Electronic Supplementary Materialon the MicrochimicaActa publication entitled:
Magnetic mesoporouspolymelamine-formaldehyde resin as an adsorbent for endocrine disrupting chemicals
Yuhong Song1†, Ruiyang Ma2†, Caina Jiao1, Lin Hao1, Chun Wang1, Qiuhua Wu1* and Zhi Wang1*
1Department of Chemistry, College of Science, Hebei Agricultural University, Baoding 071001, China
2 College of Landscape and Travel, Hebei Agricultural University, Baoding 071001, China
† These authors contributed equally to this work.
Correspondence: Professor Qiuhua Wu, College of Science, Hebei Agricultural University, Baoding 071001, China; Fax: +86-312-7528292; Tel: +86-312-7528291; E-mail: ; Professor Zhi Wang, College of Science, Hebei Agricultural University, Baoding 071001, China; Tel: +86-312-7521513; fax: +86- 312- 7521513; E-mail: ;
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Synthesis of NH2-Fe3O4
The amino-functionalized Fe3O4 nanoparticles(NH2-Fe3O4) with the size about 25 nm was synthesized by a one-pot hydrothermal procedure according to a previous report[1]. In a typical process, FeCl3·6H2O (3.0 g, 11.10 mmol), anhydrous sodium acetate (12.0 g, 146.29 mmol) and ethylenediamine (10.8 mL) were dispersed in 50 mLethanediol and subjected to ultrasonic treatment for 15 minto give a transparent solution.Then, the solution was transferred to a Teflon-lined stainless-steel autoclave and heated at 200 oC for 6 h. After being cooled down to room temperature, the dark precipitate was isolated by a magnet and washed with deionized water and ethanol for 3 times to remove the solvent and unbound ethylenediamine. The dark precipitate was dried in vacuum for 12 h before the subsequent applications.
Optimization of the MSPE procedures
For the optimization experiments, 50 mL double-distilled water spiked with 80.0 ng⋅mL-1 each of the four EDCs was used to study the extraction performance of the MSPE under different experimental conditions. The main influencing experimental parameters including the amount of the Fe3O4-mPMF, extraction time, ionic strength, sample solution pH and the type and volume of the desorption solvent were investigated to achieve a good extraction efficiency of the Fe3O4-mPMF for the four EDCs.All the experiments were performed in triplicate.
Effect of the amount of the Fe3O4-mPMF
To achieve a good extraction recovery for the four EDCs, the amount of the Fe3O4-mPMF was investigated in the range from 3 to 15 mg for the extraction. As shown in Fig. S6a, the extraction recoveries for the analytesreached the maximum plateau when 10mg of the magnetic sorbent was used. To ensure that the adsorbent was sufficient for the extraction, 12 mg of the Fe3O4-mPMF was employed in the experiments.
Effect of the extraction time
To investigate the influence of the extraction time on the extraction efficiency, the extraction time was varied in the range of 1-20 min when other conditions were kept constant. As shown in Fig. S6b, the extraction recoveries for the analytes were increased from 1 to 10 min and then remained almost unchanged, indicating that the extraction equilibrium was reached in 10 min. On the basis of the above result, 10 min of extraction time was chosen.
Effect of salt concentration
To test whether the salt had an influence on the extraction efficiency, different amounts of NaCl, i.e., 2.0, 4.0, 6.0, 8.0 and 10% (w/v), were added to the sample solution. The result indicated that no significant changes of the extraction recoveries were observed for the four EDCs in the whole NaCl concentration range investigated. Therefore, no NaCl was added in all the subsequent experiments.
Effect of the sample solution pH
The sample solution pH influences the existing forms of the analytes, and therefore can affect the extraction efficiency. In this study, the influence of sample solution pH was studied in the pH range of 2.0-12.0 which was adjusted by the addition of HCl or NaOH solution into the sample solution. Fig. S6c shows that the extraction recoveries for the four EDCs remained almost unchanged when thesample solution pH was changed from 2.0 to 8.0and then decreased rapidly when the pH was higher than 8.0.The reason for this can be thatthe four EDCs can be ionized in alkaline conditions. According to the above experimental results, the determination of the EDCs should be carried out under acidic or neutral conditions. Since the pHs of both the river water and bottled juice samples were in the range from 3.0 to 7.0, there was no need to adjust the pH of the samples.
The desorption conditions
To effectively desorb the analytes from the adsorbent, both the desorption solvent and its volume were evaluated. Firstly, six organic solvents, i.e., methanol, acetonitrile, acetone, 1% alkaline methanol (1 mol⋅L-1NaOH : methanol = 1%(v/v)), 1% alkaline acetonitrile and 1% alkaline acetone were tested as the desorption solvent. According to the results (Fig. S6d), 1% alkaline acetonitrile provided the best desorption efficiency for all the analytes.The influence of NaOH concentration in acetonitrile was then investigated by adding different amounts of 1 mol⋅L-1NaOH into acetonitrile(1%, 2% and 3% (v/v)). The result indicated that the NaOH concentration changes in acetonitrile had no significant influence on theextraction recovery. Thus all the subsequent experiments were performed using 1% alkaline acetonitrile as the desorption solvent.
Then, the volume of 1% alkaline acetonitrile was optimized in the range from 0.1 to 0.9 mL in different desorption modes. Fig. S6e shows that the desorption efficiency was increased when the volume was increased from 0.1 to 0.6 mL and all the analytes can be desorbed quantitatively from the adsorbent by using either 0.6 mL (0.3 mL × 2) or 0.9 mL (0.3 mL × 3) 1% alkaline acetonitrile. However, Fig. S6f shows that when the volume of 1% alkaline acetonitrile was increased from 0.1 to 0.9 mL, the peak areas of the analytes were decreased due to the dilution effect, thus resulting in lower detection sensitivities for the analytes. Considering that a volume of 0.1 mL eluent was too small for the experimental manipulations, 0.2 mL of 1% alkaline acetonitrile was chosen for the experiment.
