Titanium 4 tetraethoxyde

The following reagents were purchased from Acros Organics: hydrochloric acid, sodium tetraborate, sodium salicylate, methylsalicylate, salicylamide, sodium hydrocarbonate, citric acid, sodium chloride, aminoacids, titanium(IV) tetraethoxyde, and tetraethyl orthosilicate. All the reagents were of analytical grade, titanium(IV) tetraethoxyde was of technical grade.
Stock solutions of salicylate and salicylamide were prepared with doubly distilled water. Stock solution of methylsalicylate was prepared with ethanol. Only freshly prepared solutions of these substances were used.
Trinder reagent was prepared as in [13 (link)]: 4.0 g of iron (III) nitrate nonahydrate and 5.0 g of trichloroacetic acid were dissolved in 100.0 mL of doubly distilled water.

The following reagents were purchased from Acros Organics: triphenylmethane dyes (TPMD): pyrocatechol violet (PV), eriochrome cyanine R (ECR), chrome azurol S (CAS), hydrochloric acid, titanium(IV) tetraethoxyde, tetraethyl orthosilicate, and oxalic acid. All the reagents were of analytical grade, titanium(IV) tetraethoxyde was of technical grade. Stock solutions of oxalic acid and TPMD were prepared with doubly distilled water. Only freshly prepared solutions were used.
Silica–titania xerogels were obtained by drying in Ethos microwave equipment (Milestone, Sorisole, Italy). Surface area, porosity BET analysis, and BJH pore distribution analysis were carried out with ASAP 2000 (Micromeritics, Norcross, GA, USA). Absorbance of solutions (l = 1.0 cm) and xerogels water suspensions (l = 0.1 cm) was measured using Lambda 35 spectrophotometer (PerkinElmer, Waltham, MA, USA) equipped with 50 mm integrating sphere (Labsphere, North Sutton, NH, USA). The pH value was measured using Expert-001 (Econix Expert, Moscow, Russia) potentiometer with pH sensitive electrode. Chromatographic determination was conducted using MAESTRO HPLC system (Interlab, Moscow, Russia). A Kromasil C18 column (250 × 4.6 mm, 5 μm particle size) served as the stationary phase, mobile phase was distilled water (pH 2). UV detection was performed at 220 nm and a flow rate of 1.0 mL·min⁻¹.