Sodium dihydrogen phosphate

The chemicals used during the experiments were of analytical grade and were not further purified before usage. Graphite rods (6 mm diameter, 99.995% purity); potassium chloride (KCl, 99.98%); sodium dihydrogen phosphate (NaH₂PO₄, 100%) and di-sodium hydrogen phosphate anhydrous (Na₂HPO₄, 99.7%) were supplied by VWR Chemicals (Leuven, Belgium). Sodium acetate anhydrous (CH₃COONa, ≥99.0%); ammonium sulphate ((NH₄)₂SO₄, ≥99.0%), sodium chloride (NaCl, 99.5%); sodium carbonate anhydrous (Na₂CO₃, 99.3%), magnesium chloride hexahydrate (MgCl₂∙6H₂O, 99–102%); magnesium sulphate (MgSO₄, 99%); magnesium nitrate hexahydrate (Mg(NO₃)₂∙6H₂O, 99%) were provided by REACTIVUL Bucuresti (Bucharest, Romania). Potassium ferrocyanide K₄[Fe(CN)₆] and L(+)-Ascorbic acid (C₆H₈O₆, AA, ≥99%) were acquired from Merck (Darmstadt, Germany). Sodium acetate anhydrous (CH₃COONa, ≥99.0%) was purchased from ChimReactiv SRL (Bucharest, Romania). N,N-dimethylformamide (DMF) was acquired from Fluka Chemie GmbH (Buchs, Switzerland), while boric acid (H₃BO₃, 99%) was provided by Andra Chim SRL (Bucharest, Romania). The MQuant^® Nitrite Test (Merck KGaA, Darmstadt, Germany) was employed for UV-Vis investigation of nitrite solutions. Deionized water with a resistivity of at least 18.2 MΩ × cm was used to prepare all solutions.

The acetonitrile used as solvent was purchased from VWR (Radnor, United States). The ion-pair reagents used were methanesulphonic acid anhydrous ≥ 98%, 1-pentanesulphonic acid anhydrous ≥ 98% from Loba Chemie (Mumbai, India) and 1-octanesulphonic acid monohydrate from Carl Roth (Karlsruhe, Germany). Regarding buffering agents used, sodium dihydrogen phosphate ≥ 99.0% and orthophosphoric acid 85% were purchased from VWR (Radnor, United States); sodium hydroxide ≥ 97% and hydrogen peroxide 30% were purchased from Sigma-Aldrich (St. Louis, MO, USA); hydrochloric acid 37% was purchased from Carl Roth (Karlsruhe, Germany); and sulfuric acid 96% was purchased from Merck (Darmstadt, Germany). The water used for all analyses came from the purification equipment 08.1205 from TKA Germany (Niederelbert, Germany). Buffered solution adjusted to pH 2.5–3.5 using sulfuric acid was used as diluent. All sample solutions were filtered before injecting into the chromatograph using nylon syringes filters (0.22 μm) from YETI Merz Brothers GmbH (Haid, Austria).

The pods of five okra genotypes (Abelmoschus esculentus L), namely, Penkrumah, Agbagoma, Asha, Sengavi, and Balabi, (PC1, PC2, PC3, PC4, and PC5) were obtained from the Ghanaian market and authenticated at the Department of Horticulture, KNUST, Ghana. Maize starch BP (UK Chemicals) was used as the reference disintegrant in formulations coded F6, F12, and F18. Tragacanth BP (Sigma-Aldrich), paracetamol BP (Xi'an Henrikang Biotech Co., China), lactose, talc, disodium hydrogen phosphate, and sodium dihydrogen phosphate (VWR Chemicals, UK) were used. All other reagents and chemicals used were of analytical grade.

MOX (>99% purity) was purchased from LC Labs (Woburn, MA). Formalin, PAM, sodium oleate, sodium laurate, and sodium chloride were purchased from Sigma (St. Louis, MO). High‐performance liquid chromatography (HPLC)‐grade acetonitrile, sodium dihydrogen phosphate, and triethylamine were obtained from VWR International (Radnor, PA). Vigamox® (0.5% moxifloxacin eye drops, Alcon Laboratories Inc., Fort Worth, TX) was obtained from the Johns Hopkins Pharmacy. Zirconium oxide beads (0.5 mm in diameter) were purchased from Next Advance (Averill Park, NY). Sterile cell strainers (100 μm) were purchased from Fisher Scientific (Hampton, NH). Pluronic F127 (Poloxamer 407) was obtained as free samples from BASF Corporation (Tarrytown, NY). Tryptic soy agar, tryptic soy broth, sterile cotton‐tipped applicator, sterile disposable petri plates, and sterile phosphate‐buffered saline (PBS) and 20‐G needles were purchased from Thermo Fisher Scientific (Walthum, MA). Staphylococcus aureus (ATCC 25923) was obtained from ATCC (Manassas, VA). Proparacaine eye drops were obtained from Bausch and Lomb Inc. (Tampa, FL).

High purity (99.995%) graphite rods (10 cm length; 6 mm diameter) were purchased from Sigma-Aldrich (Sternheim, Germany) and were employed during electrochemical exfoliation. Ammonium sulphate was bought from Reactivul Bucuresti (Bucharest, Romania), while the ammonia solution (25%) was purchased from POCH SA (Gliwice, Poland). Azithromycin (AZT) was purchased from HiMedia Laboratories Pvt. Limited (Mumbai, India), uric acid (≥99%, UA), dopamine hydrochloride (99%, DA), and dimethylformamide (DMF) were purchased from Alfa-Aesar (Karlsruhe, Germany), while L-tyrosine (Tyr) was purchased from Fluka BioChemika (Buchs, Switzerland). Glacial acetic acid (99.5%) was purchased from CHEMICAL COMPANY (Iași, Romania) and sodium acetate was purchased from Reactivul Bucuresti (Bucharest, Romania). Sodium dihydrogen phosphate (99.7%) and di-sodium hydrogen phosphate anhydrous (100%) were purchased from VWR Chemicals (Leuven, Belgium). Acetate buffer was employed for the preparation of the solutions with pH 3.6, 4.4, and 5. Phosphate buffer was employed for the preparation of the solutions with pH 6 and 7.