Reusability of the adsorbent
To investigate the reusability of the Fe3O4-mPMF adsorbent, the used Fe3O4-mPMF was washed with 1.0mL1% alkaline acetonitrile byvortexing for 1 min for three times, and then with 2 mL water. After such washing, no carry-over was detected and the experimental results showed that the Fe3O4-mPMF could be reused 25 times without a significant loss of the adsorption capability.
Fig. S1 Schematic illustration for the preparation process of the magnetic mesoporouspolymelamine-formaldehyde (Fe3O4-mPMF).
Fig. S2 Procedures for the magnetic solid phase extraction (MSPE) of the endocrine disrupting chemicals (EDCs) with the Fe3O4-mPMF.
Fig. S3The adsorption capability of different materials for EDCs. Amount of adsorbent: 12 mg packed in 3 mL SPE cartridge; Sample volume: 50 mL; spiked analyte concentration: 80.0 ng⋅mL-1; pH value: 7.0; desorption solvent: 0.9 mL 1% alkaline acetonitrile for Fe3O4-mPMF, 0.9 mL acetonitrile for MWCNTs, 0.9 mL methanol for GCB, and 0.9 mL acetone for C18.
Fig. S4 The TEM images of the synthetic NH2-Fe3O4 (a) and reported work (b) [2].
Fig. S5(a) The nitrogen adsorption-desorption isotherms and pore size distribution curve of Fe3O4-mPMF; (b) the TGA graph for Fe3O4-mPMF.
Fig.S6Effect of (a) the amount of the Fe3O4-mPMF, (b) extraction time, (c) the sample solution pH, (d) eluent type, and (e) desorption solvent volume on the extraction recovery. (f) Effect of the desorption solvent volume on the peak area of the analytes.
Table S1 Analytical results for the determination of the EDCs in river water and bottled juice samples.
EDCs / Spiked(ng⋅mL-1) / River water sample
(n = 5) / Bottled juice sample
(n = 5)
Found
(ng⋅mL-1) / Ra
(%) / RSDs
(%) / Found
(ng⋅mL-1) / R
(%) / RSDs
(%)
BPA / 0.0 / ndb / nd
5.0 / 4.61 / 92.3 / 4.5 / 4.61 / 92.1 / 4.6
15.0 / 14.53 / 96.9 / 4.6 / 12.81 / 85.4 / 4.0
4-t-BP / 0.0 / nd / nd
5.0 / 4.28 / 85.6 / 3.9 / 5.45 / 109 / 6.9
15.0 / 15.06 / 100.4 / 5.0 / 15.47 / 104.3 / 3.7
4-t-OP / 0.0 / nd / 0.32
5.0 / 4.74 / 94.7 / 5.6 / 5.18 / 103.6 / 6.0
15.0 / 15.46 / 95.4 / 4.8 / 15.15 / 101 / 4.3
NP / 0.0 / 0.27 / nd
5.0 / 5.14 / 102.8 / 3.7 / 5.32 / 106.4 / 6.4
15.0 / 14.96 / 99.7 / 5.0 / 14.95 / 99.6 / 5.3
aR: recovery of the method; bnd: not detected.
Table S2 Some physical chemical parameters for different compounds and their extraction recoveries on the Fe3O4-mPMF.
Compounds / Structures / H bond acceptors / H bond donors / Log Kowa / Rb(%)
Fluorene / / 0 / 0 / 4.02 / 91.3
Phenanthrene / / 0 / 0 / 4.35 / 97.8
Anthracene / / 0 / 0 / 4.35 / 93.3
Fluoranthene / / 0 / 0 / 4.93 / 94.1
Pyrene / / 0 / 0 / 4.93 / 95.8
DAP / / 4 / 0 / 3.36 / 98.2
DIBP / / 4 / 0 / 4.46 / 95.1
DBP / / 4 / 0 / 4.61 / 99.1
Teflubenzuron / / 4 / 2 / 4.64 / 86.3
Flufenoxuron / / 5 / 2 / 5.97 / 89.6
Triflumuron / / 5 / 2 / 4.24 / 95.8
Monolinuron / / 4 / 1 / 2.26 / 59.4
Isoproturon / / 3 / 1 / 2.84 / 72
Monuron / / 3 / 1 / 2.03 / 74.3
Propoxur / / 4 / 1 / 1.90 / 71
Isoprocarb / / 3 / 1 / 2.37 / 70.8
Bassa / / 3 / 1 / 2.86 / 82.9
BPA / / 2 / 2 / 3.64 / 81
4-t-BP / / 1 / 1 / 3.42 / 79.5
4-t-OP / / 1 / 1 / 5.28 / 81
NP / / 1 / 1 / 5.99 / 83
Progesterone / / 2 / 0 / 3.67 / 89.5
Oestrone / / 2 / 2 / 3.43 / 91.5
Diethylstilbestrol / / 4 / 0 / 6.78 / 92.6
aoctanol/water partition coefficient; b extraction recovery.
References
[1] McCullum C., Tchounwou P., Ding L.S., Liao X., Liu Y.M., Extraction of aflatoxins from liquid foodstuff samples with polydopamine-coated superparamagnetic nanoparticles for HPLC-MS/MS analysis, J. Agric. Food Chem. 62(19) (2014) 4261-4267.
[2] Wang L., Bao J., Wang L., Zhang F., Li Y., One-pot synthesis and bioapplication of amine-functionalized magnetite nanoparticles and hollow nanospheres, Chemistry 12(24) (2006) 6341-6347.
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