Recovery Values Research Articles

Resin bound gold nanocomposites assisted SE/ATR-FTIR spectroscopy for detection of pymetrozine insecticide in vegetable samples

The goal of this work was to assess the competence of organic hydrophobic resin bound gold nanocomposites (OH/R-AuNCs) for detection of pymetrozine insecticide from vegetable samples employing surface-enhanced/attenuated total reflectance-Fourier transform infrared (SE/ATR-FTIR) spectroscopy. The adsorption isotherm models, including the Langmuir, Freundlich and Temkin, are tested to reveal the interactive behaviour between the OH/R-AuNCs and pesticide. The adsorption occurs principally by London–Van der Waals dispersion interactions and hydrogen bonding interactions between the surface of OH/R-AuNCs materials and the hydrophobic part of pesticide molecule. The characteristic absorption band obtained at 3019.94 cm−1 was utilized for the quantitative analysis of pymetrozine insecticide in vegetable samples. The method was found to be accurate and precise, with mean recovery values in the range of 94.5–110 %, correlation coefficient of 0.992 %, and detection limit of 2.65 μg mL−1. The adsorption efficiency of the designed OH/R-AuNCs significantly influences the SE/ATR-FTIR response of the pymetrozine around 90 %. The optimized and validated method was applied to determine the residual concentrations of the pymetrozine that had been applied to vegetable samples.

Enhanced electrochemical performance of 3D-printed electrodes via blue-laser irradiation and (electro)chemical treatment

Extrusion-based 3D printing technologies, especially fused filament fabrication (FFF) using conductive filaments, have significantly advanced in electroanalytical applications by enabling the fabrication of electrochemical sensors. Nonetheless, 3D-printed electrodes produced from commercially available conductive filaments (e.g., polylactic acid containing carbon black - CB/PLA) often contain a low amount of conductive material (∼20 % wt. carbon black), requiring surface activation protocols to enhance their electrochemical performance. In this study, we investigated the combination of blue-laser (BL) irradiation and (electro)chemical treatment (EC) to improve the performance of 3D-printed electrodes. For this purpose, 3D-printed CB/PLA electrodes were subject to blue laser activation (laser power = 280 mW and scan rate = 30 mm s-1) followed by an electrochemical procedure in 0.5 mol L-1 NaOH solution (application of +1.4 V and – 1.0 V both for 200 s). After the combined treatment, a considerable improvement in the voltammetric profile response (Ipa/Ipc = 1.00 and ΔEp = 136 mV) was achieved using 1 mmol L-1 [Fe(CN)6]3-/4- (equimolar concentration) as the redox probe when compared to polished electrodes (Ipa/Ipc = 0.85 and ΔEp = 690 mV). Scanning electron microscopy, infrared spectroscopy data and X-ray photoelectron spectroscopy showed that the combined treatment promotes the remotion of insulating PLA material, exposing more conductive sites and functional groups. Moreover, electrochemical impedance spectroscopy results showed low resistance to charge transfer and capacitance double-layer measurements revealed an increase in the electroactive area after surface activation. As proof of concept, emerging contaminants such as hydroxychloroquine (HCQ) and paracetamol (PRT) were determined in tap water and pharmaceutical samples using treated 3D-printed CB/PLA electrodes and square-wave voltammetry. Linear ranges of 0.20 - 12.30 µmol L-1 and 1.0–30.0 µmol L-1 with limit of detection values of 0.01 and 0.2 µmol L-1 were obtained for HCQ and PRT, respectively. Appropriate recovery values (90 - 111 %) for the analysis of spiked samples were achieved.

Development of a Multiplexed Sphingolipids Method for Diagnosis of Inborn Errors of Ceramide Metabolism.

