होम Environmental Toxicology and Chemistry Solvent selection for pressurized liquid extraction of polymeric sorbents used in air sampling

Solvent selection for pressurized liquid extraction of polymeric sorbents used in air sampling

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27
साल:
2008
भाषा:
english
DOI:
10.1897/07-566.1
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Biogeochemical toxicity and phytotoxicity of nitrogenous compounds in a variety of arctic soils

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Biokinetics of cadmium and zinc in a marine bacterium: Influences of metal interaction and pre-exposure

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Environmental Toxicology and Chemistry, Vol. 27, No. 6, pp. 1267–1272, 2008
䉷 2008 SETAC
Printed in the USA
0730-7268/08 $12.00 ⫹ .00

Methods
SOLVENT SELECTION FOR PRESSURIZED LIQUID EXTRACTION OF
POLYMERIC SORBENTS USED IN AIR SAMPLING
TOBY PRIMBS,† SUSAN GENUALDI,† and STACI MASSEY SIMONICH*†‡
†Department of Chemistry, Oregon State University, 1007 ALS, Corvallis, Oregon 97331, USA
‡Department of Environmental and Molecular Toxicology, Oregon State University, 1007 ALS, Corvallis, Oregon 97331, USA
( Received 26 October 2007; Accepted 21 December 2007)
Abstract—Pressurized liquid extraction (PLE) was evaluated as a method for extracting semivolatile organic compounds (SOCs)
from air sampling media, including quartz fiber filter (QFF), polyurethane foam (PUF), and a polystyrene divinyl benzene copolymer
(XAD-2). Hansen solubility parameter plots were used to aid in the PLE solvent selection in order to both reduce coextraction of
polyurethane and save time in evaluating solvent compatibility during the initial steps of method development. A PLE solvent
composition of 75:25% hexane:acetone was chosen for PUF. The XAD-2 copolymer was not solubilized under the PLE conditions
used. The average percent PLE recoveries (and percent relative standard deviations) of 63 SOCs, including polycyclic aromatic
hydrocarbons, polychlorinated biphenyls, and organochlorine, amide, triazine, thiocarbamate, and phosphorothioate pesticides, were
76.7 (6.2), 79.3 (8.1), and 93.4 (2.9)% for the QFF, PUF, and XAD-2, respectively.
Keywords—Pressurized liquid extraction
sen solubility parameter

Polyurethane foam

Polystyrene divinyl benzene

Quartz fiber filter

Han-

Previous research has focused on the intentional extraction
of monomers/oligomers and/or polymeric additives from polymers. Lou et al. used PLE to extract monomers and oligomers
from nylon-6 and poly(1,4-butyleneterephthalate), showing
that the PLE extraction solvent chosen and the extraction temperature were important but that solvent selection was ‘‘largely
empiric; al’’ [12]. Vandenburg et al. [13] proposed using Hildebrand solubility parameters to select solvents for the extraction of the polymeric additives Irganox 1010 and dioctyl
phthalate from ground polypropylene, polyvinyl chloride, and
nylon.
Hildebrand solubility parameters are most effective for substances lacking any significant polar or hydrogen bonding capabilities, thus substances that undergo primarily dispersiontype interactions. Hansen solubility parameters divide up the
Hildebrand parameter (␦) into three components: dispersion
(␦D), permanent dipole-permanent dipole (␦P), and hydrogen
bonding (␦H) forces (see the following equation) [14]. These
three components take into account the similarities (or dissimilarities) of the polar and hydrogen bonding components of
organic compounds to better explain the extent of interaction
[14]:

INTRODUCTION

Pressurized liquid extraction (PLE) is an exhaustive extraction technique that uses less solvent (⬃100–200 ml) and
time (⬃20 min) compared to traditional solvent extraction
techniques such as Soxhlet extraction [1]. Extraction efficiencies reported for PLE are similar to those reported for Soxhlet
and supercritical fluid extraction [2], and PLE has been shown
to be effective for the extraction of semivolatile organic compounds (SOCs) from environmental matrices, including soils,
particulate matter, fly ash, and sediments [3–7]. Fitzpatrick et
al. [7] previously reported important considerations for the
selection of PLE parameters (e.g., cycles and temperature).
For more than a decade, the global atmospheric transport
of anthropogenic SOCs has been shown to cause surface contamination in remote locations [8], and atmospheric transport
is a major environmental transport pathway for SOCs from
source regions to remote locations [9]. Often, a quartz fiber
filter (QFF) is combined with polyurethane foam (PUF) and
polystyrene divinyl benzene (XAD-2) in a QFF-PUF-(XAD2)-PUF sampling train to ensure complete collection of particulate-phase SOCs (QFF), followed by gas-phase SOCs (PUF
and XAD-2) [6,10].
Because the air sampling media used for trapping gas-phase
SOCs are polymers such as PUF and XAD-2, the appropriate
selection of PLE extraction solvents is essential in order to
minimize matrix interferences due to coextraction of the polymeric matrix while simultaneously achieving adequate extraction of the SOCs. The minimization of interferences from PLE
extraction cells has been reported [11]; however, the minimization of polymeric matrix interferences from air sampling
media has not.

␦2 ⫽ ␦2D ⫹ ␦2P ⫹ ␦2H

The human and environmental safety of the organic solvents used is also an important consideration in PLE solvent
selection. For example, if dichloromethane, a probable human
carcinogen (http://www.atsdr.cdc.gov/tfacts14.pdf), is used as
a PLE solvent to clean air sampling media and any residual
dichloromethane remains after cleaning, it may be released
during sample collection and result in human exposure [15].
To date, the use of PLE has focused on the extraction of
SOCs from various solid matrices and the intentional extraction of monomers/oligomers and additives from polymers. Two
major goals were established in the selection of solvents for

* To whom correspondence may be addressed
(staci.simonich@oregonstate.edu).
Published on the Web 1/25/2008.
1267

1268

Environ. Toxicol. Chem. 27, 2008

the PLE of SOCs from polymeric air sampling media. The
first goal was to efficiently extract the SOCs from the media,
and the second goal was to avoid coextraction of the polymeric
matrix. Using Hansen solubility parameters, PLE solvents were
selected that minimized coextraction of polymeric matrix interferences but resulted in good recoveries of 63 commonly
measured SOCs. The SOCs selected for extraction and analysis
were from nine chemical classes, and their physical chemical
properties (octanol–water partition coefficient, water solubility, and vapor pressure) spanned 7 to 10 orders of magnitude
[16].
MATERIALS AND METHODS

Semivolatile organic compounds evaluated for PLE recoveries covered several chemical classes (Table 1). A complete
list of the isotopically labeled surrogates and internal standards
that were used for quantitation has been previously reported
[16]. The SOC standards were obtained from the U.S. Environmental Protection Agency repository (Fort Meade, MD),
Chemical Services (West Chester, PA, USA), Restek (Bellefonte, PA, USA), Sigma-Aldrich (St. Louis, MO, USA), and
AccuStandard (New Haven, CT, USA). Isotopically labeled
standards were obtained from CDN Isotopes (Pointe-Claire,
QC, Canada) or Cambridge Isotopes Laboratories (Andover,
MA, USA). The standards were stored at 4⬚C until use. All
solvents (hexane, dichloromethane, and acetone) were from
Fisher Scientific (Fairlawn, NJ, USA) and were optima grade.

