Direct analysis of tobacco specific nitrosamines in tobacco products using a molecularly imprinted polymer-packed column

Tobacco specific nitrosamines (TSNAs) are highly carcinogenic by-products in tobacco samples, and their presence is regulated by the Food and Drug Administration. Molecularly imprinted polymers (MIPs) are synthetic polymers that have been "imprinted" with a template analyte in a co-polymer system, and can selectively extract analytes from complex matrices. MIPs can be incorporated into online systems, replacing traditional high performance liquid chromatography (HPLC) columns. MIP material specific for TSNAs was packed into an empty HPLC column using a slurry packing technique. The developed method with the MIP-packed HPLC column was validated on a LC-MS/MS system for the quantitation of N-nitrosonornicotine (NNN) and 4- (methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in commercial tobacco products. The method was linear over .1-10 ng/ml (.4-10 μg/g) for NNN and NNK. The limit of detection (LOD) was .03 ng/ml (12 μg/g) and the limit of quantitation (LOQ), .1 ng/ml (.4 μg/g). All column uniformity parameters with the exception of theoretical plate number were within the accepted criteria (% RSD values <15%). Theoretical plate number was <250, owing to the large (50 μm) sized MIP particles. Twenty-six tobacco products contained TSNA concentrations that were consistent with reported literature values. The TSNA-MIP based HPLC column effectively replaced a traditional reverse phase HPLC column, and was used for the direct analysis of nicotine and tobacco products without extensive sample preparation prior to instrumental analysis.

Sensitive and selective simultaneous biosensing of nandrolone and testosterone as two anabolic steroids by a novel biosensor assisted by second-order calibration

Recently, our research group have focused on an interesting project in which a novel dual template molecularly imprinted (DTMIP) biosensor was fabricated and assisted by second-order differential pulse voltammetric (DPV) data for simultaneous determination of nandrolone decanoate (ND) and testosterone decanoate (TS). An indium tin oxide (ITO) was modified with multiwalled carbon nanotubes-graphene-ionic liquid (MWCNT-Gr-IL) and then, the fullerene C₆₀ was casted onto the surface of MWCNT-Gr-IL/ITO and electrochemically reduced. Finally, DTMIPs were electrosynthesized by electropolymerization of 4-aminobenzoic acid (ABA) as monomer with ND and TS as template molecules to obtain the final structure of the biosensor (DTMIP/C₆₀/MWCNT-Gr-IL/ITO). Structure of the biosensor was electrochemically and microscopically characterized. The ND and TS generated two severely overlapped DPVs at the surface of the biosensor which forced us to assist the biosensor with three-way calibration by second-order DPV data to simultaneous determine them. Two second-order algorithms including multivariate curve resolution alternating least squares (MCR-ALS) and parallel factor analysis2 (PARAFAC2) were used to build second-order calibration models and evaluation of their performance in the analysis of synthetic samples showed more superiority of the MCR-ALS than PARAFC2 which motivated us to select PARAFC2 for the analysis of urine samples as real cases. Application of the biosensor assisted by PARAFC2 for the analysis of urine samples towards simultaneous determination of ND and TS was successful.

New Fluorescent Nanosensor for Determination of Diazepam Using Molecularly Imprinted Mn-doped ZnS Quantum Dots

In this study, molecularly imprinted Mn-doped ZnS quantum dots were used as nanosensors to determine diazepam and its metabolites. Mn-doped ZnS quantum dots (QDs) capped with L-cysteine were prepared using a sodium thiosulfate precursor and characterized by various methods. Methacrylic acid was used as a precursor for the synthesis of MIP Mn-doped ZnS QDs and then used to measure diazepam in various samples. The linear dynamic range, coefficient of determination, and detection limit were found to be 0.3 - 250 µmol/L, 0.989 and 8.78 × 10^-2 µmol/L, respectively. The interference studies showed that the prepared nanosensor was selective for diazepam and its metabolites.

Growing Trends in the Efficient and Selective Extraction of Compounds in Complex Matrices Using Molecularly Imprinted Polymers and Their Relevance to Toxicological Analysis

In the world of forensic and clinical toxicology, proper sample preparation is one of the key steps in identification and quantification of drugs of abuse. Traditional extraction methods such as solid-phase extraction and liquid-liquid extraction are often laborious and nonselective for the target analytes being measured. Molecularly imprinted polymers (MIPs) can be synthesized for sample extraction and their versatility allows the polymer to be employed in off-line, benchtop extractions or on/in-line instrument extractions, offering a faster and more selective sample preparation without the risk of interfering matrix effects. This review details the synthesis and applications of MIP materials for the extraction of drug compounds from biological matrices in publications from 1994 to today.

