Electronic Supplementary Material
Efficient solid-phase microextraction of triazole pesticides from natural water samples
using a Nafion-loaded trimethylsilane-modified mesoporous silica coating of type SBA-15
Mir Mahdi Abolghasemi a, *, Sona Hassani a, Mehdi Bamorowat b
a
Department of Chemistry, Faculty of Science, University of Maragheh, Maragheh, Iran
(55181-83111)
b
GYAH Corporation, Garmdarreh, Karaj, Iran (3164847591)

Corresponding author: Department of Chemistry, Faculty of Science, University of Maragheh,
Maragheh,
Iran,
Tel:
+98
4137276060
Fax:
+98
4137276060,
mehdiabolghasemi@gmail.com
Fig. S1. SEM image of modified Nafion/SBA-15.
E-mail
address:
Fig. S2. FT-IR spectra of methyl-modified SBA-15 and methyl-modified Nafion/SBA-15.
Temperature effect
The sample temperature can affect the rate and equilibrium of the extraction, so it is an essential
factor in HS-SPME. Generally, higher temperature can improve mass transfer of analytes from
water to headspace and further to the fiber coating [4, 15]. The effect of extraction temperature
ranging from 40 to 90 ºC for 60 min, on extraction efficiency was studied, in order to find the
optimum extraction. Fig. S2, illustrates the triazolic compounds peak area versus extraction
temperature profiles for the analytes. As can be realized, the extraction ability increases
simultaneously, when temperature rises up to 80 ºC, and then it decreases or mains unchanged
for the analytes. Here, the optimum extraction temperature was selected to be 80 ºC, on the basis
of the experimental observations.
Fig. S3. Influence of the extraction temperature on the peak area of triazolic compounds.
Extraction time
The mass transfer depends on time in the equilibrant HS-SPME process, therefor the extraction
time is a very important parameter related to the fiber extraction performance in achieving
distribution equilibrium of analytes between fiber and sample. Over the extraction time, target
compounds have sufficient chance to be transferred from aqueous phase to headspace. In the
headspace, the extraction time of samples is usually kept long enough to achieve equilibrium
between the headspace and the adsorbent in order to maximize the extraction efficiency. To
explore the effect of extraction time on extraction efficiency of the triazoles, times of 20–70 min
were tested. The plot of GC/MS peak area as a function of extraction time is presented in Fig.
S3, whereas the fiber was exposed to standard solutions of the triazoles at a concentration of 10
ng mL−1. The obtained results revealed that, all of the analytes attained the highest response
within 60 min and then decreased in 70 min slightly. Thus, 60 min was preferred as the suitable
extraction time.
Fig. S4. Effect of the extraction time on the peak area of triazolic compounds.
The effect of pH
The extraction efficiency is affected by the pH values because of changing the charge of
analytes. Consequently, since the tirazoles have acid–base properties, the pH values affect their
extraction efficiency [14, 16]. The effect of pH on the extraction efficiency was studied within
the pH range 2–8. It was found that (Fig. S4) better extraction efficiencies were obtained at pH
4-7. At pH values higher than 8 and lower than 4, the analytical signals for the tested pesticides
were reduced. Reducing in extraction efficiencies of target analytes can be attributed to
hydrolysis of pesticides in highly acidic or alkaline pHs. On the basis of these results, pH values
in the range 4-7 can be used for further analysis. It should be noted that pH of all used samples
was within the range 4-7 and hence pH adjustment was not required.
Fig. S5. The pH values because of changing the charge of analytes.
Salting-out effect
It is well known that, addition of salt may affect the solubility of analytes in the water sample.
The extraction efficiency is related to the ionic strength of the aqueous solution. Commonly,
adding an ionic salt (usually sodium chloride) to an aqueous solution, reduces the water
solubility of analytes and improves their extraction into the organic phase. The added salt
balances the activity constants of analytes in different matrices, and also the wrought ions attract
and hold water molecules, so make them less able to interact with the solute [4, 7]. The effect of
ionic strength was performed by adding NaCl as the salting-out agent to aqueous sample in the
range of 0–30% (w/v). By regulating the NaCl concentration at 20% (w/v), the extraction
efficiency was reached to its highest state. The examined concentrations, was three to eight times
greater than that achieved for an aqueous sample with no added NaCl. Thus, the 20% (w/v) of
NaCl salt was selected for all subsequent extraction.
Stirring rate
One of the significant parameters influencing the extraction efficiency of the model compounds,
is stirring rate. Stirring should be forceful and has to be kept constant in all experiments. The
stirring of the water samples reduces the thickness of the water film between the aqueous
solution and the coating, which improves the extraction efficiency of the HS-SPME method and
coating. On the other hand, the time required to reach thermodynamic equilibrium decreases
under strring condition, by enhancing the diffusion of the analytes towards the headspace [15,
16]. Extraction efficiency of the studied compounds was measured from 5 mL of the model
sample solutions containing 20% (w/v) NaCl and 60 min extraction times at various stirring
rates. The effect of stirring rate on extraction efficiency was determined from 0 rpm to 700 rpm.
The experimental results confirmed that extraction efficiency reaches a maximum and remains
constant above 500 rpm. Thus, an optimum stirring rate of 500 rpm was chosen for all
subsequent experiments.
Table S1 The results obtained for the analysis of the spiked water samples (10 ng mL-1) by the proposed method, under the optimized
conditions
.
Found a ( ng mL−1 )
Added
Sample
(ng mL−1)
Penconazole
Hexaconazole
Diniconazole
Tebuconazole
Triticonazole
Difenoconazole
Aji river
10
10.2 (0.4)
10.1(0.3)
10.1(0.4)
10.4(0.1)
10.6(0.5)
10.3(0.2)
Chichih river
10
10.6(0.6)
1.4(0.5)
10.6(0.3)
10.5(0.7)
10.6(0.2)
10.5(0.5)
a
The figures within parentheses are standard deviations for three replicate