Preconcentration of albumin on silica with attached groups of polyoxyethylated isooctyl phenol

The potencies of silica with attached groups of polyoxyethylated isooctyl phenol ( SiO 2 - TX ) as an adsorbent for the solid phase extraction ( SPE ) preconcentration of bovine serum albumin ( BSA ) in urine are examined. SiO 2 -TX is shown to effectively extract BSA (up to 96%) as an ion associate with cationic (at pH 8) and anionic (at pH 1.5) surfactants. The maximal capacity of SiO 2 -TX to BSA makes 33 mg/g in the presence of octylpyridinium bromide, 27 mg/g in the presence of cetyltrymethylammonium bromide or sodium dodecylsulfate with the linearity range in Henri’s area up to 23 and 20 mg/g of SiO 2 -TX, respectively; the distribution coefficients attain 1.8 × 10 3 mL/g. BSA is eluted quantitatively with 1–4 mL of acetonitrile containing NaOH, which makes possible the use of adsorbent for the reaction of protein with trifluoroethanol ( TFE ) before its photometric determination by the Lowry method. The influence of accompanying urine components is studied, i.e., urea, glucose, Na + , K + , Mg 2+ , chlorides, and phosphates, on the efficiency BSA extraction from model aqueous solutions on SiO 2 -TX. The detection limit for BSA makes 4 mg/L and the analytical range, from 12 to 140 mg/L.