Supporting Information
Octyl-modified magnetic graphene as a sorbent for the extraction and
simultaneous determination of fragrance allergens, musks and
phthalates in aqueous samples by gas chromatography with mass
spectrometry
Katerina Maidatsi, Theodoros Chatzimitakos, Vassilios Sakkas, Constantine D.
Stalikas*
Laboratory of Analytical Chemistry, Department of Chemistry, University of Ioannina,
Ioannina 451 10, Greece
Chromatographic conditions
The injector and mass transfer-line temperatures were set at 250oC and 290oC,
respectively. Injections were performed using a beveled, curved needle tip (0.4856
mm glass barrel, i.d.; 0.13 mm needle i.d.) purchased from Hamilton (Reno, Nevada,
USA). The column temperature was programmed at 45oC for 2 min, increased to
190oC, at a rate of 4oC/min and held for 1 min, then ramped at 10oC/min to 270oC
(held for 5 min). The total run time was 52.25 min. The mass detector was operated
in the electron impact mode at 70 eV with the electron multiplier voltage set to 1.35
kV. The solvent cut time was set to 6.0 min. The injection volume was 1.0 μL and
splitless injection mode was employed. The splitless time was 1.0 min. Helium (purity
≥ 99.999%) was used as the carrier gas at a flow rate of 1.0 mL min-1. Selective ion
monitoring (SIM) mode was adopted for the determination of the analytes.
Synthesis of graphene oxide (GO)
In brief, 133mL of a 9:1 mixture of H2SO4 (95% w/w) / H3PO4 (85% w/w) were added
to a mixture of graphite powder (1.0 g) and KMnO4 (6.0 g). The temperature was
maintained at 50℃ under stirring, for 24 h. After that, the solution was cooled
down to room temperature, in an ice bath and cool water (130 mL) containing 30%
w/w H2O2 (6 mL) was added. After settling overnight, the supernatant was decanted
away and the remaining solid was stirred overnight after the addition of 30% w/w
HCl (30 mL). The mixture was centrifuged for 10 min at 4000 rpm and washed
several times with double distilled water (DDW) till pH7. Finally, the solid was
washed with pure ethanol (3×25 mL) followed by centrifugation. Ethanol was
decanted away and the remaining graphene oxide was dried in an oven.
Synthesis of magnetic graphene oxide and graphene composites
0.09 g of GO was dispersed in 25 mL of DDW by ultrasonication, for 1 h. Then, 0.04
mol of FeCl3·6H2O and 0.02 mol of FeCl2·4H2O were dissolved in 2.5 mL of DDW and
the solution was added dropwise to the vigorously stirred GO dispersion, under a
nitrogen flow, at room temperature. Finally, 28% (w/w) ammonia solution was
added drop-by-drop up to pH 10 for the synthesis of the magnetic material. The
material was washed three times with DDW, followed by three more washings with
ethanol. Then it was dried at 70oC, for 24 h, ground in an agate mortar and stored at
room temperature.
Table S1. Elemental analysis of magnetic-GR-C8 for different refluxing time periods
(n=3).
Refluxing Time (h)
6
12
24
48
72
90
Carbon (%)
10.3
10.3
10.4
10.4
10.6
10.6
Nitrogen (%)
1.84
1.78
1.35
1.26
1.20
1.35
Table S2. Selected fragrance allergens, musks and phthalates and some of their
physicochemical properties.
