Poly(methacrylic acid-ethylene glycol dimethacrylate) monolith in-tube solid-phase microextraction applied to simultaneous analysis of some amphetamine derivatives in urine by capillary zone electrophoresis

Microextraction Techniques for Sample Preparation of Amphetamines in Urine: A Comprehensive Review

Psychological disorders and dramatic social problems are serious concerns regarding the abuse of amphetamine and its stimulant derivatives worldwide. Consumers of such drugs experience great euphoria along with serious health problems. Determination and quantification of amphetamine-type stimulants are indispensable skills for clinical and forensic laboratories. Analysis of low drug doses in bio-matrices necessitates applications of simple and also effective preparation steps. The preparation procedures not only eliminate adverse matrix effects, but also provide reasonable clean-up and pre-concentration benefits. The current review presents different methods used for sample preparation of amphetamines from urine as the most frequently used biological matrix. The advantages and limitations of various sample preparation methods were discussed focusing on the miniaturized methods.

Quantitative determination of amphetamine-type stimulants in sewage and urine by hybrid monolithic column solid-phase microextraction coupled with UPLC-QTRAP MS/MS

A needle-solid-phase microextraction (SPME) method based on hybrid monolithic column (HMC) was proposed for simultaneous separation and extraction of seven amphetamine-type stimulants (ATSs) (amphetamine, methamphetamine, cathinone, methcathinone, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, and 3,4-methylenedioxyethylamphetamine), combining with ultra-performance liquid chromatography-triple quadrupole/linear ion trap mass spectrometer (UPLC-QTRAP MS/MS). Thiol functionalized HMC (T-HMC) showed high extraction efficiency and excellent elution results towards target analytes, among three kinds of single/bi-functionalized HMCs. Various parameters of SPME operation and analytical performance were investigated systematically. The adsorption mechanism of T-HMC to ATSs was also discussed and explained as a mixed mode of electrostatic and hydrophobic interactions. Under the optimum experimental conditions, the proposed T-HMC needle-SPME-UPLC-QTRAP MS/MS method was rapid and convenient with good accuracy, low sample consumption, high sensitivity and strong anti-interference ability. This method was successfully applied to quantitative determination of seven trace ATSs in complex sewage and urine samples. In view of abundant types of HMCs, the needle-SPME based on functional HMC also had the potential to selectively separating and enriching other tract new psychoactive substances in complex matrices, and could provide a reliable tool for drug monitoring, especially in applications for forensic analysis and drug abuse.

Bioanalytical HPLC Applications of In-Tube Solid Phase Microextraction: A Two-Decade Overview

In-tube solid phase microextraction is a cutting-edge sample treatment technique offering significant advantages in terms of miniaturization, green character, automation, and preconcentration prior to analysis. During the past years, there has been a considerable increase in the reported publications, as well as in the research groups focusing their activities on this technique. In the present review article, HPLC bioanalytical applications of in-tube SPME are discussed, covering a wide time frame of twenty years of research reports. Instrumental aspects towards the coupling of in-tube SPME and HPLC are also discussed, and detailed information on materials/coatings and applications in biological samples are provided.

Development of a novel voltammetric sensor for the determination of methamphetamine in biological samples on the pretreated pencil graphite electrode

We developed a simple and reliable sensor for the determination of methamphetamine without expensive and time-consuming pretreatments using PPGE.

Solid phase microextraction and related techniques for drugs in biological samples

In drug discovery and development, the quantification of drugs in biological samples is an important task for the determination of the physiological performance of the investigated drugs. After sampling, the next step in the analytical process is sample preparation. Because of the low concentration levels of drug in plasma and the variety of the metabolites, the selected extraction technique should be virtually exhaustive. Recent developments of sample handling techniques are directed, from one side, toward automatization and online coupling of sample preparation units. The primary objective of this review is to present the recent developments in microextraction sample preparation methods for analysis of drugs in biological fluids. Microextraction techniques allow for less consumption of solvent, reagents, and packing materials, and small sample volumes can be used. In this review the use of solid phase microextraction (SPME), microextraction in packed sorbent (MEPS), and stir-bar sorbtive extraction (SBSE) in drug analysis will be discussed. In addition, the use of new sorbents such as monoliths and molecularly imprinted polymers will be presented.

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.

