Extraction and preconcentration of salbutamol and terbutaline from aqueous samples using hollow fiber supported liquid membrane containing anionic carrier

Docking guided phase display to develop fusion protein with novel scFv and alkaline phosphatase for one-step ELISA salbutamol detection

Introduction

Salbutamol (SAL) is a β2 adrenergic receptor agonist which has potential hazardous effects for human health. It is very important to establish a sensitive and convenient method to monitor SAL.

Methods

Here we introduce a method to combine the information from docking and site specific phage display, with the aim to obtain scFv with high affinity to SAL. First, single chain variable fragment (scFv) antibodies against SAL were generated through phage display. By using molecular docking approach, the complex structure of SAL with antibody was predicted and indicated that H3 and L3 contribute to the binding. Then new libraries were created by randomization specific residues located on H3 and L3 according to the docking results.

Results and discussion

Anti-SAL scFv antibodies with high efficiency were finally identified. In addition, the selected scFv was fused with alkaline phosphatase and expressed in E coli to develop a rapid and low-cost one step ELISA to detect SAL.

Complete antigen-bridged DNA strand displacement amplification immuno-PCR assay for ultrasensitive detection of salbutamol

Monitoring of low-level analytes are typical examples for analytical challenges. Salbutamol (SAL), a phenol-β2-agonist, has a very low residual content in the environment. Here, we present an ultrasensitive complete antigen-bridged PCR assay for detecting salbutamol (SAL). These DNA probes modified SAL complete antigens target recognition SAL antibodies and agglutinate synthetic DNA conjugates, thus enabling ligation of DNA probes to form a full-length DNA amplicon that contained a recognition site for cleavage endonuclease and subsequent quantification by qPCR. Moreover, SAL antibodies were modified with magnetic beads which were used to reduce the background noise and sample matrix effect, and the DNA signals were isothermally amplified by strand displacement amplification technology. Some key parameters which influence assay performance were optimized: the length of the bridge oligonucleotide, the concentration of immunomagnetic beads, SAL probes, and initiation chain, etc. Under the optimum conditions, the signal amplification of proposed Immuno-PCR assay for the detection of SAL was exponential, resulting in high potential sensitivity(~1 fg/mL) and a broad detection dynamic range (> 10⁵ fold). Using this proposed method, we detected SAL in spiked tap water and urine samples with acceptable recoveries ranging from 88.1 to 103.3%. Theoretically, the method developed here has broad applicability and practical utility in immunoassays of a wide variety of analytes.

Application of Hollow Fibre-Liquid Phase Microextraction Technique for Isolation and Pre-Concentration of Pharmaceuticals in Water

In this article, a comprehensive review of applications of the hollow fibre-liquid phase microextraction (HF-LPME) for the isolation and pre-concentration of pharmaceuticals in water samples is presented. HF-LPME is simple, affordable, selective, and sensitive with high enrichment factors of up to 27,000-fold reported for pharmaceutical analysis. Both configurations (two- and three-phase extraction systems) of HF-LPME have been applied in the extraction of pharmaceuticals from water, with the three-phase system being more prominent. When compared to most common sample preparation techniques such as solid phase extraction, HF-LPME is a greener analytical chemistry process due to reduced solvent consumption, miniaturization, and the ability to automate. However, the automation comes at an added cost related to instrumental set-up, but a reduced cost is associated with lower reagent consumption as well as shortened overall workload and time. Currently, many researchers are investigating ionic liquids and deep eutectic solvents as environmentally friendly chemicals that could lead to full classification of HF-LPME as a green analytical procedure.

Membrane Removal of Emerging Contaminants from Water: Which Kind of Membranes Should We Use?

Membrane technologies are nowadays widely used; especially various types of filtration or reverse osmosis in households, desalination plants, pharmaceutical applications etc. Facing water pollution, they are also applied to eliminate emerging contaminants from water. Incomplete knowledge directs the composition of membranes towards more and more dense materials known for their higher selectivity compared to porous constituents. This paper evaluates advantages and disadvantages of well-known membrane materials that separate on the basis of particle size, usually exposed to a large amount of water, versus dense hydrophobic membranes with target transport of emerging contaminants through a selective barrier. In addition, the authors present several membrane processes employing the second type of membrane.

