Investigating the Biodegradability of a Fluorotelomer-Based Acrylate

Subscriber access provided by Queen Mary, University of London

Article

Investigating the Biodegradability of a Fluorotelomer-Based Acrylate Polymer in a Soil-Plant Microcosm by Indirect and Direct Analysis Keegan Rankin, Holly Lee, Pablo J Tseng, and Scott Andrew Mabury Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/es502986w • Publication Date (Web): 08 Oct 2014 Downloaded from http://pubs.acs.org on October 11, 2014

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Environmental Science & Technology is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 27

1 2 3 4 5 6 7 8 9 10 11 12

Environmental Science & Technology

Investigating the Biodegradability of a Fluorotelomer-Based Acrylate Polymer in a Soil-Plant Microcosm by Indirect and Direct Analysis Keegan Rankin, Holly Lee, Pablo J. Tseng and Scott A. Mabury* Department of Chemistry, University of Toronto, 80 St. George St., Toronto, Ontario, Canada, M5S 3H6 *Corresponding author: Phone: (416) 978-1780; Fax: (416) 978-3596; Email: [email protected] Abstract

13

Fluorotelomer-based acrylate polymers (FTACPs) are a class of side-chain fluorinated

14

polymers used for a variety of commercial applications. The degradation of FTACPs through

15

ester hydrolysis and/or cleavage of the polymer backbone could serve as a significant source of

16

perfluoroalkyl carboxylates (PFCAs). The biodegradation of FTACPs was evaluated in a soil-

17

plant microcosm over 5.5 months in the absence/presence of wastewater treatment plant

18

(WWTP) biosolids, using a unique FTACP determined to be a homopolymer of 8:2

19

fluorotelomer acrylate (8:2 FTAC). Though structurally different from commercial FTACPs, the

20

unique FTACP possesses 8:2 fluorotelomer side chain appendages bound to the polymer

21

backbone via ester moieties. Liberation and subsequent biodegradation of the 8:2 fluorotelomer

22

appendages was indirectly determined by monitoring for PFCAs of varying chain lengths (C6-

23

C9) and known fluorotelomer intermediates by liquid chromatography tandem mass

24

spectrometry (LC-MS/MS). A FTACP biodegradation half-life range of 8-111 years was

25

inferred from the 8:2 fluorotelomer alcohol (8:2 FTOH) equivalent of the unique FTACP and the

26

increase of degradation products. The progress of FTACP biodegradation was also directly

27

monitored qualitatively using matrix-assisted laser desorption/ionization time-of-flight (MALDI-

28

TOF) mass spectrometry. The combination of indirect and direct analysis indicated that the

ACS Paragon Plus Environment

1


29

model FTACP biodegraded predominantly to perfluorooctanoate (PFOA) in soils, and at a

30

significantly higher rate in the presence of a plant and WWTP biosolids.

Page 2 of 27

31 32 33

Introduction Fluorotelomer-based polymers (FTPs) are commonly used surface protectants in the

34

carpet, textile, upholstery and paper industries.1 The manufacture of FTPs constitutes >80% of

35

all fluorotelomer-based raw materials produced worldwide.2 Recent concerns have been raised

36

over the role of FTPs as perfluoroalkyl carboxylate (PFCA) precursors.3,4 Residual

37

fluorotelomer alcohols (FTOHs) are known to be present in FTP materials,5,6 and have been

38

demonstrated to readily biodegrade to PFCAs in aerobic soil and waste water treatment plant

39

(WWTP) media.7-12 At levels 7 CF2), which have a demonstrated ability to accumulate in biota.20,21

55

Russell et al.3 proposed two potential degradation pathways of FTPs: 1) cleavage of the

56

ester or urethane linkage or 2) breakage of the carbon-carbon backbone. Cleavage of the linking

57

moiety would release the bound fluorotelomer appendage as FTOHs that then degrade to PFCAs.