Pressurized liquid extraction solvent evaluation
The initial selection of solvents was based on Hansen solubility parameter plots for the polymeric media and solvents.
Following this initial selection, two experiments were conducted to evaluate the suitability of the solvents for PLE. First,
the polymeric media was cleaned by PLE with the solvents to
evaluate coextraction of the polymer. After selecting PLE solvent systems that did not significantly coextract the polymeric
media, the PLE recoveries of 63 SOCs from the sampling
media were measured.
Evaluation of background interferences. In order to evaluate the potential polymeric interferences due to PLE of PUF
(Tisch Environmental, Cleves, OH, USA), three 7.6 ⫻ 7.6-cm
PUF plugs were cleaned with an accelerated solvent extractor
(ASE威) 300 (Dionex, Sunnyvale, CA, USA) in 66-ml ASE
extraction cells. Sequential extractions of 100% dichloromethane, 100% acetone, 75:25% hexane:acetone, and 100%
hexane were used. The ASE parameters for the four extractions
were cell temperature 100⬚C, static time 5 min, solvent flush
50% of cell volume, one static cycle, and an N2 purge time
of 240 s. After cleaning, one PUF plug was extracted with
100% dichloromethane, the second with 100% hexane, and the
third with 75:25% hexane:acetone using the same ASE parameters described previously, except two static cycles were
used instead of one.
Copolymers such as XAD-2 are considered nonsoluble in
organic solvents because of their cross-linking [17]. To evaluate the potential interferences from XAD-2 (Supelco, St. Louis, MO, USA), approximately 50 g of XAD-2 were cleaned
by PLE (Table 2) in a 100-ml ASE extraction cell. After cleaning, the XAD-2 was extracted with 50:50% hexane:acetone
using the ASE parameters described in Table 2. The 50:50%
hexane:acetone solvent system has been previously reported
being used with XAD-2 and PLE (http://www1.dionex.com/
en-us/webdocs/4522㛮AN347㛮V16.pdf). The PUF and XAD-2

T. Primbs et al.

extracts were concentrated using a Turbovap威 II (Caliper Life
Sciences, Hopkinton, MA, USA) at 37⬚C to approximately 600
␮l and further concentrated to a final volume of approximately
300 ␮l using a micro N2 stream concentrator.
PLE recoveries. After the selection of PLE solvents was
made using Hansen solubility parameter plots and the resulting
polymeric interferences were evaluated, the PLE recoveries of
63 SOCs were measured in triplicate. The QFFs (Whatman,
Kent, UK) were cleaned by baking at 350⬚C for 12 h [6,10],
and the PUF and XAD-2 were cleaned using the ASE conditions described in Table 2. For PUF and XAD-2 cleaning,
the extraction solvents were used in order of polarity (from
more to less polar). After cleaning, the air sampling media
was fortified with 15-␮l of 10-ng/␮l solutions of the target
SOCs using a syringe and immediately extracted using the
PLE solvents and parameters listed in Table 2. The resulting
PLE extracts were fortified with 15 ␮l of 10-ng/␮l solutions
of the 24 isotopically labeled surrogates to assess SOC recoveries from the PLE step only. The extracts were concentrated to approximately 300 ␮l and fortified with 15 ␮l of 10ng/␮l solutions that contained the four isotopically labeled
internal standards to track recoveries of the surrogates (i.e.,
recoveries from the remaining steps of the method).

Instrumental analysis
Qualitative analysis of monomeric and oligomeric interferences was conducted using gas chromatography (GC) on
an Agilent 6890 gas chromatograph (Santa Clara, CA, USA)
coupled with mass spectrometry (Agilent 5973N, mass selective detector). A 30-m ⫻ 0.25-mm inner diameter ⫻ 0.25-␮m
film thickness DB-5 column (J&W Scientific, Palo Alto, CA,
USA) was used. The GC oven temperature program was 60⬚C
held for 1 min, followed by 6.0⬚C/min to 300⬚C and then held
for 3 min, finishing with 20.0⬚C/min to 320⬚C and held for 9
min. The mass spectrometer was operated in electron impact
ionization mode and scanned from 35 to 500 m/z.
Quantitative analysis of SOC recoveries was conducted using the same GC/mass spectrometry system in selective ion

Fig. 1. Hansen solubility parameter plot of polyurethane at 25⬚C [14].
Various solvents, including 100% acetone, 100% hexane, 100% ethyl
acetate, 50:50% hexane:acetone, 75:25% hexane:acetone, and dichloromethane, are shown in the figure with respect to polyurethane. The
circle represents the solubility circle for polyurethane (see the Discussion section).

