Supplemental Data
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Micro-scale quantitation of ten phthalate esters in water
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samples and cosmetics by capillary liquid chromatography
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coupled with ultraviolet detection: effective strategies to
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reduce the production of organic waste
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C.-H. Feng ()
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E-mail address: chfeng@kmu.edu.tw
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Tel.: 886-7-312-1101 ext 2805, fax: 886-7-321-0683
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Full postal address: 100, Shih-Chuan 1st Road, Kaohsiung, 80708, Taiwan.
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Results and discussion
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Optimization of the LLE procedure
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Comparison of average recoveries of ten phthalate esters extracted with
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ethyl acetate, toluene and n-hexane (100, 84 and 80 %, respectively)
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showed that ethyl acetate was the best solvent for phthalate ester
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extraction. For extracting the 10 phthalate esters, use of ethyl acetate in a
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single extraction of 300 L, a double extraction of 150 L, and triple
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extraction of 100 L revealed average extraction efficiencies (percentages)
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of 71, 90 and 100%, respectively.
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Optimization of UAE procedure
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Comparison of extraction efficiency at 30, 40 and 50 ℃revealed average
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recovery percentages of 100, 99 and 94, respectively. Thus, 30 ℃was the
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optimal temperature for phthalate ester extraction. Because of the
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semi-volatile properties of phthalate esters, temperature increases result
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in loss of compounds. Comparison of extraction durations of 5, 10 and 15
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min showed that 15 min was the best extraction duration for phthalate
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ester extraction. Extraction of ethyl acetate was compared in a single
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extraction of 300 L, a double extraction of 150 L, and a triple
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extraction of 100 L. The comparison showed that a double extraction
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using 150 L ethyl acetate obtained the best extraction efficiency.
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Optimization of the MAE procedure
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For the microwave parameter, comparisons of 200, 700 and 1000 W
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treatments in terms of effects on extraction efficiency revealed that
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average percentages of phthalate ester extraction were 89, 100 and 94%,
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respectively. Therefore, 700 W was the optimal microwave treatment for
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phthalate ester extraction. For the equilibration time parameter,
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comparisons of 3, 6 and 9 min showed that 6 min was the best
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equilibration time for phthalate ester extraction. In terms of extraction
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repetitions, ethyl acetate extraction was tested in a 300 L single
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extraction, a 150 L double extraction and a 100 L triple extraction.
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Optimization of the DLLME procedure
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Extraction efficiencies of chloroform solvent were compared in volumes
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of 10, 15, 20, 30, 40 and 50 L. Theoretically, extraction solvent volume
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should correlate with the sedimented phase obtained. As expected,
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extraction solvent volume correlated with extraction efficiency in this
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study. Comparisons of chloroform at volumes varying from 10 to 20 L
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showed that 20 L obtained the best extraction efficiency. However, at
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extraction volumes exceeding 20 L, excessive dilution negated increases
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in extraction efficiency. Next, extraction efficiency was compared in
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various dispersive solvents, including acetone, acetonitrile and methanol.
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When used as dispersive solvents for phthalate ester extraction, the
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average recovery percentages of acetone, acetonitrile and methanol were
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93, 100 and 88, respectively. Thus, acetonitrile was the best dispersive
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solvent for DLLME. To test the effects of dispersive solvent volume,
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extraction efficiency of acetonitrile was compared in volumes of 30, 60,
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90, 120, 150 and 180 L. At dispersive solvent volumes smaller than 90
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L, collecting the sedimented phase was difficult because small droplet
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formation was unobviously. At dispersive solvent volumes exceeding 90
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L, however, the decreased distribution coefficient of phthalate esters
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visibly partitioned the compounds into aqueous solution. Therefore,
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acetonitrile 90 L was the optimal dispersive solvent volume in DLLME.
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Optimized DLLME-SFO procedure
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Comparison of varying volumes (5, 10, 15, 20, 25 and 30 L) of
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1-dodecanol solvent in terms of phthalate ester extraction efficiency in
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DLLME-SFO showed that 20 L was the optimal volume. Next,
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comparison of methanol, acetonitrile, and acetone revealed phthalate ester
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extraction efficiencies of 86, 89, and 100%, respectively. Thus, acetone
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was the best dispersive solvent for DLLME-SFO. Extraction efficiency of
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acetone solvent was then compared in volumes of 30, 60, 90, 120, 150
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and 180 L . Notably, extraction recovery decreased as acetone volume
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increased due to the effects of dilution. At dispersive solvent volumes
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smaller than 30 L, obtaining the solidifying phase was difficult.
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Therefore 30 L was the optimal solvent volume when using acetone as
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dispersive solvent in DLLME-SFO.
