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Online Third-Order Liquid Chromatographic Data with Native and Photoinduced Fluorescence Detection for the Quantitation of Organic Pollutants in Environmental Water
摘要： Third-order liquid chromatographic data were generated online for the simultaneous quantitation of six organic environmental pollutants. The employed strategy consists in reducing the linear flow rate at the column outlet. A postcolumn UV reactor and a fluorimetric detector allowed to properly record both photoinduced and native excitation?emission fluorescence matrices (EEPIFMs and EEFMs, respectively). The obtained third-order liquid chromatography data were chemometrically processed with the multivariate curve resolution?alternating least-squares model. The sensitivity of the overall analytical method was enhanced by a very simple solid-phase extraction with C18 membranes, to be able to successfully apply it to natural water samples tested as real matrices. Favorable detection limits for the investigated pollutants, ranging from 0.02 to 0.27 ng mL?1, were attained, with relative prediction errors between 2 and 7%. Since the studied samples contain uncalibrated interferents, the applied strategy achieves the second-order advantage. Implications regarding the potential achievement of the third-order advantage are discussed.
关键词： multivariate curve resolution?alternating least-squares,solid-phase extraction,second-order advantage,third-order advantage,third-order liquid chromatographic data,photoinduced fluorescence detection,organic environmental pollutants
更新于2025-09-23 15:21:21
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Metal-Ion Displacement Approach for Optical Recognition of Thorium: Application of a Molybdenum(VI) Complex for Nanomolar Determination and Enrichment of Th(IV)
摘要： An azine-based molybdenum (Mo(VI)) complex (M1) is exploited for selective detection of thorium (Th(IV)) ions through a metal-ion displacement protocol. Th(IV) displaces Mo(VI) from M1 instantly leading to the formation of the Th(IV) complex, having orange-red emission. Consequently, a red shift of the emission wavelength along with 41-fold ?uorescence enhancement is observed. This unique method allows detection of Th(IV) as low as 1.5 × 10?9 M. The displacement of Mo(VI) from M1 by Th(IV) is established by spectroscopic studies and kinetically followed by the stopped-?ow technique. The displacement binding constant for Th(IV) is notably strong, 4.59 × 106 M?1. Extraction of Th(IV) from aqueous solution to the ethyl acetate medium using M1 has been achieved. The silica-immobilized M1 e?ciently enriches Th(IV) from its reservoir through solid-phase extraction. Computational studies (density functional theory) support experimental ?ndings.
关键词： Solid-phase extraction,Molybdenum(VI) complex,Fluorescence enhancement,Thorium detection,Metal-ion displacement
更新于2025-09-23 15:21:01
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Rapid detection of sulfamethoxazole in plasma and food samples with in-syringe membrane SPE coupled with solid-phase fluorescence spectrometry
摘要： In this work, in-syringe membrane solid-phase extraction (MSPE) device was fabricated for the on-site sampling of sulfamethoxazole (SMX) in food samples followed by solid-phase fluorescence spectra analysis. The samples and fluorescamine (FA) were added to a syringe for derivation. Then, the derivative of SMX was extracted by a membrane in the syringe SPE device. Subsequently, the derivative on the membrane was measured immediately without additional elution procedure. The method was successfully applied in plasma, milk, and egg samples for the trace SMX detection, with the recovery of 98 % to 102 %, RSDs from 1 % to 6 %. Compared with liquid chromatography, direct detection of the concentrated analyte significantly improved the sensitivity. Moreover, fluorescamine made it unnecessary to separate SMX from the interference. Consequently, it was a time-saving, low-cost, and easy-operation method, which demonstrated the potential of in-syringe SPE as a promising candidate for on-site analysis.
