Graphene as Solid-Phase Extraction Adsorbent for CZE Determination of Sulfonamide Residues in Meat Samples

Determination of sulfonamide antibiotics by magnetic porous carbon solid-phase extraction coupled with capillary electrophoresis

Sulfonamide antibiotics (SAs) have been widely used as antibacterial drugs for the prevention and treatment of livestock and poultry diseases, but they seriously threaten human health because they can accumulate in humans. Therefore, it is highly important to develop methods for monitoring sulfonamide residues in aquaculture and food. In this research, based on the generation of porous carbon (PC) by the pyrolysis of sodium citrate, magnetic porous carbon (PC@Fe3O4) was synthesized by a solvothermal method and used as an adsorbent for the magnetic solid-phase extraction of SAs. The effects of the proportion of PC in PC@Fe3O4, adsorbent dosage, adsorption time, eluent type, extraction pH, salt concentration and eluent dosage on the extraction efficiency were systematically studied. The adsorption performance and behavior of PC@Fe3O4 on SAs were evaluated using adsorption kinetics and adsorption isotherms, and the adsorption mechanism was preliminarily discussed. Under optimal conditions, combined with capillary electrophoresis diode array detection, a sensitive detection method for SAs was developed. The proposed method can be used for the determination of six SAs in fishpond water and milk samples, with a linear range of 0.5-200 ng mL-1, detection limits of 0.24-0.34 ng mL-1, and spiked recoveries of 85.9-109.0 %.

Sacrificial template synthesis of hollow sulfonate group functionalized microporous organic network for efficient solid phase extraction of sulfonamide antibiotics from milk and honey samples

The highly conjugated and hydrophobic characteristics of microporous organic networks (MONs) have largely impeded their broad applications in sample pretreatment especially for the polar or ionic analytes. In this work, a novel uniform hollow shaped sulfonate group functionalized MON (H-MON-SO3H-2) was synthesized via the sacrificial template method for the efficient solid phase extraction (SPE) of sulfonamides (SAs) from environmental water, milk, and honey samples prior to HPLC analysis. H-MON-SO3H-2 exhibited large specific surface area, penetrable space, good stability, and numerous hydrogen bonding, electrostatic, hydrophobic and π-π interaction sites, allowing sensitive SPE of SAs with wide linear range (0.150-1000 μg L-1), low limit of detection (0.045-0.188 μg L-1), good precisions (intra-day and inter-day RSD < 7.3%, n = 5), large enrichment factors (95.7-98.5), high adsorption capacities (250.4-545.0 mg g-1), and satisfactory reusability (more than 80 times). Moreover, the established method was successfully applied to extract SAs from spiked samples with the recoveries of 86.1-104.3%. This work demonstrated the great potential of H-MON-SO3H-2 in the efficient SPE of trace SAs in complex environmental water and food samples and revealed the prospect of hollow MONs in sample pretreatment.

Exploration of porous imine-based covalent organic framework for solid-phase extraction of five trace sulfonamides in food samples

In this article, a highly crystalline porous imine-based covalent organic framework was synthesized at room temperature and used as solid-phase extraction (SPE) adsorbent for the purification and enrichment of trace sulfonamides (SAs) from food samples. The structure of the obtained material was characterized and studied in detail. The extraction process was optimized and the final elution was determined by the ultra-high-performance liquid chromatography-quadrupole time of flight mass spectrometry method. Low limits of detection (0.02-0.19 μg/kg) were obtained under optimal conditions, with the recoveries ranging from 70.5% to 105.3% when spiked at different levels. The adsorption process of the material for SAs was fitted by the Langmuir and Freundlich adsorption isotherm model, and the extraction capacity for Nitrofuran metabolites from food samples was also investigated for comparison. The results demonstrated that the framework was a good candidate SPE adsorbent that can be used for the enrichment of drug residues in complex matrix, and the work may provide a systematic study method for the development of porous adsorbents.

