EPA 600/R-12/703 July 2012 | www.epa.gov/ord

Removal of Peruorocarboxylic Acids (PFCAs) from Carpets Treated with 

Stain-protection Products by Using Carpet Cleaning Machines

 ce of Research and Development
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

EPA/600/R-12/703 

July 2012 

Removal of Perfluorocarboxylic Acids (PFCAs) from 

Carpets Treated with Stain-protection Products by 

Using Carpet Cleaning Machines 

Heidi F. Hubbard1, Zhishi Guo2, and Kenneth A. Krebs
 

U.S. Environmental Protection Agency
 

Office of Research and Development
 

National Risk Management Research Laboratory
 

Air Pollution Prevention and Control Division
 

Research Triangle Park, NC 27711
 

and
 

Sara K. Metzger, Corey A. Mocka, Robert H. Pope, and Nancy F. Roache
 

ARCADIS US, Inc.
 

4915 Prospectus Dr., Suite F
 

Durham, NC 27713
 

1 Current address: ICF International, 2222 East NC-54, Suite 480, Durham, NC 27713 

2 Corresponding author (guo.zhishi@epa.gov) 
 

 

 

Notice 

This document has been reviewed in accordance with the U.S. Environmental Protection Agency 

policy and approved for publication. Mention of trade names or commercial products does not 

constitute endorsement or recommendation for use. 

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Executive Summary 

E.1 Background and Objective 

Perfluorinated carboxylic acids (PFCAs) are fully fluorinated organofluorine compounds with a 

carboxylic acid functional group (-COOH). As a member of the PFCA family, perfluorooctanoic 

acid (PFOA) and its salts were once used as a surfactant in the manufacturing of perfluorinated 

polymers such as polytetrafluoroethylene (PTFE). Thus, PFOA and its salts may exist as residuals 

in PFTE or other fluoropolymer products. PFOA and other PFCAs may also exist in fluorotelomer 

products (such as stain-repellants) as unwanted reaction by-products. The U.S. Environmental 

Protection Agency (EPA) began investigating PFOA and its related chemicals in the 1990s and 

found that it is very persistent in the environment, is found at low levels both in the environment 

and in the blood of the general U.S. population, and causes developmental and other adverse 

effects in laboratory animals (U.S. EPA, 2012). In 2006, EPA and the eight major companies in the 

fluoropolymer and fluorotelomer industry launched the PFOA Stewardship Program, in which 

companies committed to reduce global facility emissions and product content of PFOA and related 

chemicals by 95 percent by 2010 and to work toward eliminating emissions and product content by 

2015 (U.S. EPA, 2012). 

Previous studies have shown that consumer articles that are made from or treated with 

fluoropolymers and fluorotelomers products may contain low levels of PFCAs. PFCAs are found 

in a variety of consumer products, including, but not limited to, treated clothing and textiles, floor 

care products, paper containers for food, and carpets. Among the consumer articles examined by 

Washburn et al. (2005) and Guo et al. (2009), carpet that was pretreated with stain-repellents and 

carpet that was treated with after-market stain-resistant formulations were the largest PFOA 

sources in homes. Once PFCAs are brought into the indoor environment, they are expected to stay 

for a long period of time because PFCAs are persistent in the environment and because most 

PFCAs are semi-volatile compounds. PFCAs can also be absorbed by household dust, which may 

serve as a source for inhalation or digestive exposure. Therefore, it is important to understand the 

feasibility of in-situ removal of PFCAs from treated carpet. To our knowledge, this issue has not 

been addressed by any publications in the existing literature. 

The main goal of this study was to quantify the efficiency of common carpet cleaning methods ― 

steam cleaning and hot water extraction ― in the removal of PFCAs from residential and 

commercial carpet that was manually treated with stain-protection solutions. The objective was to 

determine if these cleaning techniques are viable methods for reducing indoor exposure to PFCAs 

associated with carpet that was previously treated with PFCA-containing products. 

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E.2 Test Method 

E.2.1 Test Facility 

The carpet cleaning experiments were performed under close-to-realistic conditions in the U.S. 

EPA research house located in Cary, NC. The research house is a three-bedroom, ranch-style house 

with a crawl space, a central, forced-air heating system that uses natural gas, and an electric airconditioning system. The total floor area is 126 m2

. The master bedroom (MB) and front-corner 

bedroom (FCBR) were used for the carpet cleaning tests. 

E.2.2 Test Materials 

Carpet 

By the time this project started, mill-treated carpet containing high levels of PFCAs were no longer 

available in local stores, an indication that the manufacturers had taken actions to reduce or 

eliminated PFCAs from their products. In this study, two types of carpet with low-levels of 

background PFCAs were treated with after-market carpet treatment solutions (see below). The two 

types of carpet were: 1) residential carpet that was Green-Label Certified by the Carpet and Rug 

Institute (CRI) with a pile yarn content of 100% polytrimethylene terephthalate (PTT) – a product 

from recycled plastic bottles – with a textured cut pile and a woven polypropylene backing, and 2) 

commercial carpet made with Antron® fiber, a nylon 6,6, hollow-filament fiber with a soilresistant treatment incorporated into the fiber. This type of commercial carpet is commonly used in 

schools and offices. The PFCA content in these carpets were below 8 ng/g. These background 

PFCAs may have come from recycled old carpet. 

Carpet Treatment Solutions 

Two commercial carpet stain-protection treatments (CT-1 and CT-2) were used to treat the carpet. 

The total PFCA contents in these treatment solutions are presented in Section E.3.1 below. 

Carpet Cleaning Machines 

Two carpet cleaning machines were chosen to clean the carpets after treatment with a carpet stainprotection solution: 1) a residential cleaning machine (CM-1), the Rug Doctor Mighty Pro model 

MP C-20, and 2) a portable professional steam cleaner (CM-2), the Century 400 Ninja Warrior. 

The residential unit uses hot tap water for the extraction with no additional heating during the 

cleaning process; the professional steam cleaner has an 1850-watt, in-line heater that produces 

steam. Figure E.1 shows the Rug Doctor (front) and the Ninja Warrior (rear). 

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E.1. Residential and commercial carpet cleaning machines used for the tests 

Carpet Cleaning Detergent 

Two carpet cleaning agents were selected to test the removal of PFCAs from carpets, i.e., a 

residential carpet cleaning detergent (CD-2) recommended for use with the residential machine 

(CM-1) and a commercial carpet cleaning detergent (CD-1) chosen for use with the commercial 

machine (CM-2). According to the material safety data sheets (MSDSs), CD-1 contains 3 to 6% of 

dipropylene glycol methyl ether (CAS# 34590-94-8) while CD-2 contains 1 to 5% of sodium 2­

ethylhexyl sulfate (CAS# 126-92-1) and <1% of branched tridecylalcohol (CAS# 69011-36-5). 

Prior to use, each clean agent was screened for PFCAs. The residential detergent measured most 

PFCAs below the quantification limits of the instrument, with perfluorotridecanoic acid (C13) 

having the highest concentration at 3 ng/mL. The commercial detergent had only trace levels of C8 

through C10, and all were below the practical quantification limits. 

E.2.3 Test Procedure 

The test carpet was installed on a solid urethane carpet pad on the bedroom floors. Prior to the 

application of the carpet treatment solution, carpet samples were taken to determine the PFCA 

content in untreated carpet. The carpet was then treated with a carpet treatment solution. 

Following the application of the treatment and a subsequent 48-hour drying period, a series of three 

carpet cleanings was performed. A drying period of at least 48 hours followed each cleaning before 

carpet samples were collected. The first set of tests used only hot water or steam for the cleaning 

process to determine the efficiency of each carpet cleaning machine’s method of removing the 

applied PFCAs. Additionally, four experiments, one of which was a duplicate test, were conducted 

using cleaning detergents (CD-1 or CD-2) in conjunction with a carpet cleaning machine to assess 

any additional PFCA removal. The complete experimental test matrix is summarized in Table E.1. 

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Table E.1. Experimental matrix for testing of carpet care treatments 

Experiment Carpet Type Carpet Treatment 

(CT) 

Cleaning 

Machine (CM) 

Carpet 

Detergent (CD) 

1 Commercial CT-1 CM-2 None 

2 Commercial CT-2 CM-2 None 

3a Residential CT-1 CM-1 None 

4 Residential CT-1 CM-2 None 

5 Residential CT-2 CM-2 None 

6 Commercial CT-2 CM-2 CD-1 

7 Residential CT-1 CM-1 CD-2 

8b Residential CT-1 CM-1 CD-2 

9 Residential CT-2 CM-2 CD-1 

a Initial scouting test; b Duplicate test. 

E.3 Findings 

E.3.1 Extractable PFCAs in Carpet Treatment Solutions 

The total extractable PFCAs (i.e., the sum of all PFCAs quantified) in the two carpet treatment 

solutions were, respectively, 6360 and 7500 ng/g. The distributions of individual PFCAs are shown 

in Figure E.2. The error bars represent ±1 standard deviation (n = 4 for CT-1 and n = 6 for CT-2). 

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0 

500 

1000 

1500 

2000 

2500 

Concentration (ng/g) 

CT-1 

CT-2 

Figure E.2 PFCA contents in the two carpet treatment solutions (CT-1 and CT-2) 

E.3.2 PFCA Content in Carpet Before and After Cleaning 

As an example, Figure E.3 shows the general patterns of the carpet cleaning tests. The application 

of the carpet treatment solution increased the PFCA content in the carpet and, following each 

carpet cleaning event, there was reduction of PFCA content in the carpet. In this experiment, the 

total reduction after three rounds of cleaning was approximately 50%. 

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0 

500 

1000 

1500 

2000 

2500 

3000 

Pre-Application Post-Application Post-Cleaning 

Round 1 

Post-Cleaning 

Round 2 

Post-Cleaning 

Round 3 

Concentration (ng PFCAs / g carpet) 

Figure E.3 Average total PFCAs in composite carpet fiber samples for Experiment 4 

[Residential carpet treated with carpet treatment solution CT-1; hot-water extraction with the residential 

cleaning machine (CM-1); no detergent] 

E.3.3 Percent Removal of PFCAs by Carpet Cleaning 

For each experiment, the percent removal of total PFCAs after the final cleaning was calculated by 

comparison of the total PFCA concentration after application of the carpet treatment to the total 

PFCA concentration after the third round of cleaning. As shown in Figure E.4, the percent removal 

of the total PFCA ranged from 26% to 76% with an average of 55%. 

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100% 

80% 

60% 

40% 

20% 

0% 

Experiment ID 

Total Percent Removal 

1 2 3 4 5 6 7 8 9 

Figure E.4. Percent removal of total PFCAs following three rounds of cleaning for each experiment 

E.3.4 Effect of Cleaning Machine 

The two types of cleaning machines yielded similar removal efficiency for total PFCAs. The 

difference shown in Table E.2 is not statistically significant. 

Table E.2 Comparison of the removal efficiency of the two cleaning machines for total PFCAs 

following three rounds of cleaning 

ID Machine Type Cleaning Method Mean SD n 

CM-1 Residential Hot-water extraction 52.2% 6.2% 3 

CM-2 Commercial Steam cleaning 57.4% 18.5% 4 

E.3.5 Effect of Detergent 

Using detergent during carpet cleaning showed modest increase in removal efficiency (Figure E.5). 

However, comparison of the test with detergent CD-1 with the test without using any detergent 

yielded the two-tailed P value of 0.1063. By conventional criteria, this difference is considered to 

be not statistically significant. 

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% Removal

100% 

80% 

60% 

40% 

20% 

0%
�

CD-1 CD-2 None
�

Detergent 

 Figure E.5 Effect of using carpet detergent on the average removal efficiency for total PFCAs 

following three rounds of cleaning 

E.4 Research Implications 

The average American home has about 1000 square feet (93 m2) of carpet. Previous research has 

shown that treated carpets represent one of the largest sources of PFCAs in homes. Additionally, 

PFCAs are highly stable, with the potential for a long residence time indoors, and can also bind to 

house dust, making it difficult to remove the PFCAs from the indoor environment. The results of 

this research indicated that cleaning carpets can reduce the amount of PFCAs they contain, but the 

chemicals cannot be totally eliminated by the cleaning process. Carpet cleaning by hot-water or 

steam cleaning is only modestly effective in removing PFCAs. On average, the removal efficiency 

for each round of cleaning is approximately 20%. At this removal efficiency, it requires three, 

seven, and ten rounds of cleaning to remove, respectively, 50%, 80%, and 90% of total PFCAs in 

treated carpet. 

