Determination of l-tryptophan based on graphene oxide–magnetite-molecularly imprinted polymers and chemiluminescence

A new method for determination of l-tryptophan (l-try) using the flow injection chemiluminescence (FI-CL) system of KMnO4–SnCl2–CHOH based on a graphene oxide–magnetite-molecularly imprinted polymer (GM-MIP) is described. The l-try GM-MIP was synthesized using graphene oxide (G) which improved the adsorption capacity as carrier, and magnetite nanoparticles which made the polymers easier to use in the sensor. The adsorption performance and properties were characterized. The GM-MIP was used in CL analysis to increase the selectivity and the possible mechanism was also discussed. The CL sensor responded linearly to the concentration of l-try over the range from 2.10×10−7 to 7.09×10−4 M with a detection limit of 2.11×10−8 M (3σ). The relative standard deviation (RSD) for the determination of 3.0×10−5 M l-try was 2.40% (n=11). On the basis of speediness and sensitivity, the sensor is reusable and shows a great improvement in selectivity and adsorption capacity over other sensors. The sensor has been used for the determination of l-try in drug samples.