关键词： Sulfamethoxazole,Food samples,In-syringe solid-phase extraction,Solid-phase fluorescence,Fluorescamine
更新于2025-09-23 15:19:57
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Rapid screening of rhodamine B in food by hydrogel solid-phase extraction coupled with direct fluorescence detection
摘要： Rhodamine B (RhB), which is vividly colored, although illegal and potentially carcinogenic, has been reported widely as present in various foods, including chili powder, preserved plums, sausage and sweets, presenting a significant health risk. In this work, solid-phase extraction (SPE), coupled with direct fluorescence detection on the same extraction medium, is proposed for rapid onsite screening for RhB in food without sample pretreatment. Parameters that affected extraction of RhB were explored. The lowest amount of RhB, detected on glass, was 2 ng and the lowest detectable concentration in food samples was 0.5 mg/kg, as verified by HPLC. The analysis time was less than 5 min, including sampling. In addition, the recovery rate of this method was found to be triple of that from the cotton gauze reported in literature. The proposed method has promise as a rapid, onsite screening protocol for food safety.
关键词： Solid-phase extraction,Fluorescence,Food safety screening,PVA hydrogel,Rhodamine B
更新于2025-09-23 15:19:57
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Cost effective synthesis of p-type Zn-doped MgAgSb by planetary ball-milling with enhanced thermoelectric properties
摘要： A melamine-based porous organic polymer (mPMF) was synthesized as solid phase extraction (SPE) adsorbent for inline SPE-high performance liquid chromatography (HPLC)-ultraviolet detector (UV) analysis of five phytohormones. Melamine contributed to the rich π-electron and N-containing triazine structure for mPMF, which could form π-π interaction and intermolecular hydrogen bond with -COOH containing phytohormones. The synthesized mPMF adsorbent shows extremely high extraction efficiency for five target analytes (>80%) including salicylic acid, indole-3-acetic acid, abscisic acid, 2,4-dichlorophenoxyacetic acid and 1-naphthalene acetic acid. The factors affecting extraction of the target phytohormones were investigated and the optimized experimental conditions were established. The linear range was 0.2–100 μg/L for five target phytohormones. The developed method of mPMF-inline-SPE-HPLC-UV was applied for the analysis of trace target phytohormones in tomato and grape juice samples, and the recovery in the range of 83.1–116% and 87.2–121% was obtained for the spiked tomato and grape juice, respectively. This method has the advantages of high sensitivity and good reproducibility, and it has good application potential for the analysis of phytohormones in fruit samples. Moreover, inline analysis avoided the problems of sample pollution and sample loss, and provided a sample throughput of 5/h.
关键词： Phytohormones,Porous organic polymer,Fruit juice,Inline solid phase extraction,High performance liquid chromatography
更新于2025-09-19 17:15:36
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Optically-Controlled Closable Microvalves for Polymeric Centrifugal Microfluidic Devices
摘要： Microvalving is a pivotal component in many microfluidic lab-on-a-chip platforms and micro-total analysis systems (μTAS). Effective valving is essential for the integration of multiple unit operations, such as, liquid transport, mixing, aliquoting, metering, washing, and fractionation. The ideal microfluidic system integrates numerous, sequential unit operations, provides precise spaciotemporal reagent release and flow control, and is amenable to rapid, low-cost fabrication and prototyping. Centrifugal microfluidics is an attractive approach that minimizes the need for supporting peripheral hardware. However, many of the microfluidic valving methods described in the literature suffer from operational limitations and fail when high rotational frequencies or pressure heads are required early in the analytical process. Current approaches to valve closure add unnecessary complexity to the microfluidic architecture, require the incorporation of additional materials such as wax, and entail extra fabrication steps or processes. Herein we report the characterization and optimization of a laser-actuated, closable valve method for polymeric microfluidic devices that ameliorates these shortcomings. Under typical operational conditions (rcf ≤ 605 *g) a success rate >99% was observed, i.e. successful valve closures remained leak free through 605 *g. Implementation of the laser-actuated closable valving system is demonstrated on an automated, centrifugally driven dynamic solid phase extraction (dSPE) device. Compatibility of this laser-actuated valve closure approach with commercially available polymerase chain reaction (PCR) assays is established by the generation of full 18-plex STR profiles from DNA purified via on-disc dSPE. This novel approach promises to simplify microscale valving, improve functionality by increasing the number of integrated unit operations, and allow for the automation of progressively complex biochemical assays.
