Iron 3 chloride

Silica aerogel previously extracted from diatomaceous earth was used after drying to constant weight [44 ], pyrrole, sodium dodecylsulphate, iron (III) chloride were of analytical grade and obtained from Sigma-Aldrich (St Louis, MO, USA). Vacuum pump oil was obtained from Telstar Technologies (Barcelona, Spain). Milli-Q water from Millipore S.A.S (Molsheim, France) (18.2 µS/cm at 25 °C) was also used in all dilutions. Tea bags were obtained from retail outlets in Thohoyandou, South Africa. A Telstar Lyoquest-55 freeze dryer (Shangai, China) was used to freeze dry all samples and a Spectroquant UV spectrophotometer from Merck Group (Germiston, South Africa) was used for total organic carbon testing and a Stuart reciprocating shaker (Staffordshire, UK) was used for shaking. An ultrasonic processor (UP 4005) from Hielscher ultrasound technology, with amplitude of 20 to 100% and cycle of 0.1–1 (Berlin, Germany) was used in wastewater preparation, and an ALPHA Fourier-transform infrared spectrophotometer from Bruker Pty (Sandton, South Africa) was used in functional group analysis.

All solvents and chemicals used were of analytical reagent grade. 2,2-Di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH•) free radical, iron (III) chloride (97%), gallic acid (97%), β-sitosterol (95%), and Gram’s iodine solution were purchased from Sigma-Aldrich (Munich, Germany). α-Amylase from Bacillus licheniformis liquid (Cat. No. A4862), AChE from Electrophorus electricus, Fast Blue B Salt, and soluble starch were obtained from Sigma-Aldrich (Munich, Germany). Ethyl acetate, ethanol, ferric chloride (97%), methanol, sodium dihydrogen phosphate (NaH₂PO₄) and disodium phosphate (Na₂HPO₄) were obtained from Merck (Darmstadt, Germany). Acarbose was from Bayer (Leverkusen, Germany), n-hexane from BDH (Poole, England), p-anisaldehyde from ACROS organics (New Jersey, USA), and donepezil from Cayman chemicals (Ann Arbor, MI, USA). Bovine serum albumin (BSA) was purchased from PAA Laboratories GmH (Haidmannweg, Austria). Tris(hydroxymethyl)aminomethane hydrochloride (Tris HCl) buffer solution was obtained from Calbiochem (San Diego, CA, USA), and Milli-Q water (Millipore^®, Merck, Darmstadt, Germany) was used to prepare all solutions. All chromatographic separations were performed on 20 × 10 cm normal phase Silica gel 60 F254 HPTLC glass plates (Merck, Darmstadt, Germany).

Graphene paper, potassium hexacyanoferrate (III), potassium hexacyanoferrate (II) trihydrate, iron (III) chloride, potassium chloride, hydrochloric acid, human serum, and Gox (from Aspergillus niger, 145,200 unit/g) were obtained from Sigma-Aldrich (St. Louis, MO, USA). Disodium hydrogen phosphate, potassium dihydrogen phosphate, glucose, and chitosan were purchased from Merck (Darmstadt, Germany). PET sheets and double-sided adhesive tape were purchased from Biltema (Linköping, Sweden). An Ag/AgCl ink (DuPontTM 5874) was obtained from Dupont Ltd. (Stevenage, U.K.). All chemicals were of analytical reagent grade. The phosphate buffer solution (PBS, 0.1 mol L⁻¹, pH 7.4) was prepared by mixing a stock solution of potassium dihydrogen phosphate and Disodium hydrogen phosphate. All solutions were prepared using deionized water (Milli-Q purification system, MerckMillpore, MA, USA).

Reagents used in the various methods, 1,1-diphenyl-2-picrylhydrazyl hydrate (DPPH), Folin-Ciocalteu reagent and (±)-catechin were purchased from Sigma (Sigma-Aldrich Chemie GmbH, Sternheim, Germany). The following reagents were also purchased from Sigma-Aldrich Chemie: iron (III)-chloride, potassium hexacyanoferrate (III), sodium hydrogen phosphate anhydrous, sodium dihydrogen phosphate andtrichloroacetic acid. Gallic acid was purchased from Sigma (St. Louis, MO, USA). Maltodextrin of dextrose equivalent (DE) 16.5–19.5 (Sigma-Aldrich Chemie GmbH) was used as a carrier material. All other chemicals and reagents were of analytical grade.

Hexane, acetone, ethanol, methanol, HPLC-grade methanol, sodium carbonate, 2,20-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 2,2-diphenyl1-picrylhydrazyl (DPPH), Folin–Ciocalteu reagent, gallic acid solution, hydrochloric acid, sodium nitrite, aluminum chloride, sodium hydroxide, iron (III) chloride, sulfosalicylic acid, phytic acid and potassium persulfate were purchased from Sigma Aldrich (Schnelldorf, Germany). The phenolic acid (gallic acid, vanillic acid, chlorogenic acid, caffeic acid, ferulic acid) and flavonoid (catechin, epicatechin, quercetin, and kaempferol) standards were purchased from Sigma Aldrich (Schnelldorf, Germany).

TiO₂ P25 (>99.5 %, 21 nm primary particle size), benzene, dimethoxymethane, 2,4‐diamino‐6‐phenyl‐1,3,5‐triazine, aniline, 1,2‐dichloroethane, N,N‐dimethylformamide and iron(III) chloride were all purchased from Sigma‐Aldrich. 4,4′‐bis(methoxymethyl)biphenyl was purchased from Tokyo Chemical Industry (TCI) UK and methanol (reagent grade) was purchased from VWR. All reagents were used as received. All gases were purchased from BOC.