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Supplementary Materials
Development of dynamic headspace–liquid phase microextraction method performed in a home–
made extraction vessel for extraction and preconcentration of 1,4–dioxane from shampoo
*, a
Mir Ali Farajzadeh , Parinaz Nassirya, Mohammad Reza Afshar Mogaddama, Ali Akbar Alizadeh
Nabilb
a
Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran
b
Food and Drug Laboratories, Tabriz University of Medical Sciences, Tabriz, Iran
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Optimization of dichloromethane/n–hexane volume ratio in LLE step
Dichloromethane and n–hexane mixtures with different volume ratios have various polarities and can
affect distribution coefficient of the target analyte between the sample and extractive phase. To optimize
dichloromethane/n–hexane volume ratio effect in LLE step different volumes of dichloromethane and n–
hexane while total volume was kept constant (5 mL) was evaluated. According to the obtained results
(Fig. 1S) high extraction efficiency is obtained at a ratio of 50:50 (v/v) dichloromethane: n–hexane.
Therefore it was selected for further experiments.
Fig. 1S. Effect of dichloromethane/n–hexane volume ratio on the analytical signal of 1,4–dioxane from
shampoo.
Extraction conditions: sample, 3 g blank shampoo spiked with the analyte (500 mg kg–1); extraction
solvent, 5 mL of dichloromethane and n–hexane; temperature, 35 °C; centrifuging rate, 7000 rpm ; and
centrifuging time, 5 min. The error bars indicate the minimum and maximum of three independent
determinations.
.
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Optimization of dichloromethane: n–hexane mixture volume
The effect of dichloromethane: n–hexane mixture volume in LLE step was tested using different volumes
of dichloromethane: n–hexane (50:50, v/v) including 3, 4, 5, 6, and 7 mL according to the extraction
procedure described above. The results in Fig. 2S indicate that ER increases from 3 to 5 mL and then
remains constant. Therefore, 5 mL was selected as the optimum volume for the extractant.
Fig. 2S. Effect of dichloromethane: n–hexane mixture volume in LLE procedure.
Extraction conditions: are the same as used in Fig. 1S, except dichloromethane: n–hexane (50:50,v/v) was
used as an extractant. The error bars indicate the minimum and maximum of three independent
determinations.
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Salt addition
Addition of a salt decreases solubility of an analyte in aqueous phase and increases its partitioning into
organic phase. In this work, salt addition may increase the extraction efficiency of the target analyte from
shampoo to the extractant, and improves two–phase system formation. Effect of salt addition was studied
by adding NaCl in the range of 0 – 1.50 g into 3 g blank shampoo. The obtained results in Fig. 3S indicate
that analytical signal increases up to 1.0 g and then decreases. Subsequently, 1.00 g of NaCl was selected
as a salting out agent for the further studies.
Fig. 3S. Effect of salt addition on the extraction efficiency of LLE.
Extraction conditions: are the same as used in Fig. 2S, except 5 mL mixture of n–hexane:
dichloromethane (50:50, v/v) was used as the extractant. The error bars indicate the minimum and
maximum of three independent determinations.
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Optimization of n–octanol volume
To evaluate the effect of n–octanol volume, different volumes of it including (0.5, 1.0, 1.5, 2.5, 5.0, 7.5,
and 10 μL) were subjected into the developed method. According to the obtained results (Fig. 4S) the
peak areas ratio increases until 2.5 μL and then decreases at volumes 2.5 to 10 μL. It can be attributed to
dilution of the extracted analyte into organic phase which, in turn, leads to decrease in EF and analytical
signal. Thus 2.5 μL was selected as the suitable volume for n-octanol solvent.
Fig. 4S. Selection of extraction/preconcentration solvent volume in DHS–LPME.
Conditions in LLE step: are the same as used in Fig. 3S. Conditions in DHS–LPME step:
extraction/preconcentration solvent, n–octanol; temperature, 35 °C; and heating/extraction time, 8.0 min.
The error bars indicate the minimum and maximum of three independent determinations.
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Study of heating/extraction time
In this study, a DHS–LPME method was developed in which heating/extraction time has an important
effect on performance of the developed method. This parameter was studied in the range of 0.5–10 min.
The obtained results (Fig. 5S) show that the peak areas ratio and ER increase up to 8 min and then remain
constant. So, 8 min was selected as the optimum time for heating/extraction in the following experiments.
Fig. 5S. Effect of heating/extraction time.
Extraction conditions: the same as used in Fig. 4S, except 35 °C was used as extraction temperature. The
error bars indicate the minimum and maximum of three independent determinations.
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