Sphingolipids play a crucial role in cellular functions and are essential components of cell membranes, signaling molecules, and lipid metabolism. In particular, ceramide is a key intermediate in sphingolipid metabolism and defects in ceramide metabolism can lead to various inborn errors of metabolism, making ceramides important targets for clinical screening and diagnosis. Detecting altered concentration patterns of sphingolipids is desirable for distinguishing related inborn errors of metabolism for diagnosis and treatment monitoring. We developed a liquid chromatography-tandem mass spectrometry method with a pathway-oriented approach to focus on sphingolipids involved in ceramide metabolism. A total of 47 sphingolipids bearing different head groups and side chains were targeted. Precision/reproducibility, linearity, and spike recovery extraction efficiency tests were performed on plasma and serum samples from confirmed cases of sphingolipidosis. Linearity of the method showed the coefficient of determination (r2) for all standards to be >0.99 with a slope of 1.00 ± 0.01. Intra- and interday reproducibility of standards spiked into plasma and serum revealed a coefficient of variation <20%. Spike and recovery assessment showed recovery values of 80%-120% for all standards. Altered levels of sphingolipids from patients with hereditary sensory and autonomic neuropathy caused by pathogenic variants in SPTLC2 and hypomyelinating leukodystrophy related to variants in DEGS1 were detected, in agreement with trends reported in earlier studies confirming the utility of this pathway-centric method. This method can serve as a useful tool to simultaneously monitor sphingolipids, enabling screening and diagnosis of inborn errors of ceramide metabolism.

A vortex-assisted MSPD method for the extraction of Polycyclic Aromatic Hydrocarbons from shrimp with determination by GC-MS/MS

Polycyclic Aromatic Hydrocarbons (PAHs) are organic compounds with two or more condensed aromatic rings, formed from incomplete organic matter combustion. PAHs pose potential health risks due to their carcinogenic and mutagenic properties, accumulating in edible tissues of aquatic organisms, such as shrimp, which is extensively produced in the southern region of Rio Grande do Sul state (Brazil) and it is the most consumed seafood globally. Therefore, this study aimed to optimize and validate an analytical method for extracting 16 priority PAHs from shrimp samples using Vortex-Assisted Matrix Solid-Phase Dispersion (VA-MSPD) with determination by Gas Chromatography Tandem Mass Spectrometry (GC-MS/MS). The optimized method, which uses a reused solid support, was validated according to INMETRO and SANTE guidelines. PAHs demonstrated adequate linearity with correlation coefficients > 0.99. The matrix effect was assessed, and 12 out of the 16 PAHs showed a matrix effect of less than ±20%. The method's quantification limits ranged from 6.67 to 33.35 ng g-1. Accuracy and precision showed recovery values ranging from 55 to 115% with relative standard deviation (RSD) lower than 17% for all PAHs. In the applicability, 11 PAHs were detected, such as benzo[a]pyrene and benzo[b]fluoranthene, and the ∑PAHs ranged from 25.14 to 79.52 ng g-1, confirming the environmental contamination in the region and the need for monitoring these contaminants in shrimp destined for human consumption.

Effect of Sourdough-Yeast Co-Fermentation on Physicochemical Properties of Corn Fagao Batter.

Fagao is one of China's traditional gluten-free staple foods made with rice or corn flour. Corn Fagao prepared by co-fermentation with sourdough and yeast exhibits better quality and less staling compared to traditional yeast-fermented Fagao. The physicochemical properties of corn Fagao batter during sourdough-yeast co-fermentation were investigated. The results showed that compared with yeast fermentation, the gas production and viscosity of the batter increased with co-fermentation. The co-fermented batter showed a higher hydrolysis of starch and less amylose content. The integrity of starch granules in the co-fermented batter was damaged more seriously, and the crystallinity and short-range ordered structure were less than in the yeast-fermented batter, even though the crystal structure type of starch did not obviously change. The peak viscosity, minimum viscosity, final viscosity, decay value, and recovery value of the corn batter were reduced by co-fermentation, which improved the thermal stability of the batter and slowed down the aging. Co-fermentation also resulted in a more pronounced reduction in protein subunit content than yeast fermentation. The changes in the physicochemical properties of the corn Fagao batter help explain the improvement in quality of corn Fagao made from the co-fermentation method and may provide theoretical references for co-fermentation with sourdough and yeast to other gluten-free foods.

An insight into the utilization of high-sulfur green Saudi Arabian petcoke as an ecofriendly sorbent for enhanced simultaneous sequestration of heavy metal ions from industrial wastewaters

