Dispersive micro-solid-phase extraction of benzodiazepines from biological fluids based on polyaniline/magnetic nanoparticles composite

Facile extraction and determination of organophosphorus pesticides using poly (8-hydroxyquinoline) functionalized magnetic multi-walled carbon nanotubes nanocomposite in water, fruits, and vegetables samples

This study presents a dispersive micro-solid phase extraction (D-μ-SPE) approach for extracting and determining of two organophosphorus pesticides (OPPs), including diazinon and chlorpyrifos as model analytes in various samples. For this purpose, we synthesized, characterized, and utilized magnetic multi-walled carbon nanotubes coated with poly 8-hydroxyquinoline (MWCNTs/Fe3O4@PHQ) as a novel sorbent. The impact of various parameters, including sorbent type, sample pH, sample volume, sorbent amount, desorption solvent (type and volume), extraction time, and ionic strength on the extraction efficiency was investigated and optimized. Following the extraction, the desorbed pesticides in acetone were analyzed using gas chromatography with an FID detector. Under the optimized experimental conditions, the proposed method showed excellent linearity in the range of 3-1000 µg/L, low detection limit (0.9-1.5 µg/L), good relative recoveries (86-101.5 %), and high precision (RSD < 6.5 %). Finally, the applicability of this method was evaluated by analyzing the target OPPs in a variety of real samples, and obtained satisfactory results.

Development of an innovative analytical method for forensic detection of cocaine, antidepressants, and metabolites in postmortem blood using magnetic nanoparticles

Cocaine and antidepressants rank high globally in substance consumption, emphasizing their impact on public health. The determination of these compounds and related substances in biological samples is crucial for forensic toxicology. This study focused on developing an innovative analytical method for the determination of cocaine, antidepressants, and their related metabolites in postmortem blood samples, using unmodified commercial Fe3O4 nanoparticles as a sorbent for dispersive magnetic solid-phase extraction (m-d-SPE), coupled with liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis. An aliquot of 100 µL of whole blood and 5 µL of the internal standard pool were added to 30 mg of nanoparticles. The nanoparticles were separated from the sample using a neodymium magnet inserted into a 3D-printed microtube rack. The liquid was then discarded, followed by desorption with 300 µL of 1/1/1 acetonitrile/methanol/ethyl acetate. The sample was vortexed and separated, and 1.5 µL of the organic supernatant was injected into the LC-MS/MS. The method was acceptably validated and successfully applied to 263 postmortem blood samples. All samples evaluated in this study were positive for at least one substance. The most frequent analyte was benzoylecgonine, followed by cocaine and cocaethylene. The most common antidepressants encountered in the analyzed samples were citalopram and fluoxetine, followed by fluoxetine's metabolite norfluoxetine. This study describes the first report of this sorbent in postmortem blood analysis, demonstrating satisfactory results for linearity, precision, accuracy, and selectivity for all compounds. The method's applicability was confirmed, establishing it as an efficient and sustainable alternative to traditional techniques for forensic casework.

Selective and fast magnetic dispersive solid phase micro-extraction of copper and lead in water and vegetables after synthesis of magnetic mesoporous carbon

Magnetic mesoporous carbon (Fe3O4@C, MMC) was synthesized and characterized. It was used for the first time as a sorbent for the magnetic dispersive solid phase microextraction (M-dSPμE) of copper and lead in water and vegetables. FAAS was used to determine the analyte concentrations after elution. The MMC was found to be have surface area of 145.9 m2 g-1 and average pore diameter of 15 nm. The analytical parameters affecting M-dSPμE of copper and lead were optimized. They were pH of sample, 6; eluent, 2 mol L-1 HCl (3 mL); and sample volume, 250 mL. The MMC reaches equilibrium very fast without vortexing for adsorption and only 5 s for elution. The LOD and PF of the M-dSPμE method for copper and lead were found to be 0.87 μg L-1 and 83 for Cu(II) and 2.8 μg L-1 and 167 for Pb(II), respectively. The precision of the M-dSPμE method was found to be ≤ 3.2%. The M-dSPμE method was verified by certificate reference materials (TMDA-53.3 Fortified Lake water and NIST SRM 1573a Tomato Leaves). It was successfully applied to the determination of copper and lead in lake water, wastewaters, sea water, radish, spinach, lettuce, and celery samples.

