Functionalized carbon nanotube-polyaniline composite coating for on-line microextraction on a screw coupled with high performance liquid chromatography to determine opium alkaloids.

A novel and efficient on-line microextraction on a screw coupled with high-performance liquid chromatography with an ultraviolet-visible detector was developed to extract and determine trace quantities of five opium alkaloids. All detections of the analytes were achieved at 210 nm. The surface of the screw grooves was electrochemically coated with the carbon nanotubes-COOH/polyaniline composite. The surface characterization was assessed by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The prepared screw was inserted into a cartridge of a guard column, and then the constructed microextraction on a screw device was placed in the loop of a six-port HPLC injection valve. The parameters affecting the extraction efficiency of the analytes were optimized using the one variable-at-a-time method. The effective parameters for the extraction efficiency of the analytes, including sample volume, extraction time, sampling flow rate, desorption solvent type, ionic strength, and pH were investigated and optimized. Under optimal conditions, the detection limits were 3-10 µg L-1, and the linear dynamic ranges were 10-2000 µg L-1 with a coefficient of determination greater than 0.9940. The inter-day and intra-day (n = 3) relative standard deviations were less than 7% and 5%, respectively. The proposed method was simple and reproducible, with an acceptable relative recovery (90-108%) for determining opium alkaloids in water and urine samples.

Growth of bimetallic Ni-Co MOFs on a skeleton of electrospun PAN nanofibers and coating on a thin film for SPME of amitriptyline and nortriptyline in urine and plasma samples.

In this research, composited bimetallic organic framework-polyacrylonitrile (Ni-Co MOFs-PAN) was applied for thin-film solid phase microextraction (TF-SPME) of tricyclic antidepressant (TCA) drugs from biological samples. The separation and quantification of the analytes were accomplished by HPLC-UV. First, seeded nanofibers with organic ligands were electrospun on a sheet of foil. Then, with the uniform in-situ solvothermal growth of Ni-Co MOFs on the skeletal surface of nanofibers, the nanoparticles were successfully attached to the surfaces without effective bonds and produced a thin layer with a high flexibility, large active surface and abundant functional groups for adsorption. The characteristics of the produced nanocomposite were investigated by Fourier-transform infrared spectroscopy, field emission-scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and Brunauer-Emmett-Teller analysis. The stirring rate, pH, ionic strength, adsorption and desorption time along with type and volume of desorption solvents as influential factors on extraction efficiencies of the analytes, were optimized by one variable at a time method. Under optimized conditions, wide linear range for analytes in water and plasma matrices were obtained from 0.2 to 1000.0 µg L-1 and 1.0-1000.0 µg L-1, respectively, with R2 ≥ 0.9925. The limits of detection were in the range of 0.06-0.3 µg L-1 in different media. Good repeatability and reproducibility were attained within intra-day, inter-day and film-to-film RSDs% (n = 3) below 3.3 %, 3.9 % and 4.7 %, respectively. Since desirable relative recoveries were calculated between 91.4 % and 100.4 %. The method can be used for the successful extraction and measurement of amitriptyline and nortriptyline as its metabolite in different sampling time from urine and plasma matrices.

MXene nanosheets woven in polyacrylonitrile nanofiber yarns aligned spider web as a highly efficient sorbent for in-tube solid phase microextraction of beta-blockers from biofluids.

