Molecularly imprinted polymer-based device for field collection of oral fluid samples for cocaine identification.

In this paper, a low-cost, rapid, easy, and potentially portable tool for the identification of cocaine and its semi-quantitative determination in oral fluid has been proposed. A field collection device has been designed, based on a cotton pad with an indicator and a molecularly imprinted polymer (MIP) sorbent, to selective retain cocaine from oral fluid components. After sample collection, cocaine is transferred by using phosphate buffer to the MIP and then eluted with 2-propanol. The obtained extract is analysed by ion mobility spectrometry (IMS), providing a cut-off value of 20 µg L-1 that identifies 100 % true-positive and 95 % true-negative samples. The MIP-IMS procedure has been validated by the analysis of oral fluid samples, collected from cocaine users at recreation environments, by comparing the results with lateral flow immunoassay and chromatographic reference methods. Thus, the proposed methodology allows a simple and fast cocaine identification that can be carried out in field by non-specialized personnel, such as health personnel, law enforcement bodies, and customs staff.

Tuning the selectivity of molecularly imprinted polymer extraction of arylcyclohexylamines: From class-selective to specific.

A molecularly imprinted polymer (MIP) has been prepared in presence of 3-hydroxy phencyclidine (3-OH PCP) as template by bulk polymerization using N,N-dimethylformamide, as porogenic solvent, for the selective solid-phase extraction (SPE) of arylcyclohexylamines from oral fluids. Experimental variables of the extraction procedure have been studied in order to increase both, extraction recovery of 3-OH PCP, used as model analyte, and imprinting factor. By modifying the composition of the washing solvent, the selectivity of the MIP extraction procedure can be tuned, moving from an arylcyclohexylamine selective method to a 3-OH PCP specific method. The applicability of the synthesized MIP was evaluated by the analysis of oral fluids spiked with 3-OH PCP at different concentration levels, extracted using both recommended SPE procedures and analyzed by ion mobility spectrometry. Recovery values ranging from 70 to 101% and a limit of detection of 15 µg L-1 were obtained.

Development of pipette tip-based poly(methacrylic acid-co-ethylene glycol dimethacrylate) monolith for the extraction of drugs of abuse from oral fluid samples.

In this work, a monolithic polymer based on poly(methacrylic acid-co-ethylene glycol dimethacrylate) (MAA-co-EDMA) was prepared inside 200 µL pipette tips for the extraction of drug of abuse from oral fluid samples. After an appropriate surface tip modification, several polymerization mixtures with different monomer/cross-linker ratios, and percentage of porogen were studied. The most appropriate monolith to easily flow organic solvents and oral fluid samples was prepared with a MAA/EDMA ratio of 8:92 wt/wt and dodecanol containing 10 wt% toluene, as porogenic solvent. Parameters affecting the extraction procedure were evaluated and the monolith was characterized in terms of binding capacity, reusability, and precision, using α-pyrrolidinovalerophenone as model compound. Cocaine, diazepam, methamphetamine and 20 new psychoactive substances were determined in oral fluids, using the synthesized poly(MAA-co-EDMA) monolith in-tip on an eight-channel micropipette extraction and ultra-high performance liquid chromatography tandem mass spectrometry. Appropriate recoveries were obtained, ranging from 64 to 115%, with limit of detection values from 0.03 to 0.6 µg L-1, and a high precision with relative standard deviation values lower than 10% for all the evaluated drugs.

Development of a molecularly imprinted monolithic polymer disk for agitation-extraction of ecgonine methyl ester from environmental water.

In this study, a new extraction approach based on rotating molecularly imprinted polymer (MIP) disks was developed. The preparation procedure of MIP-disk is simple. Firstly, in order to immobilize MIP onto the surface of polytetrafluoroethylene (PTFE) disk, previous modification and vinylization steps of this fluoropolymer were conducted. Then, MIP synthesis was done by in situ polymerization. The resulting MIP was characterized by Fourier-transform infrared spectroscopy and scanning electron microscopy. Afterwards, two ring magnets were placed in the sides of the MIP-disk to integrate the stirring and preconcentration of sample in just one step. To demonstrate the feasibility of this novel extraction system, the selective extraction of ecgonine methyl ester (EME) from water samples was performed. Extraction conditions were also evaluated and the extracts were analyzed by ion mobility spectrometry and by ultrahigh performance liquid chromatography-tandem mass spectrometry, allowing limits of detection of 13 and 75 ng L-1, respectively. Field surface water and wastewater were analyzed using the proposed methodology, being a good alternative for the fast and potentially portable methodology for in-field screening analysis.

Trace analysis by ion mobility spectrometry: From conventional to smart sample preconcentration methods. A review.

Ion mobility spectrometry (IMS) is a rapid and high sensitive technique widely used in security and forensic areas. However, a lack of selectivity is usually observed in the analysis of complex samples due to the scarce resolution of the technique. The literature concerning the use of conventional and novel smart materials in the pretreatment and preconcentration of samples previous to IMS determinations has been critically reviewed. The most relevant strategies to enhance selectivity and sensitivity of IMS determinations have been widely discussed, based in the use of smart materials, as immunosorbents, aptamers, molecularly imprinted polymers (MIPs), ionic liquids (ILs) and nanomaterial. The observed trend is focused on the development of IMS analytical methods in combination of selective sample treatments in order to achieve quick, reliable, sensitive, and selective methods for the analysis of complex samples such as biological fluids, food, or environmental samples.

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.