Determination of nicotine in tobacco by molecularly imprinted solid phase extraction with differential pulsed elution

A molecularly imprinted solid phase extraction-differential pulsed elution (MISPE-DPE) method has been developed for the determination of nicotine in tobacco. Nicotine and a trace alkaloid myosmine were able to bind to the mo lecularly imprinted polymer (MIP) packed in a micro-column when acetonitril e was used as the mobile phase. However, over 95% of the bound myosmine cou ld be desorbed and washed away by a 20 mu l pulse of methanol, compared to only 43% of the bound nicotine. The remaining quantity of bound nicotine wa s desorbed by a 20 mu l pulse of 1% trifluoroacetic acid in water, for dire ct UV detection at 254 mm. This MISPE-DPE method provided inherent selectiv ity for nicotine that allowed both a shorter analysis time (3 min) and a lo wer analysis cost than liquid chromatographic methods. A detection limit of 1.8 mu g ml(-1) and a linear dynamic range up to 1000 mu g ml(-1) were obt ained. Preconcentration of 845 mu l of a 10 ng ml(-1) nicotine standard sol ution produced a detectable peak signal. These analytical figures of merit are superior to those reported previously for several nicotine-MIP-based me thods.