Decanol

All chromatographic analyses were performed using the Shimadzu Nexera UHPLC system (Kioto, Japan). This chromatograph is equipped with a binary solvent delivery system (LC-30AD), an autosampler with a 20 µL volume loop (SIL-20AC), a column thermostat (CTO20AC), and a diode-array UC-detector (SPD-M20A). LabSolution LC/GC 5.65 software (Shimadzu, Kioto, Japan) was used to collect and process data and control the apparatus. Acetonitrile (ACN) (HPLC Grade) and methanol (MeOH) (HPLC Grade) were purchased from Sigma–Aldrich (Steinheim, Germany). Packaging solvents, isopropanol, and methanol were purchased from J.T. Baker, Deventer, the Netherlands. Water was prepared with a Milli-Q Water Purification System (Millipore Corporation, Bedford, MA, USA). Standards of nucleosides—adenosine, guanosine, uridine—were obtained from Applichem (Darmstadt, Germany). Non-polar compounds—naphthalene, benzene, phenanthrene, caffeine, theophylline, and theobromine—were obtained from Sigma–Aldrich (St. Louis, MO, USA). For the synthesis of stationary phases (3-glycidoxypropyl) trimethoxysilane, decanol, octadecanol, cholesterol, benzyl alcohol, and phosphorus chloride were used, which were purchased from Alfa Aesar (Karlsruhe, Germany). Haskel (Burbank, CA, USA) laboratory equipment and packing pump were used to pack the stationary phases into 125 × 4.6 mm long empty columns.

A series of polar embedded stationary phases that contain phosphate and hydrophobic functional groups were tested. As a support for the synthesis, the Kromasil 100 silica gel (Akzo Nobel, Bohus, Sweden) was used. For the comparison, some stationary phases were also synthesized on Luna (Phenomenex, Torrance, CA, USA). Detailed characteristic of silica gels used for synthesis is presented in Table 2.
Four phosphodiester bonded stationary phases were tested. Structures of the materials are shown in Figure 3.
The properties of the stationary phases are listed in Table 3. Two Diol-P-C10 were synthesized on two different supports: Kromasil and Luna.
Reagents for the stationary phase synthesis: (3-glicidoxypropyl)trimethoxysilane, decanol, octadecanol, cholesterol, benzyl alcohol, and phosphoryl chloride were purchased from Alfa Aesar (Karlsruhe, Germany). Organic solvents used during synthesis: toluene, methanol, and hexane were ACS grade, purchased from Avantor Performance Materials (Center Valley, PA, USA).