Determination of eight illegal drugs in human urine by combination of magnetic solid-phase extraction with capillary zone electrophoresis

Using magnetite/silica/poly(methacrylic acid-co-ethylene glycol dimethacrylate) (Fe(3)O(4)/SiO(2)/poly(MAA-co-EDMA)) magnetic microspheres, a rapid and high-throughput magnetic solid-phase extraction coupled with capillary zone electrophoresis (MSPE-CZE) method was developed for the determination of illegal drugs (ketamine, amphetamines, opiates, and metabolites). The MSPE of target analytes could be completed within 2 min, and the eight target analytes could be baseline separated within 15 min by CZE with 30 mM phosphate buffer solution (PBS, pH 2.0) containing 15% v/v ACN as background electrolyte. Furthermore, hydrodynamic injection with field-amplified sample stacking (FASS) was employed to enhance the sensitivity of this MSPE-CZE method. Under such optimal conditions, the limits of detection for the eight target analytes ranged from 0.015 to 0.105 μg/mL. The application feasibility of MSPE-CZE in illegal drugs monitoring was demonstrated by analyzing urine samples, and the recoveries of target drugs for the spiked sample ranging from 85.4 to 110.1%. The method reproducibility was tested by evaluating the intra- and interday precisions, and relative standard deviations of <10.3 and 12.4%, respectively, were obtained. To increase throughput of the analysis, a home-made MSPE array that has potential application to the treatment of 96 samples simultaneously was used.

Development of in-tube solid-phase microextraction coupled to pressure-assisted CEC and its application to the analysis of propranolol enantiomers in human urine

A successful hyphenation of in-tube solid-phase microextraction (SPME) and pressure-assisted CEC (pCEC) was developed by installing a poly(methacrylic acid-co-ethylene glycol dimethacrylate) monolithic capillary to the six-port valve in a CEC system. The device designed was appropriate for on-line in-tube SPME coupled to pCEC or muHPLC. The evaluation of this hyphenation was first carried out for in-tube SPME-muHPLC with analytical capillaries packed with 3 microm octadecyl silica (ODS). Theobromine (TB), theophylline (TP), and caffeine (CA) were chosen as model drugs for an easy comparison with the results obtained by in tube SPME-HPLC. The detection limits of these three analytes were improved more than 100 times when compared with the direct analysis by muHPLC. Then in-tube SPME-pCEC with CEC capillaries packed with perphenylcarbamoylated beta-CD-bonded silica particles was applied to the determination and analysis of propranolol enantiomers in human urine. Under optimal extraction and separation conditions, the experimental LODs were 4 and 7 ng/mL for (S)-propranolol and (R)-propranolol, respectively. The calibration curves showed good linearity for both (S)-propranolol (R(2) = 0.9997) and (R)-propranolol (R(2) = 0.9996) over the concentration range from 20 to 5000 ng/mL. Reproducibility of the method was also investigated with intra- and interday precisions lower than 10% for both enantiomers at different concentration levels.

Recent development of monolithic materials as matrices in microcolumn separation systems

This review summarizes the development of monolithic materials, including both organic and inorganic polymers, according mainly to the papers published in the past two years. Due to their good permeability, fast mass transfer, high stability, and their ease of modification, such materials have been widely used in microcolumn separation systems, not only as stationary phases for CEC and capillary HPLC, but also as substances for sample concentration and enzyme reactor. All the research results demonstrate that monolithic materials in microseparation systems can be expected to play an increasingly important role in the analysis of complex samples.

Cation-selective exhaustive injection and sweeping MEKC for direct analysis of methamphetamine and its metabolites in urine

Direct analysis of methamphetamine, amphetamine, and p-hydroxymethamphetamine in urine was achieved by cation-selective exhaustive injection and sweeping micellar EKC. A bare fused-silica capillary (40 cm, 50 microm id) was filled with phosphate buffer (80 mM, pH 3, containing 20% ACN). Then a high-conductivity buffer (100 mM phosphate, pH 3; 6.9 kPa for 2.5 min) was injected. Samples were loaded using electrokinetic injection (10 kV, 600 s) which created long zones of cationic analytes. To enhance sensitivity by sweeping, the stacking step was performed using a phosphate buffer (50 mM, pH 3, containing 20% ACN and 100 mM SDS) at -20 kV before separation by MEKC. This method was capable of detecting the analytes at ppb levels. The calibration plots were linear (r(2) >or= 0.9948) over a range of 100-5000 ng/mL for methamphetamine, and 100-2000 ng/mL for amphetamine and p-hydroxymethamphetamine. The LODs (S/N = 3) were 20 ng/mL for methamphetamine, and 15 ng/mL for amphetamine and p-hydroxymethamphetamine. The method was applied to analysis of 14 urine samples of addicts and is suitable for screening suspected samples for forensic purposes. The results showed good agreement with fluorescence polarization immunoassay and GC-MS.