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Table of Contents 

Notice .................................................................................................................................................... 1 

Executive Summary ............................................................................................................................ 2 

Table of Contents .............................................................................................................................. 10 

List of Figures .................................................................................................................................... 12 

List of Tables...................................................................................................................................... 13 

Acronyms and Abbreviations.......................................................................................................... 15 

1. Introduction................................................................................................................................. 16 

1.1 Background...................................................................................................................................16
 

1.2 Goal and Objective .......................................................................................................................17
 

2. Materials and Methods............................................................................................................... 18 

2.1 Test Facility...................................................................................................................................18
 

2.2 Test Materials................................................................................................................................19
 

2.2.1 Carpet Selection for Research House Experiments.........................................................19
 

2.2.2 Professional Carpet Treatment Solutions........................................................................19
 

2.2.3 Carpet Cleaning Machines...............................................................................................20
 

2.2.4 Carpet Cleaning Detergents.............................................................................................21
 

2.3 Experimental Design ....................................................................................................................21
 

2.4 Test Procedure ..............................................................................................................................22
 

2.4.1 Layout of Carpet Sampling Sections...............................................................................22
 

2.4.2 Dilution and Application of the Carpet Treatment..........................................................23
 

2.4.3 Cleaning of Carpets..........................................................................................................25
 

2.5 Sampling Methods........................................................................................................................26
 

2.5.1 Collection of Carpet Samples ..........................................................................................26
 

2.5.2 Wipe Sampling.................................................................................................................27
 

2.6 Sample Analysis ...........................................................................................................................28
 

2.6.1 Extraction of Residential Carpet Samples.......................................................................28
 

2.6.2 Extraction of Commercial Carpet Samples.....................................................................28
 

2.6.3 Extraction of Liquid Samples ..........................................................................................29
 

2.6.4 QC Sample Preparation....................................................................................................29
 

2.6.5 Sample Analysis...............................................................................................................29
 

2.7 Quality Assurance and Quality Control.......................................................................................30
 

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2.7.1 Uniformity of Carpet Protector Treatment Solution .......................................................31
 

2.7.2 Calibration of LC/MS/MS ...............................................................................................32
 

2.7.3 Daily Calibration Checks.................................................................................................33
 

2.7.4 Contamination Checks.....................................................................................................33
 

2.7.5 Weight Measurements......................................................................................................33
 

3. Results........................................................................................................................................... 34 

3.1 Summary of Experimental Conditions.........................................................................................34
 

3.2 Extractable PFCA Content in Carpet Treatment Solutions.........................................................34
 

3.3 Extractable PFCA Content in Wipe Samples Taken from the Walls..........................................35
 

3.4 Extractable PFCA Content in Carpet Samples ............................................................................36
 

3.5 Percent Removal of PFCAs by Cleaning.....................................................................................41
 

4. Discussion..................................................................................................................................... 43 

4.1 Removal Efficiency of Speciated Extractable PFCAs in Carpet Samples..................................43
 

4.2 Overall PFCA Removal Efficiency..............................................................................................43
 

4.3 Comparison of Duplicate Experiments........................................................................................44
 

4.4 Factors Affecting the Efficiency of PFCA Removal...................................................................44
 

4.5 Composite vs. Individual Samples...............................................................................................46
 

4.6 Extractable PFCA Content Collected from Walls.......................................................................46
 

5. Conclusions and Recommendations......................................................................................... 47 

Acknowledgments ............................................................................................................................. 48 

References .......................................................................................................................................... 49 

Appendix A: Data.............................................................................................................................A1 

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List of Figures 

Figure 2.1. Floor plan for the research house in Cary, NC...............................................................................18
 

Figure 2.2. Residential and commercial carpet cleaning machines..................................................................20
 

Figure 2.3. Diagram of generic carpet sampling quadrant................................................................................23
 

Figure 2.4. Application cart...............................................................................................................................24
 

Figure 2.5. Diagram of first application process...............................................................................................24
 

Figure 2.6. Diagram of second application process..........................................................................................25
 

Figure 2.7. Diagram of carpet cleaning using commercial cleaner CM-2 (not to scale).................................26
 

Figure 2.8. Residential carpet after all sampling stages....................................................................................27
 

Figure 2.9. Average of individual quadrant samples for post-application PFCA concentrations in
 

each experiment and associated standard deviations.....................................................................32
 

Figure 3.1. Extractable PFCA content in carpet treatment solutions CT-1 and CT-2 .....................................35
 

Figure 3.2. Average total PFCAs in composite carpet fiber samples for Experiment 1 (C-1-2-0) .................37
 

Figure 3.3. Average total PFCAs in composite carpet fiber samples for Experiment 2 (C-2-1-0) .................37
 

Figure 3.4. Average total PFCAs in composite carpet fiber samples for Experiment 3 (R-1-1-0) .................38
 

Figure 3.5. Average total PFCAs in composite carpet fiber samples for Experiment 4 (R-1-2-0) .................38
 

Figure 3.6. Average total PFCAs in composite carpet fiber samples for Experiment 5 (R-2-2-0) .................39
 

Figure 3.7. Average total PFCAs in composite carpet fiber samples for Experiment 6 (C-2-2-1) .................39
 

Figure 3.8. Average total PFCAs in composite carpet fiber samples for Experiment 7 (R-1-1-2) .................40
 

Figure 3.9. Average total PFCAs in composite carpet fiber samples for Experiment 8 (R-1-1-2),
 

duplicate of Experiment 7...............................................................................................................40
 

Figure 3.10. Average total PFCAs in composite carpet fiber samples for Experiment 9 (R-2-2-1) ...............41
 

Figure 3.11. Calculated percent removal of total PFCAs for each experiment................................................42
 

Figure 4.1. Average percent reduction in PFCAs by experimental variable for composite samples.............45
 

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List of Tables 

Table 2.1. Conditions in the research house......................................................................................................19
 

Table 2.2. Components of carpet treatments CT-1 and CT-2...........................................................................20
 

Table 2.3. Experimental matrix for testing of carpet care treatments ..............................................................22
 

Table 2.4. Carpet fiber collection strategy ........................................................................................................27
 

Table 2.5. Analyte names, abbreviations, chemical formulas, molecular weights (g/mol), and
 

Chemical Abstracts Service registration numbers (CAS #) ..........................................................30
 

Table 2.6. Measurement quality objectives.......................................................................................................31
 

Table 3.1. Environmental parameters recorded during the cleaning experiments...........................................34
 

Table 3.2. Results of wall wipe samples collected during Experiment 3.........................................................36
 

Table 4.1. Percent removal efficiency of speciated compounds ......................................................................43
 

Table 4.2. Composite carpet sample data summarizing average percent reduction in PFCAs by
 

experiment.......................................................................................................................................44 

Table 4.3. Average percent reduction in PFCAs by experimental variable for composite samples ..............45 

Table A.1. Average extractable PFCAs (ng/g) and percent of original amount removed in composite 

carpet fiber samples at each experimental stage for Experiment 1 (C-1-2-0)..............................A2 

Table A.2. Average extractable PFCAs (ng/g) and percent of original amount removed in composite 

carpet fiber samples at each experimental stage for Experiment 2 (C-2-2-0)..............................A3 

Table A.3. Average extractable PFCAs (ng/g) and percent of original amount removed in composite 

carpet fiber samples at each experimental stage for Experiment 3 (R-1-1-0)..............................A4 

Table A.4. Average extractable PFCAs (ng/g) and percent of original amount removed in composite 

carpet fiber samples at each experimental stage for Experiment 4 (R-1-2-0)..............................A5 

Table A.5. Average extractable PFCAs (ng/g) and percent of original amount removed in composite 

carpet fiber samples at each experimental stage for Experiment 5 (R-2-2-0)..............................A6 

Table A.6. Average extractable PFCAs (ng/g) and percent of original amount removed in composite 

carpet fiber samples at each experimental stage for Experiment 6 (C-2-2-1). Re-use of 

carpet from Experiment 2..............................................................................................................A7 

Table A.7. Average extractable PFCAs (ng/g) and percent of original amount removed in composite 

carpet fiber samples at each experimental stage for Experiment 7 (R-1-1-2). 

Experiments 7 and 8 considered replicate tests. ...........................................................................A8 

Table A.8. Average extractable PFCAs (ng/g) and percent of original amount removed in composite 

carpet fiber samples at each experimental stage for Experiment 8 (R-1-1-2). 

Experiments 7 and 8 considered replicate tests. ...........................................................................A9 

Table A.9. Average extractable PFCAs (ng/g) and percent of original amount removed in composite 

carpet fiber samples at each experimental stage for Experiment 9 (R-2-2-1). Re-use of 

carpet from Experiment 5............................................................................................................A10 

Table A.10. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples 

for Experiment 1 (C-1-2-0). ........................................................................................................A11
 

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Table A.11. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples 

for Experiment 2 (C-2-2-0). ........................................................................................................A11 

Table A.12. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples 

for Experiment 3 (R-1-1-0). ........................................................................................................A12 

Table A.13. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples 

for Experiment 4 (R-1-2-0). ........................................................................................................A12 

Table A.14. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples 

for Experiment 5 (R-2-2-0). ........................................................................................................A13 

Table A.15. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples 

for Experiment 6 (C-2-2-1). ........................................................................................................A13 

Table A.16. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples 

for Experiment 7 (R-1-1-2). Experiments 7 and 8 considered replicate tests............................A14 

Table A.17. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples 

for Experiment 8 (R-1-1-2). Experiments 7 and 8 considered replicate tests............................A14 

Table A.18. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples 

for Experiment 9 (R-2-2-1). ........................................................................................................A15 

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Acronyms and Abbreviations 

AOC Articles of Commerce 

APPCD Air Pollution Prevention and Control Division 

BDL below detection limit 

CAS# Chemical Abstract Service Registry Number 

CD carpet detergent 

CFR Code of Federal Regulations 

CM carpet cleaning machine 

CRI Carpet and Rug Institute 

CT carpet treatment 

DCC daily calibration check 

FCBR front corner bedroom 

HPLC high performance liquid chromatography 

IAP internal audit program 

IDL instrument detection limit 

IS internal standard 

LC/MS/MS liquid chromatography/tandem mass spectrometry 

LOQ limit of quantification 

MBR master bedroom 

MDL method detection limit 

MQO measurement quality objective(s) 

MSDS material safety data sheet 

NR not reported 

NRMRL National Risk Management Research Laboratory 

PFAA perfluoroalkyl acid 

PFBA perfluorobutyric acid 

PFC perfluorochemical 

PFCA perfluorocarboxylic acid 

PFOA perfluorooctanoic acid 

PFOS perfluorooctanesulfonic acid 

PFTeDA perfluorotetradecanoic acid 

PFTrDA perfluorotridecanoic acid 

PQL practical quantification limit 

PTFE polytetrafluoroethylene 

PTT polytrimethylene terephthalate 

QAPP Quality Assurance Project Plan 

QC quality control 

RCS recovery check standard 

RIS recovery internal standard 

RSD relative standard deviation 

TPFCA total perfluorocarboxylic acids (the sum of all monitored PFCAs) 

U.S. EPA United States Environmental Protection Agency 

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1. Introduction 

1.1 Background 

The potential impacts of perfluorocarboxylic acids (PFCAs) on human health and the global 

environment did not draw much attention until the turn of this century, when evidence of their 

widespread presence in various environmental compartments appeared (Renner, 2001; Giesy and 

Kannan, 2002). PFCAs have been detected in air, water, and soil (Boulanger et al., 2004; Stock et 

al., 2007) and in a variety of wildlife around the world, including the United States (Kannan et al., 

2002), Arctic Canada (Martin et al., 2004), Europe, and the Mediterranean Sea (Giesy and Kannan, 

2002). More recently, low levels of PFCAs have been found in various consumer products that are 

either made from or treated with perfluorinated chemicals (Washburn et al., 2005; Guo et al., 

2009). 

PFCAs persist in the environment due to their high stability, and there is evidence that they 

bioaccumulate (Moody et al., 2002), a significant factor in their potential toxicity. 

Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), two types of 

perfluoroalkyl acids (PFAAs) that have been the most extensively studied PFCs to date, are 

essentially ubiquitous in humans; they have been found in human blood and breast milk in the 

United States (Tao et al., 2008; Calafat et al., 2006), China (So et al., 2006), and other countries 

across Europe, South America, and Asia (Kannan et al., 2004). Toxicological studies indicate that 

PFCAs cause developmental and systemic toxicity in laboratory animals (Kennedy et al., 2004; 

Lau et al., 2004; U.S. EPA, 2005). In particular, PFOS has been shown to act as an endocrine 

disruptor (Austin et al., 2003). The potential health risks associated with PFCAs have inspired 

extensive research on the sources, transport, transformation, and distribution of these chemicals 

and their precursors in environmental media, along with research into ways to reduce potential 

health risks. 