Developing effective and green sorbents for the sequestration of water pollutants has increased attention to safe and sustainable water generation. This study aimed to discover a new utilization and the ability of green, high-sulfur Saudi Arabian petcoke (SA-PET) for heavy metal ion uptake. The organic sulfur content and aromatic properties of SA-PET allowed for rapid and improved performance against various metal ions via strong complex formation reactions and cation-π interactions. Also, the effects of different analytical factors were carefully studied and optimized. At pH 6–7, the maximum recovery values of PbII, CuII, CdII, ZnII, MnII, NiII and CoII metal ions were 21.09–95.76%. The experimental results demonstrate single-layer adsorption at the binding sites on the petcoke’s surface, and they are in good agreement with the Langmuir model in explaining the adsorption process, which is driven by electrostatic interactions between the petcoke surface and the studied metal ions. The pseudo-second-order kinetics model fits the adsorption data for all the target metal ions well. Furthermore, the outstanding SA-PET's stability allowed for efficient extractions over the course of 10 successive runs with negligible loss in the metal recovery percentage. With extraction recoveries up to 96.6% and a relative standard deviation less than 5%, SA-PET's efficiency in removing the target metal ions from different industrial wastewater samples gives it excellent promise as a novel green sorbent for detoxifying heavy metals from aquatic life. In conclusions, our findings, SA-PET emerged as a viable substitute for traditional synthetic adsorbents of heavy metals, in keeping with the growing trend toward green adsorbents for more sustainable development.

Functionalized N95 Face Mask with a Chemical-Free Paper-Based Collector for Exhaled Breath Analysis: SARS-CoV-2 Detection with a Printed Immunosensor as a Case Study.

Exhaled breath electrochemical sensing is a promising biomedical technology owing to its portability, painlessness, cost-effectiveness, and user-friendliness. Here, we present a novel approach for target analysis in exhaled breath by integrating a comfortable paper-based collector into an N95 face mask, providing a universal solution for analyzing several biomarkers. As a model analyte, we detected SARS-CoV-2 spike protein from the exhaled breath by sampling the target analyte into the collector, followed by its detection out of the N95 face mask using a magnetic bead-based electrochemical immunosensor. This approach was designed to avoid any contact between humans and the chemicals. To simulate human exhaled breath, untreated saliva samples were nebulized on the paper collector, revealing a detection limit of 1 ng/mL and a wide linear range of 3.7-10,000 ng/mL. Additionally, the developed immunosensor exhibited high selectivity toward the SARS-CoV-2 spike protein, compared to other airborne microorganisms, and the SARS-CoV-2 nucleocapsid protein. Accuracy assessments were conducted by analyzing the simulated breath samples spiked with varying concentrations of SARS-CoV-2 spike protein, resulting in satisfactory recovery values (ranging from 97 ± 4 to 118 ± 1%). Finally, the paper-based hybrid immunosensor was successfully applied for the detection of SARS-CoV-2 in real human exhaled breath samples. The position of the collector in the N95 mask was evaluated as well as the ability of this paper-based analytical tool to identify the positive patient.

High-performance solid-phase microextraction based on a nanocomposite sorbent of MOF/COF hybrid for ultra-trace analysis of trifluralin in food samples using the ion mobility spectrometer

Two well-known porous hybrid materials, a metal-organic framework (MOF) based on manganese and a melamine-rich covalent organic framework (COF) were combined, resulting in a highly effective nanocomposite sorbent of Mn-terephthalic acid (TA) /COF. After investigating the properties of the synthesized adsorbent, it was finally used as a new fiber for solid-phase microextraction. The method, named high-performance solid-phase microextraction (HPSPME), was utilized for the extraction and ultra-trace analysis of trifluralin in agricultural waters, fruit, and vegetable samples by using corona discharge ionization-ion mobility spectrometer (CD-IMS). To increase the extraction efficiency, experimental parameters including, temperature and time of extraction and desorption, solution pH, and stirring rate were optimized. Considering the optimized conditions, the enrichment factor of 2002, the limit of detection (LOD) 0.08 ng mL−1 (S/N=3), and linear dynamic range (LDR) 0.25–10.00 ng mL−1 with a coefficient of determination (R2=0.9987) were obtained. Relative standard deviations (RSDs, n = 3) of <9.7, <3.5, and <8.9 % were obtained, respectively, for reproducibility of the prepared fibers, intra- and inter-day. The relative recovery values for the real samples were 84–124 %. The proposed method’s accuracy for the sample impregnated with trifluralin was also evaluated by the EPA standard method.