Pressurized liquid extraction of air sampling media

Environ. Toxicol. Chem. 27, 2008

1269

monitoring mode, using either negative chemical ionization or
electron impact ionization modes, depending on which form
of ionization gave the lowest instrumental detection limit. Details of the instruments, ions monitored, instrument limit of
detections, and GC oven temperature program have been provided elsewhere [6,16].
RESULTS AND DISCUSSION

Pressurized liquid extraction solvent selection
Hansen solubility parameter plots are used to graphically
display the Hansen solubility parameters for various solvents
and polymers. The x-axis of these plots represents the dipole–
dipole and the y-axis represents the hydrogen bonding components [14]. The z-axis (dispersion) is often not displayed for
organic compounds because there is usually little difference
between them [14].
Hansen solubility parameters were used to identify solvents
that were compatible with polyurethane. Figure 1 shows the
Hansen solubility parameter plot of polyurethane with various
organic solvents [14]. The solubility circle (Fig. 1) represents
the region where a solvent is likely to dissolve polyurethane
[14]. The closer a solvent is to the center of the circle, the
more likely it is to solubilize polyurethane [17]. Of the organic
solvents shown in Figure 1, dichloromethane and 50:50% hexane:acetone are closest to polyurethane, and hexane is the
furthest. It should be noted that at higher temperatures, Hansen
solubility parameters tend to decrease, while the solubilization
circle tends to increase [14]. However, Hansen notes that the
parameters at higher temperatures are similar to the established
values at 25⬚C [14]. The data shown in Figure 1 are for 25⬚C,
which is lower than typical PLE temperatures (⬃100⬚C).
The use of PLE to extract SOCs from polymeric air sampling media with organic solvents can lead to matrix interferences. The GC/mass spectrometer chromatograms of the
PLE of PUF using 100% dichloromethane, 100% hexane, and
75:25% hexane:acetone are overlaid in Figure 2A for comparison in order to evaluate the resulting matrix interferences.
Figure 2A also shows a solvent injection of 100% dichloromethane. The chromatographic baseline signal was elevated
when 100% dichloromethane was used as the PLE extraction
solvent as compared to 75:25% hexane:acetone and 100% hexane. This result is consistent with the Hansen solubility parameter plot for polyurethane (Fig. 1).
A copolymer of polystyrene divinyl benzene (i.e., XAD-2)
was not solubilized under the PLE conditions used. Figure 2B
shows the chromatogram of a 50:50% hexane:acetone XAD-2
extract compared to a solvent injection of hexane. Because
XAD-2 contains cross-linking, a low signal baseline was expected [17]. Solubility parameters have not been developed for
XAD-2 because it is considered nonsoluble in organic solvents
(B. Vogler, Supelco, personal communication). Figure 2B confirms the lack of XAD-2 solubilization during PLE. A Dionex
technical report has noted the formation of naphthalene during
extraction of XAD-2 at elevated temperatures; thus, a PLE temperature of 75⬚C was chosen (Table 2) (http://www1.dionex.
com/en-us/webdocs/4522㛮AN347㛮V16.pdf). For the PUF, the
PLE temperature was 100⬚C, a typical temperature for PLE.
Lower temperatures were not investigated because 100⬚C was
found to be effective and did not damage the PUF.