Despite significant progress thus far, researchers have yet to reach a consensus on the most 

important routes by which the general population is exposed to these chemicals. In particular, 

opinions differ on whether consumer products containing PFCAs are significant contributors to 

overall exposure. For instance, a study in 2005 concluded that exposures to PFOA during 

consumer use of the articles evaluated were not expected to cause adverse health effects in infants, 

children, adolescents, or adults, or result in quantifiable levels of PFOA in human serum 

(Washburn et al., 2005). In a study conducted in 2009 by Fromme et al., data from indoor 

measurements in Canada and Norway were used to estimate the average daily intake of PFOA for 

the general population in Western countries, and it was found that the inhalation of house dust 

contributed only 0.6% of the average daily intake of PFOA and a maximum of only 8.2% of the 

highest daily intake levels. By contrast, however, Tittlemier et al. (2007) identified treated 

carpeting as an important source of PFOA exposure, second only to ingestion with food. Trudel et 

al. (2008) agreed that the consumption of contaminated food is the most significant exposure 

pathway for PFOA and that the ingestion of dust and inhalation of air containing PFOA is the 

second most likely route of exposure in low- and intermediate-exposure scenarios. Their study also 

found that direct, product-related exposure dominates in high-exposure scenarios in which 

consumers have treated carpets in their homes or regularly use PFCA-containing products, such as 

stain-protection sprays. It is apparent, then, that the scarcity of data related to indoor PFCA sources 

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and exposures contributes to significant uncertainty and differences of opinion about the most 

prevalent exposure routes for these compounds. 

Elevated levels of PFCAs have been detected in house dust in Japan (Moriwaki et al., 2003), 

Canada (Kubwabo et al., 2005), and the United States (Strynar and Lindstrom, 2008), strongly 

suggesting the presence of significant indoor sources. Kubwabo et al. correlated the percentage of 

indoor carpet, in particular, to increased PFCA levels in dust. In 2005, Washburn and colleagues 

reported the PFOA content in 14 groups of articles based on theoretical calculations and analytical 

measurements. Of these groups, it was found that pre-treated carpet and carpet treated with carpetcare solution had the highest PFOA loadings, i.e., 0.2 to 0.6 mg and 0.2 to 2 mg of PFOA per kg, 

respectively (Washburn et al., 2005). Previous research by Guo et al. (2009) examined 14 classes 

of consumer products and also found pre-treated carpet and carpet treated with PFCA-containing 

carpet-care solutions to have the largest PFCA source strength, i.e., approximately 70 mg of 

PFCAs (C5 through C12) in a typical home. One study found that PFCA contamination was higher 

on the inside than the outside of sampling films placed in windows (Gewurtz et al., 2009). 

Gerwurtz’s study also found higher PFCA contamination in houses with new carpet and in carpet 

stores, suggesting that emissions from new carpets contribute to increased indoor PFCA levels. 

Due to the highly stable nature of PFCAs, few mechanisms exist, short of eliminating sources 

completely, by which PFCAs can be removed from the indoor environment. Given its high source 

strength and duration, its potential contribution to indoor dust, and its close proximity to humans, 

treated carpeting may contribute to human exposure to PFCAs directly, e.g., dermal contact and 

hand-to-mouth transfer, and indirectly via the inhalation of suspended particles from treated carpet. 

1.2 Goal and Objective 

The main goal of this study was to quantify the efficiency of common carpet cleaning methods ― 

steam cleaning and hot water extraction ― in the removal of PFCAs from residential and 

commercial carpet that was manually treated with stain-protection solutions. Our aim in the study 

was to determine if these cleaning techniques are viable methods for reducing indoor exposure to 

PFCAs. These results will be valuable to policy makers and manufacturers for risk management 

purposes and may be of particular interest to people who wish to reduce the levels of PFCA in their 

household environments. 

17
 
ted in

use with

r

ximately 300 m

)

r bedroom (FCBR) and the master bedroom (MBR),

eted areas of the MBR and FCBR measured 13.4 m

loor p

ouse was monitored but not reported for these experiments. An

n. Air exchange rate, temperature, and humidity were not

ut temperature and relative humidity

the

2

tests were condu

style h ing system

and an electric m

a total volume of appr tes

(199 ouse

the front corn R),

For this study, the car 4 m

The air exchange rate inside the periments. An

OPTO 22 data acquisition syste temperature and

in the FCBR and d were not

ded and

conditions i

ouse located in Cary, NC. Th

air hea

The total floor area is 12

Additional information on the

wo rooms of the

the front corner bedroom (FCBR) and the master bedroom (M

For this study, the carpeted areas of the MBR and FCBR measured 13

The air exchange rate inside the house was monitored but not reported for these e

continuously logge

in the FCBR and den. Air exchange rate, temperature, and humidit

were reco

 

 

 

 

 

 

 

 

 

2. Materials and Methods 

2.1 Test Facility 

Carpet cleaning tests were conducted in a research house located in Cary, NC. The research house 

is a three-bedroom, ranch-style house with a crawl space, a central, forced-air heating system that 

uses natural gas, and an electric air-conditioning system. The total floor area is 126 m2

, and the 

house has a total volume of approximately 300 m3. Additional information on the test house was 

provided by Tichenor et al. (1990) and Sparks et al. (1991). The two rooms of the house employed 

for this work were the front corner bedroom (FCBR) and the master bedroom (MBR), as shown in 

Figure 2.1. For this study, the carpeted areas of the MBR and FCBR measured 13.4 m2 and 12.2 

m2, respectively. 

Figure 2.1. Floor plan for the research house in Cary, NC 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The air exchange rate inside the house was monitored but not reported for these experiments. An 

OPTO 22 data acquisition system (OPTO 22, Temecula, CA) continuously logged temperature and 

humidity data in the FCBR and den. Air exchange rate, temperature, and humidity were not 

controlled as critical parameters, but temperature and relative humidity were recorded and 

reported. Additional conditions in the research house are listed in Table 2.1. 

18
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 2.1. Conditions in the research house 

Parameter Status 

Exterior doors and windows Closed 

Interior doors Open 

Ceiling fans On low 

Heating/air conditioning fan On 

Heating/air conditioning registers Open 

2.2 Test Materials 

2.2.1 Carpet Selection for Research House Experiments 

The following two carpet types were chosen for the research house experiments: 1) residential 

carpet that was Green-Label Certified by the Carpet and Rug Institute (CRI) with a pile yarn 

content of 100% polytrimethylene terephthalate (PTT) – a product from recycled plastic bottles – 

with a textured cut pile and a woven polypropylene backing and 2) commercial carpet made with 

Antron® fiber, a nylon 6,6, hollow-filament fiber with a soil-resistant treatment incorporated into 

the fiber. The residential carpet fiber, also called Triexta®, shares the chemical structure of 

polyester; however, unlike traditional polyester carpet, Triexta® has extreme durability, high stain 

resistance, and a much softer texture. The fiber used for the commercial carpet is considered to be 

one of the most durable in the industry, and it has been utilized extensively in schools and offices. 

A solid urethane carpet pad was selected as the underpad for each type of carpet. Each of these 

products was screened to determine the content of PFCAs prior to installation. A 1-g sample of 

fiber from each type of carpet and 1 g of the solid memory foam backing carpet pad were analyzed 

to determine their PFCA content before the experiments were initiated. All of the samples from all 

of the products were found to contain less than 8 ng/g of PFCAs. 

2.2.2 Professional Carpet Treatment Solutions 

Two carpet stain-protection treatment solutions (CT-1 and CT-2) were selected using the following 

criteria: (1) shown to contain high levels of PFCAs (greater than 10 times the PQL); and (2) 

analytical data with good recovery for the recovery internal standards. 

Table 2.2 lists the components of the selected treatment products as documented in each product’s 

material safety data sheet (MSDS). The documentation indicated that both treatments are 

dispersible in water. The PFCA content in these treatment solutions are reported in Section 3.2 

below. 

19
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 2.2. Components of carpet treatments CT-1 and CT-2 

Chemical Content (%) 

CT-1 CT-2 

Polymethylmethacrylate (CAS# 9011-14-7) 1.3 – 2.5 4.7 

NJ Trade Secret Registry #00850201001-5155P 1 – 1.5 – 

NJ Trade Secret Registry #00850201001-5259P 0 – 1.3 – 

Citric Acid (CAS# 77-92-9) 0.5 – 1 – 

Water (CAS# 7732-18-5) 90 – 97 95 

2.2.3 Carpet Cleaning Machines 

Two carpet cleaning machines were chosen to clean the carpets after treatment with a carpet stainprotection treatment: 1) a residential cleaning machine (CM-1), the Rug Doctor Mighty Pro model 

MP C-20 and 2) a portable professional steam cleaner (CM-2), the Century 400 Ninja Warrior. 

Figure 2.2 shows the Rug Doctor (front) and the Ninja Warrior (rear). The residential machines, 

which can be rented at most grocery and home improvement stores, use hot tap water for the 

extraction process with no additional heating during the cleaning process. A 28-psi (1.93×105 Pa) 

vacuum pump is used to extract the applied water, and a brush vibrates during the process. The 

professional steam cleaner has an 1850-watt, in-line heater. Steam at a pressure of approximately 

150 psi (1.03×106 Pa) soaks the carpet fibers, and dual 2-stage vacuum motors extract the residue 

from the carpet. The professional cleaning machine does not agitate the carpet fibers. 

Figure 2.2. Residential and commercial carpet cleaning machines 

20
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2.2.4 Carpet Cleaning Detergents 

Two detergents were selected to test the removal of PFCAs from carpets, i.e., a residential carpet 

cleaning detergent (CD-2) recommended for use with the residential machine (CM-1) and a 

commercial carpet cleaning detergent (CD-1) chosen for use with the commercial machine (CM-2). 

The residential detergent was purchased at a local grocery store, and the commercial detergent was 

purchased from a local distributor of janitorial supplies. According to the material safety data 

sheets (MSDSs), CD-1 contains 3 to 6% of dipropylene glycol methyl ether (CAS# 34590-94-8) 

while CD-2 contains 1 to 5% of sodium 2-ethylhexyl sulfate (CAS# 126-92-1) and <1% of 

branched tridecylalcohol (CAS# 69011-36-5). Prior to use, each cleaner was screened for PFCAs. 

The residential detergent measured most PFCAs below the quantification limits of the instrument, 

with perfluorotridecanoic acid (C13) having the highest concentration at 3 ng/mL. The commercial 

detergent had only trace levels of C8 through C10, and all were below the practical quantification 

limits. 

2.3 Experimental Design 

All experiments were conducted at the research house in Cary, NC. The FCBR was used primarily 

for the residential carpet, and the MBR was used for both residential and commercial carpet. The 

residential carpet was tested with both types of cleaning machines and detergents to represent what 

might be used in a typical household, while the commercial carpet was tested with only the 

commercial cleaning machine and the commercial detergent. An initial scouting test (Experiment 

3) was performed with the residential carpet and CM-1 to finalize testing procedures before 

beginning the planned experiments. To ensure the presence of detectable PFCAs, all experiments 

involved the application of a commercial carpet stain-protection treatment solution containing 

PFCAs (CT-1 or CT-2). Following the application of the treatment and a subsequent 48-hour 

drying period, a series of three carpet cleanings was performed. A drying period of at least 48 

hours followed each cleaning before carpet samples were collected. The first set of tests used only 

hot water or steam for the cleaning process to determine the efficiency of each carpet cleaning 

machine’s method of removing the applied PFCAs. Additionally, four experiments, one of which 

was a duplicate test, were conducted using cleaning detergents (CD-1 or CD-2) in conjunction with 

a carpet cleaning machine to assess any additional PFCA removal. The complete experimental test 

matrix is summarized in Table 2.3. 

21
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 2.3. Experimental matrix for testing of carpet care treatments 

Experiment Research House 

Location 

Carpet 

Type c 

Treatment 

Type 

Cleaning 

Machine Detergent 

1 MBR C CT-1 CM-2 None 

2 MBR C CT-2 CM-2 None 

3a FCBR R CT-1 CM-1 None 

4 FCBR R CT-1 CM-2 None 

5 FCBR R CT-2 CM-2 None 

6 MBR C CT-2 CM-2 CD-1 

7 FCBR R CT-1 CM-1 CD-2 

8b MBR R CT-1 CM-1 CD-2 

9 FCBR R CT-2 CM-2 CD-1 

a Initial scouting test.
 

b Duplicate of Experiment 7.
 

c C = Commercial; R = Residential.
 

2.4 Test Procedure 

2.4.1 Layout of Carpet Sampling Sections 

The carpet in the MBR measured 3.66 × 3.66 meters, and the carpet in the FCBR measured 3.66 × 

3.20 meters. For each room, a grid was created in order to evenly gauge five sampling sections, AE, as shown in Figure 2.3. Once each section was located, a small piece of tape the size of a dime 

was placed in its center. This was the only indicator placed on the carpet itself and acted as a 

reference point for sampling (Section 2.5.1). 