Total arsenic and arsenic species in selected seafoods: Analysis using high-performance liquid chromatography- inductively coupled plasma mass spectrometry and health risk assessment

The objective of the present study was to determine the inorganic and organic arsenic species and assess the actual risk of selected seafood produced in Sri Lanka in terms of inorganic arsenic species. A total of 80 samples, comprising 75 seafood samples and 5 freshwater samples, including mollusks, echinoderms, and crustaceans, were analyzed for their total arsenic (TA) levels and arsenic species. TA levels in seafood were determined using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) after microwave digestion. Arsenic species, including arsenobetaine (AsB), arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA), were selectively separated and quantified using High-Performance Liquid Chromatography (HPLC) coupled to ICP-MS, following water bath extraction with 30 mmol/L nitric acid. The TA levels in seafood ranged from 0.036 to 11.686 mg kg-1. The spike recovery values for the five arsenic species lay within 80 % to 120 %, and the chromatographic recovery percentages ranged from 85.5 % to 123.6 %. In most samples, 100 % AsB was detected. Sea cucumber and both marine and freshwater giant river prawns showed AsB percentages of the total arsenicals at 83.2 %, 39.7 %, and 21.3 %, respectively. DMA was found in sea cucumber and marine giant river prawn at levels of 0.065 mg kg-1 and 0.048 mg kg-1, respectively, while MMA was not detected in any samples. AsIII was found in marine water giant river prawn and freshwater giant river prawn at levels of 0.010 mg kg-1 and 0.044 mg kg-1, respectively. AsV was only found in marine giant river prawn at a concentration of 0.193 mg kg-1. No other samples contained detectable levels of inorganic arsenicals. The Target Hazard Quotient (THQ) values for marine and freshwater giant river prawn were 0.90 and 0.2, respectively, indicating no significant health risks since the THQ values were <1. Therefore, our study suggests that consuming the studied seafood does not pose any health risks in terms of arsenic.

Enhancing fiber-reinforced asphalt binders via graphene oxide grafting: A novel interfacial modulation strategy

This study reports a novel interfacial enhancement strategy for fiber-reinforced asphalt binders. The graphene oxide (GO) nanosheets were used and grafted onto polyester (PET) and polyacrylonitrile (PAN) fibers in order to enhance the performance of modified asphalt binders. Prior to this, ultraviolet ozone (UVO) treatment was primarily adopted for activating the inert surface of fibers. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Scanning electron microscope (SEM) confirmed that GO-modified fibers were successfully prepared via surface modification. For the rheological properties determined by dynamic shear rheometer (DSR), the asphalt binders with GO-modified fibers exhibit improved high-temperature rutting resistance, better creep and recovery characteristics and increased anti-fatigue properties. Remarkably, it demonstrates that the recovery (R) value of GO-PAN modified asphalt binder is increased by 21.9 %, and the non-recoverable compliance (Jnr) value of GO-PET modified asphalt binder has been reduced by 31.9 % compared to that reinforced with the unmodified fiber in multiple stress creep recovery (MSCR) tests. These enhancements are mainly attributed to the increased roughness and modulus of the GO-grafted fibers, which promote effective stress transfer at the fiber-asphalt interfaces. Results from the atomic force microscope (AFM) indicate that the Young’s modulus of GO-PET and GO-PAN is 94.2 % and 260.0 % higher than that of PET and PAN, respectively. This research not only provides a simple and cost-effective method for improving the rheological performance, but also elucidates the enhancement mechanism of interfacial behavior in fiber-reinforced asphalt binders.

Selective Chromo-Fluorogenic Chemoprobe for nM Al3+ Recognition: Experimental and Living-Cell Applications.

A rhodamine based chemoprobe BESN was engineered and employed as a selective ''OFF-ON'' chromo-fluorogenic sensor for Al3+ in H2O:MeOH (1:9, v:v). Notable changes in the absorption and emission spectra of BESN were clearly detectable upon the addition of Al3+. Sensitivity and binding mechanism studies demonstrated a good sensing performance of BESN with nanomolar detection limit (130nM), and it was found to be highly selective towards interfering metal ions. Besides, the binding constant between BESN and Al3+ was found to be 3.19 × 103M-1. Then, the validation study of BESN for Al3+ was performed based on significant analytical parameters and statistical tests. The binding of Al3+ with BESN (1:1) was probed via infrared, high-resolution mass and emission (Job's plot) spectroscopy measurements. The sensing performance of BESN could make it ideal chemosensor for real applications including vegetable, tuna fish and water samples, also for Smartphone and test-kit applications. The recovery values of the BESN to Al3+ were estimated within a range from 95.13% to 105.30% for water, 94.63% to 109.62% for tuna fish and 94.80% to 109.80% for vegetable samples. Additionally, the BESN has very low cytotoxicity and was triumphantly utilized for the recognition of Al3+ in living-cells.