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Optimized CPE procedure
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Three surfactants were evaluated: Triton X-100, Triton X-114 and
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Genapol X-080. Since the structures of Triton X-100 and Triton X-114
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contain chromophores, high concentrations of these surfactants in the
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CPE interfere with I.S., DprP, BBP and DBP in the chromatograms. Since
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the structure of Genapol X-080 does notcontain chromophores; Genapol
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X-080 was a a suitable surfactant for CPE in this study. In terms of
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physical-chemical properties, the critical mecellar concentration (CMC)
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of Genapol X-080 is 0.028 % (w v-1), and its cloud point is 42 ℃. Tests
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of the phthalate ester extraction efficiency of Genapol X-080 at
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concentrations of 1, 2, 4, 8 and 12 % (w v-1) obtained average recovery
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percentages of 86, 95, 100, 62 and 39%, respectively. As surfactant
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concentration increased, the partitioning of phthalate esters into micelle
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also increased until the volume of the redundant surfactant-rich phase was
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too large to dilute the target analytes. Therefore, the optimal Genapol
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X-080 concentration was only 4 % (w v-1) in CPE. In CPE, electrolyte
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levels may enhance extraction efficiency by altering the density of the
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aqueous solution as well as the cloud point temperature. In this study, use
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of NaCl (0, 1, 2, 3 and 4 % (w v-1)) as electrolyte for extracting phthalate
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esters achieved average recovery percentages of 100, 36, 74, 40 and 34 %,
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respectively. Therefore, NaCl should be excluded when performing CPE.
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In temperature testing, use of NaCl at temperatures of 60, 70, 80, 90 and
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100 ℃ obtained average recovery percentages of 100, 88, 95, 89 and 93
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%, respectively. Although NaCl was also tested at 50 ℃, phase separation
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was incomplete, and collecting the surfactant-rich phase was difficult.
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Therefore, 60 ℃ was the optimal temperature for CPE extraction of
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phthalate ester. Extraction efficiency was then compared at equilibration
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times of 30, 45, 60, 75, 90 and 120 min. At 45-90 min, the surfactant-rich
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phase and the aqueous phase were completely separated, and extraction
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efficiency exceeded 94%. Hence, 45 min equilibration time was selected
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for phthalate ester extraction.
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Table S1. Calibration curves for inter-day and intra-day analyses of the phthalate esters
Phthalate
esters
Linear range
(μg mL-1)
Inter-day
Intra-day
Linear equation (n=6)
r2
Linear equation (n=6)
r2
LOD
(μg mL-1)
DMP
0.5-50
y = 0.0411 x - 0.0036
0.999
y = 0.0395 x - 0.0127
0.999
0.05
DEP
0.5-50
y = 0.0319 x - 0.0150
0.998
y = 0.0308 x - 0.0203
0.997
0.02
DprP
0.5-50
y = 0.0243 x - 0.0035
0.999
y = 0.0241 x - 0.0103
0.998
0.10
BBP
0.5-50
y = 0.0230 x - 0.0129
0.998
y = 0.0236 x - 0.0190
0.997
0.10
DBP
0.5-50
y = 0.0249 x - 0.0096
0.998
y = 0.0248 x - 0.0133
0.998
0.05
DPP
0.5-50
y = 0.0187 x - 0.0086
0.998
y = 0.0192 x - 0.0141
0.998
0.06
DCHP
0.5-50
y = 0.0201 x - 0.0086
0.999
y = 0.0200 x - 0.0134
0.998
0.07
DnHP
0.5-50
y = 0.0180 x - 0.0046
0.998
y = 0.0186 x - 0.0085
0.998
0.07
DEHP
0.5-50
y = 0.0176 x - 0.0023
0.998
y = 0.0170 x - 0.0028
0.998
0.03
DOP
0.5-50
y = 0.0166 x - 0.0083
0.998
y = 0.0165 x - 0.0114
0.998
0.17
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LLE
UAE
MAE
DLLME
DLLME-SFO
CPE
120.00
Recovery (%)
100.00
80.00
60.00
40.00
20.00
0.00
PAEs
Fig. S1.
The recovery of a water sample by using six different
techniques on the extraction of the phthalate esters (PAEs).
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LLE
UAE
MAE
DLLME
DLLME-SFO
CPE
120.00
Recovery (%)
100.00
80.00
60.00
40.00
20.00
0.00
PAEs
Fig. S2.
The recovery of a toner sample by using six different techniques
on the extraction of the phthalate esters (PAEs).
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LLE
UAE
DLLME-SFO
120.00
Recovery (%)
100.00
80.00
60.00
40.00
20.00
0.00
PAEs
Fig. S3.
The recovery of a emulsion sample by using three different
techniques on the extraction of the phthalate esters (PAEs).
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