A simple glass/PDMS microfluidic chip for on-line sample pretreatment and contactless conductivity detection, which consisted of a 0.17 mm-thick glass cover and a PDMS substrate embedded with an SPE monolithic column, was presented in this paper. Using this integrated microchip system, sample extraction, injection, separation and detection were automatically performed in sequence. A sample of auramine O was concentrated by molecularly imprinted SPE (MISPE), eluted to sample reservoir, and injected by electromigration into separation channel for electrophoresis separation and contactless conductivity detection, with the calculated detection limit (S/N = 3) being 2.5 μg mL − 1 . The monolithic column was utilized to quantitatively extract auramine O , yielding an on-line enrichment factor of about 12. The microchip system is reliable and applicable to the analysis of auramine O in food sample.
A novel magnetic molecularly imprinted electrochemical sensor (MMIP-sensor) combined with magnetic molecularly imprinted solid-phase extraction (MMISPE) was constructed for rapid and sensitive detection of tetrabromobisphenol S (TBBPS) in water samples. The magnetic molecularly imprinted polymer based on magnetic graphene/multi-walled carbon nanotubes hybrid composite (MMIP/Gr-MWCNTs) was prepared as MMISPE sorbet to separate and enrich TBBPS from complex system. Adsorption results showed that the MMIP/Gr-MWCNTs possessed excellent selective adsorption toward TBBPS with a maximum adsorption capacity of 17.83 mg g − 1 . The magnetic imprinted sensor based on the magnetic Gr-MWCNTs composite modified electrode was prepared by electropolymerization of dopamine monomer . The high sensitivity of the MMIP-sensor was attributed to the large specific surface area and excellent electrical conductivity of the magnetic Gr-MWCNTs composites. The detection limit of the MIP-sensor toward TBBPS was calculated as 2.1 × 10 − 11 mol L − 1 (S/N = 3). Under the optimum conditions, the MISPE-MMIP-sensor combination system provided 10–12 fold preconcentration than that of MMIP-sensor alone determination. The MISPE-MMIP-sensor was successfully used for detection of TBBPS in drinking water , rain water , lake water and tap water with recoveries of 88.4–98.8%.