58

Recent studies demonstrated that pathway 1 could occur via microbial hydrolysis of ester

59

linkages of fluorotelomer-based material under aerobic environments, such as polyfluoroalkyl

60

phosphate esters (PAPs) and fluorotelomer stearate monoester (FTS).22,23 Alternatively,

61

breaking the polymer backbone would yield smaller oligomeric species, which could more

62

readily biodegrade because of the lower molecular weight. If the linking ester moieties are

63

inaccessible to microbes, then pathway 2 could occur via β-oxidation of the polymer backbone

64

as reported for polyacrylic acid.24

65

The approach for assessing the biodegradability of FTPs used to date, was to measure

66

both intermediates and terminal PFCA products that result from the biotransformation of FTOHs

67

rather than analytically probing the polymer directly. This indirect approach was used in the

68

three FTP biodegradation studies.3,4,13 However, the presence of intermediates and PFCAs does

69

not directly confirm FTP degradation, as the PFCAs themselves may be present in commercial

70

products or result from the degradation of other fluorotelomer-based residual materials. As such,

71

the detection of target analytes above residual levels was generally used to identify FTP

72

degradation,4 a difficult task if there is a large background signal. In two parallel studies, the

73

biodegradation half-lives for FTACPs and FTURPs were calculated to be 1200-1700 and 79-241

74

years respectively, based on polymer mass.3,13 In a separate study, Washington et al.4 reported a


3


75

biodegradation half-life for FTACPs of 870-1400 years based on polymer mass, but also

76

suggested that the half-life could be closer to 10-17 years when normalized to the polymer

77

particle surface area. The discrepancy between these half-lives is a reason the biodegradability

78

of FTPs remains widely debated.

Page 4 of 27

79

The objective of this study was to evaluate the biodegradation of a unique FTACP in a

80

soil-plant microcosm over 5 months. The unique FTACP was synthesized in-house using 8:2

81

fluorotelomer acrylate (8:2 FTAC) as the primary monomer, and exhaustively purified by

82

removing volatile FTACs and/or FTOH residuals prior to incubation. Biodegradation of the

83

model FTACP was evaluated under several different soil conditions, including soils amended

84

with WWTP biosolids and sown with the alfalfa species, Medicago truncatula. Quantification of

85

degradation products by liquid chromatography tandem mass spectrometry (LC-MS/MS) served

86

as an indirect means to determine FTACP biodegradation and were used to estimate FTACP

87

biodegradation half-lives. We also report herein, the first direct evidence of FTACP

88

biodegradation using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF)

89

mass spectrometry to analyze the polymer itself.

90 91 92 93

Experimental Chemicals. A complete list of chemicals used in this study can be found in the Supporting Information (SI).

94

Microcosm Materials. Sandy loam soil was collected from an agricultural farmland

95

(Northumberland County, ON; 44o05’N, 78o01’W) in 2009 and sieved with a 2 mm stainless

96

steel mesh. Soil characterization was performed by SGS AgriFood Laboratories (Guelph, ON)

97

and reported as follows: pH 5.5; 1.8% organic matter; cation exchange capacity of 96 µmol/g; 49


4

Page 5 of 27


98

mg/kg of NaHCO3-extractable P; 63% sand, 32% silt and 5% clay. WWTP biosolid material

99

(30% solids) was obtained from the North Toronto WWTP (Toronto, ON) in 2009. The alfafa

100

plant species Medicago truncatula was grown from seeds donated by the Stinchcombe research

101

group (Department of Ecology and Evolutionary Biology, University of Toronto, ON).

102

FTACP Polymerization. Multiple approaches were attempted to synthesize a FTACP

103

possessing three repeating monomers, but were unsuccessful. A unique FTACP homopolymer

104

was synthesized in-house by aqueous dispersion following two commercial patents,14,15 and is

105

detailed in the SI. Briefly, 8:2 FTAC and butyl acrylate were added to an aqueous solution of

106

dodecyl amine hydrochloride and hexadecylthiol in a round bottom flask equipped with a

107

magnetic stirrer and dry ice condenser. The solution was purged with nitrogen for 2.5 hours at

108

5oC and then a cold solution of vinylidene chloride and acetone was added. The polymerization

109

was initiated with 2,2´-azobis(2-methylpropionamide) dihydrochloride (AIBA) and proceeded

110

for 15 hours at 80oC. Upon completion, the aqueous dispersion was filtered and the opaque

111

FTACP material was collected.

