Calix 4 arene

Clomipramine pure powder was supplied by Novartis Pharmaceutical Company, Cairo, Egypt, with purity 99.55 ± 0.89%. Anafranil^® tablets manufactured by Novartis pharmaceutical company (Egypt) were obtained from the Egyptian market claimed to include 25 mg Clomipramine HCl per tablet. Potassium tetrakis(4-chlorophenyl)borate (KTpClPB), calix[4]arene, and o-nitrophenyl octyl ether (o-NPOE) were bought from Sigma Aldrich (Missouri, United States). Polyvinyl chloride (PVC) was bought from Fluka (Steinheim, Germany). Graphene nano-platelets (6–8 nm thick × 5 microns wide) were obtained from Strem Chemicals INC. (Newburyport, USA). Britton – Robinson (BR) buffer was prepared by mixing phosphoric acid (0.04 M), acetic acid (0.04 M) and boric acid (0.04 M). Buffer solutions of different pH values were adjusted by the addition of 0.2 M NaOH. Screen-printed carbon electrodes (C-SPE) showing a diameter of 3 mm was obtained from CH Instruments, Inc., (Texas, USA).

Sarcosine, glycine, urea, creatinine, sodium tungstate dihydrate, calix-4-arene, high molecular weight polyvinyl chloride (PVC), 2-nitrophenyl octyl ether (o-NPOE), sodium tetraphenylborate (NaTPB), and tetrahydrofuran (THF) were obtained from Sigma-Aldrich. Sodium dodecyl sulfate (SDS), aniline, ammonium persulfate, and oxalic acid were purchased from Alfa Aesar. Boric acid, phosphoric acid, acetic acid, hydrochloric acid, and sodium hydroxide were obtained from El-Nasr Company. Sarcosine solutions (1 × 10⁻² to 1 × 10⁻¹⁴ M) were prepared using Britton-Robinson buffer (pH 5.0).
Twenty-four-hour urine samples were freshly obtained from a healthy male volunteer, 35 years old, and were diluted using Britton-Robinson buffer (pH 5.0).