Determination of sulfonamides in meat by monolithic covalent organic frameworks based solid phase extraction coupled with high-performance liquid chromatography-mass spectrometric

In this work, hierarchical porous covalent organic frameworks (HP-COFs) foam, named as HP-TpBD, was prepared by using 1,3,5-trimethylphloroglucinol (Tp) and benzidine (BD) as building blocks under the assistant of NaCl template. Its potential application as the sorbent for solid phase extraction (SPE) of sulfonamides (SAs) in meat products were explored by coupling with high performance liquid chromatography-mass spectrum (HPLC-MS) analysis. The key factors affecting extraction efficiency were well studied. Under the optimum conditions, the proposed method exhibited high preconcentration factors of 100, low limit of detection (0.10-0.23 μg/kg), and wide linear ranges (0.5-200 μg/kg). In addition, the determination of SAs in real samples were realized with satisfactory recoveries (82.8-119.9%), demonstrating the applicability of the proposed method. The easy operation, superior extraction affinity and good recycle performance demonstrated the resulting HP-COF foam is a promising adsorbent for the preconcentration of trace organic compounds from complex matrix.

The fabrication of a covalent triazine-based organic framework for the solid-phase extraction of fourteen kinds of sulfonamides from meat samples

A novel covalent triazine-based organic framework (CTF), SCAU-2, was fabricated and used as an adsorbent for the solid-phase extraction of fourteen kinds of sulfonamides (SAs) from meat. Another CTF, SCAU-1, was adopted as a comparison material, as it has a similar motif. A series of structural characterization steps was carried out on the synthesized materials and several parameters were investigated during the extraction process, including the amount of adsorbent, the dilution ratio, the pH of the sample, and the washing and elution solvents. After detection with UHPLC-Q/TOF-MS/MS, the results revealed that SCAU-2 showed high extraction efficiencies towards the selected SAs. The LOD values are from 0.05 to 0.54 ng g-1, and the recoveries are from 84.1% to 91.9%, with RSDs ranging from 3.2% to 4.8% for SCAU-2 when spiked at 50 ng g-1. The results demonstrated that the proposed method has good applicability for the determination of SAs in complicated samples.

Determination of sulfonamides in milk by capillary electrophoresis with PEG@MoS2 as a dispersive solid-phase extraction sorbent

A synthetic polyethylene glycol-molybdenum disulfide (PEG@MoS₂) composite was prepared using a simple method, and the application of this material in dispersive solid-phase extraction (DSPE) was investigated for the enrichment of eight sulfonamides (SAs) in milk samples. The composite was characterized by energy dispersive spectroscopy, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and Brunauer-Emmett-Teller measurements. The results showed that the MoS₂ synthesized in the presence of PEG has the advantage of a larger surface area and that the adsorption effect of this MoS₂ was enhanced. After extraction, the eight SAs were separated by capillary zone electrophoresis with a good linear relationship (R² > 0.9902) in the range of 0.3-30 µg ml^-1 and good precision (between 0.32% and 9.83%). Additionally, good recoveries (between 60.52% and 110.91%) were obtained for the SAs in the milk samples. The developed PEG@MoS₂-based DSPE method could be applied for the enrichment of SAs in real milk samples.

Graphene-Derivatized Silica Composite as Solid-Phase Extraction Sorbent Combined with GC-MS/MS for the Determination of Polycyclic Musks in Aqueous Samples