112

Residual Removal. Post-polymerization, a series of wash and heat purging steps were

113

used to remove residual FTOH and FTAC impurities. The FTACP material was placed under

114

vacuum while periodically washed with a 80:20 methanol:water solution for 14 days. The

115

FTACP material was then melted using a 95oC oil bath while continuously purged with carbon-

116

filtered air for 20 days. A fraction of the FTACP material was then heated in the same manner

117

for 3 days during which any volatile compounds were collected in XAD cartridges. The

118

cartridges were extracted with ethyl acetate and analyzed by gas chromatography-mass

119

spectrometry (GC-MS). Although this approach differs from the method recently reported by

120

Washington et al.,25 our method was also found to exhaustively extract volatile FTOHs and


5


121

FTACs. The purified FTACP was determined to contain 4.71 and 2.63 nmole residual 8:2

122

FTOH and 8:2 FTAC per gram of FTACP representing 2.2 x 10-4 and 1.4 x 10-4 wt%,

123

respectively. Low PFCA levels, 4.7 x 10-7 wt%, were observed as impurities in the purified

124

FTACP, and explain the PFCAs concentrations observed at 0 months.

Page 6 of 27

125

FTACP Characterization. The unique FTACP was characterized by differential

126

scanning calorimetry (DSC) and MALDI-TOF mass spectrometry. DSC procedures and results

127

are presented in the SI. MALDI-TOF characterization was carried out using a Waters

128

Micromass MALDI micro MX™ TOF mass spectrometer (Waters Corporation, Milford, MA)

129

equipped with a nitrogen laser (λ = 337.1 nm) operated at a frequency of 5 Hz and rastered in a

130

pre-set pattern. Mass spectra were acquired in positive ion and reflectron modes using a flight

131

tube voltage of 12 kV. A total of 100 mass spectra were acquired per sample, and summed using

132

Waters Mass Lynx V4.1 mass spectrometry software.

133

FTACP samples were prepared for MALDI-TOF analysis using the two-layer dried

134

droplet method.26,27 Dithranol served as the matrix and lithium trifluoroacetate as the

135

cationization agent, and were co-dissolved in trichloromethane (CHCl3) at 10 mg/mL and 1

136

mg/mL, respectively. FTACP samples were prepared in α,α,α-trifluorotoluene (TFT) at 10

137

mg/mL. Deposition of 1µL of the matrix:cationization agent solution onto a stainless steel

138

Waters MALDI target plate served as the first layer. A 1µL aliquot of the FTACP solution was

139

deposited as the second layer on top of the dried matrix:cationization agent solution.

140

Biodegradation Experimental Design. The five experimental variables were prepared

141

as follows: (1) Soil Control – soil without biosolids (n = 1 per timepoint); (2) Plant/Biosolids

142

Control – biosolids-amended soil sown with plant seeds (n = 3 per timepoint); (3) FTACP/Soil –

143

soil without biosolids mixed with 50 mg FTACP (n = 3 per timepoint); (4) FTACP/Plant – soil


6

Page 7 of 27


144

without biosolids sown with plant seeds mixed with 50 mg FTACP (n = 3 per timepoint); (5)

145

FTACP/Plant/Biosolids – biosolids-amended soil sown with plant seeds mixed with 50 mg

146

FTACP (n = 3 per timepoint).

147

Biosolids-amended soils were prepared at a mixing rate of 16 g biosolids/kg of soil (~8.7

148

metric dry tons/ha) in an OdjobTM concrete mixer (Scepter Corporation, Toronto, ON). This rate

149

is similar to the 5-year maximal application rate of 8 tons/ha permitted in Ontario.28

150

Approximately 600 g soil and biosolids were transferred into each pot. Between 5–10 Medicago

151

truncatula seeds were planted in each pot for the three conditions, Plant/Biosolids Control,

152

FTACP/Plant and FTACP/Plant/Biosolids, followed by inoculation of cultured rhizobia.

153

Preparation of the rhizobia culture is described in the SI. Catch plates were placed under each

154

pot to capture some, though not all, target analytes that may have leached from the soil during

155

watering of the plants. All pots were kept in a greenhouse (Earth Sciences Centre, University of

156

Toronto, ON) for 5.5 months under natural sunlight and supplementary illumination (200

157

µmol/m2/sec) at a temperature regime of 25/21oC day/night, and watered daily.