The use of electrospinning has received much attention in the production of nanofiber webs due to its advantages such as flexibility and simplicity. The direct electrospinning of nanofibers in an aligned or twisted form and the production of nanofiber yarns can turn nanofibers into woven fabrics, which leads to an increase in the diversity of nanofiber applications and improves their end-use possibilities. In this work, a victorious nanofiber yarn spinning system was used with the help of a rotating funnel. Yarn formation was studied using a composited polyacrylonitrile (PAN)/MXene polymer solution ejected from two oppositely charged nozzles. Finaly their application for packed-in-tube solid-phase microextraction of ß-blocker drugs from biofluids was demonstrated. The separation and quantification of analytes were performed by HPLC-UV instrument. The 3D-yarn PAN/MXene sorbent exhibited high flexibility, porosity, sorbent loading, mechanical stability, and a long lifetime. The characterization of the final nanofiber was carried out utilizing Fourier-transform infrared spectroscopy, field emission scanning electron microscope, energy-dispersive X-ray mapping, transmission electron microscope and X-ray diffraction analysis. Various parameters that affect the extraction efficiency, such as extraction time, pH, ionic strength and flow rate of sample solution, and type, volume and flow rate of eluent, were investigated and optimized. Under optimized conditions, the limits of detection were obtained in the range of 1.5-3.0 µg L-1. This method demonstrated appropriate linearity for ß-blockers in the range of 5.0-1000.0 µg L-1, with coefficients of determination greater than 0.990. The inter- and intra-assay precisions (RSDs, for n = 3) are in the range of 2.5-3.5%, and 4.5-5.2%, respectively. Finally, the validated method was put in an application for the analysis of atenolol, propranolol and betaxolol in human urine and saliva samples at different hours and acceptable relative recoveries were obtained in the range of 89.5% to 110.4%.

Microextraction of organophosphorus pesticides on a screw coated with PAN/calcined ZnMgAl-LDH electrospun nanofibers.

The present research is an attempt to expand the recently reported microextraction on screw method. For this purpose, polyacrylonitrile/calcined ZnMgAl-LDH nanofiber was fabricated by the electrospinning technique on the surface of a screw. It was applied to the extraction of organophosphorus pesticides (OPP) from agricultural samples. The separation and determination of OPPs were carried out by gas chromatography-mass spectrometry. The characterization of the fabricated nanofiber was performed utilizing Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction instruments. Effective parameters on the extraction efficiency of the analytes including sample pH, ionic strength, sample flow rate and number of cycles, type, volume, and flow rate of desorption solvent were optimized by one-variable-at-a-time method. Under optimized conditions, the limits of detection were 0.03 and 0.07 µg L-1 for diazinon and chlorpyrifos, respectively. This method showed wide linearity in the range 0.10-1000 µg L-1 for diazinon and 0.25-1000 µg L-1 for chlorpyrifos with R2 > 0.996. The intra- and inter-day precisions (RSD%, n = 3) were ≤ 6.4% and ≤ 7.7%, respectively. Also, RSD% values less than 11.1% were obtained for screw-to-screw reproducibility. The applicability of the method for the extraction and determination of the analytes in complex agricultural environments such as cabbage, potato, tomato, cucumber, and beetroot was investigated. The results led to acceptable relative recoveries in the range 81.0-108.2%.

Rapid ultrasound-assisted dispersive solid-phase extraction of nonsteroidal anti-inflammatory drugs in urine using oleic acid functionalized magnetic graphene oxide.

We describe an ultrasound-assisted magnetic dispersive solid-phase extraction based on oleic acid functionalized magnetic graphene oxide followed by high-performance liquid chromatography with ultraviolet detection. The method was applied for the simultaneous determination of ibuprofen, diclofenac, naproxen, and mefenamic acid in urine. The application of sonication led to the good dispersion of the sorbent, and consequently, significant shortened the extraction time. The sorbent was successfully characterized by different techniques. The influence of the adsorption parameters was optimized using a rotational central composite design. In order to improve desorption efficiency, parameters such as type and volume of the eluent and sonication time were investigated and optimized through a one variable at a time method. Under the optimum conditions, limits of detection and precision were between 3.0-25 ng/mL (n = 5) and 3.2-7.1%, respectively. The preconcentration factors were found to be 74 for naproxen, 76 for diclofenac, 80 for ibuprofen, and 66 for mefenamic acid corresponding to the absolute recovery within the range of 82.5-100%. Finally, the proposed method was successfully applied for simultaneous determination of target analytes in human urine samples. The relative recovery was within the range of 91.4-113.3%, indicating the good reliability and accuracy of the method.