Compound
Chemical Name
Limonene
Benzyl Alcohol
Linalool
Citral
Geraniol
Hydroxycitronellal
Cinnamyl Alcohol
Eugenol
Ionone
Coumarin
Isoeugenol
Cashmeran
Diethyl Phthalate
Amyl Cinnamyl
Alcohol
Celestolide
Hexyl cinnamaldeyde
Phantolide
(4R)-1-Methyl-4-(1-methylethenyl)cyclohexene
Phenylmethanol
3,7-dimethylocta-1,6-dien-3-ol
3,7-dimethylocta-2,6-dienal
(trans)-3,7-Dimethyl-2,6-octadien-1-ol
7-Hydroxy-3,7-dimethyloctanal
(2E)-3-phenylprop-2-en-1-ol
4-Allyl-2-methoxyphenol
(3E)-4-(2,6,6-Trimethylcyclohex-2-en-1-yl)but-3-en-2-one
2H-chromen-2-one
2-methoxy-4-(prop-1-en-1-yl)phenol
1,1,2,3,3-Pentamethyl-1,2,3,5,6,7-hexahydro-4H-inden-4-one
diethyl benzene-1,2-dicarboxylate
2-Pentyl-3-phenylprop-2-en-1-ol
4.6
1.1
1.5
1.5
3.3
1.5
1.9
2.2
4.4
1.4
2.5
4.9
2.7
4.8
Boiling
Point(OC)
176
205
198
229
230
94
250
254
126
301
266
256
295
200
1-(6-tert-butyl-1,1-dimethyl-2,3-dihydroinden-4-yl)ethanone
(2E)-2-Benzylideneoctanal
1-(2,3-Dihydro-1,1,2,3,3,6-hexamethyl-1H-inden-5yl)ethanone
4,6,6,7,8,8-Hexamethyl-1,3,4,6,7,8hexahydrocyclopenta[g]isochromene
1-(5,6,7,8-tetrahydro-3,5,5,6,8,8-hexamethyl-2naphthalenyl)-ethanone
Di-n-butylphthalate
Benzyl 3-phenylprop-2-enoate
1,2-Benzenedicarboxylic acid
6.6
4.8
6.7
309
308
357
5.9
330
5.7
357
4.5
3.7
5.8
340
371
436
Galaxolide
Tonalide
Dibutyl Phthalate
Benzyl Cinnamate
Dicyclohexyl
Phthalate
Log Ko/w
Table S3. Recovery values (%) and relative standard deviations (within-day and between-days RSDs) obtained with the magnetic GR-C8sorbent, at two concentration levels of fragrance allergens, musks and phthalates.
Compound
Limonene
Benzyl Alcohol
Linalool
Citral
Geraniol
Hydroxycitronelal
Cinnamyl Alcohol
Eugenol
Ionone
Coumarin
Isoeugenol
Cashmeran
Diethyl Phthalate
Amyl Cinnamyl Alcohol
Celestolide
Hexylcinnamaldeyde
Phantolide
Galaxolide
Tonalide
Dibutyl Phthalate
Benzyl Cinnamate
Dicyclohexyl Phthalate
Recovery (%) at
LOQ level
Within-day
repeatability
(RSD %)
83
94
92
95
97
91
96
91
103
97
98
91
91
96
96
104
96
103
96
104
84
90
6.1
3.2
6.9
7.9
4.0
4.3
7.6
7.6
6.3
4.9
7.4
8.3
7.1
6.4
6.8
5.2
6.1
6.8
4.4
5.3
8.5
7.1
Between-days (3
days)
reproducibility
(RSD %)
6.7
7.9
7.3
7.6
4.9
6.5
9.0
6.7
7.4
8.0
8.3
7.9
8.9
8.1
8.8
7.8
8.2
8.5
6.4
6.7
8.6
7.3
Recovery (%) at
10×LOQ level
Within-day
repeatability
(RSD %)
Between-days (3 days)
reproducibility
(RSD %)
90
90
91
97
94
102
99
93
85
105
97
88
104
94
89
99
91
96
90
97
96
94
7.3
4.3
5.4
8.0
4.4
4.9
8.0
6.1
6.7
4.1
4.2
7.2
2.6
6.3
3.2
6.5
5.9
5.6
2.1
6.5
4.6
8.5
7.3
5.8
7.1
8.2
4.9
7.6
8.9
6.3
9.4
4.7
4.9
8.8
2.6
6.4
6.4
8.5
7.6
5.6
4.8
6.8
4.6
8.5
Table S4. Comparison of analytical performance data with other data reported in the literature.