158

Soils were sampled at 1.5, 3.5 and 5.5 months by sacrificing the entire pot, and then

159

immediately mixed with 100–300 mg of sodium azide (NaN3) to halt microbial activity. Initial

160

concentrations of target analytes were measured in soil using one pot (n = 1) of all five

161

conditions prior to the addition of the model FTACP. Soil was sampled in triplicate (n = 3) from

162

each of the three pots in all conditions at each time point, except for the Soil Control in which

163

soil was sampled from 1 pot. For Plant/Biosolids Control, FTACP/Plant and

164

FTACP/Plant/Biosolids, the plant shoots and roots were harvested, cleaned of soil particles and

165

archived together. Catch plates were also archived. All archived microcosm compartments were

166

stored at 4oC until analysis.


7


167

Page 8 of 27

Extraction and Analysis. Soil extractions was performed on 2 g soil samples by

168

sonication at 60oC for 15-20 minutes in 5 mL of a basic methanol (1% (v/v) ammonium

169

hydroxide). Following centrifugation at 6000 rpm, the supernatant was decanted into a new

170

polypropylene tube, and the soil extracted a second time. The supernatants were combined and

171

blown to dryness. Plant matter was lyophilized and homogenized finely using a mortar pestle,

172

and 2 g samples extracted twice in 10 mL basic methanol sonication at 60oC for 15-20 minutes.

173

The extracts were cleaned using ENVI Carb cartridges (Supelclean, 1 mL/100 mg) and blown to

174

dryness. Catch plates were rinsed with 10 mL basic methanol and blown to dryness. Soil, plant

175

and catch plate extracts were reconstituted with 2 mL methanol, passed through 0.2 µm Nylon

176

filters, and then analyzed using an Agilent 1100 high pressure liquid chromatography (HPLC)

177

coupled to an Applied Biosystems/MDS Sciex API4000 triple quadrupole MS (Concord, ON)

178

operated in negative electrospray ionization mode. Chromatographic separation was performed

179

using a GeminiNX C18 column (4.6 x 50 mm, 3 µm; Phenomenex, Torrance, CA). Detailed

180

instrumental parameters used be found in the SI.

181

The unique FTACP was extracted from soils using α,α,α-trifluorotoluene (TFT). For

182

each pot, 2 x 5 g soil samples were each extracted with 5 mL of TFT by sonication and vortexing

183

for 5 minutes at room temperature. The two extracts per pot were combined and the solids

184

removed. The extract was then blown to dryness under nitrogen and re-constituted in 1 mL of

185

TFT. MALDI-TOF analysis was carried out using the procedures described above.

186

Quality Assurance (QA). Quantitation of the PFCAs, fluorotelomer carboxylates

187

(FTCAs) and fluorotelomer unsaturated carboxylates (FTUCAs) was performed using mass-

188

labeled internal standards except for those analytes where no corresponding mass-labeled

189

standards were available at the time of the experiment. In these few cases, quantification was


8

Page 9 of 27


190

performed using structurally similar internal standards as surrogate standards (Table S1). Spike

191

and recoveries from soil, plant and catch plate ranged from 51-132, 73-135 and 32-105%,

192

respectively. Additional QA information is provided in the SI.

193 194 195

Results and Discussion FTACP Characterization. Structural characterization of the unique FTACP was

196

performed by MALDI-TOF producing a characteristic pattern indicative of a synthetic polymer

197

with repeating signals having a spacing of 518 Da for both major and minor series shown in SI

198

Figure S2. The number average molecular weight (Mn, Equation 1), weight average molecular

199

weight (Mw, Equation 2) and polydispersity index (PDI, Equation 3) were calculated from the

200

major repeating series to be 3007 and 3747 Da, and 1.25, respectively. These values are below

201

the ~40000 molecular weight postulated by Russell et al. for commercial FTACPs,3 which could

202

result in our unique FTACP being more susceptibility to biodegradation.