Quantification of sedative-hypnotics in human urine and plasma via polystyrene-based solid phase extraction-LC-MS/MS analysis

Owing to the adverse effects of the overuse of common sedative-hypnotics on human health, the development of an efficient analytical method for the detection of drugs in clinical emergencies and forensic science is significant. Although conventional analytical methods, such as immunoassay, liquid chromatography (LC), gas chromatography, and mass spectrometry (MS) are reliable, they exhibit drawbacks such low-throughput screening and high costs. Thus, in this study, we developed a novel high-throughput method consisting of a polystyrene-based solid phase extraction (SPE) and an LC with tandem MS analysis for the detection of drugs in biological samples and investigated its precision and reliability via the detection of twelve sedative-hypnotics in human urine and plasma samples. Good linear relationship (r ≥ 0.99) were achieved within the concentration range of 0.1-20 ng/mL for the 12 analytes in urine samples. Whereas, in the plasma samples, the correlation coefficient was greater than 0.99 in the concentration range 1-100 ng/mL for lorazepam and clonazepam and in the range 0.5-100 ng/mL for the remaining analytes. The intra- and inter-day precision, autosampler and freeze-thaw stabilities, and lower limit of quantitation (LLOQ) for all twelve analytes in the urine and plasma samples were favorable. Furthermore, sedative-hypnotics were detected in clinical samples obtained from the Hebei General Hospital using this method. These results indicated that the analytical method proposed in this study can be effectively applied in toxicology screening and drug abuse monitoring.The method developed in this study could be applied in clinical and forensic toxicology laboratories for sedative-hypnotic drug screening, providing support for drug abuse monitoring and clinical diagnosis.

Dispersive magnetic solid phase extraction of triazole fungicides based on polybenzidine/magnetic nanoparticles in environmental samples

A polybenzidine-modified Fe3O4@SiO2 nanocomposite was successfully synthesized through a chemical oxidation method and employed as a novel sorbent in dispersive magnetic solid phase extraction (DMSPE) for the preconcentration and determination of three triazole fungicides (TFs), namely diniconazole, tebuconazole, and triticonazole in river water, rice paddy soil, and grape samples. The synthesis method involved a polybenzidine self-assembly coating on Fe3O4@SiO2 magnetic composite. Characterization techniques such as FT-IR, XRD, FESEM, EDX, and VSM were used to confirm the correctness of the synthesized nano-sorbent. The target TFs were determined in actual samples using the synthesized nanocomposite sorbent in combination with gas chromatography-flame ionization detection (FID). Several variables were carefully optimized , including the sample pH, sorbent dosage, extraction time, ionic strength, and desorption condition (solvent type, volume, and time). Under the optimized experimental conditions, the method exhibited linearity in the concentration range 5-1000 ng mL-1 for triticonazole and 2-1000 ng mL-1 for diniconazole and tebuconazole. The limits of detection (LOD) for the three TFs were in the range 0.6-1.5 ng mL-1. The method demonstrated acceptable precision with intra-day and inter-day relative standard deviation (RSD) values of less than 6.5%. The enrichment factors ranged from 248 to 254. Finally, the method applicability was evaluated by determining TFs in river water, rice paddy soil, and grape samples with recoveries in the range 90.5-106, indicating that the matrix effect was negligible in the proposed DMSPE procedure.

Polyaniline-co-polyindole functionalized magnetic porous carbon derived from MIL-53(Fe) for separation/enrichment of nitrophenols pollutants before determination with high-performance liquid chromatography-ultraviolet detection

Herein, a novel polyaniline-co-polyindole functionalized magnetic porous carbon derived from MIL-53(Fe) was prepared and employed as an excellent nano-adsorbent to preconcentrate trace amounts of nitro-phenols in water and wastewater samples. Briefly, magnetic MIL-53(Fe) was synthesized by the addition of magnetite nanoparticles, terephthalic acid, and FeCl3 to the reaction medium. The magnetic MIL-53(Fe) was pyrolyzed under nitrogen protection to obtain a magnetic porous carbon nanocomposite, and finally, the nanomaterial was functionalized with polyaniline-co-polyindole via oxidation polymerization. The obtained nano-adsorbent was characterized via X-ray diffraction, Fourier-transform infrared spectroscopy, vibrating sample magnetometry, and transmission and scanning electron microscopies. After that, the fabricated nano-material was utilized as an excellent nano-adsorbent for the preconcentration of trace nitro-phenols (2-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol) in environmental water, and wastewater samples. The detection limits were obtained from 0.1 to 0.15 μg/L after performing the optimization process. The new method was in the range of 0.4-300 μg/L. The proposed method exhibited a good precision from 3.2% to 9.6% for within-day assay, and 5.2%-13.2% for between-day assay at three concentration levels (1, 50, and 250 μg/L). Eventually, this method was utilized to preconcentrate/determine the target analytes in three water, and wastewater samples, satisfactory (relative standard deviations, 5.4%-9.3%; relative recovery, 88%-109%).

