采用原位聚合法，以西地那非为模板分子，甲基丙烯酸月桂酯为功能单体，乙二醇二甲基丙烯酸酯为交联剂，二甲基甲酰胺和十二醇为致孔剂，偶氮二异丁腈为引发剂，在不锈钢柱中制备西地那非分子印迹整体柱，并以西地那非分子印迹整体柱为在线固相萃取柱。粉碎均匀的保健食品样品用乙腈超声萃取30 min，再以8 000 r·min^-1转速离心5 min，取上清液，残渣用乙腈重复萃取2次，合并上清液，并氮吹至近干。残留物用乙腈溶解并定容至1.0 mL，经0.22 μm有机尼龙膜过滤，采用分子印迹整体柱在线固相萃取-液相色谱-串联质谱法测定滤液中西地那非的含量。以Zorbax SB C₁₈色谱柱为固定相，以不同体积比的0.1%（体积分数）甲酸溶液和乙腈的混合液为流动相进行梯度洗脱，串联质谱分析中采用电喷雾离子源（正离子扫描）和多反应监测模式。西地那非的质量浓度在0.5~100.0 μg·L^-1内与其对应的峰面积呈线性关系，检出限（3S/N）为0.15 μg·kg^-1。以空白样品为基体进行加标回收试验，所得回收率为93.5%~99.7%，测定值的相对标准偏差（n=6）为0.80%~2.1%。

A sildenafil molecularly imprinted monolithic column was prepared in a stainless steel tube mold by in situ polymerization with sildenafil as template molecule, lauryl methacrylate as functional monomer, ethylene glycol dimethacrylate as crosslinker, dimethylformamide and dodecanol as porogens, and azobisisobutyronitrile as the initiator. The sildenafil molecularly imprinted monolithic column was used as on-line solid phase extraction column. The health food sample of crushing uniform was extracted ultrasonically for 30 min with acetonitrile, and then centrifugated for 5 min at the speed of 8 000 r·min^-1. The supernatant was taken and the residue was extracted twice with acetonitrile. The supernatant was combined and evaporated to near dryness by N₂-blowing. The residue was dissolved and diluted to1.0 mL with acetonitrile. The above solution was filtered with 0.22 μm organic nylon film. LC-MS/MS was applied to the determination of sildenafil in the filtrate with on-line solid phase extraction of molecularly imprinted monolithic column. Zorbax SB C₁₈ chromatographic column was used as stationary phase, and the mixture of 0.1% (φ) formic acid solution and acetonitrile mixed in different ratios was used as mobile phase in gradient elution. ESI⁺ and multi-reactions monitor mode were adopted in MS/MS. Linear relationship between values of peak area and mass concentration of sildenafil was kept in the range of 0.5-100.0 μg·L^-1, with detection limit (3S/N) of 0.15 μg·kg^-1. On the base of blank sample, test for recovery was made by standard addition method; values of recovery found were in the range of 93.5%-99.7%, with RSDs (n=6) of determined values in the range of 0.80%-2.1%.