203 204 205 206 207 208 209 210 211 212

Mn = ΣMiNi ΣNi

(Eq. 1)

Mw = ΣMi2Ni ΣMiNi

(Eq. 2)

PDI = Mw Mn

(Eq. 3)

As the intended FTACP structure was to contain three repeating units and resemble the

213

suggested structure of commercial FTACPs (Figure 1A),3 the monomeric species 8:2 FTAC,

214

butyl acrylate and vinylidene chloride were all included in the polymerization. However, after

215

close inspection of the mass spectrum (Figure S2) and a comparison of the experimental and

216

theoretical isotopic pattern for the 1819 m/z signal (Figure S3), it was determined that neither

217

butyl acrylate nor vinylidene chloride were incorporated into the FTACP. The peak spacing of


9


Page 10 of 27

218

518 Da corresponds to the mass of 8:2 FTAC and confirms the successful polymerization of a

219

FTACP. Our unique FTACP was determined to be solely a homopolymer of 8:2 FTAC

220

containing hydrogen and hexadecylthiol end groups (Figure 1B), and have primarily between 2

221

to 16 fluorotelomer appendages. Though the two FTACPs shown in Figure 1 have structural

222

differences, our unique FTACP (Figure 1B) possesses certain features that make it a suitable

223

surrogate to investigate the stability of commercial FTACPs. Firstly, the MALDI-TOF results

224

demonstrated that our FTACP contains 8:2 fluorotelomer appendages covalently bound to the

225

hydrocarbon backbone through an ester linkage. FTACs are the principle monomer used in the

226

preparation of commercial FTACPs,14,15 and have the same bonding of fluorotelomer appendages

227

to the polymer backbone. Secondly, the side-by-side configuration of the 8:2 fluorotelomer

228

appendages in our FTACP could render the ester moiety more sterically constrained than a

229

commercial FTACP, which have additional interspersed non-fluorinated monomers. The

230

presence of non-fluorinated monomers could affect the lability of the ester moieties making

231

commercial FTACPs more susceptible to microbial hydrolysis. Thus, our unique FTACP likely

232

represented a suitable experimental probe for assessing the lability of FTPs having moderate

233

molecular weights.

234

Indirect Analysis of FTACP Biodegradation. The observed intermediate and product

235

trends for FTACP/Soil, FTACP/Plant and FTACP/Plant/Biosolids are consistent with the

236

biotransformation of 8:2 FTOH to PFOA previously reported in aerobic soil,10,11 which suggests

237

either degradation of the unique FTACP or residual 8:2 FTOH or 8:2 FTAC. From the 50 mg of

238

unique FTACP spiked into each pot, the 8:2 FTOH equivalence was calculated to be 8.88 x 104

239

nmole using the Mn and Mw values as outlined in the SI. As described earlier, residual 8:2 FTOH

240

and 8:2 FTAC in the exhaustively purified FTACP material were estimated to be 4.71 and 2.63


10

Page 11 of 27


241

nmole per gram of FTACP, which equates to as much as 0.236 and 0.132 nmole residual 8:2

242

FTOH and 8:2 FTAC per pot (Table 1). For the control pots, Soil Control and Plant/Biosolids

243

Control, PFOA was observed to have the highest background level at 5.87 and 36.5 nmole,

244

respectively. Therefore, the detection of intermediates and products, as much as 1800 nmole at

245

5.5 months, presumably resulted from the biotransformation of the unique FTACP and not from

246

the conversion of residuals.

247

FTACP biodegradation was inferred from the observed intermediates, 8:2 FTCA and 7:3

248

FTCA, 8:2 FTUCA and 7:3 FTUCA, and PFCA (C6-C9) products detected in soil, plant and

249

catch plate (Tables S6-S11). The inclusion of the stable intermediate 7:3 FTCA and terminal

250

PFCAs C6-C8 expands upon the conceptual model used by Russell et al. in their FTACP

251

biodegradation study,3 which solely considered the primary biotransformation of 8:2 FTOH to

252

PFOA via 8:2 FTOH  8:2 FTCA  8:2 FTUCA  7:2 secondary FTOH (sFTOH)  PFOA.

253

Unfortunately, the analysis of 8:2 FTOH was omitted from our investigation as any volatile

254

products released from the soil and/or plants could not be quantified because the pots were

255

exposed to the open atmosphere of the greenhouse; thus the overall proportion of products, as

256

determined through indirect measurement, from FTACP degradation is likely reported here.

