Novel materials as capillary coatings for in‐tube solid‐phase microextraction for bioanalysis

Nano-sized magnetic molecularly imprinted polymer solid-phase microextraction for highly selective recognition and enrichment of sulfamethoxazole from spiked water samples

This research, described ultrasound-assisted dispersive magnetic solid-phase microextraction, which is efficient for the enrichment and determination of sulfamethoxazole, based on magnetic molecularly imprinted polymer (USA-DMSPME-MIP). Meanwhile, the initial characterization of Fe3O4-MIP was completed by conventional methods and well-known protocols to obtain recognition and adsorbing performance at pre-specified optimum conditions. Fe3O4-MIP exhibited information regarding its selective recognition pattern towards sulfamethoxazole. The USA-DMSPME-MIP parameters were optimized by response surface methodology, and based on optimum conditions, this efficient method for the extraction and enrichment of sulfamethoxazole from spiked water samples and quantification by HPLC-UV was used. The enhanced technique indicates the limit of detection is 2 ng mL-1 for sulfamethoxazole, along with excellent linear range with coefficients of determination >0.99 and good recoveries for spiked water samples (94.2 and 98.2 %) with RSDs less than 3.5 %.

Solid-phase microextraction with MIL-53(Al)-polymer monolithic column coupled to pressurized capillary electrochromatography for determination of chlorogenic acid and ferulic acid in sugarcane samples

In this paper, a polymer monolithic column based on poly (Butyl methacrylate-co-ethylene glycol dimethacrylate) (poly (BMA-co-EDGMA)) doped with MIL-53(Al) metal-organic framework (MOF) was prepared using an in situ polymerization method. The characteristics of MIL-53(Al)-polymer monolithic column were studied through scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FT-IR), energy-dispersive spectroscopy (EDS), X-ray powder diffractometry (XRD), and nitrogen adsorption experiment. Due to its large surface area, the prepared MIL-53(Al)-polymer monolithic column has good permeability and high extraction efficiency. Using MIL-53(Al)-polymer monolithic column for solid-phase microextraction (SPME), coupled to pressurized capillary electrochromatography (pCEC), a method for the determination of trace chlorogenic acid and ferulic acid in sugarcane was established. Under optimized conditions, chlorogenic acid and ferulic acid have a good linear relationship (r ≥ 0.9965) within the concentration range of 50.0-500 µg/mL, the detection limit is 0.017 µg/mL, and the relative standard deviation (RSD) is less than 3.2%. The spike recoveries of chlorogenic acid and ferulic acid were 96.5% and 96.7%, respectively. The results indicate that the method is sensitive, practical, and convenient. It has been successfully applied to the separation and detection of trace organic phenolic compounds in sugarcane samples.

Aptamer affinity-based microextraction in-line coupled to capillary electrophoresis mass spectrometry using a porous layer/nanoparticle -modified open tubular column

An aptamer affinity based microextraction column is developed to be directly in-line coupled to capillary electrophoresis-mass spectrometry (CE-MS) for analyzing mycotoxins in food samples. Single-stranded DNA aptamers for selective recognition of aflatoxin B1 (AFB1) and ochratoxin A (OTA) targets are co-immobilized via covalent bonds on the surface of the inlet end of a capillary, which is pre-modified with three-dimensional porous layer and gold nanoparticles to enhance the specific surface area and loading capacity. The outlet of the capillary is designed as a porous tip to serve as the spray source for injection to the mass spectrometry. All the necessary processes for pretreatment and analysis of a sample are accomplished in one injection, including aptamer affinity-based microextraction, CE separation and MS detection of analytes. AFB1 and OTA are simultaneously determined in a wide linear range with sample consumption of only 1 μL and the limit-of-detection as low as 1 pg/mL. The microextraction column exhibits excellent repeatability and stability, which can be used over 45 runs within a month with CE separation efficiency and only MS intensity slightly decreased. Mycotoxins in three kinds of cereal based infant foods are accurately analyzed using the proposed method. The study provides a robust and universal approach that would have potential applications in a variety of analytical fields based on selective molecular recognition coupling to CE-MS analysis.

In-Tube Solid-Phase Microextraction Directly Coupled to Mass Spectrometric Systems: A Review

Since it was introduced in 1997, in-tube solid-phase microextraction (in-tube SPME), which uses a capillary column as extraction device, has been continuously developed as online microextraction coupled to LC systems (in-tube SPME-LC). In the last decade, new couplings have been evaluated on the basis of state-of-the-art LC instruments, including direct coupling of in-tube SPME to MS/MS systems, without chromatographic separation, for high-throughput analysis. In-tube SPME coupling to MS/MS has been possible thanks to the selectivity of capillary column coatings and MS/MS systems (SRM mode). Different types of capillary columns (wall-coated open-tubular, porous-layer open-tubular, sorbent-packed, porous monolithic rods, or fiber-packed) with selective stationary phases have been developed to increase the sorption capacity and selectivity of in-tube SPME. This review focuses on the in-tube SPME principle, extraction configurations, current advances in direct coupling to MS/MS systems, experimental parameters, coatings, and applications in different areas (food, biological, clinical, and environmental areas) over the last years.