Carrier-mediated extraction: Applications in extraction and microextraction methods

The present review is mainly focused on the overview of carrier mediated extraction (principles and applications) being reported over the last two decades and discusses the extraction process through carriers in various extraction methods such as Bulk liquid membranes, supported liquid membranes, emulsion liquid membranes and polymer inclusion membranes. Several types of carriers such as neutral, anionic, cationic, macrocyclic and supramulecular carriers are discussed. Also their application for metal, anions, drugs and environmental compounds are investigated. Carriers have been demonstrated to be useful for the selective extraction and recovery of numerous cations and anions enhancing the extraction properties of traditional solvent extraction and ion-exchange processes. Several types of carriers have different transport mechanisms. In these mechanisms, transport configurations are addressed and emphasized and the detailed information on the type of carrier are presented along with their specific separation modes. The performance of different carriers in terms of selectivity as well as efficiency are also discussed. Finally, the application of different carriers for the extraction of various compounds are compared and reviewed. To our best knowledge no reviews have been published on carrier-mediated extraction methods.

Identification of the major metabolites of (R)-salbutamol in human urine, plasma and feces using ultra high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

(R)-Salbutamol is a selective β2-adrenoreceptor agonist, which produces a short-acting bronchodilator effect and is widely used for the treatment of respiratory diseases in humans. Drug metabolism and identification of the metabolites play an essential role in the evaluation of the overall efficacy and safety of the drugs in clinical practices. There are few reports on the identification of major metabolites of (R)-salbutamol in humans, and the number of identified metabolites is very limited. In this research, a method of ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry was developed for the discovery and identification of (R)-salbutamol and its major metabolites in human biological samples. Totally, twelve metabolites of (R)-salbutamol were found and identified and all the metabolites could be found in urine, one metabolite in plasma and two metabolites in feces. Among all the metabolites, eight metabolites have never been reported before. The results indicated that (R)-salbutamol was mainly metabolized through isomerization, oxidation, reduction, glucuronidation, and sulfation pathways in vivo. The possible metabolic pathways of (R)-salbutamol were subsequently presented in this study, which contribute to a better understanding of the metabolism of (R)-salbutamol in humans.

Hollow fibre supported liquid membrane extraction for BTEX metabolites analysis in human teeth as biomarkers

The use of human teeth as biomarkers has been previously applied to characterize environmental exposure mainly to metal contamination. Difficulties arise when the contaminants are volatile or its concentration level is very low. This study presents the development of a methodology based on the transport through hollow fibre membrane liquid-phase microextraction (HF-LPME), followed by HPLC-UV measurement, to determine three different metabolites of BTEX contaminants, mandelic acid (MA), hyppuric acid (HA), and methylhippuric acid (4mHA). The driving force for the liquid membrane has been studied by using both non-facilitated (pH gradient 2-12) and facilitated transport (ionic and non-ionic carriers). Enrichment factors of several hundreds were accomplished. Different ionic and non-ionic water insoluble compounds were used as metabolite carriers for the facilitated transport at HF-LPME. Three organic solvents were used to constitute the liquid membrane, dodecane, dihexyl ether and n-decanol. Other parameters affecting the extraction process, such as extraction time, stirring speed, acceptor buffer and salt content were optimised in spiked solutions and selected those that presented the best enrichment factors for all analytes. Final conditions were established for donor solution as 20mL, pH2 of 0.5M NaCl, the OLM (Organic Liquid Membrane) as n-decanol and the acceptor solution as 40μL of 1M NaOH. The selected extraction time was 20h with stirring speed of 500rpm. Validation of the optimised method included the determination of individual linearity range (MA: 0.002-5.7μg; HA: 0.01-7.9μg; 4mHA 0.002-5.3μg), limits of detection (MA: 1.6ng; HA: 0.2ng; 4mHA 0.2ng), repeatability (RSD 7-10%) and reproducibility (5-8%). The developed method was applied to the analysis of MA, HA and 4mHA in teeth samples of 8 workers exposed to BTEX.