257

Incubation of the unique FTACP in all soil conditions resulted in the accumulation of

258

perfluorohexanoate (PFHxA), perfluoroheptanoate (PFHpA) and PFOA concurrently with the

259

reduction of 8:2 FTCA and 8:2 FTUCA as shown in Figure 2 for FTACP/Plant; similar trends

260

are illustrated in SI Figure S5 (FTACP/Soil) and S6 (FTACP/Plant/Biosolids). As expected,

261

PFOA was the dominant product constituting 57, 70 and 80% of products in all microcosm

262

compartments in FTACP/Soil, FTACP/Plant and FTACP/Plant/Biosolids, respectively (Table

263

S13). The formation of the stable intermediate 7:3 FTCA is consistent with transformation


11


Page 12 of 27

264

pathways of 8:2 FTCA and 8:2 FTUCA observed in aerobic microbial degradation.29

265

Subsequent dealkylation and defluorination steps of 7:3 FTCA presumably explains the

266

production of perfluorohexanoate (PFHxA) and perfluoroheptanoate (PFHpA).30 The

267

accumulation of 7:3 FTCA, PFHxA and PFHpA varied depending on the experimental

268

conditions, but all were observed to be minor products. The α-oxidation of 8:2 FTOH to PFNA

269

has been reported with different mammalian hepatocytes,31-33 but at ≤1% of the total stable

270

products; PFNA was only observed within background levels in this study.

271

Measured concentration of target analytes in soil varied substantially amongst

272

FTACP/Soil, FTACP/Plant and FTACP/Plant/Biosolids (Table 1) and detailed in the SI (Table

273

S6 and S9), which suggests an influence between the degree of FTACP biodegradation and

274

probable microbial activity. At 5.5 months, the summed analytes level in FTACP/Soil,

275

FTACP/Plant and FTAC/Plant/Biosolids were determined to be 2.54 x 102 nmole, 6.94x 102

276

nmole and 1.80 x 103 nmole, respectively. Enhanced microbial activity has been demonstrated

277

to increase with plant production,34 and is consistent with the increase in analytes for

278

FTACP/Plant and FTACP/Plant/Biosolids. PFCAs and PFCA precursors arising from the

279

WWTP biosolids themselves were accounted for using a control experiment in biosolid amended

280

soil and an alfalfa plant (Plant/Biosolids Control), as described in the SI. The observed

281

concentrations in these controls were significantly lower than those reported for

282

FTACP/Plant/Biosolids.

283

Target analytes were also observed to increase in alfalfa plants throughout incubation.

284

Uptake into plants has previously been reported for PFOA and PFOS,35-37 consistent with the

285

increase of PFHxA, PFHpA and PFOA levels in the plant as observed in this study (Figure 2B

286

and S6B). Plant PFOA levels were observed up to 44.0 ± 12.7 nmole and 49.3 ± 12.9 nmole for


12

Page 13 of 27


287

PFOA at 5.5 months for FTACP/Plant and FTAC/Plant/Biosolids (Table S7). The relative

288

percentage of PFCAs that translocated into the plant decreased with increasing PFCA chain

289

length (Table S12). Most intermediates in the plants fell below the LOD or were detected at

290

levels

325

FTACP/Plant ≈ FTACP/Plant/Biosolids).

326

The MALDI-TOF results were then re-plotted as a function of relative intensity with

327

respect to the most abundant signal; 1301 m/z. In FTACP/Soil pots, the relative signal

328

distribution 1.5, 3.5 and 5.5 months did not differ significantly (Figure 4A), whereas, an

329

increased contribution from the higher order fluorotelomer units resulted in a change in the

330

relative signal distribution from 1.5 to 3.5 and 5.5 months for FTACP/Plant and

331

FTACP/Plant/Biosolids pots (Figure 4B and 4C). Additionally, a greater increase in the Mn and

332

Mw was calculated from 1.5 to 3.5 and 5.5 months for FTACP/Plant and FTACP/Plant/Biosolid


14

Page 15 of 27


333

pots (Table S17). Thus, an increase in the alteration of FTACPs having a lower molecular

334

weight (

Investigating the Biodegradability of a Fluorotelomer-Based Acrylate

Recommend Documents