Polyaniline and Polyaniline-Based Materials as Sorbents in Solid-Phase Extraction Techniques

Polyaniline (PANI) is one of the best known and widely studied conducting polymers with multiple applications and unique physicochemical properties. Due to its porous structure and relatively high surface area as well as the affinity toward many analytes related to the ability to establish different types of interactions, PANI has a great potential as a sorbent in sample pretreatment before instrumental analyses. This study provides an overview of the applications of polyaniline and polyaniline composites as sorbents in sample preparation techniques based on solid-phase extraction, including conventional solid-phase extraction (SPE) and its modifications, solid-phase microextraction (SPME), dispersive solid-phase extraction (dSPE), magnetic solid-phase extraction (MSPE) and stir-bar sorptive extraction (SBSE). The utility of PANI-based sorbents in chromatography was also summarized. It has been shown that polyaniline is willingly combined with other components and PANI-based materials may be formed in a variety of shapes. Polyaniline alone and PANI-based composites were successfully applied for sample preparation before determination of various analytes, both metal ions and organic compounds, in different matrices such as environmental samples, food, human plasma, urine, and blood.

A nanocomposite of silica coated magnetite nanoparticles and aniline-anthranilic acid co-polymeric nanorods with improved stability and selectivity for fluoroquinolones dispersive micro solid phase extraction

Adsorbents composed of polyaniline nanostructures or their derivatives immobilized on magnetic nanoparticles had gained increasing interest for application in dispersive micro-solid phase extraction. However, reproducible binding between polymeric PANI nanopaterials and magnetic nanomaterials are still a challenging task. Furthermore, other challenges are the enhancement of physical and chemical stability of adsorbent magnetic nanoparticles as well as improvement of polymeric PANI nanoparticles selectivity towards target analytes. This work described the reproducible preparation of a nanocomposite of aniline-anthranilic acid co-polymeric nanorods with silica coated magnetite nanoparticles by physical mixing of its basic components. The prepared nanocomposite had proven stability against chemical and atmospheric attack. The formed nanocomposite in this work had advantages regarding stability and selectivity towards fluoroquinolones as compared with analogues prepared from polyaniline polymers and/or uncoated magnetite nanoparticles. The selectivity of the formed adsorbent was further optimized for microextraction of four fluoroquinolone antibacterial agents. The application of the prepared nanocomposite was exemplified in microextraction of the studied fluoroquinolones from spiked milk samples to enable their detection down to their stated maximum residue limits.

Rapid and sensitive analysis of trace β-blockers by magnetic solid-phase extraction coupled with fourier transform ion cyclotron resonance mass spectrometry

A rapid and sensitive method for analyzing trace β-blockers in complex biological samples, which involved magnetic solid-phase extraction (MSPE) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS), was developed. Novel nanosilver-functionalized magnetic nanoparticles with an interlayer of poly(3,4-dihydroxyphenylalanine) (polyDOPA@Ag-MNPs) were synthesized and used as MSPE adsorbents to extract trace β-blockers from biological samples. After extraction, the analytes loaded on the polyDOPA@Ag-MNPs were desorbed using an organic solvent and analyzed by FTICR-MS. The method was rapid and sensitive, with a total detection procedure of less than 10 min as well as limits of detection and quantification in the ranges of 3.5–6.8 pg/mL and 11.7–22.8 pg/mL, respectively. The accuracy of the method was also desirable, with recoveries ranging from 80.9% to 91.0% following the detection of analytes in human blood samples. All the experimental results demonstrated that the developed MSPE-FTICR-MS method was suitable for the rapid and sensitive analysis of trace β-blockers in complex biological samples.

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A MSPE-FTICR-MS method was developed for the rapid and sensitive analysis of β-blockers.

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Novel magnetic nanoparticles (polyDOPA@Ag-MNPs) were synthesized.

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The polyDOPA@Ag-MNPs showed high enrichment capacity during MSPE of β-blockers.

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The loaded β-blockers were desorbed and analyzed using ESI-FTICR-MS.

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Trace β-blockers in human blood were successfully detected.

