Application of poly(methacrylic acid-ethylene glycol dimethacrylate) monolith microextraction coupled with capillary zone electrophoresis to the determination of opiates in human urine

Facile synthesis of amino-functionalized magnetic materials for efficient enrichment of anionic metabolites from biological samples

The analysis of biological samples is often affected by the background matrix. Proper sample preparation is a critical step in the analytical procedure for complex samples. In this study, a simple and efficient enrichment strategy based on Amino-functionalized Polymer-Magnetic MicroParticles (NH₂-PMMPs) with coral-like porous structures was developed to enable the detection of 320 anionic metabolites, providing detailed coverage of phosphorylation metabolism. Among them, 102 polar phosphate metabolites including nucleotides, cyclic nucleotides, sugar nucleotides, phosphate sugars, and phosphates, were enriched and identified from serum, tissues, and cells. Furthermore, the detection of 34 previously unknown polar phosphate metabolites in serum samples demonstrates the advantages of this efficient enrichment method for mass spectrometric analysis. The limit of detections (LODs) were between 0.02 and 4 nmol/L for most anionic metabolites and its high sensitivity enabled the detection of 36 polar anion metabolites from 10 cell equivalent samples. This study has provided a promising tool for the efficient enrichment and analysis of anionic metabolites in biological samples with high sensitivity and broad coverage, facilitating the knowledge of the phosphorylation processes of life.

Polyoxometalate-based materials in extraction, and electrochemical and optical detection methods: A review

Polyoxometalates (POMs) as metal-oxide anions have exceptional properties like high negative charges, remarkable redox abilities, unique ligand properties and availability of organic grafting. Moreover, the amenability of POMs to modification with different materials makes them suitable as precursors to further obtain new composites. Due to their unique attributes, POMs and their composites have been utilized as adsorbents, electrodes and catalysts in extraction, and electrochemical and optical detection methods, respectively. A survey of the recent progress and developments of POM-based materials in these methods is therefore desirable, and should be of great interest. In this review article, POM-based materials, their properties as well as their identification methods, and analytical applications as adsorbents, electrodes and catalysts, and corresponding mechanisms of action, where relevant, are reviewed. Some current issues of the utilization of these materials and their future prospects in analytical chemistry are discussed.

Supercritical fluid extraction of papaverine and noscapine from poppy capsules followed by preconcentration with magnetic nano Fe3O4@Cu@diphenylthiocarbazone particles

A novel magnetite adsorbent modified with copper and diphenylthiocarbazone was synthesized and used as a sorbent for magnetic solid phase extraction (MSPE) of two opium alkaloids: papaverine and noscapine.

Investigation of pH-induced conformational change and hydration of poly(methacrylic acid) by analytical ultracentrifugation

Analytical ultracentrifugation was performed on poly(methacrylic acid) (PMAA) with a series of weight average molar masses (Mw) in aqueous solutions as a function of pH. The scales of the sedimentation coefficient (s) and the diffusion coefficient (D) to Mw at infinite dilutions were obtained at different pH values, indicating that PMAA chains adopt a collapsed structure at low pH values, and stretch at pH higher than 5.2. Our results show that the sedimentation coefficient exhibits a minimum at pH ∼ 6.0, presumably due to the effect of the conformational change and the hydration state of PMAA chains. When pH increases from 6.0 to 8.5, PMAA chains with high molar mass shrink a little bit, presumably because the sodium ions act as a bridging agent between nonadjacent carboxylate groups. Furthermore, the weight average molar mass of PMAA at pH 8.5 increases by one fold than that at pH 4.0, indicating the condensation of sodium ions and the increase in the number of hydration water molecules around carboxylate groups at high pH values.

A new platform for sensing urinary morphine based on carrier assisted electromembrane extraction followed by adsorptive stripping voltammetric detection on screen-printed electrode