PLE recovery of SOCs
Pressurized liquid extraction has been reported to have similar extraction efficiencies compared to Soxhlet [5], super-

Fig. 2. (A) Total ion chromatogram of interferences due to coextraction
of monomers and oligomers from polyurethane foam (response vs
time). The figure shows the effects of three pressurized liquid extraction solvents on polyurethane foam: dichloromethane (DCM),
100% hexane (Hex), and 75:25% hexane:acetone (Hex:Ace). Also
shown for reference is a solvent injection of DCM. (B) Total ion
chromatogram comparing polystyrene divinyl benzene (XAD-2) interferences using the pressurized liquid extraction solvent mixture of
50:50% Hex:Ace compared to a solvent injection of Hex.

critical fluid extraction, and microwave-assisted extraction [2].
For the PUF recovery study, the 75:25% hexane:acetone solvent system was chosen over hexane to ensure the extraction
of polar, current-use pesticides. For example, atrazine recoveries were only 12%, and atrazine desethyl was not detected
using hexane (n ⫽ 1). For more nonpolar SOCs (e.g., organochlorines and polycyclic aromatic hydrocarbons), hexane was
as effective as the 75:25% hexane:acetone solvent system. For
QFF, PUF, and XAD-2, the average percent recoveries (and
percent relative standard deviations) were 76.7 (6.2), 79.3
(8.1), and 93.4 (2.9)%, respectively (Table 1). For the PUF,
the chlordane and nonachlor PLE recoveries were lower
(⬃50%). If needed, an additional extraction cycle could be
used to increase recoveries of these SOCs.
The average absolute percent SOC recoveries (and percent
relative standard deviations) over the entire analytical method
for the QFF, PUF, and XAD-2 were 66.3 (4.8), 76.0 (5.5), and
77.1 (3.3)%, respectively. These recoveries included the solvent evaporation steps and resulted in SOC recoveries that
were lower than the PLE step alone. Estimated method detection limits, calculated using U.S. Environmental Protection
Agency method 8280A [18] and assuming an average air volume of 644 m3, ranged from 0.0001 to 100, 0.001 to 114, and
0.0003 to 108 pg/m3 for the QFF, PUF, and XAD-2, respectively.

1270

Environ. Toxicol. Chem. 27, 2008

T. Primbs et al.

Table 1. Average pressurized liquid extraction semivolatile organic compound recoveries (% relative standard deviation) from quartz-fiber filter
(QFF), polyurethane foam (PUF), and polystyrene divinyl benzene (XAD-2) (n ⫽ 3) using the parameters and solvents listed in Table 2. HCH
⫽ hexachlorocyclohexane; DDD ⫽ dichlorodiphenyldichloroethane; DDE ⫽ dichlorodiphenyldichloroethylene; EPTC ⫽ s -ethyl
dipropylthiocarbamate; PCB ⫽ polychlorinated biphenyl
QFF

PUF

XAD-2

Amide pesticide
Alachlor
Acetochlor
Metolachlor

78.7 (5.8)
68.3 (5.6)
84.9 (7.4)

81.7 (8.5)
42.7 (12.6)
96.1 (3.8)

97.0 (2.1)
87.9 (3.1)
102.6 (1.9)

Organochlorine pesticides and metabolites
HCH, gamma
HCH, alpha
HCH, beta
Heptachlor
Heptachlor epox
Endrin
Endrin aldehyde
Chlordane, trans
Chlordane, cis
Nonachlor, trans
Nonachlor, cis
Chlordane, oxy
Aldrin
o,p⬘-DDT
o,p⬘-DDD
o,p⬘-DDE
p,p⬘-DDT
p,p⬘-DDD
p,p⬘-DDE
Mirex

76.3
74.9
83.1
77.8
72.7
58.9
59.7
70.6
69.7
69.3
57.1
70.6
66.5
77.8
84.3
73.2
92.5
84.3
79.0
60.4

Organochlorine sulfide pesticides
Endosulfan I
Endosulfan II

73.3 (9.2)
73.9 (7.9)

Phosphorothioate pesticides
Methyl parathion
Malathion
Diazinon
Parathion
Ethion
Chlorpyrifos

73.6
69.2
79.6
77.1
97.6
73.6

Thiocarbamate pesticides
EPTC
Pebulate
Triallate

79.9 (3.8)
91.2 (2.5)
82.7 (5.5)