Analytes
Technique
Fragrance
allergens
GC-MS
Phthalate
esters
Nitro and
polycyclic
musks
Phthalate
esters
Musks
HPLC
Musks
GC-MS
Fragrance
allergens
Phthalate
esters
Fragrance
allergens
Fragrance
allergens,
phthalate
esters,
musks
GC-MS
Preconcentration
technique
Detection
limits, μg L-1
Recovery
%
Ultrasound-assisted
emulsification–
microextraction
Liquid-liquid extraction
0.006-0.95
LVI-GC-MS
Microextraction by
packed sorbents
GC-ECD
Solid-phase
microextraction
Stir-bar sorptive
extraction
Solid-phase
microextraction
Dispersive liquid-liquid
microextraction
Magnetic solid-phase
extraction
Solid phase
microextraction
Magnetic solid-phase
extraction
TD-GC-MS
HPLC
GC-MS
GC-ΜS
Consumption of
organic solvent
(μL)
100
Total time of
sample analysis
(min)
22.5
Ref
75-110
Sample
preparation
time (min)
13
1-3
84-110
30
3000
20
[2]
5-84
75-135
-
50
33
[3]
0.0003-0.016
0-116
25
-
50
[4]
0.02-0.3
81-95
266
48
14.6
[5]
0.014-0.022
45-50
55
-
25
[6]
0.007-1
29-112
10
100
46
[7]
0.05-0.1
79-99
20
1000
15
[8]
0.001-0.3
73-124
30
50-100
22.5
[9]
0.0003-0.0032
83-105
30
300
52.25
This work
[1]
Figure S1. FT-IR spectra of graphene oxide (blue line) and magnetic-GR-C8 (pink line).
Τotal chromatographic area
35000
30000
25000
20000
Allergens
15000
Musks
10000
Phthalates
5000
0
20
40
60
80
100
150
Sample volume, mL
Figure S2. Effect of sample volume on the extraction using magnetic GR-C8 sorbent.
Total chromatographic area
60000
Allergens 300 rpm
50000
Allergens 600 rpm
40000
Allergens 900 rpm
30000
Musks 300 rpm
20000
Musks 600 rpm
Musks 900 rpm
10000
Phthalates 300 rpm
0
15
30
Phthalates 600 rpm
45
Phthalates 900 rpm
Stirring time, min
Figure S3. Effect of stirring rate and stirring time.
Total Chromatographic area
20000
15000
10000
Allergens
Musks
Phthalates
5000
0
0
1
2
3
4
5
Na2SO4, % w/v
Figure S4. Effect of ionic strength on the total chromatographic area.
Total chromatographic area
25000
Allergens
20000
Musks
15000
10000
Phthalates
5000
0
acetone
hexane
MTBE
hexane-EA
EA
EA-MTBE
Solvents
Figure S5. Effect of solvent type on the total chromatographic area of different
classes of analytes.
Total chromatographic area
25000
20000
15000
Allergens
10000
Musks
5000
Phthalates
0
0
1
2
5
10
Ultrasonication time, min
Figure S6. Effect of ultrasonication time on the desorption of analytes.
Figure S7. GC-MS chromatogram of a standard solution of 22 target analytes
(concentrations between 100 and 200 ng L-1) after extraction with the sorbent. Peak
assignment: 1) Limonene, 2) Benzyl alcohol, 3) Linalool, 4) Citral, 5) Geraniol, 6)
Hydroxycitronellal, 7) Cinnamyl alcohol, 8) Eugenol, 9) Ionone, 10) Coumarin, 11)
Isoeugenol, 12) Cashmeran, 13) Diethyl phthalate, 14) Amylcinnamylalcohol, 15)
Celestolide, 16) Hexylcinnamaldeyde, 17) Phantolide, 18) Galaxolide, 19) Tonalide,
20) Dibutyl phthalate, 21) Benzyl cinnamate, 22) Dicyclohexyl phthalate.
Figure S8. GC-MS chromatogram of a sample from biological treatment plant, after
extraction with the sorbent. Peak assignment: 1) Limonene, 2) Linalool, 3)
Hexylcinnamaldeyde, 4) Galaxolide, 5) Tonalide, 6) Dibutyl phthalate, 7) Docosane, 8)
Dicyclohexyl phthalate.
Figure S9. GC-MS chromatogram of a blank sample. Peak assignment: I.S. Internal
standard (docosane).
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