Highly efficient detection of salbutamol in environmental water samples by an enzyme immunoassay

Salbutamol (SAL) has potential hazardous effects on health, and has been found in natural water globally. To protect consumers from risks related to SAL residues, a fast and highly sensitive enzyme-linked immunosorbent assay (ELISA) was developed for the detection of SAL in environmental water samples. SAL hapten was synthesized and conjugated to proteins to be used as the immunogen for producing polyclonal antibodies. Under optimized conditions, the ELISA showed a 50% inhibitory concentration (IC₅₀ value) of 0.466μg/L, with a limit of detection (LOD, IC₁₀ value) of 0.021μg/L. The LOD of the ELISA was 5-fold lower than the maximum residue limits. The average recoveries of SAL from environmental samples, including tap water, river water and wastewater, ranged from 80.1 to 115.6%, which is well within the requirements of residue detection. Moreover, the results of the ELISA correlated well with high-performance liquid chromatography results, with a correlation coefficient of 0.988. These results suggest that the proposed ELISA method has potential application for the monitoring of SAL residues in environmental water samples.

Multivariate optimization of the hollow fibre liquid phase microextraction of muscimol in human urine samples

A liquid phase microextraction based on hollow fibre followed by liquid chromatographic determination was developed for the extraction and quantitation of the hallucinogenic muscimol from urine samples. Method applicability on polar hallucinogens was also tested on two alkaloids, a psychedelic hallucinogen, tryptamine and a polar amino acid, tryptophan which exists in its charged state in the entire pH range. A multivariate design of experiments was used in which a half fractional factorial approach was applied to screen six factors (donor phase pH, acceptor phase HCl concentration, carrier composition, stirring rate, extraction time and salt content) for their extent of vitality in carrier mediated liquid microextractions. Four factors were deemed essential for the effective extraction of each analyte. The vital factors were further optimized for the extraction of single-spiked analyte solutions using a central composite design. When the simultaneous extraction of analytes was performed under universal factor conditions biased towards maximizing the enrichment of muscimol, a good composite desirability value of 0.687 was obtained. The method was finally applied on spiked urine samples with acceptable enrichments of 4.1, 19.7 and 24.1 obtained for muscimol, tryptophan and tryptamine respectively. Matrix-based calibration curves were used to address matrix effects. The r(2) values of the matrix-based linear regression prediction models ranged from 0.9933 to 0.9986. The linearity of the regression line of the matrix-based calibration curves for each analyte was directly linked to the analyte enrichment repeatability which ranged from an RSD value of 8.3-13.1%. Limits of detection for the developed method were 5.12, 3.10 and 0.21ngmL(-1) for muscimol, tryptophan and tryptamine respectively. The developed method has proven to offer a viable alternative for the quantitation of muscimol in human urine samples.

Development of a Efficient and Sensitive Dispersive Liquid-Liquid Microextraction Technique for Extraction and Preconcentration of 10 β2-Agonists in Animal Urine

Dispersive liquid–liquid microextraction (DLLME) coupled with ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) was developed for the extraction and determination of 10 β₂-agonists in animal urine. Some experimental parameters, such as the type and volume of the extraction solvent, the concentration of the dispersant, the salt concentration, the pH value of the sample solution, the extraction time and the speed of centrifugation, were investigated and optimized. Under the optimized conditions, a good enrichment factors (4.8 to 32.3) were obtained for the extraction. The enrichment factor show that the concentration rate of DLLME is significantly higher than other pretreatment methods, and the detection sensitivity has been greatly improved. The calibration curves were linear, the correlation coefficient ranged from 0.9928 to 0.9999 for the concentration range of 0.05 to 50 ngmL^-1 and 0.1 to 50 ngmL^-1, and the relative standard deviations (RSDs, n = 15, intra and inter-day precision) at a concentration of 5 ngmL^-1 were in the range of 1.8 to 14.6%. The limits of detection (LODs) for the 10 β₂-agonists, based on a signal-to-noise ratio (S/N) of 3, were in the range of 0.01 to 0.03 ngmL^-1. The proposed method was used to identify β₂-agonists in three types of animal urine (swine, cattle, sheep), and the relative recoveries from each matrix were in the range of 89.2 to 106.8%, 90.0 to 109.8% and 89.2 to 107.2%, respectively.

Hollow fibre liquid phase micro-extraction by facilitated anionic exchange for the determination of flavonoids in faba beans (Vicia faba L.)

INTRODUCTION

Flavonoids are polyphenolic compounds found ubiquitously in foods of plant origin. They are commonly extracted from plant materials with ethanol, methanol, water, their combination or even with acidified extracting solutions. The disadvantages of these methods are the use of high quantity of organic solvent, the possible loss of analytes in the different steps and the laborious process of the techniques. In addition, the complexity of the phenolic mixtures present in plant materials requires a preliminary clean-up and fractionation of the crude extracts.

