N hexane

The standard mixture of 18 PAHs in solvent acetonitrile: toluene (92:8) (EPA Method 8310 PAH Mixture, Restek, Bellefonte, PA, USA) includes acenaphthene, acenaphthylene, anthracene, benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, benzo(k)fluoranthene, chrysene, dibenz(a,h)anthracene, fluoranthene, fluorene, indeno(1,2,3-cd)pyrene, 1-methylnaphthalene, 2-methylnaphthalene, naphthalene, phenanthrene, and pyrene. Isotope compounds were obtained from Dr. Ehrenstorfer GmbH (Augsburg, Germany), including the internal standards: benzo(a)anthracence-13C6, and benzo(g,h,i)pyrylene-13C12. All solvents (acetonitrile, n-hexane), which are of HPLC grade or pro analysis, were obtained from Fisher chemical (Pittsburgh, PA, USA). MgSO₄ and NaCl were obtained from Merck. The sorbent Primary Secondary Amin (PSA) and octadecylsilane (C18) were purchased from Agilent (Santa Clara, CA, USA).

The monomers 2-(dimethylamino)ethyl methacrylate (DMAEMA, Sigma Aldrich, Taufkirchen, Germany) and 2-hydroxyethyl methacrylate (HEMA, Sigma Aldrich) were stored for 24 h at 5 °C with inhibitor remover for hydroquinone (Sigma Aldrich) before use. Azobisisobutyronitrile (AIBN, Sigma Aldrich), methacryloyl chloride (MAC, Sigma Aldrich), methyl iodide (Sigma Aldrich), ammonium persulfate (APS, Sigma Aldrich), tetramethylethylenediamine (TEMED, Sigma Aldrich), tetrahydrofuran (THF, Fisher Scientific, Schwerte, Germany), n-hexane (Fisher Scientific), ethanol (Fisher Scientific), triethylamine (TEA, TCI Chemicals Deutschland, Eschborn, Germany), sodium hydroxide (NaOH, Sigma Aldrich), potassium chloride (KCl, Sigma Aldrich), sodium sulfate (Na₂SO₄, Sigma Aldrich), myoglobin (Myo, Sigma Aldrich), and bovine serum albinum (BSA, Sigma Aldrich) were all used as received. Proteins were dissolved in 0.01 M phosphate-buffered saline (1 g/L) and pH was adjusted to the isoelectric point (IEP) of BSA (pH 4.8) or Myo (pH 7) with 1 M HCl. 1,3-Propane sultone (PS, Sigma Aldrich) was heated with hot water above its melting point (31 °C) before used in liquid form. Commercially available PA TFC flat-sheet membranes NF270 (DuPont, Neu Isenburg, Germany) were cut in circular shape (diameter 48 mm) before used in dead-end mode filtration cells.

Standard Pyrethrin II (w/w, 30%, technical Grade, contains Pyrethrin I) was obtained from Toronto Research Chemicals Inc. (Toronto, ON, Canada). Sodium chloride and anhydrous sodium sulfate were analytical reagent grade and purchased from Beijing Chemical Reagent Company (Beijing, China). Acetonitrile, acetone and n-hexane were both HPLC-grade and purchased from Fisher Scientific (Pittsburgh, PA, USA). Aquapro Ultrapure Water System supply ultrapure water. Florisil SPE cartridges (0.5 g/3 mL) were purchased from ANPEL (Shanghai, China). Stock standard solution of pyrethrins (1000 mg/L) was prepared in acetone and stored at −20 °C. Working standard solutions were prepared by dilution with acetone and stored at −20 °C.

The procedure of anchoring silver nanoparticles onto f-EG was adapted from a method described for CNTs [32 (link)] consisting of the reduction reaction of silver ions (Ag+) using N,N-dimethylformamide (DMF, from Panreac, Barcelona, Spain), obtaining [(f-EG)+Ag]. A total of 140 mg of silver nitrate was mixed with 8 mL of absolute ethanol (both from Fisher Scientific, Loughborough, UK) and left under magnetic stirring, at room temperature, for 15 min. At the same time, 280 mg f-EG was mixed with 16 mL DMF and magnetically stirred, at room temperature, for 15 min. These two suspensions were then mixed together and stirred for 72 h, protected from light, being subjected to ultrasounds for 15 min every 24 h. Finally, the product was filtered and washed with diethyl ether and hexane (95% n-hexane from Fisher Scientific, Loughborough, UK) and then dried for 2 h at 150 °C under vacuum.

Methanol, n-hexane, water and dichloromethane of analytical grade were purchased from Fisher Scientific (Loughborough, Leicestershire, UK). All of the other chemicals and reagents were purchased from Sigma (Sigma-Aldrich GmbH, Steinheim, Germany).