Preparation of an efficient magnetic nano-sorbent based on modified cellulose and carboxylated carbon nano-tubes for extraction of pesticides from food and agricultural water samples before GC-FID analysis.

This paper reports the direct synthesis approach of carboxamide functionalized magnetic nano-composite named Fe3O4@SiO2-NH2@dialdehyde cellulose (DAC)@CNT-COOH as an effectual sorbent for the co-extraction of seven agricultural insecticides and herbicides from vegetable, fruit, and water samples using the magnetic dispersive micro-solid-phase extraction procedure. Under the optimized extraction conditions (sorbent amount: 18.1 mg; desorption time: 6.5 min; desorption solvent volume: 185 µL; desorption solvent: acetonitrile; extraction time: 9.5 min; pH of sample solution: 7.0, and salt content: 5.0 % w/v sodium chloride), good linearity within the range 0.5-1200 ng/mL (R2 ≥ 0.998) was achieved. Extraction efficiencies were in the range 63.4-84.1 %, the limits of detection were 0.08-1.0 ng/mL, and acceptable relative recoveries (87.6-103.8 %), and precisions were also achieved (RSDs < 6.8 %, n = 3). Ultimately, the obtained results showed that the developed method could be applied to determine trace amounts of desired analytes in various agricultural water and food 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.

Electromembrane extraction based on agarose gel for the extraction of phenolic acids from fruit juices.

Extraction of polar acidic compounds is a challenging task in electromembrane extraction. In this study, gel-electromembrane extraction was employed for the extraction of phenolic acids as the polar acidic compounds from fruit juices. For this aim, the extraction of phenolic acids from the juice samples (4 mL, pH = 6.0) was carried out across the agarose gel membrane (concentration of agarose; 3% (w/v), pH of gel; 10.0, and thickness of membrane: 3 mm) into the acceptor solution (100 µL, pH = 12.0). Also, this extraction process was conducted by applying the optimum potential (25 V) for 15 min to the extraction system. Under the optimized condition, acceptable linearity (R2 ≥ 0.993) over a concentration range of 10.0-2500 ng mL-1 was achieved. The limits of detection were between 3.0 and 15.2 ng mL-1, while the corresponding repeatabilities ranged from 5.3 to 11.4% (n = 4). The recoveries achieved for the extraction of target compounds were ranged from 26.8 to 74.4%. The proposed method was used for the extraction of phenolic acids from orange, apple and kiwi juices, and the obtained relative recoveries in the range of 78.0-104.2% and RSDs in the range of 6.3 to 11.3% indicated successful extraction of phenolic acids.

Gel electromembrane extraction using rotating electrode: A new strategy for mass transfer enhancement of basic drugs from real human urine samples.

This study proposed a new method of EME based on agarose gel named rotating electrode gel electromembrane extraction (RE-G-EME) for extraction and determination of naloxone, naltrexone, and nalbuphine as basic drugs from real human urine samples. In this new method, a rotating electrode connected to the armature was used to agitate the acceptor phase (AP). With this new development, the extraction efficiency enhanced due to increasing analytes mass transfer from gel membrane interface toward the AP. The effective parameters on the extraction efficiency were optimized and the maximum recoveries of the analytes were obtained under the optimal extraction conditions (3.0% (w/v) agarose with pH 5.0 as gel membrane; voltage: 25 V; pH of the donor phase (DP): 6.0; pH of the AP: 4.0; stirring rate of the DP: 750 rpm; electrode rotation speed within AP: 125 rpm; extraction time: 25 min). The method offered limits of detection (LODs) and extraction recoveries in the range of 0.3-1.5 ng mL-1, and 74.3% - 87.0%, respectively. Also, the repeatability of the proposed method was measured for four repeated experiments and was in the acceptable range of 4.3% - 8.1%. To understand the influence of agitation of the AP on the extraction efficiency, a comparative study was carried out between conventional G-EME and RE-G-EME methods. The results showed that, for short the extraction times (t ≤ 10 min), extraction efficiency of G-EME was almost the same as that of RE-G-EME. However, at longer extraction times (25 min), the extraction efficiency of RE-G-EME was significantly higher than that of G-EME. Finally, the proposed method was successfully applied to determine concentrations of model drugs in real urine samples with relative recoveries of 81.1-96.1% indicating good reliability of the proposed method.

Combination of gel-electromembrane extraction with switchable hydrophilicity solvent-based homogeneous liquid-liquid microextraction followed by gas chromatography for the extraction and determination of antidepressants in human serum, breast milk and wastewater.

The current study presents for the first time a combination of the gel electromembrane extraction (GEL-EME) and switchable hydrophilicity solvent-based homogeneous liquid-liquid microextraction (SHS-HLLME) methods which can be used as an efficient hyphenated extraction procedure. This coupled method, which was followed by GC-FID, was applied for quantification of antidepressants (desipramine, clozapine, and citalopram) in biological and wastewater samples. The effective parameters of both GEL-EME and SHS-HLLME procedures were optimized. Using an agarose gel membrane, analytes were extracted from 7.0 mL of the sample solution to 500 µL of the aqueous acceptor solution. The maximum extraction of analytes of interest was obtained under the optimized conditions (pH of acceptor solution, 5.0; pH of gel membrane, 5.0; pH of sample solution, 7.0, voltage value, 30 V; and extraction time, 30 min). Then, the acceptor solution was transferred to the extraction cell and the SHS-HLLME procedure was conducted again under the optimized conditions. Dipropylamine (50 µL) was selected as an extraction solvent. The introduced technique exhibited good linearities with coefficients of determinatin (R2) higher than 0.983 and an acceptable linear range of 5.0-1000 ng/mL. Accordingly, the limit of detection was ≤ 1.0 ng/mL (S/N = 3) for all analytes, and the high enrichment factors were obtained in the range of 178.7-194.8. Moreover, the corresponding repeatability was from 4.0 to 8.7% (n = 3). The proposed method was successfully utilized to determine trace levels of the drugs in human serum, wastewater, and breast milk samples.