Column preconcentration of lead in aqueous solution with macroporous epoxy resin-based polymer monolithic matrix

The objective of this article was to investigate the feasibility of epoxy resin-based monoliths prepared by stepwise polymerization and column preconcentration of metal ions using large-scale monolithic matrix. A novel macroporous polymer monolith matrix was prepared from epoxy resin (EP) and ethylenediamine (EDA) and pore-forming reagent (polyethylene glycol, PEG-1000) by in situ step-addition polymerization. The morphology of the resulting polymer monolith was characterized by scanning electron microscopy (SEM). A solid-phase extraction (SPE) cartridge prepared from a simple glass-tube was used for the preconcentration and determination of Pb(II) combined with flame atomic absorption spectroscopy (FAAS). The characteristics of the monoliths for the extraction of Pb(II) in aqueous solution were investigated. The experimental results showed that trace Pb(II) ions could be quantitatively preconcentrated in the pH range of 4.0-9.0 with recoveries of >95%. The maximum static adsorption capacity of the monolith adsorbent was 106.8 mg g(-1). The column was eluted by 1.0 mol L(-1) HNO3 and recovery of Pb(II) was more than 97%. Moreover, the polymer monolith adsorbent shows superior reusability and stability. The precision and the accuracy of the proposed procedure were satisfactory by analyzing a standard reference material and three natural water samples. It was shown that the EP-EDA monolith was suitable for the preconcentration of environmental Pb(II) as an ion-selective SPE adsorbent.

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

A novel poly(methacrylic acid-ethylene glycol dimethacrylate) (MAA-EGDMA) monolith microextraction method coupled with CZE was proposed for rapidly determining a mixture of opiates comprising heroin, 6-monoacetylmorphine, morphine, codeine, papaverine, and narcotine in human urine. The extraction device contained a regular plastic syringe, the poly(MAA-EGDMA) monolithic capillary tube (530 microm id x 3 cm) and a plastic pinhead, which connected the monolithic capillary tube and the syringe without leakage. In the polymer monolith microextraction, the sample solution was ejected via the monolithic capillary tube by a programmable syringe pump, followed by desorption with an aliquot of appropriate solution, which was collected into a vial for the subsequent analysis by CZE. The best separation was achieved using a buffer composed of 0.1 M disodium hydrogen phosphate (adjusted to pH 4.5 with 1 M hydrochloric acid) and 20% methanol v/v with temperature and voltage of 25 degrees C and 25 kV, respectively. By applying electrokinetic injection with field-enhanced sample stacking, detection limits of 6.6-19.5 ng/mL were achieved. Excellent method of reproducibility was found over a linear range of 80-2000 ng/mL.

Novel polymer monolith microextraction using a poly(methacrylic acid-ethylene glycol dimethacrylate) monolith and its application to simultaneous analysis of several angiotensin II receptor antagonists in human urine by capillary zone electrophoresis

Novel polymer monolith microextraction (PMME) using a poly(methacrylic acid-ethylene glycol dimethacrylate) (poly(MAA-EGDMA)) monolith in conjunction with capillary zone electrophoresis (CZE) was developed for the determination of several angiotensin II receptor antagonists (ARA-IIs) in human urine. The extraction device consisted of a regular plastic syringe (1 mL), a poly(MAA-EGDMA) monolithic capillary (2 cm x 530 microm I.D.) and a plastic pinhead connecting the former two components seamlessly. The extraction was achieved by driving the sample solution through the monolithic capillary tube using a syringe infusion pump, and for the desorption step, an aliquot of organic solvent was injected via the monolithic capillary and collected into a vial for subsequent analysis by CZE. The best separation was realized at 25 kV using a buffer that consisted of 50% acetonitrile and 50% buffer solution (v/v) containing 10 mM disodium hydrogenphosphate (adjusted to pH 2.3 with 1M hydrochloric acid). The method was successfully applied to the determination of telmisartan (T), irbesartan (I) and losartan (L) in urine samples with candesartan (C) as internal standard, yielding the detection limit of 15-20 ng/mL. Close correlation coefficients (R>0.999) and excellent method reproducibility were obtained for all the analytes over a linear range of 0.08-3 microg/mL.