Solid-phase Extraction Protocol Research Articles

The Determination of Polycyclic Aromatic Hydrocarbons (PAHs) with HPLC-DAD-FLD and GC-MS Techniques in the Dissolved and Particulate Phase of Road-Tunnel Wash Water: A Case Study for Cross-Array Comparisons and Applications.

Accelerated solvent extraction (ASE) and solid phase extraction (SPE) protocols tailored to either gas chromatography mass spectrometry (GC-MS) or high-performance liquid chromatography coupled to diode-array and fluorescence detection (HPLC-DAD-FLD) were developed for the determination of EPA 16 polycyclic aromatic hydrocarbons (PAHs) in the particulate and dissolved phase of road-tunnel wash water. An analytical approach was developed, assessed, and applied on environmental samples collected from five road tunnels in Norway. The absolute recoveries ranged from 57 to 104% for the particulates, and from 42 to 79% for the dissolved water phase. The target PAH compounds were separated in 34.75 min using the GC method and in 22.50 min by HPLC. In the particulate phases, higher molecular weight PAHs were detected in the range of 0.043 to 0.93 µg/g, and lower molecular weight PAHs were detected in the range of 0.020 to 1.0 µg/g, while the intermediate ones were present in the range of 0.075 to 2.0 µg/g. In contrast to the particulates, the dissolved phase mainly contained lower molecular weight PAHs in the range of 0.0098 to 0.50 µg/L. GC-MS demonstrated lower detection limits (LODs) than HPLC-DAD-FLD for 13 out of the 16 PAHs. A cross-array comparison of the two analytical techniques indicated that some target PAHs were detected solely or in higher concentrations with HPLC-DAD-FLD, indicating the occurrence of false positive peaks or/and co-eluting components. The resulting concentrations in the road tunnel wash water samples were used to calculate specific PAH forensic ratios to pinpoint the potential sources of PAH pollution. These ratios revealed that there are several potential sources for the origin of PAHs in tunnel wash water.

Back Cover: A novel sensitive analytical method for the simultaneous analysis of vancomycin and teicoplanin in human urine via single HPLC coupled with Photodiode array and Mass Spectrometry in series

DOI: 10.1002/jssc.202200002 The cover picture shows a novel analytical protocol using single HPLC coupled with photodiode array and mass spectrometry in series, for the simultaneous determination of two glycopeptides with structural similarities: vancomycin and teicoplanin in human urine. According to the cover picture, for the treatment of the urine samples, a solid phase extraction protocol was developed and optimized, making the specific analytical method more sensitive and reliable for the simultaneous determination of these glycopeptides in difficult matrices such as urine samples.

A One-Step Polyphenol Removal Approach for Detection of Multiple Phytohormones from Grape Berry

Phytohormones play an important role in regulating the maturation process and the quality-related metabolite accumulation of fruits, and their concentration variation has always been concerned during fruit development. However, berry fruits, such as grape berries, are rich in a large number of secondary metabolites, which brings great challenges to the isolation and determination of hormones. In this work, we used grapes as experimental materials and proposed a solid-phase extraction (SPE) protocol to efficiently isolate multiple hormones from phenol-rich matrix using a mixture of dichloromethane, methanol and formic acid as eluent. A highly sensitive method based on ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS) was developed to quantify a total of 11 plant growth regulators, including the recognized phytohormones, in grape pericarp and seed. The established method showed satisfactory precision (RSD < 11.3%) and linearity (R2 > 0.9980). The limits of detection (LOD) and the limit of quantification (LOQ) were 0.001–0.75 ng/mL and 0.004–2.5 ng/mL, respectively. The recovery for the three levels of analytes spiked ranged from 63% to 118%, and the matrix effect was between 73% and 119%. Finally, the proposed method was applied to investigate the dynamic hormone concentration in Vitis vinifera L. cv. Cabernet Sauvignon berries from different vineyards, and assess the changes in endogenous hormones in grapes after treatment with exogenous growth regulators. We found that the contents of IP, ABA and IAA in pericarp and IP, IAA, IBA and SA in seed were significantly down-regulated after 10 days of treatment with NAA concentrations of 10 mg/L and 40 mg/L. In conclusion, this method helps to elucidate the role played by phytohormones in the maturation process and the accumulation of quality-related metabolites in phenol-rich fruits.