Synthesis and characterization of molecularly imprinted polymers for the selective extraction of oxazepam from complex environmental and biological samples

Oxazepam, one of the most frequently prescribed anxiolytic drugs, is not completely removed from wastewater with conventional treatment processes. It can thus be found at trace levels in environmental water, with human urine constituting the major source of contamination. This study focused on the development and characterization of molecularly imprinted polymers (MIPs) for the selective solid-phase extraction of oxazepam at trace levels from environmental water and human urine samples. Two MIPs were synthesized, and their selectivity in pure organic and aqueous media were assayed. After optimizing the extraction procedure adapted to a large sample volume to reach a high enrichment factor, the most promising MIP was applied to the selective extraction of oxazepam from environmental water. Extraction recoveries of 83 ± 12, 92 ± 4 and 89 ± 10% were obtained using the MIP for tap, mineral and river water, respectively, while a recovery close to 40% was obtained on the corresponding non-imprinted polymer (NIP). Thanks to the high enrichment factors, a limit of quantification (LOQ) of 4.5 ng L^-1 was obtained for river water. A selective extraction procedure was also developed for urine samples and gave rise to extraction recoveries close to 95% for the MIP and only 23% for the NIP. Using the MIP, a LOQ of 357 ng L^-1 was obtained for oxazepam in urine. The use of the MIP also helped to limit the matrix effects encountered for the quantification of oxazepam in environmental samples and in human urine samples after extraction on an Oasis HLB sorbent.

Synthesis of Diazepam-Imprinted Polymers with Two Functional Monomers in Chloroform Using a Bulk Polymerization Method

Diazepam is a benzodiazepine that has the potency to be misused because it is effective, easily obtained, and inexpensive. The misuse of diazepam is to replace illegal drugs and be a sedative. Separation of diazepam is needed to detect possible drug abuse and to monitor drug levels in blood to ensure the effectiveness of the drug. This study was conducted to obtain a molecularly imprinted solid-phase extraction (MI-SPE) sorbent to separate diazepam from serum samples. This work started at the synthesis stage with the bulk polymerization method, using methyl methacrylate and acrylamide as functional monomers, diazepam as a template, and ethylene glycol dimethacrylate as a crosslinker. The polymer obtained was identified by its adsorption capacity and packaged into a solid-phase extraction (SPE) cartridge, and the extraction conditions were optimized. The optimization results were then used to extract diazepam from the serum sample. The test results showed that the adsorption ability of the molecularly imprinted polymer (MIP) with the functional monomer, methyl methacrylate, was 63.98 ± 0.1%, which is higher than that of the acrylamide MIP monomer, with a value of 43.27 ± 0.1%. The MIP sorbent of methyl methacrylate was applied to the SPE with 200 mg of polymer in a 3 mL cartridge. Diazepam added to serum samples were then passed through the MIP-SPE producing a percent recovery value of 95.31 ± 1.1% for MIP and 60.83 ± 0.3% for nonimprinted polymer (NIP). The results showed that the MI-SPE sorbent made from the monomer methyl methacrylate gave higher extraction recovery results than acrylamide, and it could be used for extracting diazepam from serum samples with or without other substances.

Biological sample preparation by using restricted-access nanoparticles prepared from bovine serum albumin: application to liquid chromatographic determination of β-blockers

Restricted-access nanoparticles (RANPs) were prepared from bovine serum albumin by coacervation. They have an average sized of 311 nm. They were characterized and used to capture the β-blockers atenolol, metoprolol and propranolol from untreated biological samples. It is shown that both high protein affinity drugs (propranolol) and low protein affinity drugs (atenolol) could be rapidly extracted from plasma. This is revealed by kinetic and isothermal adsorption studies. On the other hand, almost all proteins from the sample were excluded. This demonstrates the efficiency of RANPs as restricted-access material. Sample preparation was carried out by solid phase microextraction using a probe obtained by the fixation of the RANPs at the end of a glass capillary. Atenolol (in concentrations from 100 to 1200 μg L^-1), metoprolol (from 80 to 1000 μg L^-1) and propranolol (from 15 to 200 μg L^-1) were extracted from spiked plasma samples and analyzed by LC MS/MS without using a separation column. Correlation coefficients >0.99, good precision, accuracy, robustness, and lack of memory effects were observed for all of the analytes. The detection limits (at an S/N of 3) are 25.6, 14.6, and 3.8 μg L^-1 for atenolol, metoprolol and propranolol, respectively. Ten samples can be simultaneously extracted within ∼15 min. Plasma samples of patients undergoing medical treatment were successfully analyzed with the method. Graphical abstract Schematic representation of a bovine serum albumin-based restricted access nanoparticle that exclude proteins from a human plasma sample but capture the small analytes.

