Cocaine abuse determination by ion mobility spectrometry using molecular imprinting

A cocaine-based molecular imprinted polymer (MIP) has been produced by bulk polymerization and employed as selective solid-phase extraction support for the determination of cocaine in saliva samples by ion mobility spectrometry (IMS). The most appropriate conditions for washing and elution of cocaine from MIPs were studied and MIPs were characterized in terms of analyte binding capacity, reusability in water and saliva analysis, imprinting factor and selectivity were established and compared with non-imprinted polymers. The proposed MIP-IMS method provided a LOD of 18μgL^-1 and quantitative recoveries for blank saliva samples spiked from 75 to 500μgL^-1 cocaine. Oral fluid samples were collected from cocaine consumers and analysed by the proposed MIP-IMS methodology. Results, ranging from below the LOD to 51±2mgL^-1, were statistically comparable to those obtained by a confirmatory gas chromatography-mass spectrometry method. Moreover, results were compared to a qualitative lateral flow immunoassay procedure providing similar classification of the samples. Thus, MIP-IMS can be considered an useful alternative that provided fast, selective and sensitive results with a cost affordable instrumentation that does not require skilled operators.