Triazine herbicides and metabolites
Atrazine desisopropyl
Atrazine desethyl
Atrazine
Simazine

81.5
78.9
75.1
78.9

(15.6)
(14.4)
(6.6)
(8.4)

94.5
93.3
89.7
86.5

(7.8)
(11.9)
(5.2)
(6.4)

107.7
102.7
90.2
102.7

(3.4)
(1.4)
(1.0)
(1.3)

Miscellaneous pesticides
Metribuzin
Etridiazole
Dacthal
Trifluralin
Hexachlorobenzene

97.3
79.7
93.7
79.5
78.7

(4.6)
(3.6)
(1.7)
(0.8)
(2.4)

111.6
117.5
105.5
80.0
81.5

(4.8)
(7.6)
(2.5)
(16.2)
(2.4)

90.8
116.5
95.4
82.6
93.3

(7.0)
(0.7)
(3.7)
(4.5)
(1.0)

Polycyclic aromatic hydrocarbons
Acenaphthene
Fluorene
Phenanthrene
Pyrene
Fluoranthene
Chrysene ⫹ triphenylene
Retene
Benzo[k]fluoranthene
Benzo[b]fluoranthene
Benzo[e]pyrene
Indeno[1,2,3-cd]pyrene
Dibenz[a,h]anthracene
Benzo[ghi]perylene

77.1
82.9
81.9
77.7
79.3
75.3
80.5
81.9
83.4
84.0
69.9
73.3
77.4

(4.2)
(2.4)
(2.5)
(3.2)
(3.9)
(7.1)
(4.4)
(9.8)
(9.7)
(10.1)
(8.9)
(9.2)
(8.9)

77.3
78.7
83.0
83.3
82.5
86.0
93.7
84.3
83.3
84.7
76.9
81.9
82.0

(2.2)
(2.2)
(3.6)
(3.9)
(3.7)
(3.7)
(3.2)
(4.2)
(4.5)
(4.8)
(4.0)
(3.4)
(4.3)

81.2
92.1
99.4
89.4
92.2
87.5
114.2
79.6
99.2
101.8
93.7
89.9
88.9

(4.4)
(2.2)
(2.2)
(2.7)
(3.0)
(1.9)
(3.0)
(2.4)
(0.7)
(3.6)
(1.4)
(2.4)
(2.5)

(1.2)
(2.3)
(1.0)
(3.8)
(4.6)
(6.7)
(15.4)
(6.2)
(8.4)
(6.6)
(5.7)
(3.3)
(2.9)
(6.8)
(6.1)
(5.8)
(10.7)
(6.2)
(3.7)
(2.6)

(8.1)
(12.7)
(7.1)
(8.4)
(12.4)
(8.9)

64.7
60.2
82.0
77.6
67.2
107.8
44.1
49.9
43.9
48.3
58.5
61.1
65.5
80.6
87.9
83.9
87.4
95.7
87.5
76.4

(1.3)
(2.2)
(1.9)
(3.6)
(1.2)
(4.3)
(14.7)
(0.8)
(1.0)
(1.2)
(1.8)
(1.3)
(3.3)
(3.3)
(4.2)
(3.6)
(2.1)
(5.3)
(3.2)
(0.4)

60.4 (0.5)
80.1 (3.0)
75.8
92.3
81.0
75.9
113.9
90.9

(2.3)
(5.4)
(1.5)
(8.4)
(9.1)
(2.8)

81.4 (1.7)
116.9 (3.5)
123.1 (4.2)

94.5
92.2
89.9
111.6
122.4
107.3
92.9
104.1
82.6
99.3
93.9
118.2
99.2
94.4
94.9
104.2
89.8
106.3
91.0
86.5

(1.1)
(0.4)
(1.0)
(2.6)
(1.3)
(2.2)
(1.4)
(1.1)
(3.7)
(1.6)
(2.5)
(1.4)
(1.3)
(1.5)
(1.7)
(7.7)
(0.4)
(3.2)
(1.8)
(2.5)