22
 
 

 

 

 

 

 

 

A ▼ B ▼

▪ ▪

E ▼

▪

C ▼ D ▼

▪ ▪

Figure 2.3. Diagram of generic carpet sampling quadrant 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2.4.2 Dilution and Application of the Carpet Treatment 

The dilution of the carpet treatment varied slightly for each set of tests. The treatment (CT-1) 

dilution for the scouting test (Experiment 3) was 1:1 distilled water to treatment solution to ensure 

measurable concentrations of PFCA through three cleanings. The manufacturer’s recommendation 

was 4:1, and the resulting concentrations of PFCAs from the 1:1 dilution on the carpet indicated 

that a lower concentration of application treatment would be more applicable for this study; 

therefore, a dilution of 4:1 was used for all subsequent applications with both products. An exact 

measurement for the dilution was not critical because the dried product on the carpet fiber was 

collected and extracted for analysis before each test. 

To start the application, the diluted carpet stain-protection treatment solution was placed in a 

commercial sprayer recommended in the product use guide for application of the treatment. The 

sprayer was modified by adding a pressure gauge to better control the application rate and 

uniformity of the application. Then, the sprayer was inserted into the “application cart,” an 

apparatus manufactured in-house (Figure 2.4). The application cart was on wheels in order to 

provide a more uniform application of the solution, and it held the nozzle of the sprayer 

approximately 0.6 m from the ground. 

23
 
 

 

 

 

 

 

Figure 2.4. Application cart 

First, the carpet treatment was applied according to Figure 2.5. For each path, the applicator was 

pumped to a pressure of 10 psi (6.89×104 Pa), the spray nozzle was turned on, and the cart was 

pulled in the direction of the arrows for approximately 24 s. At the end of each path, the spray 

nozzle was turned off. A grid on the wall allowed for proper path widths based on the swath of the 

sprayer; the MBR had seven paths, while the FCBR had eight. 

↓

↓

↓

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End 

(Door) 

↓

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↓

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↓

↓

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↓

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↓

↓

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↓

↓

↓

↓

↓

↓

↓

↓

Figure 2.5. Diagram of first application process 

24
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Once the application shown in Figure 2.5 was completed, a second, S-shaped application was 

performed, as shown in Figure 2.6. During this application, the process was not stopped at the end 

of each path. Instead, the application was done in a continuous motion, only stopping to pump the 

applicator to 8-10 psi (5.52×104 - 6.89×104 Pa) when necessary. After application the carpet was 

allowed to dry for at least 48 hour before carpet samples were collected. 

 

 

 

 

 

 

 

↓ ← ← ← ← ← ← ← ← ← ← Start 

→ → → → → → → → → → → → ↓

↓ ← ← ← ← ← ← ← ← ← ← ←

→ → → → → → → → → → → → ↓

↓ ← ← ← ← ← ← ← ← ← ← ←

→ → → → → → → → → → → → ↓

End ← ← ← ← ← ← ← ← ← ← ←

Figure 2.6. Diagram of second application process 

2.4.3 Cleaning of Carpets 

The manufacturer’s instructions were followed for each carpet cleaning machine. When using the 

commercial cleaner (CM-2), the carpets were cleaned in paths that were approximately 3-3.5 ft 

(0.91-1.07 m) wide with about 1 in (2.54 cm) of overlap. Figure 2.7 demonstrates this process, 

where each section of the schematic represents a path, and the arrows indicate the direction of 

cleaning. For each path, there were four passes with the carpet cleaning apparatus with the cleaning 

solution being expelled and vacuumed up in the first pass and any remaining solution being 

vacuumed up in the final three passes, which, in turn, dried the carpet. Each 3-ft pass was timed for 

approximately10 seconds. The residential cleaner (CM-1) followed a similar cleaning process, 

except that 6-ft-wide paths were used. 

25
 
 ↓

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↓

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↓ ↓ ↓ ↓ ↓ ↓ ↓

↓ ↓ ↓ ↓ ↓ ↓ ↓

↓ ↓ ↓ ↓ ↓ ↓ ↓

↓ ↓ ↓ ↓ ↓ ↓ ↓

↓ ↓ ↓ ↓ ↓ ↓ ↓

↓ ↓ ↓ ↓ ↓ ↓ ↓

End 

(Door) ←←← ←←← ←←←

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 2.7. Diagram of carpet cleaning using commercial cleaner CM-2 (not to scale) 

2.5 Sampling Methods 

2.5.1 Collection of Carpet Samples 

A carpet sample from each of the five sampling locations (Figure 2.3) was collected according to 

Table 2.4, using a 82-mm-diameter carpet cutter (05-174 Instant Repair Tool, Crain Cutter 

Company, Milpitas, CA). Methanol was used to clean the tool between samples to prevent crosscontamination. Each sample was placed in an individually-labeled plastic bag and transferred to the 

EPA campus for processing and analysis. Each 82-mm-diameter carpet sample was processed by 

removing the fibers from the backing and placing them in an aluminum foil dish. Each set of carpet 

samples was placed in a separate dessicator. After a minimum of 16 hours, the fiber sample was 

removed and mixed. A 1-g sub-sample was transferred to a 50-mL polypropylene centrifuge tube 

(Evergreen Scientific, Los Angeles, CA), and a second 1-g sub-sample was weighed and placed in 

a plastic bag. Once all individual samples from the stage had been processed, the plastic bag 

containing the remaining 5 g of carpet from quadrants A-E were used to compile five composite 

fiber samples. The bag was shaken to ensure that all fibers were distributed evenly, and five 

individual 1-g sub-samples of composite carpet fiber were removed from the plastic bag and 

placed in separate centrifuge tubes. In summary, each stage of the experiment produced a total of 

10 samples, each weighing 1 g, i.e., five individual fiber samples (A-E) and five composite fiber 

samples composed of fibers from all five sampling locations. The individual sample data were used 

only to evaluate the uniformity of the application of the carpet treatment, while the composite 

samples were used to evaluate cleaning efficiency. 

26
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 2.4. Carpet fiber collection strategy 

Stage of Experiment Number of Samples 

Collected from Carpet 

Number of Fiber 

Samples Processed for 

Analysis a 

Number of Composite 

Fiber Samples 

Processed for Analysis b 

Prior to Treatment 

Application (Initial 

Sampling) 

5 5 5 

Post-Treatment 

Application 

(Application Sampling) 

5 5 5 

Post-cleaning, Round 1 

(Clean 1 Sampling) 5 5 5 

Post-cleaning, Round 2 

(Clean 2 Sampling) 5 5 5 

Post-cleaning, Round 3 

(Clean 3 Sampling) 5 5 5 

a One ~1-g sample per sampling location.
 

b Five ~1-g samples taken from an equal mixture of fiber samples from all five locations.
 

Figure 2.8 shows a residential carpet after all sampling stages were completed. 

Figure 2.8. Residential carpet after all sampling stages 

2.5.2 Wipe Sampling 

Wipe samples were collected only during Experiment 3, the scouting test, to evaluate over-spray 

during the application process. These data illustrate any possible exposure from wall surfaces in a 

typical home. Using ASTM Method D 6661, Field Collection of Organic Compounds from 

Surfaces Using Wipe Sampling (ASTM, 2010), as a general guideline, a 10 cm × 10 cm template 

27
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

was used to outline the wipe area using painters tape. Four wipe areas were sampled on each of the 

four walls in the center of the carpet length, four inches above the baseboard molding. For each 

wipe sample, approximately 2 mL of methanol were applied to a piece of cotton gauze. The gauze 

was pressed firmly to the wall, and the sample area was wiped vertically with minimal overlap 

between strokes. Then, the sample area was wiped horizontally. The gauze used for the wipe was 

stored in a 50-mL polypropylene centrifuge tube and later extracted using the same procedure that 

was used for the residential carpet samples, which is described in Section 2.6.1. Background wipe 

samples were collected at each location before application of the carpet treatment. 

2.6 Sample Analysis 

2.6.1 Extraction of Residential Carpet Samples 

To each of the residential fiber samples prepared in Section 2.5, 45 mL of HPLC-grade methanol 

(pre-screened for PFCAs) and 100 μL of recovery check standard (2 ng/μL each of perfluoro-n-[1, 

2-13C2] decanoic acid Wellington Laboratoies, Canada) were added. The samples were extracted 

for 24 ± 2 hr using a Nutating Mixer (Model VSN-5, PRO Scientific, Inc., Oxford, CT). The 

extract was transferred to a 170-mL borosilicate glass blow-down tube. The original sample vial 

was rinsed three times with ~3 mL of methanol, and each of the rinse liquids was transferred to a 

170-mL concentration tube. A spatula was used to agitate the samples during rinsing. Next, the 

sample was concentrated to approximately 1.5 mL in a heated (50 °C) nitrogen atmosphere by 

using a RapidVap N2 Evaporation System (Model 791000, LabConco, Kansas City, MO), which 

was previously modified at the factory to remove all PTFE parts and coatings. 

The blow-down sample was transferred to a 10-mL volumetric flask through a 0.1-μm Anotop 

syringe filter (Whatman International, Madestone, England). The tube was rinsed five times with a 

solution consisting of 60% (v/v) methanol and 40% (v/v) 2 mM ammonium acetate aqueous 

solution (hereafter referred to as 60:40 solution). The rinse liquids were filtered and combined with 

the blow-down sample in the volumetric flask. After adding 100 μL of the internal standard 

solution (0.5 ng/μL each of perfluoro-n-[1, 2, 3, 4-13C4] octanoic acid), the sample was brought 

to10 mL with 60:40 solution and sonicated for 10 min. The sample solution was transferred to a 

15-mL polypropylene tube and stored at 4 °C until LC/MS/MS analysis. 

2.6.2 Extraction of Commercial Carpet Samples 

After extraction, due to clogging of the 0.1-μm Anotop filter, the sample first had to be first filtered 

through a Corning 0.22-μm cellulose acetate, low-binding filter and into a polystyrene tube. The 

170-mL concentration tube was rinsed five times, and the extract was passed through the 0.22-μm 

Corning filter. Then, the sample extract was transferred through a 0.1-μm Anotop syringe filter into 

a 10-mL volumetric flask. The filter tube was rinsed five times with 60:40 solution into the flask. 

After adding 100 μL of the internal standard solution, the sample was brought to volume with 

60:40 solution and sonicated for 10 min. The sample solution was transferred to a 15-mL 

polypropylene tube and stored at 4 °C until LC/MS/MS analysis. 

28
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2.6.3 Extraction of Liquid Samples 

Approximately 1 mL of the liquid sample was weighed, spiked with 1 mL of a 2 ng/μL recovery 

check standard solution, and diluted to 10 mL with 60:40 solution. The diluted samples were 

sonicated for 10 min and then filtered with a 0.1-μm Anotop syringe filter. After filtration, 1 mL of 

the filtrate was transferred into a 10-mL volumetric flask and spiked with 100 μL of the internal 

standard. The resulting solution was sonicated for 10 min, transferred to a polypropylene tube, and 

stored at 4 °C until LC/MS/MS analysis. Note: for samples with levels of PFCAs above the 

calibration range, a second dilution of 1:10 was needed before adding the recovery check standard. 

2.6.4 QC Sample Preparation 

A set of five quality control (QC) samples was prepared for every batch of carpet extractions, i.e., a 

field blank, a solvent blank, and three recovery internal standard blanks. The field blank consisted 

of 45 mL of methanol and 100 μL of recovery internal standard, and it went through the same 

extraction process as the residential carpet samples described in Section 4.6.1. The solvent blank 

consisted of 60:40 solution with 100 μL of internal standard, brought to volume in a 10-mL 

volumetric flask. Each recovery internal standard blank contained 60:40 solution with 100 μL 

internal standard and 100 μL recovery internal standard, brought to volume in a 10-mL volumetric 

flask. All samples including field blank samples were sonicated, transferred to 15-mL 

polypropylene tubes, and stored at 4 °C with the corresponding batch of extraction samples until 

LC/MS/MS analysis. The analyte content in the solvent blank was subtracted from all samples and 

field blanks if it exceeded the practical quantification limit (PQL). The analyte content in the field 

blanks was required to be below the PQL. 