Determination and contamination status of mercury and other heavy metals in artisanal and small-scale gold mining at Banyumas region, Central Java, Indonesia, using ICP-OES

ABSTRACT The determination of mercury and other heavy metals (As, Cd, Cr, Ni, and Pb) has been carried out as toxic metals for the human body. Sample preparation was carried out by the microwave digested assist. The determination of heavy metals was carried out using the ICP-OES. The validation parameters used were linearity, Limit of Detection (LoD), Limit of Quantitation (LoQ), precision, and accuracy. Mercury, Arsen, Cadmium, Chromium, Nickel, and Lead average content in sediment gold ore processing waste was 1617.64, 5525.09, 20.24, 484.96, 259.67, and 1210.27 μg/kg, respectively. Linearity used a standard solution of 10–1000 μg/kg, and it produced a regression equation with r2 > 0.9992. The Limit of Detection (LoD) and the Limit of Quantitation (LoQ) was below 1.56 μg/kg and 6.27 μg/kg, respectively. The precision was calculated by the repeatability method, with a result of %RSD below 2.30%. Accuracy was obtained by recovering a spiked standard. The recovery value was found to be between 83% and 118%. Geoaccumulation Index (Igeo), Metal Pollution Index (MPI), Degree of Contamination (Cdeg), and Potential Ecological Risk Index (PERI) in this study was −8.62–1.43, 0.02–5.33, 8.80, and 168.59, respectively. The waste processing site at Artisanal and Small-Scale Gold Mining is generally contaminated by mercury and other heavy metals. All the validation parameters of the method are in the acceptability range, so the method can be used as a routine method for determining mercury and other heavy metals (As, Cd, Cr, Ni, and Pb) levels in gold ore processing waste.

Novel Discrete and Imprinted Fluoride-Selective Sensors: Bridging the Gap from DMSO to Aqueous Samples.

Fluoride in drinking water has beneficial or harmful health effects depending on its concentration. This highlights the need for new low-cost and portable sensors capable of in situ monitoring of F- ions. Unfortunately, achieving high levels of water compatibility and fluoride specificity remains a challenge. Here, four new urea-based discrete sensors are prepared and characterized. The sensors containing anthracenyl- (5) and 9H-fluorenyl- (7) signaling units exhibit intense luminescent emissions in dimethyl sulfoxide, the former being particularly sensitive and selective to fluoride. In water, 5 displays a superior sensitivity (871M-1) and a detection limit (8µm) below international guidelines, albeit with cross-sensitivity to H2PO4‾. To enhance the performance, 5 and 7 are embedded into a fluoride-imprinted polymeric matrix to give solid-state sensors (5P and 7P, respectively). 5P shows good sensitivity (360M-1) and specificity in water. Besides, it has a low detection limit (35µm) and a response linear range (118-6300µm) encompassing the limit established by the Environmental Protection Agency (211µm). Furthermore, 5P also displays good reusability and adequate recovery values in real-sample testing (102±2%), constituting the first example of a low-cost anion-imprinted polymeric probe tailored for the selective sensing of fluoride in aqueous samples.

Dispersive liquid–liquid microextraction based on solidification of floating organic droplet and spectrophotometric determination of Allura red using green deep eutectic solvent as disperser solvent: Green profile assessment

In this study, dispersive liquid–liquid microextraction based on the solidification of a floating organic drop (DLLME-SFO) was investigated for allura red (AR) preconcentration from water and food samples using green deep eutectic solvent (DES) as a disperser solvent. Compared to the conventional disperser solvents, the DES, which consists of choline chloride and citric acid (1:1), exhibited a higher AR recovery with simple preparation, being eco-friendly and low expense. The proposed protocol showed relatively high recovery values of AR in real samples (97.0–99.5 %). The optimum conditions for AR extraction were pH=3.0, 250.0 µl DES volume, CTAB (4.0 × 10−4 mol L−1), KCl (0.10 mol L−1), 100 µl of 1-dodecanol, and centrifugation: 4.0 min. at 4000 rpm. The validated method showed linearity from 100 to 5000 µg L−1 with 14.4 enrichment factor for 10.0 mL sample. The limit of detection was 29.9 µg L−1 and the relative standard deviation was 3.7 % for five replicate analysis of 300.0 µg L−1. The AR content in studied food samples was determined by spectrophotometry and high-performance liquid chromatography (HPLC). Our proposed method is simple and fast, as the whole process for AR extraction requires only 9.0 min. The analytical eco-scale AGREEnness calculator (AGREE), the blue applicability grade index (BAGI), and the ChlorTox scale were evaluated.