Facile synthesis of a novel magnetic covalent organic frameworks for extraction and determination of five fungicides in Chinese herbal medicines

A novel magnetic covalent organic framework was synthesized via one step coating approach with solvothermal reaction employing 2,4,6-tris(4-aminophen-yl)-1,3,5-triazine and 2,4,6-triformylphloroglucinol as two building blocks by covalent bonding. The prepared magnetic covalent organic frameworks were properly characterized by different techniques and employed as adsorbent of magnetic solid phase extraction. An analytical method was developed for simultaneous determination of five fungicides in two Chinese herbal medicine samples via magnetic solid phase extraction coupled to UHPLC-MS/MS analysis. Under optimized magnetic solid phase extraction conditions, the method exhibited satisfactory recoveries (74.0-109.6%) with the relative standard deviations of 0.4-4.6%, low limits of detection (0.003-0.015 μg kg^-1 ), and good linearity (R² > 0.9960). Compared with the traditional extraction method, the proposed method required a lower amount of adsorbent (3 mg) and extraction time (5 min). The adsorbent also had favourable reusability (not less than 8 times). Therefore, the magnetic covalent organic frameworks could be a promising adsorbent for the extraction and quantitation of pesticide residues in Chinese herbal medicines. This article is protected by copyright. All rights reserved.

Salting-out homogeneous liquid-liquid microextraction for the determination of azole drugs in human urine: Validation using total error concept

A salting-out homogeneous liquid-liquid microextraction was proposed for the quantification of four azole drugs in human urine prior to high-performance liquid chromatography analysis. The procedure involved the mixing of the sample with acetonitrile in appropriate volumes followed by the addition of sodium sulfate solution in order to facilitate phase separation. The parameters influencing the extraction performance were studied and optimized using a two-step experimental design. The analytical procedure was thoroughly validated using the accuracy profiles as a graphical decision-making tool. The β-expectation tolerance intervals did not exceed the acceptance criteria of ±15% meaning that 95% of future results will be included in the defined bias limits. The limits of detection of the procedure were satisfactory, ranging between 0.01 and 0.03 μg/mL. The mean analytical bias in the spiking levels was satisfactory and ranged between -10.3 and 4.2% while the relative standard deviation was lower than 5.6%. Monte-Carlo simulations followed by capability analysis were employed to investigate the ruggedness of the sample preparation protocol. The developed method offers advantages compared to previously reported approaches for the same type of analysis including extraction efficiency and scaling down of the sample volume and extraction time.

Molecularly imprinted polypyrrole@CuO nanocomposite as an in-tube solid-phase microextraction coating for selective extraction of carbamazepine from biological samples

A nanocomposite of molecularly imprinted polypyrrole on copper oxide (MIP@CuO) was introduced as a new coating for in-tube solid-phase microextraction (IT-SPME). The method coupled with HPLC-UV was successfully applied for analysis of carbamazepine (anticonvulsant and bipolar disorder medication) in biological samples. First, in order to increase the surface area and stability of the coating, copper oxide (CuO) nanosheets were synthesized on the inner surface of a copper tube using a chemical method. Then, molecularly imprinted polypyrrole coating (using carbamazepine as a template) was deposited on CuO by a facile in-situ electrodeposition method. According to the results, The MIP@CuO coating shows long life time, enhanced extraction efficiency, and good clean-up, for pre-concentration and determination of carbamazepine in biological samples. The synthesized adsorbent also showed high selectivity to carbamazepine compared to other drugs with similar structure. Important factors affecting the extraction efficiency of the analyte in the in-tube SPME method, such as salt concentration, extraction and desorption times, flowrates of the sample solution, and eluent, were optimized. Under optimal conditions, the method showed good linearity for carbamazepine in the range of 0.05-500 μg L^-1, 0.10-500 μg L^-1, and 0.10-500 μg L^-1 in water, urine, and plasma samples, respectively, with coefficients of determination better than 0.996. The limits of detection were in the range of 0.01-0.05 μg L^-1 in different matrices. The intra- and inter-assay precisions (RSD%, n = 3) were in the range of 6.7-8.1 % and 7.1-9.5 %, respectively.

Application of HKUST-1 metal-organic framework as coating for headspace solid-phase microextraction of some addictive drugs

In the present study, a copper-based metal-organic framework (HKUST-1) was used first time for preconcentration trace amounts of addictive drugs in biological samples. HKUST-1 was synthesized and coated onto the surface of stainless steel wire. The prepared coating was used in headspace solid-phase microextraction method coupled with gas chromatography-mass spectrometry for preconcentration and determination of some addictive drugs in biological fluids. Prepared coating shows good extraction efficiency due to large surface area, and π-π stacking interaction with selected analytes. Under optimum conditions, the method was validated with a reasonable determination coefficient (R²  > 0.9961) and suitable linear dynamic range (0.5-1000 μg L^-1 ). Also, the limits of detections were obtained in the range of 0.1-0.4, 0.2-0.6, and 0.4-0.7 μg L^-1 for water, urine, and plasma samples, respectively. The limits of quantification of present method were obtained in the range 0.5-1.3, 0.7-1.5, and 1.0-1.9 μg L^-1 in water, urine, and plasma samples, respectively. The intra-day and inter-dye single fiber and fiber to fiber relative standard deviations were observed in the range 3.0-13.9% and 3.5-12.3%, respectively. Finally, the present method was applied for the determination of the drugs in biological samples.