2.6.5 Sample Analysis 

Sample quantification was conducted using an Agilent 1100 HPLC equipped with an Applied 

Biosystems API 3200 Triple Quadrupole Mass Spectrometer with a Turbo V ion-spray interface. A 

C18 reversed-phase guard column and analytical C18 reversed phase column were used for analyte 

separation. Samples were injected at a flow rate of 0.250 mL/min and maintained at 50 °C. The 

initial gradient mobile-phase composition was 25% mobile phase B, where mobile phase A was 

95% 2 mM aqueous ammonium acetate-5% methanol, and mobile phase B was 95% methanol-5% 

2 mM aqueous ammonium acetate, held for 0.5 min. A linear gradient was used from 25% to 85% 

B over 4.5 min, then increased to 100% B over 0.10 min and held for 2 min. Then, a linear gradient 

decreased mobile phase B to 25% over 2 min, where it was held for 3 min. PFCAs were observed 

in the negative ion mode, and both primary and secondary ion transitions were collected for each 

analyte. The instrument was calibrated for 11 PFCA homologues (Table 2.5) plus the recovery 

check standards at eight concentration levels in the concentration range of 0.3 to 100 ng/mL with 

triplicate injections. This procedure followed methods detailed in Liu et al. (2009). 

29
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 2.5. Analyte names, abbreviations, chemical formulas, molecular weights (g/mol), and 

Chemical Abstracts Service registration numbers (CAS #) 

Analyte Abbreviation Formula MW CAS # 

Perfluorobutyric acid PFBA – C4 C4HF7O2 214.04 375-22-4 

Perfluoropentanoic acid PFPeA – C5 C5HF9O2 264.04 2706-90-3 

Perfluorohexanoic acid PFHxA – C6 C6HF11O2 314.05 307-24-4 

Perfluoroheptanoic acid PFHpA – C7 C7HF13O2 364.05 375-85-9 

Perfluorooctanoic acid PFOA – C8 C8HF15O2 414.06 335-67-1 

Perfluorononanoic acid PFNA – C9 C9HF17O2 464.07 375-95-1 

Perfluorodecanoic acid PFDA – C10 C10HF19O2 514.07 335-76-2 

Perfluoroundecanoic acid PFUdA – C11 C11HF21O2 564.08 2058-94-8 

Perfluorododecanoic acid PFDoA – C12 C12HF23O2 614.09 307-55-1 

Perfluorotridecanoic acid PFTrDA – C13 C13HF25O2 664.11 72629-94-8 

Perfluorotetradecanoic acid PFTeDA – C14 C14HF27O2 714.12 376-06-7 

Perfluoro-n-[1,2-13C2] 

hexanoic acid a 13C-PFHxA 13C2 

12C4HF11O2 316.04 n/a 

Perfluoro-n-[1,2,3,4-13C4] 

octanoic acid b 13C-PFOA 13C4 

12C4HF15O2 418.03 n/a 

Perfluoro-n-[1,2-13C2] 

decanoic acid a 13C-PFDA 13C2 

12C8HF15O2 516.07 n/a 

a Recovery check standard. 

b Internal standard. 

2.7 Quality Assurance and Quality Control 

A Category II quality assurance project plan (QAPP) was developed and approved before the start 

of the project and detailed the Measurement Quality Objectives (MQOs) for the project, which are 

summarized in Table 2.6. For this study conducted at the EPA research house, the data quality 

objective for the precision of solvent extraction was relaxed to ± 30% to incorporate more 

information to better interpret the desired goal of this project. All data that fell outside the original 

MQOs listed below are highlighted in the data tables presented in Appendix A. 

30
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 2.6. Measurement quality objectives 

Measurement Parameter Objective Method 

Calibration of 

LC/MS/MS 

Coefficient of 

determination (r2

) for 

calibration curve 

> 0.99 Linear regression 

Instrument 

detection limit ≤0.2 ng/mL EPA method (40 CFR 136, 1986) 

PFCA quantification 

by LC/MS/MS 

Accuracy 85-115% Internal audit program 

Daily calibration check standards 

Precision 20% RSD for duplicate injections 

Agreement of primary 

and secondary ions 25% Percent deviation (in highest 10% of samples) 

Precision 20% a RSD for replicate extractions 

Solvent extraction Accuracy 80-120% Recovery internal standard 

System blank < IDL Extraction w/o AOCb sample 

Weight of AOC samples Accuracy ±2 mg NIST-traceable weights 

a For data completeness, some extraction results presented below had precisions between 20% and 30%;
 

data with precisions of greater than 30% were discarded.
 

b Articles of Commerce.
 

2.7.1 Uniformity of Carpet Protector Treatment Solution 

The variability of the carpet treatment application and the inconsistency of the cleaning machine 

process (temperature, time of cleaning in single location, and operator variations) made the 

collection of truly duplicate carpet samples impossible. Individual samples from each of the five 

sampling locations were collected at each stage of the experiment, as indicated previously in 

Figure 2.3. Sampling in five different locations accounted for potential variations in both the 

treatment application and carpet cleaning. These five samples were analyzed individually and also 

combined to create a large mass composite carpet fiber sample. The accumulation and mixing of 

sub-samples from different locations eliminated application and cleaning variability and lack of 

uniformity in treatment applications. Five 1-g samples were removed from the composite samples 

after mixing. These replicate samples served as proxy duplicates. Figure 2.9 presents the results of 

the average of the five individual samples collected from positions A-E post-application from each 

experiment to demonstrate variations in the application of the treatment. A high standard deviation 

for the averages of the individual samples is an indicator of application variability. These data from 

individual samples are presented in Appendix A. The composite samples, as a physical average of 

carpet conditions, ideally would reduce these inconsistencies in PFCA deposition and removal. 

31
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

16000 

12000 

8000 

4000 

0 

Experiment 

Average TPFCAs (ng/g) 

1 2 3 4 5 6 7 8 9 

Figure 2.9. Average of individual quadrant samples for post-application PFCA concentrations in each 

experiment and associated standard deviations 

2.7.2 Calibration of LC/MS/MS 

The instrument was calibrated for 11 PFCA homologs (Table 2.5) plus the recovery check 

standards at eight concentration levels in the concentration range of 0.3 to 100 ng/mL with 

triplicate injections. The instrument detection limits (IDLs) for individual PFCAs in the injected 

sample were ≤ 0.2 ng/mL. The practical quantification limit (PQL) for the injection sample was < 1 

ng/mL, which is equivalent to 1 ng/g for carpet extracts and 10 ng/g for liquid samples. 

Initially, standards were prepared from individual analytes (Liu et al., 2009). However, in March 

2010 calibrations were performed using a composite standard mix distributed by the manufacturer 

that contained the all of the analytes of interest. This change was due to the availability of a 

composite standard and the resulting simplification of the standard preparation process. 

The acceptance criterion for the calibration curve was that the coefficient of determination (r2

) be 

no less than 0.99. The average of the r2 values for 14 compounds over seven calibrations was 0.995 

± 0.003, giving 100% completeness for the MQO for calibration. 

An internal audit program (IAP) standard was analyzed for each of the seven calibrations. The IAP 

standard contained at least three of the calibrated PFCAs using a different chemical source 

(Oakwood Laboratories or Aldrich) and was prepared by someone other than the analyst who 

prepared the calibration standards. The analyst who conducted the calibration received the IAP 

standard without knowing the concentrations. IAP standards were analyzed after each calibration 

as a measurement of calibration verification. The average of the percent accuracy for each analyte 

32
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ranged from 76% to 115%. Only two data points out of 26 did not meet the MQO criterion for 

acceptance of ± 15%, giving 92% completeness for this QA criterion. 

2.7.3 Daily Calibration Checks 

Daily calibration check (DCC) standards, approximately 10 ng/mL for each analyte, were analyzed 

to evaluate the performance of the LC/MS/MS. The DCC was conducted at the beginning of each 

analytical sequence and at the end of the sequence or, for extended sequences, after 24 hours of 

instrumental analysis. Analytical results of a sample batch were considered acceptable only if the 

percent recovery of the DCC was within 100 ± 15% and the percent relative standard deviation 

(%RSD) of triplicate injections of the DCC was within ± 15%. The MQO for DCC recovery was 

relaxed for this study to 100 ± 30%, and the percent relative standard deviation (%RSD) of 

triplicate injections of the DCC was instead required to be within ± 30%. Data that fell outside the 

original MQO for DCCs are highlighted in the data tables in Appendix A. Data that fell outside the 

relaxed MQOs were not used in this report. We collected 952 data points for the DCC 

measurements with only 55 points falling outside the relaxed MQO, giving 94% completeness 

using the relaxed MQO. 

2.7.4 Contamination Checks 

All purchased and prepared solvents, glassware, and the HPLC system were checked routinely for 

PFCA contamination. Also, a solvent blank was prepared with each set of standards and samples to 

assess the solvent and the HPLC system. Solvents and blanks were rejected if they contained the 

analytes of interest at concentrations higher than the IDL for individual PFCAs in the injection 

sample of ≤0.2 ng/mL. 

2.7.5 Weight Measurements 

Two balances were employed for weight measurements during this project, i.e., 1) a five-place 

microbalance and 2) a three-place pan balance. The microbalance was used early in the project for 

weighing the calibration standards for the LC/MS/MS. Both balances are calibrated every 12 

months. To monitor the daily performance of the balances, two Class A weights were weighed at 

the beginning and end of each weigh session. The precision of each balance for this project was 

determined by averaging the measurements for each class A weight and determining the standard 

deviation for those measurements. The accuracy was determined by comparison of the class A 

weight measurement to the certified value of the weight. Table 2.7 presents these MQO 

measurements. 

Table 2.7. MQOs for weight measurements 

Parameter Microbalance Pan Balance 

Precision (n > 10) 10 mg: 9.997 ± 0.038 mg 

20 g: 19.999 ± 0.00014 g 

1 g: 1.000 ± 0.001 g 

10 g: 10.002 ± 0.001 g 

Accuracy % 10 mg: 99.97% 

20 g: 99.99% 

1 g: 100.05% 

10 g: 100.01% 

33
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3. Results 

3.1 Summary of Experimental Conditions 

The research house conditions for the nine experiments are summarized in Table 3.1.The relative 

humidity and air exchange rate were measured but not controlled during the research house 

experiments. After each application and subsequent cleaning, the relative humidity was elevated 

for several hours during the drying period for the carpets. The temperature was controlled by the 

conventional heating and air conditioning system in the house. The HVAC fan was operated 

continuously, and the ceiling fans in the FCBR, MBR, den, and living room were kept on low 

speed, blowing upward. Measurements for relative humidity and temperature were monitored in 

the FCBR and den by a Vaisala INTERCAP humidity and temperature transmitter recording to an 

OPTO DAS. The air exchange rate inside the house was not reported for any of the experiments. 

The only purpose of presenting the environmental data in Table 3.1 is to show that the carpet 

cleaning experiments were conducted under typical indoor environmental conditions. The data was 

not used anywhere else in this report. 

Table 3.1. Environmental parameters recorded during the cleaning experiments 

Experiment a Temperature, 0C b Relative Humidity, % b 

Average c High Low Average c High Low 

1 and 4 

22 ± 1d 

24 ± 0.5e 

24 

25 

20 

22 

59 ± 6 

54 ± 4 

77 

65 

48 

44 

2 and 5 

22 ± 1d 

24 ± 1e 

24 

26 

20 

22 

61 ± 4 

56 ± 2 

75 

65 

55 

51 

3 

21 ± 1d 

19 ± 1e 

26 

22 

19 

18 

24 ± 6 

25 ± 4 

58 

40 

14 

18 

6 and 9 

21 ± 1d 

23 ± 0.5e 

23 

25 

19 

21 

59 ± 6 

52 ± 4 

75 

63 

47 

42 

7 and 8 NAf NAf NAf NAf NAf NAf 

a Tests are grouped together by the start date for each test (one test being conducted in the FCBR and
 

the other in the MBR). Test 3 was the initial scouting test conducted in the FCBR.
 

b Measurement locations: front corner bedroom (FCBR) and den.
 

c Mean ± standard deviation for n > 2500 (Sample number varied with each experiment).
 

d Transmitter in the FCBR.
 

e Transmitter in the Den.
 

f Not available ― Data lost due to power failure at the house.
 

3.2 Extractable PFCA Content in Carpet Treatment Solutions 

The levels of PFCAs quantified in the undiluted carpet protector treatments CT-1 and CT-2 are 

presented in Figure 3.1. The error bars show ±1 standard deviation with n = 4 for CT-1 and n = 6 

34
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

for CT-2. The treatments were analyzed for 11 PFCAs; however, the levels of PFTeDA (C14) in 

the treatment solutions were below the limit of detection. The total PFCA content for CT-1 and 

CT-2 was, respectively, 6360 and 7500 ng/g. 

