A dummy molecularly imprinted monolith for selective solid-phase microextraction of vanillin and methyl vanillin prior to their determination by HPLC

The authors have synthesized a dummy molecularly imprinted monolith (MIM) in the tip of a micropipette using a sol-gel method. The MIM was applied to selective solid-phase microextraction (SPME) of vanillin (VN) and methyl vanillin (MV) prior to their determination by HPLC. The MIM was characterized by thermogravimetric analysis, scanning electron microscopy and FTIR. Some parameters affecting SPME were optimized. Then, a sensitive SPME/HPLC method was developed for the determination of VN and MV in infant milk powder. Under optimized conditions, the response is linear in the 2 to 3000 μg∙kg −1 VN concentration range and in the 3 to 2000 μg∙kg −1 range for MV. The detection limits (for an S/N ratio of 3) are 0.5 and 1 μg∙kg −1 , and the recoveries are between 83 and 110% for VN and between 80 and 101% for MV. A dummy molecularly imprinting monolith was synthesized and applied for SPME of vanillin and methyl vanillin before HPLC. The detection limits of the method for vanillin and methyl vanillin in milk powder were 0.5 and 1 μg·kg −1 , respectively.