Methods in food defence: a simple and robust screening for 16 rodenticides by LC-DAD/FLD following QuEChERS–based extraction

Fortunately, the intentional contamination of food or water supplies out of criminal or terroristic motivation is a rather rare event. However, in the face of asymmetric warfare and as the consequences of such an event would be severe, food defence as a necessary supplement to food safety is gaining increased attention. While some progress has been made in developing non-target detection devices, the contamination of food or water supplies using readily available rodenticides may still be revealed only by complex analytical techniques. The presented study therefore aimed to develop a quick and easy screening method for the detection of sixteen globally common rodenticides in foodstuffs. Robust operation with limited personnel and analytical resources were one benchmark to be met by the method, which uses a slightly modified QuEChERS (quick, easy, cheap, effective, rugged, safe) protocol for dispersive solid-phase extraction and subsequent ion-pair chromatography with diode-array and fluorescence detection. Quantification limits were as low as 5 µg/kg with satisfying bias (recovery) and repeatability rates of 77 to 117% and 1.8 to 17.1%, respectively. The developed method provides reliable and robust detection of these deadly poisons at toxic concentrations, which was demonstrated impressively in an improvised assault scenario.

Development of sol-gel silica-based mixed-mode zwitterionic sorbents for determining drugs in environmental water samples

Four novel mixed-mode zwitterionic silica-based functionalized with strong moieties sorbents were synthesized and evaluated through solid-phase extraction (SPE) to determine acidic and basic drugs in environmental water samples. All sorbents had the same functionalization: quaternary amine and sulfonic groups and C18 chains so that hydrophobic and strong cationic exchange (SCX) and strong anionic exchange (SAX) interactions could be exploited, in addition, two of them had carbon microparticles embedded.All sorbents retained both acidic and basic compounds in the preliminary assays but only the basic compounds were retained selectively through ionic exchange interactions when a clean-up step was introduced. The SPE method was therefore optimized to promote the selective retention of the basic compounds, initially with the two best-performing sorbents.After optimization of the SPE protocol, these sorbents were evaluated for the analysis of environmental water samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method with the best-performing sorbent was then validated with 100 mL of river samples and 50 mL of effluent wastewater samples in terms of apparent recoveries (%Rapp) spiking samples at 50 ng/L (river) and 200 ng/L (river and effluent), matrix effect, linear range, method quantification and detection limits, repeatability, and reproducibility. It should be highlighted that %Rapp ranged from 40 to 85% and matrix effects ranged from -17 to -4% for spiked river samples. When the method was applied to river and effluent wastewater samples, most compounds were found in the range from 24 to 1233 ng/L with detection limits from 1 to 5 ng/L.

Development of a Sensitive and High-Throughput Assay for Simultaneous Quantification of 5 Tyrosine Kinase Inhibitors and 2 Active Metabolites in Human Plasma Using Ultra-high Performance Liquid Chromatography Coupled to Tandem Mass Spectrometry.

Breakpoint cluster region-Abelson (BCR-ABL) tyrosine kinase inhibitors (TKIs) demonstrate improved therapeutic efficacy in chronic myeloid leukemia (CML). However, drug-drug interactions, nonadherence, and host-related factors may influence plasma concentrations. Therefore, therapeutic drug monitoring may be necessary for patients presenting inadequate treatment responses or adverse events. Herein, the authors aimed to develop a more sensitive and high-throughput method than those previously reported to simultaneously quantify 5 TKIs (imatinib, nilotinib, dasatinib, bosutinib, and ponatinib) and 2 active metabolites (N-desmethyl imatinib and N-desmethyl ponatinib) using ultra-performance liquid chromatography coupled with tandem mass spectrometry. Plasma samples were prepared according to a solid-phase extraction protocol using an Oasis MCX µElution plate. The assay fulfilled the requirements of the US Food and Drug Administration for assay validation, with a lower limit of quantification of 0.2 ng/mL for dasatinib, 0.3 ng/mL for N-desmethyl ponatinib, 0.5 ng/mL for N-desmethyl imatinib, bosutinib, and ponatinib, and 2.5 ng/mL for imatinib and nilotinib. Within-batch and batch-to-batch precision at the lower limit of quantification and quality control levels were within 14.3% and 10.9%, respectively. Within-batch and batch-to-batch accuracies ranged from 15.5% to 13.0% and 5.70% to 7.03%, respectively. A positive electrospray ionization mode was used with a run time of 6.0 minutes. The assay applicability was verified by the successful measurement of 78 clinical samples from patients undergoing CML therapy. The method allows assessment of trough concentrations of TKIs and active metabolites in patients with CML, and hence can be used to assess blood samples in routine clinical settings.