Facile Fabrication of Diatomite-Supported ZIF-8 Composite for Solid-Phase Extraction of Benzodiazepines in Urine Samples Prior to High-Performance Liquid Chromatography

A novel diatomite-supported zeolitic imidazolate framework-8 sorbent (ZIF-8@Dt-COOH) was in situ fabricated and developed for solid-phase extraction of three benzodiazepines (triazolam, midazolam and diazepam) in urine followed by high-performance liquid chromatography. ZIF-8@Dt-COOH was easily prepared by coating ZIF-8 on the surface of Dt-COOH and characterized by Fourier transform infrared spectra, X-ray powder diffractometry and scanning electron microscopy. Compared with bare Dt-COOH, the extraction efficiency of ZIF-8@Dt-COOH for the target was significantly increased from 20.1–39.0% to 100%. Main extraction parameters, including ionic strength and pH of solution, loading volume, washing solution, elution solvent and elution volume, were optimized in detail. Under optimum conditions, the developed method gave linearity of three BZDs in 2–500 ng/mL (r ≥ 0.9995). Limits of detection (S/N = 3), and limits of quantification (S/N = 10) were 0.3–0.4 ng/mL and 1.0–1.3 ng/mL, respectively. In addition, the average recoveries at three spiked levels (5, 10 and 20 ng/mL) varied from 80.0% to 98.7%, with the intra-day and inter-day precisions of 1.4–5.2% and 1.5–8.2%, respectively. The proposed method provided an effective purification performance and gave the enrichment factors of 24.0–29.6. The proposed method was successfully employed for the accurate and sensitive determination of benzodiazepines in urine.

Recent developments in sample preparation techniques combined with high-performance liquid chromatography: A critical review

This review article compares and contrasts sample preparation techniques coupled with high-performance liquid chromatography (HPLC) and describes applications developed in biomedical, forensics, and environmental/industrial hygiene in the last two decades. The proper sample preparation technique can offer valued data for a targeted application when coupled to HPLC and a suitable detector. Improvements in sample preparation techniques in the last two decades have resulted in efficient extraction, cleanup, and preconcentration in a single step, thus providing a pathway to tackle complex matrix applications. Applications such as biological therapeutics, proteomics, lipidomics, metabolomics, environmental/industrial hygiene, forensics, glycan cleanup, etc., have been significantly enhanced due to improved sample preparation techniques. This review looks at the early sample preparation techniques. Further, it describes eight sample preparation technique coupled to HPLC that has gained prominence in the last two decades. They are (1) solid-phase extraction (SPE), (2) liquid-liquid extraction (LLE), (3) gel permeation chromatography (GPC), (4) Quick Easy Cheap Effective Rugged, Safe (QuEChERS), (5) solid-phase microextraction (SPME), (6) ultrasonic-assisted solvent extraction (UASE), and (7) microwave-assisted solvent extraction (MWASE). SPE, LLE, GPC, QuEChERS, and SPME can be used offline and online with HPLC. UASE and MWASE can be used offline with HPLC but have also been combined with the online automated techniques of SPE, LLE, GPC, or QuEChERS for targeted analysis. Three application areas of biomedical, forensics, and environmental/industrial hygiene are reviewed for the eight sample preparation techniques. Three hundred and twenty references on the eight sample preparation techniques published over the last two decades (2001-2021) are provided. Other older references were included to illustrate the historical development of sample preparation techniques.

Calcium/Copper Alginate Framework Doped with CuO Nanoparticles as a Novel Adsorbent for Micro-extraction of Benzodiazepines from Human Serum

Background:

Sample preparation is one of the most challenging phases in pharmaceutical analysis, especially in biological matrices, affecting the whole analytical methodology.

Objective:

In this study, a new Ca(II)/Cu(II)/alginate/CuO Nanoparticles Hydrogel Fiber (CCACHF) was synthesized through a simple, green procedure and applied for fiber micro solid-phase extraction (FMSPE) of diazepam (DIZ) and oxazepam (OXZ) as model drugs prior to high-performance liquid chromatography-UV detection (HPLC-UV).

Methods:

Composition and morphology of the prepared fiber were characterized and the effect of main parameters on the fiber fabrication and extraction efficiency have been studied and optimized.

Results:

In optimal conditions, calibration curves were linear, ranging between 0.1–500 μg L−1 with regression coefficients of 0.9938 and 0.9968. Limit of Detection (LOD) (S/N=3) and Limit of Quantification (LOQ) (S/N=10) of the technique for DIZ and OXZ were 0.03 to 0.1 μg L−1. Within-day and between-day Relative Standard Deviations (RSDs) for DIZ and OXZ were 6.0–12.5% and 3.3–9.4%, respectively.

Conclusion:

The fabricated adsorbent has been substantially employed to the extraction of selected benzo-diazepines (BZDs) from human serum real specimens and the obtained recoveries were also satisfactory (82.1-109.7%).

