sodium citrate,
chloride were obtained from Merck (Darmstadt, Germany). Ethylene glycol
dimethacrylate (EDMA), 2-hydroxyethyl methacrylate (HEMA), and azoisobisbutyronitrile
(AIBN) were purchased from Sigma (Chemical Co., ABD). Cortisol (98%),
fluticasone, clobetasol propionate, methanol, and acetic acid were
supplied from Merck (Darmstadt, Germany). All of the aqueous solutions
were created using deionized (DI) water (18.2 MΩ cm) and pure
lab Ultra Analytic (ELGA Lab Water, UK). The pH was measured using
a pH meter, and solution preparations were done in an ultrasonic water
bath. Pencil tips (Tombow 2.0, HB), purchased from nearby stationery
stores, were used as pencil graphite electrodes (PGEs).