关键词： PCR,laser-actuated valve,microvalving,dynamic solid phase extraction,polymeric microfluidic devices,centrifugal microfluidics
更新于2025-09-19 17:13:59
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Electrochemiluminescence solid-state imprinted sensor based on graphene/CdTe@ZnS quantum dots as luminescent probes for low-cost ultrasensing of diethylstilbestrol
摘要： A novel molecularly imprinted electrochemiluminescence (MIP-ECL) sensor was fabricated for diethylstilbestrol (DES), which exploited the strategy of specific identification by molecularly imprinted polymers (MIPs) instead of expensive biomolecules. Core-shell quantum-dots (QDs) of CdTe@ZnS were utilized to enhance ECL emission. The sensor was assembled as a solid-state electrode by immobilizing CdTe@ZnS/reduced-graphene oxide (r-GO) composite on a glassy carbon electrode (GCE) surface, and then being covered with MIPs film with specific cavities. The fabricated sensor (denoted as MIP/CdTe@ZnS/r-GO/GCE) was based on the obstruction of ECL signals by DES molecules enriched on MIP film. The ECL intensity of the QDs-K2S2O8 system was reduced when the DES molecules were selectively rebound onto the MIP film by molecularly imprinted solid phase extraction (MISPE). Accordingly, the logarithm of the quenched ECL intensity versus the logarithm of the DES concentration was in a good linear relationship over a wide range from 1.8×10?3 to 25.0 nmol/L with the limit of detection (LOD) of 0.25 pmol/L (S/N = 3). The sensor also exhibits excellent selectivity with fast response and good accuracy. Lake water and milk samples were assayed by this sensor, and the recoveries ranging from 92.2% to 108.3% were obtained.
关键词： Solid-state electrode,Molecularly imprinted film,Diethylstilbestrol,CdTe@ZnS quantum-dots,Electrochemiluminescence sensor,Solid phase extraction
更新于2025-09-12 10:27:22
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Anion exchange polymeric sorbent coupled to high‐performance liquid chromatography with <scp>UV</scp> diode array detection for the determination of ten <i>N</i> ‐nitrosamines in meat products: a validated approach
摘要： Among mechanisms and molecules presumably involved in the carcinogenicity induced by meat consumption, the N-nitrosamines (N-NAs) are a class of compounds characteristic of processed meats. In this work, an analytical method for the determination of 10 N-Nitrosamines (N-Nitrosomorpholine, N-Nitriosomethyethylamine, N-Nitrosopyrrolidine, N-Nitrosodiethylamine, N-Nitrosopiperidine, N-Nitrosodipropylamine, N-Nitrosomethylaniline, N-Nitrosodibutylamine, N-Nitrosodiphenylamine, N-Nitrosodibenzylamine) in fresh meats and meat products was developed, optimized and validated. The method is based on optimized sample purification by solid phase extraction (anion exchange polymeric sorbent) and separation/detection by high performance liquid chromatography coupled to UV diode array detection. The validation procedure allowed to ascertaining good analytical performances in terms of sensitivity, selectivity towards interfering compounds, accuracy and robustness. The values obtained for precision (range: 4.3% - 14.4%) and recovery percentages (range: 80.8% - 95.1%) were compared to reference values indicated in the Decision No. 657/2002/EC, resulting as compliant. The measurement uncertainty (lower than 14.6%) was satisfactory for each N-NA as well.
关键词： meat,food safety,solid phase extraction,validation,diode array detection,Nitrosamines,processed meats,HPLC,carcinogenic compounds,anion exchange sorbent
更新于2025-09-11 14:15:04