Rapid determination of folic acid and riboflavin in urine by polypyrrole magnetic solid-phase extractant combined ultra-performance liquid chromatography

Determination of folic acid and riboflavin in biological samples is difficult due to their high polarity, low concentration, chemical instability, and complex matrix. In this study, the polypyrrole-coated magnetic nanocomposite (Fe₃O₄@PPy) was synthesized innovatively with the assistance of hexadecyltrimethylammonium bromide. To evaluate the adsorption mechanism and the feasibility of synthesized Fe₃O₄@PPy as an adsorbent, the adsorption capacities, kinetics and thermodynamics of folic acid and riboflavin were investigated systemically. Furthermore, in light of the chemical instability of folic acid and riboflavin a method for rapid extraction and detection of them from human urine within 10 min was developed successfully by combining magnetic solid phase extraction with ultra-performance liquid chromatography (MSPE/UPLC). The adsorption parameters including sorbent amount, pH value, extraction time, desorption solvent and desorption time were studied. Under optimum conditions, the performance of the established determination method was validated with the linearly dependent coefficients (>0.9995), the limits of detection (0.02-0.05 µg/mL), the limits of quantification (0.07-0.18 µg/mL), and the recoveries (92.2-105.1%, with relative standard deviation < 3.3%). The rapid extraction and detection of folic acid and riboflavin from real urine samples were achieved subsequently. The present study suggests that the developed method exhibits a promising application in the analysis of free folic acid and riboflavin in human urine samples, which can provide a reference for the clinical drug monitoring and treatment.

Application of Tandem Dispersive Liquid-Liquid Microextraction as an Efficient Method for Preconcentration of Two Antidepressant Drugs in Real Samples Combined with High Performance Liquid Chromatography

In the present work, tandem dispersive liquid-liquid microextraction (TDLLME) coupled with liquid chromatography was used for the determination of the two antidepressant drugs citalopram (CIT) and sertraline (SER) in complicated matrices. Indeed, the present approach was used to improve the suitability and appropriateness of the dispersive liquid-liquid microextraction (DLLME) method in complicated matrices. Firstly, 10 mL of the sample solution containing the two understudied drugs was extracted into an organic solvent (200 μL of 1,2-dichloromethane) using the DLLME method. Then the extracted analytes were back-extracted into 100 μL of an aqueous acceptor phase. The total extraction time of this method is about 6 min. To achieve the best efficiency for this method, efficient parameters like the kind and volume of the organic solvent and the effect of the ionic strength on the effectiveness of extraction were reviewed and improved. Under the optimized experimental conditions, TDLLME showed good linearity in the range of 100.0-7000.0 ng mL-1. The limits of detection were found to be 10.0 ng mL-1 for CIT and 2.0 ng mL-1 for SER. The relative standard deviation (RSD) is obtained in the range of 0.7-4.1%.

Development of extraction separation technology based on deep eutectic solvent and magnetic nanoparticles for determination of three sex hormones in milk

A rapid, reliable and eco-friendly method for the determination of three sex hormones in five kinds of milk was developed and validated by combining vortex-assisted liquid-liquid microextraction (VALLME) and magnetic solid-phase extraction (MSPE). Deep eutectic solvents (DESs) such as choline chloride/urea were considered as the extraction solvent in VALLME and multi-walled carbon nanotubes (MMWCNTs) were used as the adsorbent which could adsorb DESs on the surface. The optimum experimental conditions were as follows: amount of MMWCNTs for 10 mg, volume of acetone for 4 mL, no sodium chloride and extraction pH at 7. After the optimization of several main variables, satisfactory sensitivity levels were achieved as low as 1.0-1.3 ng mL^-1 and 2.5-4.5 ng mL^-1 for the limit of method detections and the limit of method quantitation, respectively. The recoveries of the three hormones in different milk samples were in the range of 80.1%-116.4%. Consequently, this method is suitable for monitoring the trace amount of sex hormones in milk matrices.

Modern microextraction techniques for natural products

Natural product analysis has gained wide attention in recent years, especially for herbal medicines, which contain complex ingredients and play a significant clinical role in the therapy of numerous diseases. The constituents of natural products are usually found at low concentrations, and the matrices are complex. Thus, the extraction of target compounds from natural products before analysis by analytical instruments is very significant for human health and its wide application. The commonly used traditional extraction methods are time-consuming, using large amounts of sample and organic solvents, as well as expensive and inefficient. Recently, microextraction techniques have been used for natural product extraction to overcome the disadvantages of conventional extraction methods. In this paper, the successful applications of and recent developments in microextraction techniques including solvent-based and sorbent-based microextraction methods, in natural product analysis in recent years, especially in the last 5 years, are reviewed for the first time. Their features, advantages, disadvantages, and future development trends are also discussed.