Polycyclic musks (PCMs) have recently received growing attention as emerging contaminants because of their bioaccumulation and potential ecotoxicological effects. Herein, an effective method for the determination of five PCMs in aqueous samples is presented. Reduced graphene oxide-derivatized silica (rGO@silica) particles were prepared from graphene oxide and aminosilica microparticles and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. PCMs were preconcentrated using rGO@silica as the solid-phase extraction sorbent and quantified by gas chromatography–tandem mass spectrometry. Several experimental parameters, such as eluent, elution volume, sorbent amount, pH, and sample volume were optimized. The correlation coefficient (R) ranged from 0.9958 to 0.9992, while the limits of detection and quantitation for the five PCMs were 0.3–0.8 ng/L and 1.1–2.1 ng/L, respectively. Satisfactory recoveries were obtained for tap water (86.6–105.9%) and river water samples (82.9–107.1%), with relative standard deviations <10% under optimal conditions. The developed method was applied to analyze PCMs in tap and river water samples from Beijing, China. Galaxolide (HHCB) and tonalide (AHTN) were the main PCM components detected in one river water sample at concentrations of 18.7 for HHCB, and 11.7 ng/L for AHTN.

Nanomaterials for sample pretreatment prior to capillary electrophoretic analysis

Nanomaterials are, in analytical science, used for a broad range of purposes, covering the area of sample pretreatment as well as separation, detection and identification of target molecules.

Analysis of antibiotics by CE and their use as chiral selectors: An update

The widespread use of antibiotics in medicine and as growth-promoting agents has increased the demand for suitable analytical techniques for their analysis. Analytical methods based on CE or miniaturized CE systems have proved over the years their ability for the analysis of antibiotics. Since our last review (Electrophoresis 2014, 35, 28-49) several new CE methodologies have been reported for antibiotic analysis. This review presents an update of the literature published from June 2013 to June 2015 for the analysis of antibiotics by CE. UV continues being the most used detection system for antibiotics analysis by CE. Strategies to improve sensitivity as the use of sensitive detection systems and the application of preconcentration techniques appear to be the major developments. Furthermore, the use of portable and miniaturized devices for antibiotic analysis is presented in detail. Applications of the developed methodologies to the determination of residues of antibiotics in biological, food, and environmental samples are carefully described. Finally, new developments and applications of antibiotics as chiral selectors in CE are also included.

Graphene-Based Materials as Solid Phase Extraction Sorbent for Trace Metal Ions, Organic Compounds, and Biological Sample Preparation

Graphene is a new carbon-based material that is of interest in separation science. Graphene has extraordinary properties including nano size, high surface area, thermal and chemical stability, and excellent adsorption affinity to pollutants. Its adsorption mechanisms are through non-covalent interactions (π-π stacking, electrostatic interactions, and H-bonding) for organic compounds and covalent interactions for metal ions. These properties have led to graphene-based material becoming a desirable adsorbent in a popular sample preparation technique known as solid phase extraction (SPE). Numerous studies have been published on graphene applications in recent years, but few review papers have focused on its applications in analytical chemistry. This article focuses on recent preconcentration of trace elements, organic compounds, and biological species using SPE-based graphene, graphene oxide, and their modified forms. Solid phase microextraction and micro SPE (µSPE) methods based on graphene are discussed.

Recent advances in sample preparation techniques and methods of sulfonamides detection - A review

Sulfonamides (SAs) have been the most widely used antimicrobial drugs for more than 70 years, and their residues in foodstuffs and environmental samples pose serious health hazards. For this reason, sensitive and specific methods for the quantification of these compounds in numerous matrices have been developed. This review intends to provide an updated overview of the recent trends over the past five years in sample preparation techniques and methods for detecting SAs. Examples of the sample preparation techniques, including liquid-liquid and solid-phase extraction, dispersive liquid-liquid microextraction and QuEChERS, are given. Different methods of detecting the SAs present in food and feed and in environmental, pharmaceutical and biological samples are discussed.

Graphene-based materials: fabrication and application for adsorption in analytical chemistry

Graphene, a single layer of carbon atoms densely packed into a honeycomb crystal lattice with unique electronic, chemical, and mechanical properties, is the 2D allotrope of carbon. Owing to the remarkable properties, graphene and graphene-based materials are likely to find potential applications as a sorbent in analytical chemistry. The current review focuses predominantly on the recent development of graphene-based materials and demonstrates their enhanced performance in adsorption of organic compounds, metal ions, and solid phase extraction as well as in separation science since mostly 2012.