Electromembrane extraction (EME) coupled with electrochemical detection on screen-printed carbon electrode has been developed for the quantification of morphine in urine samples. Charged morphine molecules were extracted from an aqueous sample by applying an electrical potential through a thin supported liquid membrane (SLM) into an acidic aqueous acceptor solution (20 µL) placed inside the lumen of a hollow fiber. Then, the acceptor solution was mixed with 20 µL of NaOH solution (0.1 M) and analyzed using screen printed electrochemical strip. Differential pulse voltammetry (DPV) peak current at 0.18 V was selected as the signal and the influences of experimental parameters were investigated and optimized using Box-behnken design and also one-variable-at-a-time methodology as follows: adsorptive accumulation time, 40 s; SLM, 2-nitrophenyl octyl ether+10% tris-(2-ethylhexyl) phosphate+10% di-(2-ethylhexyl) phosphate; pH of the sample solution, 6.0; pH of the acceptor solution, 1.0; EME time, 24 min; EME potential, 90 V and stirring rate, 1000 rpm. The calibration curve which was plotted by the variation of DPV currents as a function of morphine concentration was linear within the range of 0.005-2.0 µg mL(-1). The limit of detection and the limit of quantification were 0.0015 (S/N=3) and 0.005 µg mL(-1), respectively. Finally, the proposed method was able to determine morphine simply and effectively at concentration levels encountered in toxicology and doping.

Sensitive and fast determination of papaverine by adsorptive stripping voltammetry on renewable mercury film electrode

The renewable mercury film electrode, applied for the determination of papaverine traces using differential pulse adsorptive stripping voltammetry (DP AdSV) is presented. The calibration graph obtained for papaverine is linear from 1.25 nM (0.42 µg L−1) to 95 nM (32.2 µg L−1) for a preconcentration time of 60 s, with correlation coefficient of 0.998. For the renewable mercury electrode (Hg(Ag)FE) with a surface area of 9.1 mm2 the detection limit for a preconcentration time of 60 s is 0.7 nM (0.24 µg L−1). The repeatability of the method at a concentration level of the analyte as low as 17 µg L−1, expressed as RSD is 3.3% (n=5). The proposed method was successfully applied and validated by studying the recovery of papaverine from drugs, urine and synthetic solution.

A selective pretreatment method for determination of endogenous active brassinosteroids in plant tissues: double layered solid phase extraction combined with boronate affinity polymer monolith microextraction

BACKGROUND

Brassinosteriods (BRs), a group of important phytohormones, have various effects on plant growth and development. However, their physiological functions in plants have not been fully understood to date. Endogenous BRs in plant tissue are extremely low and the elucidation of BRs functions relies on sensitive detection method. Reported methods for the determination of BRs required large amount of plant tissue, tedious pretreatment process, and were lack of selectivity. Therefore, development of a simple and selective method for the sensitive quantification of BRs is highly needed.

RESULTS

We established a pretreatment method of BRs in plant tissues by employing double layered solid phase extraction (DL/SPE) combined with boronate affinity polymer monolith microextraction (BA/PMME). After the initial depigmentation with DL/SPE cartridge, BA/PMME was employed to selectively extract BRs from sample matrix. Uniquely, most sample matrix was successfully removed by BA monolith purification. Using this method, BRs was determined by liquid chromatography-mass spectrometry (LC-MS). Endogenous active BRs could be detected in only 1 g fresh weigh (FW) leaves or 0.5 g FW flower tissues.

CONCLUSION

A DL/SPE-BA/PMME pretreatment method for the determination of endogenous brassinosteroids in plant tissues was developed and validated. The proposed method was sensitive and selective. Besides, it may be further developed for the determination of other BRs including their precursors and conjugates.

Microextraction techniques combined with capillary electrophoresis in bioanalysis

Over the past two decades, many environmentally sustainable sample-preparation techniques have been proposed, with the objective of reducing the use of toxic organic solvents or substituting these with environmentally friendly alternatives. Microextraction techniques (MEs), in which only a small amount of organic solvent is used, have several advantages, including reduced sample volume, analysis time, and operating costs. Thus, MEs are well adapted in bioanalysis, in which sample preparation is mandatory because of the complexity of a sample that is available in small quantities (mL or even μL only). Capillary electrophoresis (CE) is a powerful and efficient separation technique in which no organic solvents are required for analysis. Combination of CE with MEs is regarded as a very attractive environmentally sustainable analytical tool, and numerous applications have been reported over the last few decades for bioanalysis of low-molecular-weight compounds or for peptide analysis. In this paper we review the use of MEs combined with CE in bioanalysis. The review is divided into two sections: liquid and solid-based MEs. A brief practical and theoretical description of each ME is given, and the techniques are illustrated by relevant applications.