OBJECTIVE

To develop a hollow fibre liquid phase micro-extraction (HF-LPME) method for a one step clean-up and pre-concentration of flavonoids.

METHODOLOGY

Two flavonoids (catechin and rutin) has been extracted by HF-LPME and analysed by HPLC. The related driving force for the liquid membrane has been studied by means of facilitated and non-facilitated transport. Different ionic and non-ionic water insoluble compounds [trioctylamine (TOA), tributyl phosphate (TBP), trioctylphosphine oxide (TOPO) and methyltrioctylammonium chloride (aliquat 336)] were used as carriers. The liquid membrane was constituted by a solution of n-decanol in the presence or absence of carriers.

RESULTS

Maximum enrichment factors were obtained with n-decanol/aliquat 336 (20%) as organic liquid membrane, sodium hydroxide (NaOH) (0.1 M) as donor solution, sodium chloride (NaCl) (2 M) as acceptor solution and 3 h as extraction time. Under these conditions, good results for validation parameters were obtained [for linearity, limit of detection (LOD), limit of quantitation (LOQ) and repeatability].

CONCLUSIONS

The developed method is simple, effective and has been successfully applied to determine catechin and rutin in ethanolic extracts of faba beans.

Improvement of the adsorption of quaternary ammonium on polypropylene affinity membrane through the control of its surface properties

Polypropylene fiber meshes were plasma-treated in order to attach new chemical functions corresponding to acidic or basic groups without altering the roughness of such thin material. An almost complete wettability of these plasma-treated materials is obtained. Because of the plasma-grafting of acid or amino moieties, such surface treatment allows increasing the adsorption rate of quaternary ammonium molecule like Aliquat 336. This increase was explained by specific interactions of ammonium head of the Aliquat 336 and hydrophilic group of plasma-treated PP, followed by the adsorption of a further layer of Aliquat 336 through hydrophobic interactions of its hydrocarbon chain. These interactions between the carrier and the polymeric surface were characterized leading to physisorption mechanism. Such new material could be applied to the extraction process since no evidence of aging was given.

Determination of salbutamol by direct chiral reversed-phase HPLC using teicoplanin as stationary phase and its application to natural water analysis

A direct chiral LC-UV method was optimized for the determination of salbutamol (SAL) β2 -agonist in environmental water. Two commercially available columns were evaluated: teicoplanin Chirobiotic-T™ (150 × 2.1 mm i.d., 5 µm) and vancomycin Chirobiotic-V™ (150 × 2.1 mm i.d., 5 µm). Finally, teicoplanin chiral stationary phase was selected for SAL enantiomer resolution. In order to preserve its integrity and maintain the column performance for longer time, the use of additives such as triethylamine (TEA) in the mobile phase was avoided. Experimental design was applied to simultaneously evaluate the influence of several parameters involved in enantiomer separation and to establish the conditions for acceptable resolution and performance in short analysis time. Optimum mobile phase was methanol-20 mM ammonium acetate buffer at pH 4.5 (98:2, v/v). A solid-phase extraction procedure for sample pre-concentration and clean-up allowed the determination of chiral SAL residues in natural water samples spiked at low concentrations in the range 1.0-20 ng mL(-1) . Reproducible recoveries, between 77 and 98%, were obtained and matrix effect was negligible. Injection of sample solutions at low elution strength permitted the SAL enantioresolution in the natural water complex matrix with satisfactory sensitivity and precision.

Occurrence of pharmaceutical compounds in wastewater process streams in Dublin, Ireland

The aim of this work is to establish baseline levels of pharmaceuticals in three wastewater treatment plant (WWTP) streams in the greater Dublin region to assess the removal efficiency of the selected WWTPs and to investigate the existence of any seasonal variability. Twenty compounds including several classes of antibiotics, acidic and basic pharmaceuticals, and prescribed medications were selected for investigation using a combination of membrane filtration, solid phase extraction (SPE) cleanup, and liquid chromatography-electrospray ionization tandem mass spectrometry. Fourteen of the selected compounds were found in the samples. Increased effluent concentrations, compared to influent concentrations, for a number of compounds (carbamazepine, clotrimazole, propranolol, nimesulide, furosemide, mefenamic acid, diclofenac, metoprolol, and gemfibrozil) were observed. The detected concentrations were generally below toxicity levels and based on current knowledge are unlikely to pose any threat to aquatic species. Mefenamic acid concentrations detected in both Leixlip and Swords effluents may potentially exert ecotoxicological effects with maximum risk quotients (i.e., ratio of predicted exposure concentration to predicted no effect concentration) of 4.04 and 1.33, respectively.