Effect of flow patterns on recovery of invertases from Saccharomyces cerevisiae using polyethylene glycol/magnesium sulfate system in microchannels

The use of microdevices in extraction processes in aqueous two-phase systems (ATPS) has been studied for years in the literature. However, the effects of flow patterns still need to be adequately explored, especially for real samples. In this sense, the present study investigated the performance of microdevices in the recovery and partial purification of invertases with varying flow patterns. The invertases from Saccharomyces cerevisiae and the polyethylene glycol 1500/magnesium sulfate system were used in the experiments. Beyond the flow pattern, the study sought to maximize recovery and purification factor (PF) values by varying other operating conditions, including residence time, volumetric ratio, and channel diameter. It was observed that the short slug and long slug patterns showed better separation performance than the parallel pattern regardless of residence time and volumetric ratio. Increasing the residence time from 15 to 35 min increased the top recovery and PF values by two times, indicating that S. cerevisiae invertase partition is slow to the top phase. The maximum values of recovery (57.01 % ± 2.67 %) and PF (4.16 ± 0.06) were reached in the condition with long slug pattern, 35 min of operation, volumetric ratio of 2:1, and a channel diameter of 0.51 mm. The present study provides valuable information for integrating microdevices in a protocol for purifying invertase from S. cerevisiae and other proteins in real systems.

Amperometric sensor based on carbon nanotube, ionic liquid, and polyaspartic acid for ascorbic acid determination

AbstractAn amperometric sensor for ascorbic acid determination has been developed by modifying the surface of a glassy carbon electrode (GCE) with polyaspartic acid (PolyAsp), carboxylated multi‐walled carbon nanotube (c‐MWCNT), and ionic liquid (IL, 1‐butyl‐3‐methylimidazolium hexafluorophosphate). The amount of each modification material on the surface was optimized in order to achieve good analytical performance. The operating conditions of c‐MWCNT−IL/PolyAsp/GCE were optimized. The performance characteristics of c‐MWCNT−IL/PolyAsp/GCE were investigated at optimum pH (8.0) and optimum potential (+0.20 V), and the sensor responded linearly to ascorbic acid between 5.3–2766.3 μM with a sensitivity of 19.64 μA mM−1 and detection limit of 3.0 μM. Determination of ascorbic acid in vitamin C tablet, vitamin C injection solution, and orange juice was successfully performed with the presented sensor and the recovery values were found between 98.9% and 101.6%.

Lab-made automated parallel-dispersive pipette extraction device for the determination of polycyclic aromatic hydrocarbons in distilled beverages (sugarcane spirits) using HPLC-DAD

This work describes the development of a new automated parallel dispersive tip microextraction method (Au-Pa-DPX) for the determination of eleven polycyclic aromatic hydrocarbons (PAHs) in four samples of Brazilian sugarcane spirit beverages, with separation and detection done by the HPLC-DAD. The results obtained with the Au-Pa-DPX approach were also compared with those obtained via the conventional parallel manual DPX method with the same samples and optimized extraction process. Desorption solvent and cycles of desorption, cleaning and extraction were optimized using response surface methodology and univariate approaches. For the Au-Pa-DPX method, the coefficient of determination (R2) ranged from 0.9948 to 0.9997. The limits of detection and quantification were all 0.303 μg l-1 and 1.00 μg l-1, respectively. Interday and intraday precision ranged from 7.6 % to 31.7 % and 0.40 % to 15.8 %, respectively. For the manual parallel DPX method, the interday and intraday precision ranged from 8.2 % to 38.1 % and 5.40 % to 18.7 %, respectively. The relative recovery values obtained with the proposed method ranged from 53.29 to 124.94 %. The enrichment factors ranged from 15.13 to 22.35. The sum of PAH concentrations in the four samples ranged from undetected to 25.58 μg l-1. These results, when correlated to other methods, highlight the gains in regards to precision obtained with the automated apparatus. Furthermore, when compared to other methods from the literature, it is an interesting green alternative for the determination of these analytes and this sample, with high throughput (4.67 min per sample), low consumption of solvents and samples, generating less waste and reducing health risks to the analyst.