On-site sample preparation of trace aromatic amines in environmental waters with monolith-based multichannel in-tip microextraction apparatus followed by HPLC determination

A novel on-site preparation strategy for the determination of trace aromatic amines (AAs) in environmental waters was developed in the present study. To extract AAs effectively, 4-vinylbenzoic acid was copolymerized with ethylene dimethacrylate (ED)/divinylbenzene (DVB) in a pipette tip to obtain a new monolith-based adsorbent (MBA). The MBAs were employed as the extraction phases of home-made multichannel in-tip microextraction apparatus (ITMA) which was used to perform field sample preparation of AAs in different water samples followed by HPLC/DAD analysis. Due to the abundant functional groups, the prepared MBA displayed satisfying extraction performance for studied AAs. Under the optimized conditions, limits of detection varied from 2.1 to 26 ng/L with good coefficients of determination and precision. The recoveries for real water samples with different fortified concentrations were in the range of 78.1-119%, and the RSD values varied from 0.85 to 11%. In addition, the results achieved with the introduced method were well comparable to that obtained with conventional laboratory sample pretreatment process. Compared with existing approaches, the proposed method exhibits some merits such as s high throughput, good sensitivity and eco-friendliness. Most of important, the MBA/ITMA for on-site preparation avoids the storage and transportation of large volumes of waters, and guarantees the analytical accuracy of studied AAs.

CO2-effervescence assisted dispersive micro solid-phase extraction based on a magnetic layered double hydroxide modified with polyaniline and a surfactant for efficient pre-concentration of heavy metals in cosmetic samples

In this paper, a CO2-effervescence assisted dispersive micro solid-phase extraction procedure (CO2-EA-DμSPE) using a magnetic layered double hydroxide modified with polyaniline and a surfactant (Zn-Al-LDH-PA-DBSNa-Fe3O4) was applied for the pre-concentration of heavy metals (Ni2+, Pb2+, Co2+, and Cd2+). The final analysis of the analytes was carried out by atomic absorption spectroscopy. XRD, FTIR, and SEM studies were used for the characterization of the synthesized nanoadsorbent. For the maximum extraction efficiency, effective factors (including pH, nanoadsorbent dosage, and volume of the eluent) were investigated using the central composite design (CCD) method. Under the optimum conditions, the preconcentration factor was more than 20. The linear ranges for Ni2+, Pb2+, Co2+, and Cd2+ were obtained as (5-550), (7-750), (5-500), and (3-100) ng mL-1, respectively. The proposed method provided low detection limits (1.4, 2.1, 1.5, and 0.9 ng mL-1 for Ni2+, Pb2+, Co2+, and Cd2+, respectively) and suitable repeatability (relative standard deviation values (RSDs) below 6.1%, n = 6). Finally, the current method was successfully used for the extraction of heavy metals from cosmetic samples.

Smart Synthesis of Trimethyl Ethoxysilane (TMS) Functionalized Core-Shell Magnetic Nanosorbents Fe3O4@SiO2: Process Optimization and Application for Extraction of Pesticides

In the current study, a smart approach for synthesizing trimethyl ethoxysilane–decorated magnetic-core silica-nanoparticles (TMS-mcSNPs) and its effectiveness as nanosorbents have been exploited. While the magnetite core was synthesized using the modified Mössbauer method, Stöber method was employed to coat the magnetic particles. The objective of this work is to maximize the magnetic properties and to minimize both particle size (PS) and particle size distribution (PSD). Using a full factorial design (2^k-FFD), the influences of four factors on the coating process was assessed by optimizing the three responses (magnetic properties, PS, and PSD). These four factors were: (1) concentration of tetraethyl-orthosilicate (TEOS); (2) concentration of ammonia; (3) dose of magnetite (Fe₃O₄); and (4) addition mode. Magnetic properties were calculated as the attraction weight. Scanning electron microscopy (SEM) was used to determine PS, and standard deviation (±SD) was calculated to determine the PSD. Composite desirability function (D) was used to consolidate the multiple responses into a single performance characteristic. Pareto chart of standardized effects together with analysis of variance (ANOVA) at 95.0 confidence interval (CI) were used to determine statistically significant variable(s). Trimethyl ethoxysilane–functionalized mcSNPs were further applied as nanosorbents for magnetic solid phase extraction (TMS-MSPE) of organophosphorus and carbamate pesticides.