0 

500 

1000 

1500 

2000 

2500 

Concentration (ng/g) 

CT-1 

CT-2 

Figure 3.1. Extractable PFCA content in carpet treatment solutions CT-1 and CT-2 

(The error bars represent ±1 SD; n = 4 for CT-1 and n = 6 for CT-2) 

3.3 Extractable PFCA Content in Wipe Samples Taken from the Walls 

The results from the wipe samples collected during Experiment 3 to evaluate overspray during the 

application process are presented in Table 3.2. Background wipe samples were collected from each 

of the four locations prior to the application of the carpet stain-protection treatment. Three of the 

four background samples showed no evidence of PFCAs on the walls prior to application. The 

fourth background sample was lost during analysis. The concentration of PFCAs measured on the 

wall varied significantly from location to location, ranging from 2.3 ng/cm2 to 47.4 ng/cm2

. This 

exposure source is minimal when compared to the post-application concentration on the carpet of 

approximately 4000 ng/cm2 of carpet area, as measured from the protectant application rate on the 

carpet. 

35
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 3.2. Results of wall wipe samples collected during Experiment 3 

Wipe Samples Wipe A, 

ng/cm2 

Wipe B, 

ng/cm2 

Wipe C, 

ng/cm2 

Wipe D, 

ng/cm2 

PFBA-C4 0.8 1.0 0.1b 1.4 

PFPeA-C5 0.5 0.7 0.0 b 1.0 

PFHxA-C6 2.5 3.3 0.2 5.3 

PFHpA-C7 6.9 8.6 0.4 10.9 b 

PFOA-C8 3.8 4.7 0.2 6.1 

PFNA-C9 4.5 5.9 0.3 7.8 

PFDA-C10 2.9 3.9 0.2 4.9 

PFUnDA-C11 2.4 3.2 0.1 4.1 

PFDoDA-C12 1.8 2.2 0.2 b 2.7 

PFTrDA-C13 1.2 1.4 0.1 b 1.5 

PFTeDA-C14 1.8b 1.9b 0.5 b 2.0 

Total PFCA, ng/cm2 29.1 36.8 2.3 47.7 

Perfluoro-n-[1,2-13C2] decanoic acid 

(recovery check standard) 113% 117% 120% 121% a 

a Did not pass MQO of ± 20% but is presented with the relaxed MQO. 

b nn = values below quantification limit; nn = values above calibration range. 

3.4 Extractable PFCA Content in Carpet Samples 

The concentrations of individual PFCAs and total PFCA in composite carpet fiber samples for 

Experiments 1 through 9 are presented in Appendix A, Tables A.1 through A.9. The results of total 

PFCAs are presented graphically in this section in Figures 3.2 through 3.10. The composite 

samples represent fibers collected from each of the five sampling locations compiled into one 

sample and then divided into five replicate samples. The data in each graph represent the reportable 

data using both the QAPP standard MQOs and the relaxed MQOs from each experiment. The 

relaxed data are highlighted in the data tables in Appendix A. The error bars represent the 

variability between replicate samples and are equal to ± one standard deviation. 

In the following graphs, each experiment is coded with the parameters of the experiment as 

presented in Table 4.3. The resulting code is presented as: Type of carpet: R = residential or C = 

commercial; carpet stain-protection treatment: 1 or 2; carpet cleaning machine: 1 or 2; and carpet 

detergent: 0 = no detergent, 1 or 2 [i.e., Experiment 1 (C-1-2-0) = Commercial carpet, CT1, CM1, 

and no detergent]. 

It was noticed that the commercial carpet (see Figures 3.2, 3.3, and 3.7) retained more PFCAs after 

treatment than the residential carpet did. 

36
 
 

 

0 

1000 

2000 

3000 

4000 

5000 

6000 

Concentration (ng PFCAs / g carpet) 

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning 

Round 1 Round 2 Round 3 

Figure 3.2. Average total PFCAs in composite carpet fiber samples for Experiment 1 (C-1-2-0) 

0 

2000 

4000 

6000 

8000 

10000 

Concentration (ng PFCAs / g carpet) 

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning 

Round 1 Round 2 Round 3 

Figure 3.3. Average total PFCAs in composite carpet fiber samples for Experiment 2 (C-2-1-0) 

37
 
 

 

0 

1000 

2000 

3000 

4000 

Concentration (ng PFCAs / g carpet) 

Pre-Application Post- Post-Cleaning Post-Cleaning Post-Cleaning 

Application Round 1 Round 2 Round 3 

Figure 3.4. Average total PFCAs in composite carpet fiber samples for Experiment 3 (R-1-1-0) 

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning 

Round 1 Round 2 Round 3 

Figure 3.5. Average total PFCAs in composite carpet fiber samples for Experiment 4 (R-1-2-0) 

0 

500 

1000 

1500 

2000 

2500 

3000 

Concentration (ng PFCAs / g carpet) 

38
 
 

 

 

0 

1000 

2000 

3000 

4000 

Concentration (ng PFCAs / g carpet) 

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning 

Round 1 Round 2 Round 3 

Figure 3.6. Average total PFCAs in composite carpet fiber samples for Experiment 5 (R-2-2-0) 

0 

3000 

6000 

9000 

12000 

Concentration (ng PFCAs /g carpet) 

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning 

Round 1 Round 2 Round 3 

Figure 3.7. Average total PFCAs in composite carpet fiber samples for Experiment 6 (C-2-2-1) 

[Re-use of carpet from Experiment 2] 

39 
 

 

 

0 

1000 

2000 

3000 

4000 

Concentration (ng PFCAs / g carpet) 

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning 

Round 1 Round 2 Round 3 

Figure 3.8. Average total PFCAs in composite carpet fiber samples for Experiment 7 (R-1-1-2) 

0 

1000 

2000 

3000 

4000 

5000 

Concentration (ng PFCAs / g carpet) 

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning 

Round 1 Round 2 Round 3 

Figure 3.9. Average total PFCAs in composite carpet fiber samples for Experiment 8 (R-1-1-2), 

duplicate of Experiment 7 

40
 
 

 

 

 

 

 

 

0 

1000 

2000 

3000 

4000 

5000 

Concentration (ng PFCAs / g carpet) 

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning 

Round 1 Round 2 Round 3 

Figure 3.10. Average total PFCAs in composite carpet fiber samples for Experiment 9 (R-2-2-1) 

[Re-use of carpet from Experiment 5] 

3.5 Percent Removal of PFCAs by Cleaning 

For each experiment, the percent removal of total PFCAs after the final cleaning was calculated by 

comparison of the total PFCA concentration after application of the carpet treatment to the total 

PFCA concentration after the third round of cleaning. These data are presented in Appendix A, 

Tables A1 through A9. Figure 3.11 is a graphic representation of these results. 

41
 
 

0% 

20% 

40% 

60% 

80% 

100% 

Total Percent Removal 

1 2 3 4 5 6 7 8 9 

Experiment 

Figure 3.11. Calculated percent removal of total PFCAs for each experiment 

42
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4. Discussion 

4.1 Removal Efficiency of Speciated Extractable PFCAs in Carpet Samples 

A relative comparison of the post-application concentration of the speciated carpet treatment to the 

concentration after the third cleaning for each experiment as percent removal of individual 

compounds PFPeA-C5 through PFDoDA-C12 is presented in Table 4.1. PFBA-C4 and PFTrDAC13 are not presented due to incomplete data sets. Three of the four experiments with detergent (7, 

8, and 9) and two of the experiments without detergent (4 and 5) present a clear trend that the 

higher removal efficiency was associated with the lower molecular weight compounds rather than 

high molecular weight compounds. This trend is confirmed in the comparison of duplicate 

experiments 7 and 8. However, in experiments 1, 2, 3, and 6, the trend indicated that the removal 

efficiencies were more uniform. No clear conclusion about speciated removal efficiency could be 

determined from these data. 

Table 4.1. Percent removal efficiency of speciated compounds 

Experiment 1 (C120) 2 (C220) 3 (R110) 4 (R120) 5 (R220) 6 (C221) 7 (R112) 8 (R112) 9 (R221) 

PFPeA-C5 29% 63% 57% 100% NR 60% 89% 79% 84% 

PFHxA-C6 29% 70% 70% 100% 89% 70% 94% 91% 91% 

PFHpA-C7 28% 62% 58% 52% 76% 64% 80% 73% 81% 

PFOA-C8 44% 67% 40% 27% 38% 73% 47% 43% 61% 

PFNA-C9 25% 70% 38% 18% 39% 81% 13% 30% 64% 

PFDA-C10 28% 64% 59% 22% 84% 81% 73% 64% 58% 

PFUnDA-C11 3% 59% 44% 5% 4% NR 4% 23% 79% 

PFDoDA-C12 19% 59% 49% 14% NR 89% 43% 20% 70% 

4.2 Overall PFCA Removal Efficiency 

For the nine cleaning tests conducted, the overall PFCA removal efficiency after three rounds of 

cleaning ranged from 26% to 76% (Table 4.2). Repeated cleanings with and without detergent did 

not return either carpet to its pre-application concentration of < 8 ng/g of TPFCAs. On average, 

each round of carpet cleaning removed approximately 20% of the total PFCAs. The overall 

removal efficiency of the PFCAs could be attributed to the differences in the carpet fibers of each 

of the products. Although there was high variability in the percent of PFCAs removed in each 

round of cleaning (Appendix A), certain trends were evident. In general, the first round of carpet 

cleaning resulted in the largest decrease in PFCAs. The decrease in PFCAs from the second to the 

third cleaning continued to show removal of PFCAs, albeit with less efficiency, almost indicating a 

leveling off of PFCA removal with each cleaning system. 

43
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 4.2. Composite carpet sample data summarizing average percent reduction in 

PFCAs by experiment 

Experiment Experimental ID Total Removal, % 

1 C-1-2-0 26% 

2 C-2-2-0 64% 

3 R-1-1-0, scouting 52% 

4 R-1-2-0 45% 

5 R-2-2-0 63% 

6 C-2-2-1 76% 

7 a R-1-1-2 58% 

8 a R-1-1-2 46% 

9 R-2-2-1 70% 

a Duplicate experiments. 

4.3 Comparison of Duplicate Experiments 

Experiments 7 and 8 were performed using the same residential carpet, treatment, cleaning 

machine and detergent and represents the only duplicate experiment that was conducted. 

Experiment 8 had slightly higher initial PFCA concentrations than Experiment 7. Analysis for 

average PFCA removal following each round of cleaning showed less than 30% variance between 

the duplicate experiments, which was within the ± 30% deviation indicated in the relaxed MQOs 

for this investigation, suggesting that these data are reproducible. 

4.4 Factors Affecting the Efficiency of PFCA Removal 

To investigate the data more closely, average reductions in PFCAs were examined by experimental 

variable. These data are presented in Table 4.3 and Figure 4.1. Although it is not possible to draw 

statistically relevant conclusions due to the large number of variables relative to the number of 

experiments and the cross-correlation of the variables, some preliminary conclusions can be drawn. 

A detergent, either CD-1 or CD-2, was used in Experiments 6 through 9. The detergent was used in 

addition to the carpet cleaning machine potentially to enhance PFCA removal. As compared to 

Experiments 1 through 4, the experiments that used detergent exhibited no statistically significant 

increases in percent removals of PFCAs after three rounds of cleaning. As compared by detergent 

(none vs. 1 or 2), CD-1 does appear to have removed a greater amount of PFCAs, 73% as 

compared to ≥50% for both CD-2 and no detergent, but percent removals for most individual 

experiments ranged from 45% to 76% regardless of detergent use. A larger number of replicate 

experiments would be needed to determine with greater certainty the effects of detergent 

application. 

44
 
 

 

 

 

 

 

 

 

Table 4.3. Average percent reduction in PFCAs by experimental variable 

for composite samples 

Variable Type Total Removal 

Carpet 

Residential 56% 

Commercial 55% 

Treatment 

CT-1 46% 

CT-2 68% 

Carpet Cleaning CM-1 52% 

Machine CM-2 57% 

CD-1 73% 

Detergent CD-2 52% 

No Detergent 50% 

Average PFCA Removal 

100% 

80% 

60% 

40% 

20% 

0% 

Residential

Commercial

CT-1 CT-2 

CM-1 CM-2 

CD-1 CD-2

None 

Carpet Protectant Carpet Cleaning Detergent 

Machine 

Figure 4.1. Average percent reduction in PFCAs by experimental variable 

for composite samples 

45
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The concentrations presented in these results represent PFCAs available via methanol extraction, 

which may not equal the level of PFCAs available under actual normal use conditions for carpet. 

For example, it has been shown that extraction of PFCAs from carpets using either water or sweat 

(laboratory-prepared sweat simulant), which are more common household solvents than methanol, 

recovered only about 10% to 65% of the PFCAs that were recovered with up to 24 hours of 

methanol extraction (Mawn et al., 2005). As treated carpet ages, wear and fiber degradation may 

also increase the availability of PFCAs through methods such as dust formation or transfer to other 

surfaces. 