Pilot monitoring scheme of water pollutants in Important Bird and Biodiversity Areas

In this study we have established a monitoring scheme to determine the presence and distribution of widely used pharmaceuticals, pesticides, organophosphate esters (OPEs) and perfluoroalkyl substances (PFAS) in water bodies from Important Bird and Biodiversity Areas (IBAs) from Spain. The monitoring scheme included the georeferenced sampling of rocky mountain, Atlantic forest, riparian forest, Mediterranean forest, agricultural, inland aquatic and coastal aquatic IBAs, with the aim to evaluate the impact of widely used chemicals in those aquatic resources. Water samples were extracted using a generic solid-phase extraction protocol and analyzed by 3 analytical methods based on liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Quality parameters such as compound recovery, intra and inter-day variation, linearity and limits of detection were calculated in order to validate the methods. In addition, the ionization conditions and the optimization of the most appropriate transitions permitted unequivocal identification. Once the sampling and analytical procedure was set-up, 59 target compounds were monitored in 63 samples. Pharmaceutical, followed by pesticides, OPEs and PFAS were widespread along all IBAs studied at concentrations from 0.5 to 41083 ng/L. Overall, this study highlights the need to monitor the presence of contaminants in areas of high ecological interest to contribute to pollution control and mitigation towards protection of biodiversity.

Supercritical fluid chromatography time-of-flight mass spectrometry enantiomeric determination of basic drugs in sewage samples

Many pharmacologically active compounds are chiral species, and their therapeutic or toxicological effects might differ between isomers. Herein, we develop a fast and sensitive chiral analysis methodology for the determination of eight pharmaceuticals, considered as emerging environmental pollutants and belonging to two different chemical classes, in wastewater and sludge samples. Compounds were separated using supercritical fluid chromatography (SFC) combined with time-of-flight mass spectrometry (TOF-MS) detection. The stationary phase, the modifier and the additive combined with supercritical carbon dioxide (CO2), in the SFC mobile phase, played a major effect in the enantiomeric resolution of selected compounds. Moreover, the composition of the mobile phase affected their ionization efficiency in the electrospray ionization source. Methanol (MeOH), containing a 0.1% of ammonia, was used as CO2 modifier for the separation of compounds in a polysaccharide-type column. Total analysis time was 15.5 min, achieving resolution factors between 1.03 and 2.49 for the eight pairs of enantiomers. In combination with mixed-mode solid-phase extraction and matrix solid-phase dispersion protocols, compounds were determined in wastewater and sludge samples, with limits of quantification in the range of 0.010–0.020 µg L−1 and 3.7–11.1 ng g−1, for aqueous and solid samples, respectively. The amine-type drugs (tramadol, propranolol and venlafaxine) were mostly found in wastewater samples, whilst azolic antimycotics were mainly quantified in sludge. The first group of compounds showed enantiomeric fractions significantly different to those existing in the commercial counterpart pharmaceuticals.

Droplet Magnetofluidic Assay Platform for Quantitative Methylation-Specific PCR.

Early cancer detection requires identification of cellular changes resulting from oncogenesis. Abnormal DNA methylation patterns occurring early in tumor development have been widely identified as early biomarkers for multiple types of cancer tumors. Methylation-Specific PCR (MSP) has permitted highly sensitive detection of these methylation changes at known biomarker locations. MSP requires multiple sample preparation steps including protein digestion, DNA isolation, and bisulfite conversion prior to detection. In this work, we present a streamlined assay platform and instrumentation for integration of all sample processing steps required to obtain quantitative MSP signal from raw biological samples through the use of droplet magnetofluidic principles. In conjunction with this platform, we present a streamlined protocol for solid-phase DNA extraction from cells and bisulfite conversion of genomic DNA, minimizing the processing steps and reagent volume for implementation on a compact assay platform.

