Dextrin-assisted gel electromembrane extraction of chiral drugs: Improving the extraction efficiency and investigation of enantioselectivity of extraction.

The present study investigates the use of dextrins (maltodextrin, ß-cyclodextrin, and hydroxypropyl-ß-cyclodextrin) to improve the efficiency of the agarose-based gel electromembrane extraction technique for extracting chiral basic drugs (citalopram, hydroxyzine, and cetirizine). Additionally, it examines the enantioselectivity of the extraction process for these drugs. To achieve these, dextrins were incorporated into either the sample solution, the membrane, or the acceptor solution, and then the extraction procedure was performed. Enantiomers were separated and analyzed using a capillary electrophoresis device equipped with a UV detector. The results obtained under the optimal extraction conditions (sample solution pH: 4.0, acceptor solution pH: 2.0, gel membrane pH: 3.0, agarose concentration: 3 % w/v, stirring rate: 1000 rpm, gel thickness: 4.4 mm, extraction voltage: 62.3 V, and extraction time: 32.1 min) indicated that incorporating dextrins into either the sample solution, membrane or the acceptor solution enhances extraction efficiency by 17.3-23.1 %. The most significant increase was observed when hydroxypropyl-ß-cyclodextrin was added to the acceptor solution. The findings indicated that the inclusion of hydroxypropyl-ß-cyclodextrin in the sample solution resulted in an enantioselective extraction, yielding an enantiomeric excess of 6.42-7.14 %. The proposed method showed a linear range of 5.0-2000 ng/mL for enantiomers of model drugs. The limit of detection and limit of quantification for all enantiomers were found to be < 4.5 ng/mL and <15.0 ng/mL, respectively. Intra- and inter-day RSDs (n = 4) were less than 10.8 %, and the relative errors were less than 3.2 % for all the enantiomers. Finally, the developed method was successfully applied to determine concentrations of enantiomers in a urine sample with relative recoveries of 96.8-99.2 %, indicating good reliability of the developed method.

In-tube gel electromembrane extraction: A green strategy for the extraction of narcotic drugs from biological samples.

The development of green and miniature extraction methods is always a major and controversial challenge in the field of sample preparation. In this work, in-tube gel electromembrane extraction (IT-G-EME) was developed as a miniaturized extraction device for the extraction of six narcotic drugs (codeine, oxycodone, hydrocodone, tramadol, thebaine, and noscapine) from biological samples. A transparent capillary tube (∼6 cm) was used as a microextraction unit. The middle part of the tube was filled with a narrow plug (∼3 mm) of the agarose gel (3.0% w/v) as a membrane and the other sides were filled with aqueous extractant solution (pH 2.0, 20 µL) and sample solution (pH 5.0, 200 µL). By applying electrical potential (400 V), the target drugs with positive charge were migrated from sample solution toward the extractant solution through gel membrane during short extraction time (5 min). Then, the enriched analytes in extractant solution was analyzed by HPLC-UV. Under the optimized conditions, the calibration curves were linear within the permissible range of 10.0-1500 ng/mL (r2 ≥ 0.991). Limits of detection and extraction recoveries were in the range of 3.0-4.5 ng/mL and 61.9-86.9%, respectively. On the basis of four replications, the repeatability of the method was also evaluated in terms of intra- and inter-day RSDs (%), which did not exceed from 6.6 and 7.9%, respectively in aqueous media. The figures of merit were also assessed in biological samples. Eventually, the developed method was profitably used for simultaneous determination of narcotic drugs in the real urine and plasma samples.

Analysis of methamphetamine, methadone, tramadol, and buprenorphine in biological samples by ion mobility spectrometry after electromembrane extraction in tandem with slug flow microextraction.

A novel tandem extraction method based on electromembrane extraction (EME) and slug flow microextraction (SFME) was developed for the extraction of some narcotics (methamphetamine, methadone, tramadol, and buprenorphine) from biological samples. The analytes were quantified by corona discharge-ion mobility spectrometry (CD-IMS). In this method, initially, analytes were extracted using an EME procedure (step-1). After that, the acceptor solution of the first step containing target analytes was applied in an SFME procedure (step-2) as a donor solution for further preconcentration. In the second step, analytes were extracted from an aqueous solution into an organic extractant. The optimum EME and SFME conditions were as follows: type of supported liquid membrane: 2-nitrophenyl octyl ether containing 10% v/v di-(2-ethylhexyl) phosphate, acceptor solution pH: 1.0, sample solution pH: 4.0, voltage: 248 V, extraction time: 17.5 min, tilting number of glass capillary tube: 10 times, type of the organic extractant: toluene, the concentration of NaOH solution: 400 mM. Under optimum extraction conditions, good linearity was obtained in the range of 0.50-750.0 ng/mL with coefficients of determination (r2) ≥ 0.991. The limits of detection and quantification were achieved in the range of 0.15-3.5 ng/mL and 0.50-12.0 ng/mL, respectively. The inter-day and intra-day precisions (n = 3) provided RSDs lower than 12.8% and 12.7%, respectively. Enrichment factors and extraction recoveries of the analytes were in the range of 255.7 to 505.4 and 37.6-78.3%, respectively. Comparing the EME/HPLC-UV with EME-SFME/CD-IMS showed that using the tandem extraction method improved the enrichment factors by more than 2.7 times and limits of detection and quantification by more than 15 times. Finally, this procedure was used to quantify target analytes in plasma and urine samples.