102.0 (1.1)
97.8 (2.3)
80.7
74.0
81.2
77.1
100.4
81.8

(1.4)
(5.8)
(2.2)
(3.4)
(8.5)
(2.6)

83.8 (1.4)
88.8 (1.3)
91.9 (2.2)

Environ. Toxicol. Chem. 27, 2008

Pressurized liquid extraction of air sampling media

1271

Table 1. Continued
QFF
Polychlorinated biphenyls
PCB 74
PCB 101
PCB 118
PCB 153
PCB 138
PCB 187
PCB 183

79.5
82.1
95.9
73.3
78.8
76.8
78.0

Average

76.7 (6.2)

PUF

(1.4)
(2.2)
(5.0)
(2.4)
(3.2)
(1.7)
(1.5)

96.9
90.4
90.7
97.8
103.4
88.6
82.0

XAD-2

(8.1)
(7.8)
(8.4)
(8.7)
(8.7)
(8.9)
(9.2)

93.5
88.7
70.9
103.9
95.2
91.0
91.9

79.3 (8.1)

(0.6)
(3.1)
(4.6)
(1.6)
(6.2)
(1.5)
(1.6)

93.4 (2.9)

Table 2. Accelerated solvent extractor (ASE威) 300 (Dionex, Sunnyvale, CA, USA) parameters and solvents used to clean polystyrene divinyl
benzene (XAD-2) and polyurethane foam (PUF). Quartz-fiber filters (QFFs) were cleaned by baking at 350⬚C for 12 h. ASE parameters and
solvents used for the extraction of semivolatile organic compounds from XAD-2, PUF, and QFF are also given. Solvents included hexane (Hex)
and acetone (Ace). The multiple solvents used for the extraction of the QFF, in addition to the cleaning of the XAD-2 and PUF, were sequential
extractions. The ASE威 parameters: Temp (extraction cell temperature), static hold time for extraction (Static) in minutes, solvent flush percent
of cell volume (Flush%), static cycle (Cycles), and an N2 purge time (Purge) in seconds. NA ⫽ not applicable
Media
Cleaning
XAD-2
PUF
QFF
Extraction
XAD-2
PUF
QFF

No. of extractions

Cycles

Temp (⬚C)

Static

Flush%

Purge

100% Ace
25:75 Hex:Ace
50:50 Hex:Ace
100% Ace
75:25 Hex:Ace
690:10 Hex:Ace
NA

1
1
3
1
1
1
NA

5
5
3
1
1
1
NA

75
75
75
100
100
100
NA

5
5
5
5
5
5
NA

100
100
100
100
100
100
NA

240
240
240
240
240
240
NA

50:50 Hex:Ace
75:25 Hex:Ace
50:50 Hex:Ace
100% Hex

1
1
1
1

3
2
3
3

75
100
100
100

5
5
5
5

100
100
100
100

240
240
240
240

Solvent

Polymers (i.e., PUF and XAD-2) are effective sorbents for
sampling gas-phase SOCs from the atmosphere, and PLE is a
rapid and effective cleaning and extraction method for the
extraction of SOCs with a wide range of physical and chemical
properties. Care should be taken in PLE solvent selection when
extracting SOCs from polymeric sampling materials, and Hansen solubility parameters can provide useful guidance to save
time in evaluating solvent compatibility during the initial steps
of method development.

4.

5.

6.

Acknowledgement—The research described in the present study has
been funded in part by the U.S. Environmental Protection Agency
(U.S. EPA) under the Science to Achieve Results Graduate Fellowship
Program to Toby Primbs. The U.S. EPA has not officially endorsed
this publication, and the views expressed herein may not reflect the
views of the U.S. EPA. We also thank the National Science Foundation
CAREER (ATM-0239823) for funding. This work was made possible
in part by the National Institutes of Health (grant P30ES00210).
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