Hypercrosslinked polymer microspheres decorated with anion- and cation-exchange groups for the simultaneous solid-phase extraction of acidic and basic analytes from environmental waters

Mixed-mode ion-exchange sorbents were introduced to improve the selectivity and retention of solid-phase extraction (SPE) sorbents. Mixed-mode ion-exchange sorbents integrate reversed-phase chemistry with ion-exchange groups to promote favourable interactions with ionic species. Nevertheless, a need to extract analytes with acidic and basic properties simultaneously within the same SPE cartridge led to the introduction of novel amphoteric/zwitterionic sorbents, which incorporate cation- and anion-exchange moieties within the same functional group attached to the polymeric network.In the present study, the development, preparation and SPE evaluation of two novel hypercrosslinked zwitterionic polymeric sorbents, functionalised with either strong anion-exchange (SAX) and weak cation-exchange (WCX) or weak anion-exchange (WAX) and strong cation-exchange (SCX) groups (namely HXLPP-SAX/WCX and the HXLPP-WAX/SCX), is presented for the simultaneous retention of acidic and basic compounds. The sorbents were prepared by a precipitation polymerisation route which yielded poly(divinylbenzene-co-vinylbenzylchloride) as a precursor polymer; subsequently, the precursor polymer was hypercrosslinked, to increase the specific surface areas and capacities of the sorbents, and then functionalised to impart the zwitterionic character. The HXLPP-SAX/WCX sorbent was decorated with quaternised sarcosine groups and the HXLPP-WAX/SCX sorbent was decorated with taurine moieties. The SPE parameters were optimised to exploit the ionic interactions between compounds and the functional groups. The optimal conditions involve a washing step to remove the compounds retained by hydrophobic interactions, thus increasing the selectivity. The optimised SPE protocol used the quaternised sarcosine-based sorbent followed by liquid chromatography and tandem mass spectrometry, and was applied to determine compounds with acidic and basic properties from environmental samples, such as river water and effluent wastewater samples, with excellent selectivity and matrix effect values below -30% and apparent recovery results ranging from 52% to 105% for most of the compounds. The analytical method was validated for environmental water samples and used in the analysis of samples in which some of the target compounds were found at ng L−1 concentration levels.

Aptamer-functionalized metal-organic framework-coated nanofibers with multi-affinity sites for highly sensitive, selective recognition of ultra-trace microcystin-LR

A novel aptamer-functionalized metal-organic framework nanofibrous composite (viz. PAN/UiO@UiO2-N3-aptamer) with a high aptamer coverage density was proposed based on the electrospinning and seeded growth method, and used for specific affinity recognition of trace Microcystin-LR (MC-LR). Heterobifunctional ligand was used to modify the metal–organic framework nanoparticles (MOF NPs) surface, which could passivate the MOF surface with respect to unmodified DNA, followed by coupling massive aptamers on MOF of the solid-phase microextraction (SPME) fiber using click chemistry. Characterizations including morphology, spectra analysis, mechanical stability, binding capacity and specificity were fulfilled. Applied to the analysis of MC-LR, the good selective and sensitive recognition were obtained with the detection limit as low as 0.003 ng/mL, which was better than most non-specific SPME or solid-phase extraction (SPE) protocols. The stability and reproducibility were acceptable, and the intra-day, inter-day and column-to-column relative standard deviations (RSDs) for the recovery of MC-LR were gained in the range from 2.5% to 14.3%, respectively. Satisfactory recoveries of MC-LR in environmental water samples were measured as 96.3 ± 4.7% - 98.9 ± 2.7% (n = 3) in tap water, 94.4 ± 2.5% - 96.1 ± 3.5% (n = 3) in pond water, and 97.0 ± 2.1% - 97.9 ± 3.1% (n = 3) in river water, respectively. This work demonstrated that the electrospun nanofibrous composite with massive aptamers would be a better alternative for ultra-trace MC-LR detection with good selectivity, matrix-resistance ability and high resolution.

