Methanol meoh

All standards of polyphenols, methanol (MeOH), and water HPLC grade were purchased from Sigma-Aldrich (Bellefonte, USA) and Extrasynthese (Lyon FRANCE). Syringe filters (0.2 µm PTFE) were obtained from Supelco (Milan, Italy). The formic acid and ammonium formate were purchased from Fluka (Steinheim, Germany). The individual polyphenols standard solution (1mg/mL) in pure methanol was stored at −20 °C. The mix of polyphenols standard solutions ranged from 1.0 to 50.0 mg/L and was made by appropriate dilutions of the stock solution (200 mg/L) with methanol/water (60:40) and stored at −20 °C.

The reference standards of chrysophanol, physcion, rhein, aloe-emodin, and emodin were provided by the National Institutes for Food and Drug Control (Beijing, China) (Figure 1). HPLC-grade acetonitrile, methanol (MeOH), and formic acid were purchased from Sigma-Aldrich Co. All other chemicals and reagents used were of analytical grade obtained from Shanghai Aladdin Chemical Reagent Company. The Polypropylene SPE tube (3 mL) used for packing the sorbent and the PE Frit (20 μm) were all obtained from Shanghai ANPEL Laboratory Technologies. The water used for HPLC system and SPE process was prepared by using a Millipore Milli-Q system (Bedford, MA, USA). Silica gels (particle size of 40–60 μm, surface area of 500 m² g⁻¹) were supplied by Shanghai Aladdin Chemical Reagent Company. The commercialized C18 SPE columns (100 mg, 3 mL) were provided by the company of Waters (Milford, MA, USA), which were used as comparison with self-made BTO-SPE.
By dissolving the reference standards into MeOH, the stock solutions of chrysophanol, rhein, physcion, aloe-emodin, and emodin were prepared at concentrations of 1 mg mL⁻¹, respectively. Then, the stock solutions were mixed and diluted with 0.1% phosphoric acid water/methanol solution (50 : 50, v/v) to prepare working solutions. All the prepared stock solutions and working solutions were stored in a refrigerator at 4°C ready for use.

Unless specified, all reagents were obtained from Bio-Rad Laboratories (Hercules, CA, USA). Solvents used for the sample preparation and LC–MS/MS analysis have >99.9% purity, as reported by the manufacturing companies. Acetonitrile (ACN) CHROMASOLV was obtained from Honeywell (Charlotte, NC, USA). Methanol (MeOH) and formic acid (HCOOH) were purchased from Sigma (St. Louis, MO, USA).

Hydrochloric acid (HCl, 37%, Sigma-Aldrich, Vienna, Austria), ammonium paratungstate ((NH₄)₁₀H₂(W₂O₇)₆, 99.99%, Sigma-Aldrich, Tokyo, Japan), hydrogen peroxide (H₂O₂, 30%, Sigma-Aldrich, Madrid, Spain), bismuth(III) nitrate pentahydrate (Bi(NO₃)₃·5H₂O, 98%, Sigma-Aldrich, Mexico City, Mexico), methanol (MeOH, 99.8%, Sigma-Aldrich, St. Louis, MO, USA), N,N-dimethylformamide (DMF, 99.8%, Sigma-Aldric, Ankara, Turkey), trimesic acid (C₆H₃(CO₂H)₃, 95%, Sigma-Aldrich, Shanghai, China), sodium sulfate (Na₂SO₄, 99.0%, Sigma-Aldrich, Bangalore, India), glycerol (C₃H₈O₃, 99+%, Alfa Aesar, Selangor, Malaysia) and sulfuric acid (Alfa Aesar, Haverhill, MA, USA). All materials were analytical grade and used without further purification.

All reagents and solvents were used without further purification. 3,4-dimethoxythiophene was purchased from Matrix scientific. 3,4-Ethylenedioxythiophene (EDOT), 3-chloro-1,2-propanediol, p-toluene sulfonic acid monohydrate, toluene, tetrahydrofuran (THF), hexane, 3-mercaptopropionic acid (MPA), 2,2-Dimethoxy-2-phenylacetophenone (DMPA), Sodium Hydroxide (NaOH), Potassium hydroxide (KOH), Tris(2-carboxyethyl) phosphine hydrochloride (TCEP), Methanol (MeOH) and dichloromethane were purchased from Sigma. Potassium tert-butoxide (tBuOK) was purchased from ACROS. Ethanol (EtOH) was purchased through Fisher. Aptamer 5′-HS-(CH2)6-AGACAAGGAAAATCCTTCAATGAAGTGGGTCG-(CH2)7-MB-3′ with a 5′ thiol group as covalent linkage site and 3′ methylene blue (MB) as electrochemical reporter was purchased through Biosearch Technologies, Inc., Platinum/Iridium wires were purchased from A-M systems.

Fosetyl-aluminum (technical grade) was purchased from Sigma-Aldrich S.r.l. (Milano, Italy).
Individual stock standard was prepared at 1 mg·ml⁻¹ in water and stored in the dark at −20°C. Working standard solutions were prepared by diluting the stock standard and kept at +4°C in amber vials.
The mixture dispensed on agricultural field was R6 ERRESEI ALBIS™ (Bayer CropScience AG, Dormagen, Germany), containing fosetyl at 66.7% [14 ].
Solvents such as methanol (MeOH) and acetonitrile (CH₃CN) (ultra gradient, ultra purity solvent) were purchased from Sigma-Aldrich S.r.l. (Milano, Italy); water ultra HPLC grade was from ROMIL (Cambridge, GB).
Materials such as diatomaceous earth sorbent (hydromatrix) was obtained from Dionex (Thermo Fisher Scientific, Sunnyvale, CA); polytetrafluoroethylene (PTFE) membrane disc filters (diameter: 37 mm, porosity: 2.0 µm) were from Pall Corporation (VWR International S.r.l., Milan, Italy); Strata X (200 mg/6 ml) cartridges, and Luna C₁₈ column (150 mm × 2 mm, 5 µm) were purchased from Phenomenex (Torrance, CA, USA); and SeQuant ZIC-pHILIC polymeric column (150 × 2.1 mm, 5 µm) was acquired from Merck S.p.a (Vimodrone, Milano, Italy).

2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydryl (DPPH), 5,5′-dithiobis (2-nitrobenzoic acid) (DTNB), acetylcholinesterase (AChE), acetylthiocholine (AcSCh), butylated hydroxytoluene (BHT), dichloromethane (DMC), dimethyl sulfoxide (DMSO), donepezil, methanol (MeOH), magnesium chloride hexahydrate, phosphate buffered saline (PBS), tris hydrochloride (Tris-HCl) and sodium sulfate anhydrous were purchased from Sigma-Aldrich (San Luis, MO, USA). Mueller Himton broth, Mueller Hinton II broth and fluid thioglycollate medium were purchased from DIPCO (Quito, Ecuador). The standard aliphatic hydrocarbons were purchased from ChemService (West Chester, PA, USA). Helium was purchased from INDURA (Quito, Ecuador). All chemicals were of analytical grade and used without further purification.