Dynamic supported liquid membrane tip extraction of glyphosate and aminomethylphosphonic acid followed by capillary electrophoresis with contactless conductivity detection

A dynamic supported liquid membrane tip extraction (SLMTE) procedure for the effective extraction and preconcentration of glyphosate (GLYP) and its metabolite aminomethylphosphonic acid (AMPA) in water has been investigated. The SLMTE procedure was performed in a semi-automated dynamic mode and demonstrated a greater performance against a static extraction. Several important extraction parameters such as donor phase pH, cationic carrier concentration, type of membrane solvent, type of acceptor stripping phase, agitation and extraction time were comprehensively optimized. A solution of Aliquat-336, a cationic carrier, in dihexyl ether was selected as the supported liquid incorporated into the membrane phase. Quantification of GLYP and AMPA was carried out using capillary electrophoresis with contactless conductivity detection. An electrolyte solution consisting of 12 mM histidine (His), 8 mM 2-(N-morpholino)ethanesulfonic acid (MES), 75 microM cetyltrimethylammonium bromide (CTAB), 3% methanol, pH 6.3, was used as running buffer. Under the optimum extraction conditions, the method showed good linearity in the range of 0.01-200 microg/L (GLYP) and 0.1-400 microg/L (AMPA), acceptable reproducibility (RSD 5-7%, n=5), low limits of detection of 0.005 microg/L for GLYP and 0.06 microg/L for AMPA, and satisfactory relative recoveries (90-94%). Due to the low cost, the SLMTE device was disposed after each run which additionally eliminated the possibility of carry-over between runs. The validated method was tested for the analysis of both analytes in spiked tap water and river water with good success.

Hollow fiber-based liquid phase microextraction combined with high-performance liquid chromatography for the analysis of gabapentin in biological samples

Three-phase hollow fiber microextraction technique combined with high performance liquid chromatography-ultra violet (HPLC-UV) was applied for the extraction and determination of gabapentin in biological fluids. Gabapentin (GBP) was derivatized with 1-fluoro-2,4-dinitrobenzene, as a UV absorbent agent in borate buffer (pH 8.2) before extraction. The derivative product of GBP was extracted from the 8.5 mL of acidic solution (source phase) into an organic phase (dihexyl ether) impregnated in the pores of a hollow fiber and finally back-extracted into 24 microL of the basic solution (pH 9.1) located inside the lumen of the hollow fiber (receiving phase). The extraction took place due to pH gradient between the inside and outside of the hollow fiber membrane. In order to achieve maximum extraction efficiency, different parameters affecting the extraction conditions were optimized. Under the optimized conditions, preconcentration factor of 95 and detection limit (LOD) of 0.2 microg L(-1) were obtained. The calibration graph was linear within the range of 0.6-5000 microg L(-1). Finally, the feasibility of the proposed method was successfully confirmed by extraction and determination of GBP in human urine and plasma samples in the range of microgram per liter and suitable results were obtained (RSDs<6.3%).

JEM spotlight: recent advances in analysis of pharmaceuticals in the aquatic environment

Both ecosystem and human health rely on clean, abundant supplies of water, thus many classes of potential pollutants are regulated. In recent years, the possible risks associated with largely uncontrolled inputs of pharmaceuticals to rivers, lakes, groundwater, and coastal waters, mainly via wastewater, have been a focus of much research. During this time, our capacity to sequester, identify, and quantify pharmaceuticals in environmental matrices has improved. Devices have emerged to allow passive uptake of drugs to augment or replace laborious grab sampling. Advances in sample preparation have streamlined extraction procedures and removed interfering matrix components. New instrumental techniques have allowed faster, more accurate and sensitive detection of drugs in water samples. This review highlights all of these advances, from sample collection to instrumental analysis, which will continue to help us better understand the fate and effects of pharmaceuticals in aquatic systems.