Internal Extractive Electrospray Ionization Mass Spectrometry for Quantitative Determination of Fluoroquinolones Captured by Magnetic Molecularly Imprinted Polymers from Raw Milk

Antibiotics contamination in food products is of increasing concern due to their potential threat on human health. Herein solid-phase extraction based on magnetic molecularly imprinted polymers coupled with internal extractive electrospray ionization mass spectrometry (MMIPs-SPE-iEESI-MS) was designed for the quantitative analysis of trace fluoroquinolones (FQs) in raw milk samples. FQs in the raw milk sample (2 mL) were selectively captured by the easily-lab-made magnetic molecularly imprinted polymers (MMIPs), and then directly eluted by 100 µL electrospraying solvent biased with +3.0 kV to produce protonated FQs ions for mass spectrometric characterization. Satisfactory analytical performance was obtained in the quantitative analysis of three kinds of FQs (i.e., norfloxacin, enoxacin, and fleroxacin). For all the samples tested, the established method showed a low limit of detection (LOD ≤ 0.03 µg L⁻¹) and a high analysis speed (≤4 min per sample). The analytical performance for real sample analysis was validated by a nationally standardized protocol using LC-MS, resulting in acceptable relative error values from −5.8% to +6.9% for 6 tested samples. Our results demonstrate that MMIPs-SPE-iEESI-MS is a new strategy for the quantitative analysis of FQs in complex biological mixtures such as raw milk, showing promising applications in food safety control and biofluid sample analysis.

Molecular Imprinting Applications in Forensic Science

Producing molecular imprinting-based materials has received increasing attention due to recognition selectivity, stability, cast effectiveness, and ease of production in various forms for a wide range of applications. The molecular imprinting technique has a variety of applications in the areas of the food industry, environmental monitoring, and medicine for diverse purposes like sample pretreatment, sensing, and separation/purification. A versatile usage, stability and recognition capabilities also make them perfect candidates for use in forensic sciences. Forensic science is a demanding area and there is a growing interest in molecularly imprinted polymers (MIPs) in this field. In this review, recent molecular imprinting applications in the related areas of forensic sciences are discussed while considering the literature of last two decades. Not only direct forensic applications but also studies of possible forensic value were taken into account like illicit drugs, banned sport drugs, effective toxins and chemical warfare agents in a review of over 100 articles. The literature was classified according to targets, material shapes, production strategies, detection method, and instrumentation. We aimed to summarize the current applications of MIPs in forensic science and put forth a projection of their potential uses as promising alternatives for benchmark competitors.

Electroanalytical determination of diazepam in tablet and human serum samples using a multiwalled carbon nanotube embedded molecularly imprinted polymer-modified carbon paste electrode

In this study a new MWCNT–MIP nanocomposite modified carbon paste electrode for determination of diazepam has been developed.

Direct doping analysis of beta-blocker drugs from urinary samples by on-line molecularly imprinted solid-phase extraction coupled to liquid chromatography/mass spectrometry

The hydrophilic layer forms hydrogen bonds with water, minimizing the interference of this solvent in the analyte–polymer complex.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Synthesis of Nimetazepam - Molecularly Imprinted Polymer and SPE Application

The synthesis and performance of a molecularly imprinted polymer (MIP) designed to enable the clean-up of the interferences existing in alprazolam (Alpra) drug samples is described. The MIP was synthesized using non-covalent molecularly imprinted method. Nimetazepam (Nimet), which has a similar chemical structure as the major impurities in Alpra drug samples, was used as the dummy template. Methacrylic acid was used as the monomer. Both the affinity and selectivity of the MIP for Nimet and structurally related compounds were examined through batch-rebinding studies. The specific binding amount of Nimet was determined to be 11.4 mg•g-1. The MIP was used as the sorbent in solid phase extraction (MI-SPE) and methanol was used as the washing solvent for the clean-up of Nimet in the Alpra complex samples. The effective clean-up of Nimet was achieved, with a recovery > 90% for Alpra, in the stimulated samples.