Preparation of electrospun polyacrylonitrile/ϒ-cyclodextrin metal-organic framework nanofibers for extraction of multi-classes herbicides from cereal samples before HPLC-UV analysis.

This study employed thin-film solid-phase microextraction procedure as a simple, sensitive, green, and solvent-free method for the co-extraction of multi-classes herbicides from cereal samples before HPLC-UV analysis. To provide an efficient sorbent, electrospun nanofibers of the crosslinked polyacrilonitril/ϒ-cyclodextrin-metal-organic framework (PAN/ϒ-CD-MOF) were successfully fabricated and assessed as a new thin-film adsorbent. Under the optimal conditions (desorption solvent: acetonitrile, desorption time: 5 min, sample solution pH: 7.0, salt concentration: 15% (w/w), and extraction time: 15 min), good linearity in the range of 2.5-1250.0 ng/mL (r2 ≥ 0.992) was obtained. The detection limits were 0.75-2.50 ng/mL. The extraction recoveries and relative recoveries were 64.9-75.7% and 92.9-106.1%, respectively. The method showed good precision as the relative standard deviations were ≤ 6.3%. Finally, the developed method was applied efficiently for trace analysis of the herbicides in wheat, rice, and barley samples. Generally, the proposed method provided a simple, sensitive, environmentally friendly, and relatively fast approach.

Development of electrically assisted solvent bar microextraction followed by high performance liquid chromatography for the extraction and quantification of basic drugs in biological samples.

In this study, a new extraction procedure is introduced based on electrically assisted solvent bar microextraction. In the first step, the analytes are transferred from sample solution to the hollow fiber supported organic solvent. After that, with the aid of an electrical field, the analytes migrated into the aqueous extractant. The proposed approach was used to extract the three basic drugs (including lidocaine, diltiazem, and propranolol) from the plasma and urine samples. Under the optimized condition, (the supported organic solvent: 1-octanol, stirring rate: 300 rpm, pH of sample solution: 12.0, salt concentration: 2.0% (w/v), extraction time: 15 min, aqueous extractant: (30 µL, 100 mM HCl), back-extraction time: 2 min, back-extraction voltage: 100 V), the proposed procedure presented wide linearities with coefficients of determination more than 0.992 over a concentration range of 5.0-1000 ng mL-1. The limit of detection was also determined in the range of 0.5 to 5.0 ng mL-1, repeatability (intra-day) was between 3.3 and 11.1% (n = 4), and reproducibility (inter-day) was between 4.3 and 14.6% (n = 4 days). It was indicated that the proposed approach could effectively extract the analytes from the plasma and urine samples, and the relative recoveries were between 90.2 and 105.6%, indicating the validity of this method.

Two-phase agarose gel-electromembrane extraction: Effect of organic solvent as an acceptor phase in electroendosmosis flow phenomenon.

In this study, a new mode of gel electromembrane extraction (G-EME) namely as "Two-phase G-EME", is suggested for the sensitive quantification of five basic drugs (desipramine, clomipramine, trimipramine, citalopram and clozapine) in biological samples. Compared to classical G-EME which is based on aqueous-gel-aqueous layout, herein, the aqueous acceptor phase (AP) was replaced with organic solvent. Briefly, negative electrode was immersed into the organic AP (with low conductivity) and positive electrode into the aqueous donor phase (DP). Based on our results, this simple adjustment significantly reduced electroendosmosis (EEO) flow phenomenon which is considered as the main issue in G-EME. In the workflow, target analytes were extracted from the 7.0 mL sample, across the fabricated agarose gel membrane, to the 100 µL of the AP under the optimized extraction conditions (organic solvent type: acetonitrile; pH of gel membrane: 5.0, pH of sample solution: 4.0, voltage: 45 V and extraction time: 22 min). Then, the organic AP with analytes was analyzed by gas chromatography (GC) instrument with flame-ionization detector (FID). The methodology offered limits of detection (LODs) and recoveries in the range of 1.0-1.5 ng mL-1 and 48.5-89.0 %, respectively. Finally, we note that two-phase G-EME assembly was able to extract analytes-of-interest in the convenient and safe manner from the hazardous and difficult-to-process biological specimens such as human serum and urine.