1.7 + 77 C R2 = 0.972 8 .0+ 6 .0+ R = 0.968 R2 = 0.838 R = 0.635 !0. 0+ ! o . o o o+- ------- +-------------- + --------------. + -------------- +, 0. 060 0. 120 0* 180 0.240 ' Equilibrium Concentration in Water Phase, C, mg/1 ------ + 0. 300 V- FIGURE 1 FM-3925 ADSORPTION AND DESORPTION ISOTHERMS 006554 3 6 . 0+ + --------- .-- + -------------------------- + -- --------------------- + --------------------------.+ . 0.00 0.40 0.80 0. 0 0.60 Equilibrium Concentration in Solution, C, mg/1 FIGURE 2 FM-3925 DESORPTION FROM GLASS TUBE TABLE IV FM-3925 DESORPTION FROM GLASS TUBE DATA ---+C42 1.00 V S Initial First Desorption Second Desorption Third Desorption Equilibrium Cone, in Solution, C, mg/1 1.007 0.141 0.043 0.042 Amount Remaining on Tube, x/m, yig/Tube 46.1 40.5 38.8 27.1 I 006555 APPENDIX I RAW FM-3925 SOIL ADSORPTION DATA Cvg/i) Initial FM-3422 Cone., ug/1 Equil. Cone., C, g/l A B are Duplicate Samples, Duplicate-Injections into GC 2160 (100%) 1210 ( 5 6 %) 691 (32%) 389 (18%) 216 (10% 21.6 (1%) A 176,177 136,140 104,105 52,52 39,38 <5 B 250 154,151 85,80 46,45 35,34 <5 Equil. Cone, in First Desorption A B are Duplicate Samples,, Duplicate Injections into GC AB 120,119 56,56 28,25 16,16 <5, <5 <5 112,112 62,59 35,35 16,17 9,9 <5 Equil. Cone, in Second Desorption A B are Duplicate Samples; Duplicate Injections into GC AB 59,59 42,40 11 10,9 <5 <5 62,62 - 15 <5, <5 <5 Equil. Cone, in Third Desorption A 8 B are Duplicate Samples, Duplicate Injections into GC AB 60,63 26,26 <5, <5 8,8 6, 6 <5 44,42 - 15,15 8,8 <5, <5 <5 Initial 1st 2nd 3rd Control Control AB 815,872 185,191 86,84 82 1140,1200 96,94 <5, <5 <5, <5 006556 Equil. Cone, yg/1 AB 111 250 138 153 105 83 52 46 39 35 APPENDIX II AVERAGES OF DUPLICATE INJECTIONS FROM APPENDIX I (ug/i) First Desorption AB 120 112 56 61 27 35 16 17 <5 9 Second Desorption AB 59 62 41 11 15 10 <5 <5 Third Desorption AB 62 43 26 _ <5 15 88 6 <5 Initial First Desorption Second Desorption Third Desorption Control AB 844 itg/1 188 85 82 1170 yg/1 95 <5 <5 Mean +. S.D. 1007 + 231 141.5 + 6 5 . 8 43 + 59.4 41.5 + 57.3 006