In-situ fabrication of zeolite imidazole framework@hydroxyapatite composite for dispersive solid-phase extraction of benzodiazepines and their determination with high-performance liquid chromatography-VWD detection

A novel zeolite imidazole framework@hydroxyapatite composite (ZIF-8@HAP) was constructed via in-situ growth and developed for efficient dispersive solid-phase extraction (DSPE) of three benzodiazepines from urine samples. The prepared composite was characterized by scanning electron microscopy, energy-dispersive spectrometer, Fourier-transform infrared spectrometry, X-ray diffractometry, zeta potential analyzer, and nitrogen adsorption-desorption experiment. Characterization results showed typical dodecahedron ZIF-8 crystals that were uniformly located on the surface of rod-like HAP. The combination of ZIF-8 and HAP made the surface area significantly enhanced from 4.68 to 205.44 m² g^-1. Compared with a commercial C₁₈ adsorbent, ZIF-8@HAP exhibited superior removal performance for interfering components from urine and offered better extraction properties for the analytes. The prepared ZIF-8@HAP was applied as an adsorbent in DSPE, and the main experimental parameters, including pH and ionic strength of solution, adsorbent amount, adsorption time, elution solvent, and volume, were investigated. Under optimal conditions, the adsorption for 250 ng mL^-1 of each analyte in 4 mL of urine was accomplished within 2 min using 60 mg of adsorbent. The method of ZIF-8@HAP-based DSPE followed by high-performance liquid chromatography gave enhancement factors of 13.3-15.3, linear ranges of 2.5-500 ng mL^-1, and limits of detection (S/N = 3) of 0.7-1.4 ng mL^-1. The relative recoveries at three spiked levels ranged from 88.7 - 102% with intra-day and inter-day precisions from 3.0 - 10.3% and 2.3 - 12.3%, respectively. These results indicated that the proposed strategy had promising applicability for convenient, rapid, and efficient determination of benzodiazepines in urine samples.Graphical abstract In-situ fabrication of ZIF-8@HAP composite for dispersive solid-phase extraction of benzodiazepines in urine samples.

A poly(N,N-dimethylaminoethyl methacrylate-co-ethylene glycol dimethacrylate) monolith for direct solid-phase extraction of benzodiazepines from undiluted human urine

A novel polymeric monolith using N,N-dimethylaminoethyl methacrylate as the monomer and ethylene glycol dimethacrylate as the crosslinker was successfully synthesized in a syringe and applied for direct solid-phase extraction of four benzodiazepines (bromazepam, triazolam, midazolam and diazepam) from undiluted urine samples prior to high performance liquid chromatography. The monolith was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption-desorption experiments. Moreover, extraction parameters, including loading, washing and eluting conditions were optimized. Under the optimized conditions, the proposed method obtained linear ranges of 2.0-500 ng mL^-1 with correlation coefficients (r) higher than 0.9997. The limits of detection (S/N = 3) and limits of quantification (S/N = 10) were 0.4-0.6 ng mL^-1 and 1.4-2.0 ng mL^-1, respectively. The recoveries at three spiked levels ranged from 83.7% to 103% with the intra- and inter-day precisions from 0.6-7.6% to 2.7-9.8%. The present monolith allowed direct loading of crude urine samples without any filtration or dilution step. Besides, the sorbent offered an enhancement factor of 16.7-20.6 and was stable enough for ten replicate cycles of extraction/desorption of urine samples. The developed method presented an alternative strategy for the accurate and convenient determination of benzodiazepines in urine samples.

Headspace solid-phase microextraction sampling of endogenous aldehydes in biological fluids using a magnetic metal-organic framework/polyaniline nanocomposite

Nanoporosity, crystal structure, good thermal and mechanical stability, high surface-to-volume ratio, nanoscale cavities, and uniform pore topology have made metal-organic frameworks one of the best class of sorbents for adsorption/separation purposes. In this research, a metal-organic framework/polyaniline magnetite nanocomposite was synthesized and intercalated by polyaniline by electrophoretic deposition on the surface of a thin steel wire, to prepare a solid-phase microextraction fiber. It was coupled with gas chromatography-flame ionization detection and employed for the extraction and determination of aldehydes in biological samples. The magnetic nanocomposite was characterized using scanning electron microscopy, energy dispersive X-ray analysis, and Fourier transform infrared spectroscopy. Under the optimal experimental conditions, the calibration curves were linear in the range of 0.01-1 and 0.1-1 µg/L for hexanal and heptanal, respectively. The limits of detections for hexanal and heptanal were 0.001 and 0.01 µg/L, respectively. Intrafiber repeatability for six replicate analyses of 0.2 µg/L of the analytes was over the range 3.5-7.1%. Interfiber (fiber-to-fiber) reproducibility, calculated by six replicate analyses of the same concentration using three different fibers, and was found to be 10.4-15.7%. The developed procedure was successfully utilized for the analysis of hexanal and heptanal in human plasma and urine samples.