Long-lasting copper carbon nanotubes for non-enzymatic electrochemical sensing of glyphosate

Accurate electrochemical detection of glyphosate (GLY) presents significant challenges due to its non-electroactive nature on conventional electrode materials. To address this challenge, copper-modified electrodes have been developed to form a complex with GLY, enhancing detection capabilities. In this study, we propose an innovative material: copper-modified carbon nanotubes on a glassy carbon electrode (Cu/CNT/GCE). The detection mechanism of GLY using Cu/CNT/GCE involves the formation of a copper-GLY complex, which inhibits the electrochemical response of copper, proportionally to the GLY concentration. This effect is enhanced by the synergistic interaction between copper and carbon nanotubes, increasing the electrochemical stability and detection capacity of the system. To evaluate the electrochemical performance of Cu/CNT/GCE, cyclic voltammetry was performed at different electrolyte concentrations and pH levels. Square wave voltammetry was employed for the electrochemical quantification of GLY, showing a linear correlation between GLY concentration and the inhibition of the copper response. The proposed sensor exhibited a low limit of detection (0.098 ppm) and a limit of quantification (0.326 ppm). Furthermore, the electrode demonstrated long-term stability, retaining 95 % of its signal after one year of storage. This stability is attributed to the carbon nanotube support, which prevents corrosion of copper particles. Recovery values ranged from 94 to 106 % for Citromax™ and Orium™ glyphosate with precision. The method showed excellent selectivity for GLY detection, even in the presence of other herbicides such as diuron and oryzalin. These properties suggest that Cu/CNT/GCE presents promising features for the electrochemical monitoring of GLY in diverse environmental samples.

Determination of tetracycline residues in potatoes and soil by LC-MS/MS: Method development, validation, and risk assessment

A method utilizing liquid-liquid extraction (LLE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and validated according to the Commission Implementing Regulation (CIR) EU 2021/808 for quantifying four tetracyclines (TCs) in potatoes and soil. The method demonstrated recovery values ranging from 70 to 121% and precision (repeatability and within-laboratory reproducibility), with coefficient of variation (CV) values below 18% for all TCs in both matrices. The limits of quantification (LOQs) for the TCs ranged from 0.90 to 1.87 μg/kg in potatoes and from 0.68 to 1.25 μg/kg in soil. The decision limit (CCα) and detection capability (CCβ) ranged from 10.4 to 12.3 μg/kg and 11.9 to 14.3 μg/kg, respectively. Analysis of 538 potato and soil samples from Egyptian farms revealed a 13.2% occurrence of TC residues, with a higher frequency in soil (19.33%) than in potatoes (7.06%). Target hazard quotient (THQ) values indicated that TC residues in potatoes do not pose a health risk to Egyptian consumers.

Zinc and Lead Leaching from Sphalerite-Galena Concentrate Using Deep Eutectic Solvents Based on Choline Chloride: Effect of Roasting and Iodine as Oxidizing Agent.

The traditional metallurgical routes for producing lead and zinc from primary sources have a significant environmental footprint. Thus, using less pollutant solvents, such as deep eutectic solvents (DESs), would offer a greener solution in metal extraction. This study explores the use of three DESs based on choline chloride (ChCl) (1:2 ChCl-urea, 1:2 ChCl-ethylene glycol, and 1:2 ChCl-glycerol) for recovering Zn and Pb from a sphalerite-galena concentrate of the mining region in Ecuador. Leaching tests of the concentrate (untreated and roasted at 600 °C) in each DES were conducted (30 °C-24 h). The effect of adding iodine as an oxidizing agent was also evaluated. Recoveries of 2% (Zn) and 14% (Pb) were reported when leaching the untreated concentrate with DES. These recovery values increased to 11% (Zn) and 99% (Pb) after adding iodine during the leaching of the untreated concentrate. Roasting had a similar effect on leaching, increasing the recovery values of Zn (75%) and Pb (90%). Combining roasting as a pretreatment and iodine as an oxidizing agent produced higher Zn recoveries (99%) and Pb (99%). These results were compared to recoveries in acid leaching (H2SO4 and HNO3), revealing the potential of DESs as an alternative for metal recovery from primary sources.