4.5 Composite vs. Individual Samples 

The analysis of individual quadrant samples was conducted only to show the uniformity of the 

application of the carpet treatment, as presented in Section 2.7.1, Figure 2.9. Complete uniformity 

of application is not possible with the manual application procedure that was recommended by the 

manufacturer of the carpet treatment products. Thus, the discussion focused only on the data 

obtained from composite carpet samples. 

4.6 Extractable PFCA Content Collected from Walls 

The collection of wipe samples from the wall surfaces was conducted during the initial scouting 

experiment as a point of interest and does not concern the central discussion of PFCA removal 

from carpets. However, these samples do demonstrate that PFCAs are, in fact, deposited on the 

surface of the walls during the process of applying a carpet treatment (Table 3.2). Although the 

reported concentration of PFCAs on the surfaces of the walls was several orders of magnitude 

lower than that applied to the carpet, the presence of PFCAs on the walls after applying a carpet 

treatment should still be noted. 

46
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5. Conclusions and Recommendations 

The efficiency of PFCA removal from treated carpet by hot water extraction and stream cleaning 

was evaluated under close-to-realistic conditions in a research house. On average, each carpet 

cleaning event removed approximately 20% of total PFCAs. At this removal efficiency, it takes 

three, seven, and ten rounds of cleaning to remove, respectively, 50%, 80%, and 90% of total 

PFCAs. 

The average American home has about 1000 square feet (93 m2

) of carpet. Previous research has 

shown that treated carpets represent one of the largest sources of PFCAs in homes. Additionally, 

PFCAs are highly stable, with the potential for a long residence time indoors, and can also bind to 

house dust, making it difficult to remove the PFCAs from the indoor environment by any available 

mechanisms. The use of a carpet cleaning machine may be a risk management option for people 

who wish to reduce their indoor exposure to PFCAs. However, as mentioned above, this method is 

only modestly effective in removing PFCAs from treated carpet. 

Using the household hot water machine in four experiments with the residential carpet, reductions 

of PFCA averaged between 45% and 58% after three rounds of cleaning. The removal efficiency 

using the commercial cleaning machine on the commercial carpet had the highest variability. The 

results from two experiments using the commercial cleaning machine with a steam extraction 

indicated only a 26% reduction of PFCAs for carpet treatment 1 (CT-1), but there was a reduction 

of 64% for carpet treatment 2 (CT-2). Differences in the carpet fibers of each product may have 

also contributed to the overall removal efficiency of PFCAs. No significant difference in the 

reduction of PFCAs was observed when detergent was added to the carpet cleaning machine. With 

the commercial steam cleaner using a commercial detergent, a slight improvement was noted 

during one experiment in which an effective removal of more than 70% of total PFCA was 

obtained. However, the difference was not statistically significant. 

Further work is needed in the following areas to better understand human exposure to PFCAs from 

treated carpeting: (1) PFCA transfer mechanisms from carpets to indoor air, household surfaces, 

and dust; (2) the relationship between PFCA-treated carpet and inhalation exposure with regard to 

particle resuspension; (3) determination of the significance of dermal exposure; and (4) effective 

risk management measures for reducing PFCA levels in houses with PFCA-treated carpet. It is also 

recommended that market monitoring be continued to determine if all the carpet-treatment 

products on today’s market are virtually PFCA-free. 

47
 
 

 

 

 

Acknowledgments 

We thank Andrew Lindstrom and Mark Strynar of the EPA National Exposure Research 

Laboratory for technical consultation and assistance; Robert Wright and Joan Bursey of the EPA 

National Risk Management Research Laboratory and Libby Nessley of ARCADIS for QA support. 

48
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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51
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Appendix A: Data 

Data for total PFCA content in carpet fibers for all the experiments are presented below. 

Both individual carpet fiber samples and composite fiber samples, five per type, were 

collected at five stages of each experiment. These stages included before the application of 

a carpet treatment solution, after the application of a carpet treatment solution, and after 

each of three rounds of cleaning with a carpet cleaning machine. The PFCA concentrations 

(as mean ± standard deviation) in composite carpet fiber samples for Experiments 1 

through 9 are presented in Tables A1- A9. Averaged PFCA concentrations at each step for 

individual samples are not presented, but post-application data are given in Tables A10­

A18 to demonstrate the lower data quality for individual samples and to give an indication 

of application uniformity, as discussed previously in Section 2.7.1. 

In the following tables, each experiment is coded with the parameters of the experiment, as 

presented in Table 2.3. The resulting code is presented as: Type of carpet: R = residential or 

C = commercial; carpet stain-protection treatment: 1 or 2; carpet cleaning machine: 1 or 2; 

and carpet detergent: 0 = no detergent, 1, or 2 [i.e., Experiment 1 (C-1-2-0) = Commercial 

carpet, CT1, CM1, and no detergent]. BDL indicates that a result was below the instrument 

detection limit of 0.2 ng/mL, while NR indicates that data could not be reported because 

the results did not meet data quality requirements or were not obtained. Italicized values 

indicate that the results are above the highest calibration concentration of 100 ng/mL. 

PFTeDAwas not found above the practical quantification limit (PQL) and, therefore, was 

not reported. 

Data highlighted in bold font did not pass one or more of the QAPP-stated MQOs, but they 

passed the relaxed MQOs of ± 30% established for this project. 

A-1
 
Table A.1. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fibe

experimental stage for Experiment 1 (C-1-2-0). 

Pre-Application 

n=5 

Post-Application 

n=3 

Post-Cleaning 1 

n=2 

Post-Cleaning 2 

n=5 

Post-Cleani

n=4 

PFBA-C4 BDL 63.4 ± 13 55.6 ± 6.6 52.3 ± 2.8 49.5 ± 1.8 

PFPeA-C5 BDL 55.1 ± 10 82.7 ± 9.2 43.2 ± 3.0 39.3 ± 1.

PFHxA-C6 BDL 399 ± 91 349 ± 46 310 ± 9.6 24 ± 17 

PFHpA-C7 BDL 1150 ± 201 1530 ± 140 1000 ± 57 819 ± 77 

PFOA-C8 7.5 ± 1.0 809 ± 126 828 ± 89 560 ± 17 450 ± 39 

PFNA-C9 BDL 934 ± 118 1030 ± 155 864 ± 69 703 ± 89 

PFDA-C10 BDL 514 ± 88 363 ± 8.9 446 ± 37 373 ± 63 

PFUnDA-C11 BDL 382 ± 94 227 ± 6.1 413 ± 25 373 ± 42 

PFDoDA-C12 BDL 235 ± 66 201 ± 10 195 ± 8.5 190 ± 31 

PFTrDA-C13 BDL (NR) 71.8 ± 1.1 91.6 ± 6.6 73.4 ± 10 

Total PFCAs 7.5 ± 1.0 4540 ± 801 4740 ± 437 3980 ± 135 3350 ± 36

A-2
 
Table A.2. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fibe

experimental stage for Experiment 2 (C-2-2-0). 

Pre-Application 

n=5 a 

Post-Application 

n=5 

Post-Cleaning 1 

n=3 

Post-Cleaning 2 

n=4 

Post-Cleani

n=4 

PFBA-C4 BDL (NR) (NR) (NR) (NR) 

PFPeA-C5 BDL 73.2 ± 4.8 35.4 ± 4.0 26.8 ± 2.4 27.0 ± 2.3 

PFHxA-C6 BDL 411 ± 41 158 ± 4.4 115 ± 15 122 ± 12 

PFHpA-C7 BDL 2520 ± 90 1340 ± 18 916 ± 99 962 ± 68 

PFOA-C8 BDL 1480 ± 140 744 ± 68 492 ± 78 495 ± 37 

PFNA-C9 BDL 1980 ± 113 1060 ± 86 602 ± 85 591 ± 51 

PFDA-C10 BDL 1090 ± 81 610 ± 47 377 ± 74 391 ± 34 

PFUnDA-C11 BDL 549 ± 29 287 ± 7.7 191 ± 31 227 ± 28 

PFDoDA-C12 BDL 488 ± 60 271 ± 6.7 207 ± 45 198 ± 21 

PFTrDA-C13 BDL (NR) 154 ± 14 98.8 ± 8.6 105 ± 11 

Total PFCAs BDL 8580 ± 471 4660 ± 234 3030 ± 424 3120 ± 25

a Recovery standards for these samples exceeded the measurement quality objective (MQO) but data were all BDL and presente

A-3
 
Table A.3. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fibe

experimental stage for Experiment 3 (R-1-1-0). 

Pre-Application 

n=3 

Post-Application 

n=2 

Post-Cleaning 1 

n=3 

Post-Cleaning 2 

n=3 a 

Post-Cleani

n=3 a 

PFBA-C4 BDL 135 ± 29 95.5 ± 2.8 83.6 ± 7.9 59.0 ± 11 

PFPeA-C5 BDL 112 ± 15 73.2 ± 2.8 62.1 ± 3.1 48.1 ± 8.

PFHxA-C6 BDL 524 ± 53 309 ± 14 189 ± 9.1 159 ± 27 

PFHpA-C7 BDL 716 ± 84 483 ± 46 342 ± 26 298 ± 56 

PFOA-C8 BDL 384 ± 16 290 ± 18 249 ± 14 232 ± 36 

PFNA-C9 BDL 447 ± 23 315 ± 15 283 ± 13 278 ± 48 

PFDA-C10 BDL 257 ± 11 187 ± 15 127 ± 5.4 106 ± 19 

PFUnDA-C11 BDL 279 ± 10 225 ± 15 159 ± 9.1 155 ± 25 

PFDoDA-C12 BDL 197 ± 26 143 ± 0.92 112 ± 6.2 99.8 ± 18 

PFTrDA-C13 BDL 136 ± 15 107 ± 1.7 82.1 ± 5.9 82.2 ± 9.

Total PFCAs BDL 3190 ± 236 2230 ± 6.1 1690 ± 81 1520 ± 25

a Recovery standards for these samples were between 45-70% but data included for completeness. 

A-4
 
Table A.4. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fibe

experimental stage for Experiment 4 (R-1-2-0). 

Pre-Application 

n=5 

Post-Application 

n=4 

Post-Cleaning 1 

n=5 

Post-Cleaning 2 

n=5 

Post-Cleani

n=3 

PFBA-C4 BDL 55.1 ± 3.9 35.7 ± 4.0 BDL BDL 

PFPeA-C5 BDL 53.0 ± 1.6 41.0 ± 5.5 BDL BDL 

PFHxA-C6 BDL 413 ± 22 334 ± 43 BDL BDL 

PFHpA-C7 0.821 ± 1.4 668 ± 24 564 ± 36 381 ± 21 319 ± 9.7 

PFOA-C8 BDL 349 ± 28 292 ± 16 273 ± 14 256 ± 3.6 

PFNA-C9 BDL 367 ± 5.3 303 ± 23 303 ± 15 302 ± 8.9 

PFDA-C10 BDL 177 ± 14 156 ± 14 139 ± 13 139 ± 14 

PFUnDA-C11 BDL 195 ± 15 168 ± 14 165 ± 12 185 ± 15 

PFDoDA-C12 BDL 85.8 ± 1.9 79.2 ± 8.1 75.9 ± 6.3 73.7 ± 3.

PFTrDA-C13 BDL 73.9 ± 1.6 66.6 ± 9.5 56.4 ± 6.5 56.7 ± 3.

Total PFCAs 0.821 ± 1.4 2440 ± 42 2040 ± 119 1470 ± 62 1330 ± 3

A-5
 
Table A.5. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fibe

experimental stage for Experiment 5 (R-2-2-0). 

Pre-Application 

n=5 

Post-Application 

n=5 

Post-Cleaning 1 

n=4 

Post-Cleaning 2 

n=5 a 

Post-Cleaning 

n=5 

PFBA-C4 BDL 10.8 ± 0.88 BDL (NR) (NR) 

PFPeA-C5 BDL 59.2 ± 4.7 29.8 ± 1.1 (NR) (NR) 

PFHxA-C6 BDL 252 ± 24 143 ± 5.5 BDL 26.0 ± 1.7 

PFHpA-C7 BDL 870 ± 64 480 ± 29 227 ± 8.1 213 ± 23 

PFOA-C8 BDL 389 ± 6.9 261 ± 15 168 ± 2.8 240 ± 12 

PFNA-C9 BDL 583 ± 40 367 ± 18 230 ± 10 353 ± 22 

PFDA-C10 BDL 312 ± 48 180 ± 11 68.7 ± 9.7 49 ± 10 

PFUnDA-C11 BDL 229 ± 25 228 ± 11 177 ± 10 219 ± 19 

PFDoDA-C12 BDL 173 ± 13 171 ± 9.8 124 ± 5.4 (NR) 

PFTrDA-C13 BDL 95.0 ± 6.0 (NR) (NR) (NR) 

Total PFCAs BDL 3100 ± 333 1940 ± 83 1060 ± 21 1144 ± 70 

a Recovery standards for reported data only 64% but data included for completeness.
 b Total PFCA % removal as calculated from the results from the first cleaning. All others calculated from the third cleaning.
 