Magnetic Molecularly Imprinted Nano-Conjugates for Effective Extraction of Food Components-A Model Study of Tyramine Determination in Craft Beers.

In this paper, magnetic molecularly imprinted nano-conjugates were synthesized to serve as selective sorbents in a model study of tyramine determination in craft beer samples. The molecularly imprinted sorbent was characterized in terms of morphology, structure, and composition. The magnetic dispersive solid phase extraction protocol was developed and combined with liquid chromatography coupled with mass spectrometry to determine tyramine. Ten samples of craft beers were analyzed using a validated method, revealing tyramine concentrations in the range between 0.303 and 126.5 mg L−1. Tyramine limits of detection and quantification were 0.033 mg L−1 and 0.075 mg L−1, respectively. Therefore, the fabricated molecularly imprinted magnetic nano-conjugates with a fast magnetic responsivity and desirable adsorption performance could be an effective tool for monitoring tyramine levels in beverages.

On-line duplex molecularly imprinted solid-phase extraction for analysis of low-abundant biomarkers in human serum by liquid chromatography-tandem mass spectrometry

In the present work, a pair of molecularly imprinted polymers (MIPs) targeting distinct peptide targets were packed into trap columns and combined for automated duplex analysis of two low abundant small cell lung cancer biomarkers (neuron-specific enolase [NSE] and progastrin-releasing peptide [ProGRP]). Optimization of the on-line molecularly imprinted solid-phase extraction (MISPE) protocol ensured that the MIPs had the necessary affinity and selectivity towards their respective signature peptide targets – NLLGLIEAK (ProGRP) and ELPLYR (NSE) – in serum. Two duplex formats were evaluated: a physical mixture of the two MIPs (1:1 w/w ratio) inside a single trap column, and two separate MIP trap columns connected in series. Both duplex formats enabled the extraction of the peptides from serum. However, the trap columns in series gave superior extraction efficiency (85.8±3.8% and 49.1±6.7% for NLLGLIEAK and ELPLYR, respectively). The optimized protocol showed satisfactory intraday (RSD≤23.4 %) and interday (RSD≤14.6%) precision. Duplex analysis of NSE and ProGRP spiked into digested human serum was linear (R2≥0.98) over the disease range (0.3-30 nM). The estimated limit of detection (LOD) and limit of quantification (LOQ) were 0.11 nM and 0.37 nM, respectively, for NSE, and 0.06 nM and 0.2 nM, respectively, for ProGRP. Both biomarkers were determined at clinically relevant levels. To the best of our knowledge, the present work is the first report of an automated MIP duplex biomarker analysis. It represents a proof of concept for clinically viable duplex analysis of low abundant biomarkers present in human serum or other biofluids.

Selective Solid-Phase Extraction of Meropenem from Human Blood Plasma Using a Molecularly Imprinted Polymer

This study employed a selective and high adsorption performance for meropenem. Molecularly imprinted polymer for meropenem (MeIP) as the selective sorbent was prepared through a bulk polymerization reaction. Methacrylic acid, ethylene glycol dimethacrylate, benzoyl peroxide, and dimethyl sulfoxide were applied as functional monomer, crosslinker agent, initiator, and solvent, respectively. Scanning electron microscopy, thermogravimetric analysis, Brunauer-Emmett-Teller analysis, and Fourier transform infrared spectroscopy were used to characterize the morphology, pore size, and structure of imprinted polymers. The maximum adsorption capacity was achieved at pH = 3, after 4 h contacted, under 150 rpm, and 25 mg of polymer applied. The maximum adsorption capacity of MeIP for meropenem was 51.963 mg/L; the synthesized polymer had superior selectivity to meropenem compared to that of the other antibiotics (imprinting factor, IF = 2.58). Furthermore, the thermodynamic and kinetic analyses indicated that the results were in accord with the Freundlich model and the pseudo-second-order kinetic model, respectively. MeIP was selective in batch adsorption, and molecularly imprinted solid-phase extraction protocols were selective to meropenem. It was then applied to analyze meropenem in human blood plasma and resulted in 78.52 ± 2.71 of recovery.

