Facile Preparation of Chitosan‐modified Mesoporous Titanium Dioxide Film on Fused‐silica Capillary for Selective Enrichment of Phosphopeptides

Abstract Chitosan (Cts), a positively charged natural polysaccharide, is employed to functionalize mesoporous titanium dioxide (mTiO 2 ) nanoparticles. The prepared Cts/mTiO 2 composite was used as a stationary phase to coat the inner wall of fused‐silica capillary and obtain uniform Cts/mTiO 2 film. The Cts/mTiO 2 film is applied to detect and enrich phosphopeptides in complex biological samples based on typical in‐tube solid phase microextraction (IT‐SPME) system. This unique Cts/mTiO 2 film exhibits excellent enrichment performances of high selectivity ( β ‐casein and BSA in molar ratio of 1 : 1000), sensitivity (detection limit as low as 40 fmol of β ‐casein tryptic digest solution) and high adsorption capacity (124.5 μg mg −1 ). Meanwhile, the Cts/mTiO 2 film possesses preferable reusability and can be reused more than 10 times. These results confirm that the Cts/mTiO 2 film possesses potential and satisfactory prospects in phosphoproteomics analysis.