Magnetic Particles: Their Applications from Sample Preparations to Biosensing Platforms

The growing interest in magnetic materials as a universal tool has been shown by an increasing number of scientific publications regarding magnetic materials and its various applications. Substantial progress has been recently made on the synthesis of magnetic iron oxide particles in terms of size, chemical composition, and surface chemistry. In addition, surface layers of polymers, silica, biomolecules, etc., on magnetic particles, can be modified to obtain affinity to target molecules. The developed magnetic iron oxide particles have been significantly utilized for diagnostic applications, such as sample preparations and biosensing platforms, leading to the selectivity and sensitivity against target molecules and the ease of use in the sensing systems. For the process of sample preparations, the magnetic particles do assist in target isolation from biological environments, having non-specific molecules and undesired molecules. Moreover, the magnetic particles can be easily applied for various methods of biosensing devices, such as optical, electrochemical, and magnetic phenomena-based methods, and also any methods combined with microfluidic systems. Here we review the utilization of magnetic materials in the isolation/preconcentration of various molecules and cells, and their use in various techniques for diagnostic biosensors that may greatly contribute to future innovation in point-of-care and high-throughput automation systems.

Materials for Solid-Phase Extraction of Organic Compounds

This review provides an overview of the most recent developments involving materials for solid-phase extraction applied to determine organic contaminants. It mainly concerns polymer-based sorbents that include high-capacity, as well as selective sorbents, inorganic-based sorbents that include those prepared using sol-gel technology along with structured porous materials based on inorganic species, and carbon nanomaterials, such as graphene and carbon nanotubes. Different types of magnetic nanoparticles coated with these materials are also reviewed. Such materials, together with their main morphological and chemical features, are described, as are some representative examples of their application as solid-phase extraction materials to extract organic compounds from different types of samples, including environmental water, biological fluids, and food.

Magnetic Polyamide Nanocomposites for the Microextraction of Benzophenones from Water Samples

In this article, the influence of the monomers on the extraction efficiency and the effect of the addition of surfactants during the synthesis have also been considered. The sorption capacity of the resulting nanocomposites has been evaluated, in the dispersive micro-solid phase extraction format, by determining that of six benzophenones in water using ultra performance liquid chromatography (UPLC) combined with photodiode array detection. Under the optimum conditions, the limits of detection were in the range of 0.5–4.3 ng/mL and the repeatability, expressed as the relative standard deviation (RSD), varied between 1.5% and 5.6%. The proposed method has been applied for the analysis of real water samples, providing relative recoveries in the interval of 84–105%

Magnetic halloysite nanotube/polyaniline/copper composite coupled with gas chromatography-mass spectrometry: A rapid approach for determination of nitro-phenanthrenes in water and soil samples

A fast, sensitive and reliable ultrasound-assisted magnetic dispersive solid-phase microextraction (UAMDSPME) setup was developed and evaluated for the enrichment of nitro- phenanthrenes compound in environmental samples prior to GC-MS determination. A new type of nanocomposite sorbent was made based on halloysite nanotubes (HNTs). HNTs is a type of natural material, have attracted great interest because of their large surface area and high chemical and thermal stability. The hybrid nanocomposite (magnetic HNT@PANI@Cu) was obtained by coating the magnetic HNTs by polyaniline (PANI) and afterwards decorating with metalic copper. Its morphology and surface properties were characterized using Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, energy dispersive spectroscopy and vibrating sample magnetometry. In this work several factors that may affect the extraction efficiencies such as desorption solvent type and its volume, sonication times for extraction and desorption, sorbent amount, organic modifier content, salt concentration and matrix effect were investigated in detail. Under the optimal conditions, the limit of detection (S/N = 3) was 0.25 ng L^-1 and the linearity was in the range of 0.01-100 μg L^-1. The method precision expressed as relative standard deviations (RSDs%) were 4.6-6.1% (intra-day), and 7.2-9.6% (inter-day). Finally, the presented method was successfully applied to the rapid determination of trace levels of nitro-phenanthrenes in spiked water and soil samples.