A-6
 
Table A.6. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fibe

experimental stage for Experiment 6 (C-2-2-1). Re-use of carpet from Experiment 2. 

Pre-Application 

n=4 a 

Post-Application 

n=5 b 

Post-Cleaning 1 

n=5 

Post-Cleaning 2 

n=4 

Post-Cleanin

n=2 

PFBA-C4 (NR) 27.7 ± 3.4 21.4 ± 3.0 12.7 ± 1.3 11.5 ± 1.5 

PFPeA-C5 27.0 ± 2.3 84.7 ± 9.0 61.3 ± 6.7 30.4 ± 2.1 33.5 ± 4.5 

PFHxA-C6 122 ± 12 577 ± 38 384 ± 40 200 ± 3.2 171 ± 22 

PFHpA-C7 962 ± 68 2640 ± 179 2010 ± 176 1200 ± 39 958 ± 135 

PFOA-C8 495 ± 37 1700 ± 116 1190 ± 67 595 ± 30 454 ± 0.14 

PFNA-C9 591 ± 51 2330 ± 49 1480 ± 23 615 ± 27 445 ± 15 

PFDA-C10 391 ± 34 1460 ± 106 1000 ± 59 415 ± 8.1 276 ± 5.9 

PFUnDA-C11 227 ± 28 (NR) 438 ± 16 181 ± 8.5 75.3 ± 6.0 

PFDoDA-C12 198 ± 21 669 ± 99 377 ± 12 123 ± 38 71.4 ± 0.0

PFTrDA-C13 105 ± 11 380 ± 16 243 ± 13 50.1 ± 5.4 40.7 ± 4.9 

Total PFCAs 3120 ± 252 10450 ± 445 7210 ± 239 3420 ± 43 2540 ± 13

a Pre-Application data are the results of Post-Cleaning 3 for Experiment 2.
 b Initial post-application results are higher than previous experiments due to the re-use of the carpet from Experiment 2.
 

A-7
 
Table A.7. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fibe

experimental stage for Experiment 7 (R-1-1-2). Experiments 7 and 8 considered replicate tests

Pre-Application 

n=5 

Post-Application 

n=5 

Post-Cleaning 1 

n=5 

Post-Cleaning 2 

n=5 

Post-Cleaning 

n=5 

PFBA-C4 BDL 85.4 ± 4.1 27.5 ± 1.0 28.8 ± 5.5 19.0 ± 1.9 

PFPeA-C5 BDL 79.9 ± 5.4 12.6 ± 0.47 16.7 ± 1.0 9.11 ± 1.4 

PFHxA-C6 BDL 537 ± 29 69.9 ± 2.1 60.9 ± 8.8 29.8 ± 1.6 

PFHpA-C7 BDL 809 ± 36 276 ± 18 263 ± 31 163 ± 22 

PFOA-C8 BDL 417 ± 27 311 ± 13 324 ± 26 220 ± 17 

PFNA-C9 BDL 495 ± 42 436 ± 39 516 ± 53 430 ± 32 

PFDA-C10 BDL 288 ± 20 142 ± 29 159 ± 23 79.0 ± 4.4 

PFUnDA-C11 BDL 258 ± 17 214 ± 32 281 ± 39 247 ± 20 

PFDoDA-C12 BDL 83.0 ± 6.4 47.5 ± 3.1 60.7 ± 7.2 47.6 ± 3.5 

PFTrDA-C13 BDL (NR) (NR) 62.3 ± 11 53.2 ± 5.1 

Total PFCAs BDL 3110 ± 136 1580 ± 123 1770 ± 234 1300 ± 97 

A-8
 
Table A.8. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fibe

experimental stage for Experiment 8 (R-1-1-2). Experiments 7 and 8 considered replicate tests

Pre-Application 

n=5 

Post-Application 

n=5 

Post-Cleaning 1 

n=5 

Post-Cleaning 2 

n=5 

Post-Clea

n=4 

PFBA-C4 BDL 78.1 ± 3.5 30.6 ± 1.6 20.3 ± 1.8 15.5 ± 0

PFPeA-C5 BDL 63 ± 2.5 22.9 ± 1.1 17.5 ± 1.5 13.1 ± 0

PFHxA-C6 BDL 384 ± 16 76.4 ± 9.3 49.3 ± 4.5 34.2 ± 

PFHpA-C7 BDL 904 ± 28 343 ± 25 320 ± 21 241 ± 

PFOA-C8 BDL 548 ± 10 314 ± 21 347 ± 30 310 ± 

PFNA-C9 BDL 482 ± 32 394 ± 22 340 ± 25 340 ± 

PFDA-C10 BDL 234 ± 4.9 148 ± 15 84.8 ± 6.8 84.2 ± 

PFUnDA-C11 BDL 1620 ± 91 1240 ± 132 1150 ± 102 1250 ± 

PFDoDA-C12 BDL 63.2 ± 0.59 58.2 ± 6.9 50.4 ± 0.30 49.9 ± 

PFTrDA-C13 BDL 49.8 ± 6.8 59.8 ± 4.4 49.3 ± 3.6 50.5 ± 

Total PFCAs BDL 4430 ± 142 2680 ± 218 2370 ± 209 2390 ± 

A-9
 
Table A.9. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fibe

experimental stage for Experiment 9 (R-2-2-1). Re-use of carpet from Experiment 5. 

Pre-Application 

n=5 a 

Post-Application 

n=5 

Post-Cleaning 1 

n=1 

Post-Cleaning 2 

n=5 

Post-Clea

n=3 

PFBA-C4 (NR) 9.29 ± 0.74 7 2.84 ± 0.58 3.24 ± 

PFPeA-C5 (NR) 56.8 ± 2.5 34 20.5 ± 0.50 8.56 ± 

PFHxA-C6 26.0 ± 2.0 296 ± 6.5 98 45.0 ± 0.96 27.7 ± 

PFHpA-C7 213 ± 23 1060 ± 37 624 415 ± 11 199 ± 

PFOA-C8 240 ± 12 607 ± 26 370 263 ± 60 236 ± 

PFNA-C9 353 ± 22 835 ± 33 522 368 ± 18 304 ± 

PFDA-C10 49.0 ± 10 328 ± 25 173 113 ± 24 137 ± 

PFUnDA-C11 219 ± 19 377 ± 17 314 241 ± 12 193 ± 

PFDoDA-C12 (NR) 286 ± 11 208 141 ± 22 85 ± 

PFTrDA-C13 (NR) (NR) 159 88.9 ± 27 72.9 ± 

Total PFCAs 1144 ± 70 3840 ± 25 2510 1700 ± 107 1190 ± 

a Pre-Application data are the results of Post-Cleaning 3 for Experiment 5. 

A-10
 
 

 

 

 

 

 

Table A.10. Average extractable PFCAs (ng/g) post-application in individual carpet fiber 

samples for Experiment 1 (C-1-2-0). 

Post-Application 

n=5 

Standard Deviation 

n=5 

PFBA-C4 63.8 67.5 

PFPeA-C5 57.1 61.9 

PFHxA-C6 324 287 

PFHpA-C7 977 818 

PFOA-C8 684 544 

PFNA-C9 794 629 

PFDA-C10 479 398 

PFUnDA-C11 341 270 

PFDoDA-C12 213 166 

PFTrDA-C13 179 152 

Total PFCAs 4110 3390 

Table A.11. Average extractable PFCAs (ng/g) post-application in individual carpet fiber 

samples for Experiment 2 (C-2-2-0). 

Post-Application 

n=5 

Standard Deviation 

n=5 

PFBA-C4 23.6 4.3 

PFPeA-C5 94.9 31 

PFHxA-C6 515 117 

PFHpA-C7 2960 472 

PFOA-C8 1680 274 

PFNA-C9 2310 344 

PFDA-C10 1300 190 

PFUnDA-C11 619 109 

PFDoDA-C12 472 60 

PFTrDA-C13 245 44 

Total PFCAs 10220 1610 

A-11
 
 

 

 

 

 

 

Table A.12. Average extractable PFCAs (ng/g) post-application in individual carpet fiber 

samples for Experiment 3 (R-1-1-0). 

Post-Application 

n=5 

Standard Deviation 

n=5 

PFBA-C4 112 27 

PFPeA-C5 98.9 28 

PFHxA-C6 490 134 

PFHpA-C7 634 154 

PFOA-C8 355 85 

PFNA-C9 445 97 

PFDA-C10 240 56 

PFUnDA-C11 245 34 

PFDoDA-C12 169 23 

PFTrDA-C13 126 16 

Total PFCAs 2920 640 

Table A.13. Average extractable PFCAs (ng/g) post-application in individual carpet fiber 

samples for Experiment 4 (R-1-2-0). 

Post-Application 

n=4 

Standard Deviation 

n=4 

PFBA-C4 63.9 13 

PFPeA-C5 56.9 13 

PFHxA-C6 413 83 

PFHpA-C7 730 115 

PFOA-C8 407 45 

PFNA-C9 384 68 

PFDA-C10 203 15 

PFUnDA-C11 200 41 

PFDoDA-C12 108 18 

PFTrDA-C13 85.0 11 

Total PFCAs 2650 392 

A-12
 
 

 

 

 

 

 

 

Table A.14. Average extractable PFCAs (ng/g) post-application in individual carpet fiber 

samples for Experiment 5 (R-2-2-0). 

Post-Application 

n=5 

Standard Deviation 

n=5 

PFBA-C4 12.0 1.7 

PFPeA-C5 67.1 9.8 

PFHxA-C6 273 59 

PFHpA-C7 906 182 

PFOA-C8 421 104 

PFNA-C9 564 147 

PFDA-C10 336 56 

PFUnDA-C11 243 53 

PFDoDA-C12 192 41 

PFTrDA-C13 102 22 

Total PFCAs 3120 663 

Table A.15. Average extractable PFCAs (ng/g) post-application in individual carpet fiber 

samples for Experiment 6 (C-2-2-1).a 

Post-Application 

n=5 

Standard Deviation 

n=5 

PFBA-C4 37.2 11 

PFPeA-C5 158 74 

PFHxA-C6 672 171 

PFHpA-C7 3090 660 

PFOA-C8 1920 424 

PFNA-C9 2670 602 

PFDA-C10 1660 264 

PFUnDA-C11 721 115 

PFDoDA-C12 681 148 

PFTrDA-C13 493 125 

Total PFCAs 12100 2580 

a Re-use of carpet from Experiment 2. 

A-13 
 

 

 

 

 

 

Table A.16. Average extractable PFCAs (ng/g) post-application in individual carpet fiber 

samples for Experiment 7 (R-1-1-2). Experiments 7 and 8 considered replicate tests. 

Post-Application 

n=4 

Standard Deviation 

n=4 

PFBA-C4 113 51 

PFPeA-C5 95.2 46 

PFHxA-C6 524 86 

PFHpA-C7 753 141 

PFOA-C8 365 69 

PFNA-C9 460 91 

PFDA-C10 272 47 

PFUnDA-C11 293 33 

PFDoDA-C12 69.5 51 

PFTrDA-C13 44.2 12 

Total PFCAs 2960 586 

Table A.17. Average extractable PFCAs (ng/g) post-application in individual carpet fiber 

samples for Experiment 8 (R-1-1-2). Experiments 7 and 8 considered replicate tests. 

Post-Application 

n=5 

Standard Deviation 

n=5 

PFBA-C4 79.9 15 

PFPeA-C5 63.3 15 

PFHxA-C6 342 86 

PFHpA-C7 674 157 

PFOA-C8 416 100 

PFNA-C9 471 100 

PFDA-C10 253 62 

PFUnDA-C11 243 43 

PFDoDA-C12 61.0 13 

PFTrDA-C13 49.9 10 

Total PFCAs 2650 589 

A-14
 
 

 

 

 

Table A.18. Average extractable PFCAs (ng/g) post-application in individual carpet fiber 

samples for Experiment 9 (R-2-2-1). a 

Post-Application 

n=4 

Standard Deviation 

n=4 

PFBA-C4 7.52 5.1 

PFPeA-C5 51.7 18 

PFHxA-C6 271 68 

PFHpA-C7 965 269 

PFOA-C8 585 169 

PFNA-C9 801 234 

PFDA-C10 355 88 

PFUnDA-C11 369 78 

PFDoDA-C12 282 67 

PFTrDA-C13 136 26 

Total PFCAs 3830 954 

a Re-use of carpet from Experiment 5. 

A-15