SiO2@TiO2复合材料分离富集酪蛋白磷酸肽

TiO2具有选择性吸附磷酸肽的特点。为了得到高比表面积的TiO2，提高磷酸肽的分离富集效果，本研究采用层层自组装法，制备出了比表面积为116.26 m2/g、平均孔直径为8.42 nm的SiO2@TiO2核壳型复合材料，并将该材料用于酪蛋白磷酸肽（casein phosphopeptides，CPPs）的分离富集。利用高效液相色谱法（high performance liquid chromatography，HPLC）测定出该材料对CPPs的吸附率为93.0%，解吸率达到81.5%。通过液相色谱-四极杆-飞行时间质谱鉴定出CPPs样品经富集后，洗脱液中的5 种磷酸肽成分的序列分别为PS*H、PS*PR、S*SRS*E、PHS*和PS*SRS*EP；并以茶碱为内标的HPLC法测定了CPPs样品、氨糖软骨素钙片、婴儿配方奶粉中CPPs的含量，测定结果的平均添加回收率介于92.5%～95.1%之间。因此，本实验所制备的SiO2@TiO2核壳型复合材料性能优异，对CPPs分离富集效果明显，用于实际样品测定的结果准确可靠。

Separation and Enrichment of Casein Phosphopeptides Using SiO2@TiO2 Composite

Titania can selectively adsorb phosphopeptides. In order to obtain TiO2 with high specific surface area and improve the separation and enrichment of phosphopeptide, a SiO2@TiO2 composite was prepared by layer-by-layer selfassembly method. The specific surface area and average pore diameter of SiO2@TiO2 are 116.26 m2/g and 8.42 nm, respectively. The core-shell composite was used in the separation and enrichment of casein phosphopeptides (CPPs). The adsorption rate of CPPs was determined to be 93.0% by high performance liquid chromatography (HPLC), and the desorption rate was 81.5%. The sequence of the five phosphopeptides present in the eluent was identified as PS*H, PS*PR, S*SRS*E, PHS* and PS*SRS*EP by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-TOFMS ), respectively. The contents of CPPs in commercial CPPs product, calcium tablets and infant formula were determined by HPLC with theophylline as the internal standard, and the results showed that average recoveries of CPPS were 92.5%–95.1%. It can be concluded that the core-shell SiO2@TiO2 composite had excellent properties and allowed efficient separation and enrichment of CPPs, and the proposed method was accurate and reliable to determine CPPs in real samples.