Rapid Determination of Per- and Polyfluoroalkyl Substances (PFAS) in Harbour Porpoise Liver Tissue by HybridSPE®-UPLC®-MS/MS.

A rapid hybrid solid phase extraction (HybridSPE®) protocol tailored to ultra-performance liquid chromatography–electrospray ionization tandem mass spectrometry (UPLC®–ESI–MS/MS) analysis was developed for the determination of 15 per- and polyfluoroalkyl substances (PFAS) in liver tissue from harbour porpoises (Phocoena phocoena). The HybridSPE® technique has been applied in trace concentration bioanalysis, but it was mainly used for liquid biological media until now. In this study, the protocol was applied on tissue matrix, and it demonstrated acceptable absolute recoveries (%) ranging from 44.4 to 89.4%. The chromatographic separation was carried out using a gradient elution program with a total run time of 4 min. The inter-day method precision ranged from 2.15 to 15.4%, and the method limits of detection (LODs) ranged from 0.003 to 0.30 ng/g wet weight (w.w.). A total of 20 liver samples were analyzed to demonstrate the applicability of the developed method in liver tissue from a wildlife species.

Development and validation of an LC-MS/MS method to quantify the bromodomain and extra-terminal (BET) inhibitor JQ1 in mouse plasma and brain microdialysate: Application to cerebral microdialysis study

JQ1, is a cell-permeable small-molecule inhibitor of bromodomain and extra-terminal protein (BET) function with reportedly good CNS penetration, however, unbound and pharmacologically active CNS JQ1 exposures have not been characterized. Additionally, no quantitative bioanalytical methods for JQ1 have been described in the literature to support the CNS penetration studies. In the present article, we discuss the development and validation of a sensitive and reliable liquid chromatography-tandem mass spectrometry (LC–MS/MS) quantitative methods to determine JQ1 in mouse plasma and brain microdialysate. JQ1 and the internal standard, dabrafenib (ISTD), were extracted from plasma and microdialysate samples using a simple solid phase extraction protocol performed on an Oasis HLB μElution plate. Chromatographic separation of JQ1 and ISTD was achieved on a reversed phase C12 analytical column with gradient elution profile of mobile phases (MP A: water containing 0.1 % formic acid and MP B: acetonitrile containing 0.1 % formic acid) at a flow rate of 0.6 mL/min. The mass spectrometric detection was performed in the positive MRM ion mode by monitoring the transitions 457.40 > 341.30 (JQ1) and 520.40 > 307.20 (ISTD). The calibration curves demonstrated good linearities over the concentration range of 5−1000 ng/mL for the mouse plasma method (r2 ≥ 0.99) and 0.5−500 ng/mL for the microdialysate method (r2 ≥ 0.99). The experimental limit of quantification obtained was 5 and 0.5 ng/mL for the mouse plasma and microdialysate method, respectively, with the coefficient of variation less than 10 % for the analyte peak area. All the other validation parameters, including intra-and inter-day accuracy and precision, matrix effect, selectivity, carryover effect, and stability, were within the USFDA bioanalytical guidelines acceptance limits. The LC–MS/MS method was successfully applied to a mouse pharmacokinetic and cerebral microdialysis study to characterize the unbound JQ1 exposure in brain extracellular fluid and plasma.

Development and Optimisation of Solid-Phase Extraction of Extractable and Bound Phenolic Acids in Spelt (Triticum spelta L.) Seeds.

A solid-phase extraction (SPE) technique was developed and optimised for isolation and concentration of extractable and bound phenolic acids from germinated spelt seeds, for analysis by liquid chromatography–mass spectrometry. Samples initially underwent solvent extraction under different conditions to maximise the yield of phenolic antioxidants. Optimal extraction conditions for extractable phenolics were absolute methanol as solvent, sample-to-methanol ratio 1:9, and reconstitution in non-acidified water. The bound phenolics were extracted from sample pellets using hydrolysis with 2 M NaOH, acidification of the hydrolysate with formic acid, and simultaneous isolation and purification using Strata X polymeric RP tubes. Compared to liquid-liquid extraction, this direct SPE protocol has significant advantages in terms of higher extraction efficiencies of total and individual phenolics and their antioxidant activities. These data suggest that direct SPE represents a rapid and reliable method for quantitative analysis of both the extractable and the commonly overlooked bound phenolics in Triticum spelta seeds.