Role of microextraction sampling procedures in forensic toxicology

The last two decades have provided analysts with more sensitive technology, enabling scientists from all analytical fields to see what they were not able to see just a few years ago. This increased sensitivity has allowed drug detection at very low concentrations and testing in unconventional samples (e.g., hair, oral fluid and sweat), where despite having low analyte concentrations has also led to a reduction in sample size. Along with this reduction, and as a result of the use of excessive amounts of potentially toxic organic solvents (with the subsequent environmental pollution and costs associated with their proper disposal), there has been a growing tendency to use miniaturized sampling techniques. Those sampling procedures allow reducing organic solvent consumption to a minimum and at the same time provide a rapid, simple and cost-effective approach. In addition, it is possible to get at least some degree of automation when using these techniques, which will enhance sample throughput. Those miniaturized sample preparation techniques may be roughly categorized in solid-phase and liquid-phase microextraction, depending on the nature of the analyte. This paper reviews recently published literature on the use of microextraction sampling procedures, with a special focus on the field of forensic toxicology.

In-line solid-phase extraction-capillary electrophoresis coupled with mass spectrometry for determination of drugs of abuse in human urine

In-line solid-phase extraction-capillary electrophoresis coupled with mass spectrometric detection (SPE-CE-MS) has been used for determination of 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), codeine (COD), hydrocodeine (HCOD), and 6-acetylmorphine (6AM) in urine. The preconcentration system consists of a small capillary filled with Oasis HLB sorbent and inserted into the inlet section of the electrophoresis capillary. The SPE-CE-MS experimental conditions were optimized as follows: the sample (adjusted to pH 6.0) was loaded at 930 mbar for 60 min, elution was performed with methanol at 50 mbar for 35 s, 60 mmol L(-1) ammonium acetate at pH 3.8 was used as running buffer, the separation voltage was 30 kV, and the sheath liquid at a flow rate of 5.0 μL min(-1) was isopropanol-water 50:50 (v/v) containing 0.5% acetic acid. Analysis of urine samples spiked with the four drugs and diluted 1:1 (v/v) was studied in the linear range 0.08-10 ng mL(-1). Detection limits (LODs) (S/N = 3) were between 0.013 and 0.210 ng mL(-1). Repeatability (expressed as relative standard deviation) was below 7.2%. The method developed enables simple and effective determination of these drugs of abuse in urine samples at the levels encountered in toxicology and doping.

Novel strategies for sample preparation in forensic toxicology

This paper provides a review of novel strategies for sample preparation in forensic toxicology. The review initially outlines the principle of each technique, followed by sections addressing each class of abused drugs separately. The novel strategies currently reviewed focus on the preparation of various biological samples for the subsequent determination of opiates, benzodiazepines, amphetamines, cocaine, hallucinogens, tricyclic antidepressants, antipsychotics and cannabinoids. According to our experience, these analytes are the most frequently responsible for intoxications in Greece. The applications of techniques such as disposable pipette extraction, microextraction by packed sorbent, matrix solid-phase dispersion, solid-phase microextraction, polymer monolith microextraction, stir bar sorptive extraction and others, which are rapidly gaining acceptance in the field of toxicology, are currently reviewed.

Endogenous opiates and behavior: 2006

This paper is the 29th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning 30 years of research. It summarizes papers published during 2006 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurological disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).

Polymer monolith microextraction with in situ derivatization and its application to high-performance liquid chromatography determination of hexanal and heptanal in plasma

A simple, rapid and sensitive method for the determination of hexanal and heptanal in plasma by high-performance liquid chromatography (HPLC) has been developed, which is based on polymer monolith microextraction (PMME) with in situ derivatization. 2,4-dinitrophenylhydrazine (DNPH) as a derivatizing reagent was first adsorbed on a poly (methacrylic acid-co-ethylene glycol dimethacrylate) (MAA-EGDMA) monolith, and then microextraction was performed simultaneously with derivatization on the monolith. The several parameters affecting the in situ derivatization simultaneously with PMME were investigated, including the flow rate, pH, buffer concentration, and temperature. The whole pretreatment process can be accomplished within 8 min. The limits of detection for hexanal and heptanal were found to be 2.4 and 3.6 nmol/L, respectively. The recoveries in plasma sample were in the range of 83-87% with the inter- and intra-day precisions less than 6.8%. This method was successfully applied to the analysis of hexanal and heptanal in plasma samples from different cancer patients.