Direct q 8 uv water purification system

An X-ray diffractometer (Panalytical X’Pert Pro, Almelo, The Netherlands) using copper/Kα radiation (λ = 1.5418 Å) captured XRD patterns. A Tensor II spectrometer (Bruker, Denkendorf, Baden-Württemberg, Germany) was utilized to record the FT-IR spectra. A scanning electron microscope (MIRA3, Tescan, Brno, Czech Republic) provided the FE-SEM images and the EDX patterns. An autolab potentiostat/galvanostat (PGSTAT-302N, Eco Chemie, Utrecht, The Netherlands) recorded all electrochemical determinations. The General Purpose Electrochemical System (GPES) as selected software monitored all testing protocols. A conventional three-electrode system was used at 25 ± 1 °C. An Ag/AgCl/KCl (3.0 M) electrode, a platinum wire and MnO₂NR-IL/CPE were used as the reference, auxiliary and working electrodes, respectively. A pH meter (Metrohm type 713) was utilized to determine all solution pH values. All solutions were prepared freshly by deionized water (DIW, Millipore Direct-Q^® 8 UV water purification system, Darmstadt, Germany). Sulfanilamide, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF₆) ionic liquid, and all materials were purchased from Merck (Darmstadt, Germany) with analytical research purity. Orthophosphoric acid as well as relevant salts have been applied to achieve all phosphate buffer solutions (PBS), set in a pH range of 2.0–9.0.

Iron(III) acetylacetonate, an
ACS reagent with a purity of at least 97.0% (Fe(C₅H₇O₂)₃), and cobalt(II) acetate tetrahydrate,
an ACS reagent with a purity of at least 98.0% (Co(CH₃COO)₂·4H₂O), were procured from Sigma-Aldrich.
These compounds served as the precursors for Fe and Co, respectively.
Polyacrylonitrile (PAN), having a weight-average molecular weight
(Mw) of 150,000, was also sourced from Sigma-Aldrich and was used
as the carbon precursor. N,N-Dimethylformamide
(DMF), an anhydrous solvent with a purity of 99.9%, was obtained from
VWR and used to dissolve both the metal salts and the PAN polymer,
enabling the formulation of electrospinning solutions. To extract
metals in catalysts to quantify the Fe and Co content, nitric acid
(67–70%, ARISTAR PLUS grade for trace metal analysis, HNO₃) and hydrochloric acid (34–37%, ARISTAR PLUS grade
for trace metal analysis, HCl) were used, both of which were acquired
from VWR. No additional purification was performed on the purchased
chemicals. All water used in the experiments was purified using a
Millipore Direct-Q 8 UV water purification system, resulting in a
water resistivity of 18.2 MΩ·cm at a temperature of 25
°C.

Acetonitrile, methanol (HPLC grade), standard bioactive compounds and formic acid (analytical grade) were purchased from Fluka, Sigma-Aldrich (St. Louis, MO, USA). Ultra-pure water was obtained from a Direct-Q 8 UV water purification system (EMD Millipore Corporation, Billerica, MA, USA). A mixed standard stock solution (1 mg/mL) of sixteen bioactive compounds which includes six antibiotics (erythromycin, ketoconazole, fluconazole, chloramphenicol, rifampicin and miconazole), nine phenolic compounds (catechin, kaempferol, chebulagic acid, chlorogenic acid, Asiatic acid, ferulic acid, arjunic acid, gallic acid and boswellic acid) and an anticancerous compound, Paclitaxel were prepared in methanol. The working standard solutions were then prepared by appropriate dilution of the mixed standard solution with Acetonitrile to a series of concentration ranges from 0.1–1000 ng/mL. The standard stock and working solutions were stored at −20 °C until use and vortexed for 30 s prior to injection.