Ultrasensitive detection of SARS-CoV-2 RNA and antigen using single-molecule optofluidic chip.

Nucleic acids and proteins are the two most important target types used in molecular diagnostics. In many instances, simultaneous sensitive and accurate detection of both biomarkers from the same sample would be desirable, but standard detection methods are highly optimized for one type and not cross-compatible. Here, we report the simultaneous multiplexed detection of SARS-CoV-2 RNAs and antigens with single molecule sensitivity. Both analytes are isolated and labeled using a single bead-based solid-phase extraction protocol, followed by fluorescence detection on a multi-channel optofluidic waveguide chip. Direct amplification-free detection of both biomarkers from nasopharyngeal swab samples is demonstrated with single molecule detection sensitivity, opening the door for ultrasensitive dual-target analysis in infectious disease diagnosis, oncology, and other applications.

Zeolitic imidazolate framework-8 decorated with gold nanoparticles for solid-phase extraction of neonicotinoids in agricultural samples.

A composite built with aminated zeolitic imidazolate framework and gold nanoparticles (AuNPs) for solid-phase extraction (SPE) of neonicotinoids in agricultural samples is presented. The composite was prepared through the assembly of AuNPs onto the surface of metal-organic framework based on the strong interaction between the amino group and AuNP. These metallic surfaces provided additional interactions based on the affinity of amino and cyano groups present in the target compounds. The composite was characterized by scanning electron microscopy, powder X-ray diffraction, Fourier-transform infrared spectroscopy, and surface area measurements. Regarding the SPE protocol, several parameters that can influence the extraction performance were optimized, such as sample volume or composition of elution solvent, among others. After elution, the analytes were determined via HPLC with diode-array detection. Under the selected conditions, satisfactory recoveries of five pesticides (thiamethoxan, clothianidin, imidacloprid, acetamiprid, and thiacloprid) were obtained (between 80 and 110%) in real samples, whereas the limits of detection ranged from 0.019 to 0.041μgL-1 in aqueous samples and 0.3 to 0.8μgg-1 in solid samples.

Hydrophobic polymer tethered magnetic zirconium-based metal-organic framework as advance and recyclable adsorbent for microwave-assisted extraction of polycyclic aromatic hydrocarbons from environmental water samples

Hydrophobic poly (glycidyl methacrylate) tethered magnetic amino-functional zirconium metal-organic framework (UiO-66-NH2) was fabricated for the first time for rapid microwave-assisted magnetic solid-phase extraction of trace polycyclic aromatic hydrocarbons from environmental water samples. UiO-66-NH2 endowed the nanocomposite with remarkable specific surface area (175.2 m2/g) and short diffusion route, while poly (glycidyl methacrylate) provided hydrophobic interaction towards hydrophobic polycyclic aromatic hydrocarbons, both of which contributed to the satisfactory extraction performance. The successful preparation of the nanocomposite was confirmed by transmission electronic microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, N2 adsorption-desorption experiment, powder X-ray diffraction patterns, contact angle measurement and vibrating sample magnetometry. In addition, an optimized protocol for microwave-assisted magnetic solid-phase extraction was carried out, including adsorbent amount (20–160 mg), adsorption time (30–150 s), desorption time (10–80 s) and desorption solvents (methanol, acetonitrile, acetone and ethyl acetate). Under the most favorable conditions, the microwave-assisted method afforded magnetic solid-phase extraction with short extraction time (1 min), a wide linear response (1.56–200 μg/L), good linearity (R2 ≥ 97.83%), low limits of detection (0.04–4.68 μg/L) and good precision (RSD ≤ 6.39%) for six polycyclic aromatic hydrocarbons. The proposed method was successfully applied in analysis of real water samples with mean recoveries in the range of 82.6–118.4% at three spiked levels and the relative standard deviations less than 10.7%. The results indicated that our developed method had great potential in enrichment and detection of trace polycyclic aromatic hydrocarbons in real aqueous samples.