Ligandless reversed-phase switchable-hydrophilicity solvent liquid–liquid microextraction combined with flame-atomic absorption spectrometry for the determination of copper in oil samples

Quantitative and qualitative detection of target heavy metals using anti-interference colorimetric sensor Array combined with near-infrared spectroscopy

An anti-interference colorimetric sensor array (CSA) technique was developed for the qualitative and quantitative detection of target heavy metals in corn oil. This method involves a binding mechanism that triggers changes in atomic energy levels and visible color changes. A custom-built olfactory visualization device was employed to gather spectral data, revealing distinct CSA color difference patterns. Subsequently, three pattern recognition algorithms were used to create an identification model for the target heavy metals. The results showed that the ACO-KNN (Ant Colony Optimization-K-Nearest Neighbor) model outperformed the other models, achieving accuracy rates of 90.28% and 89.58% for the calibration and prediction sets, respectively. The ACO-PLS (Partial Least Square) model was more stable with the lowest root mean square error of prediction (RMSEP), which were 0.1730 and 0.1180, respectively. The limit of detection (LOD) and quantification (LOQ) of Pb and Hg were (0.3, 0.6, 1.1 and 2.2) x 10-3 mg/L, respectively.

Miniaturized 3D-printed hand-operable dispersive sample pretreatment device with replaceable chitosan/polydopamine thin film metal sorbent for enhanced metal analysis

To address the increasing demand for sensitive and selective sample preparation methods for metal analysis; preconcentration of intended analyte from complex sample matrices before analysis is required to improve the performance of analysis instruments. In this study, we have engineered a sustainable and portable syringe-based hand-operable three-dimensionally (3D) printed sample pretreatment apparatus equipped with a replaceable bio-based thin- film metal sorbent. This device effectively addresses the challenges of sample matrix interference in metal analysis. A metal sorbent film composed of chitosan (CS) and polydopamine (PDA) leveraged the diverse functional groups in the CS/PDA matrix to significantly enhance the extraction efficiency for various metals. Our approach demonstrated excellent analytical performance, with coefficients of determination (R2) of 0.9982 for copper (Cu) and 0.996 for chromium (Cr). The method achieved low limits of detection (LOD) of 0.3 μg L-1 for Cr and 0.7 μg L-1 for Cu. Precision and practicality assessments using actual urine samples yielded satisfactory relative standard deviations (RSD%) ranging from of 1.6 %-8.5 % for both metals, indicating minimal interference from the sample matrix. Moreover, our approach exhibited robust performance even after seven consecutive extraction and desorption cycles, highlighting its sustainability and practical applicability for laboratory and on-site sample pretreatment.

Portable one-step effervescence tablet-based microextraction combined with smartphone digital image colorimetry: Toward field and rapid detection of trace nickel ion

In this study, the one-step switchable hydrophilic solvent (SHS)-based effervescence tablet microextraction (ETME) was coupled with smartphone digital image colorimetry (SDIC) for the field detection of nickel ion (Ni2+) for the first time. Both extractant and CO2 were generated in situ when the novel SHS-based effervescence tablet was placed in the sample solution. The complexant 1-(2-pyridinylazo)-2-naphthaleno (PAN) dissolved from the effervescence tablet to form a stable complex with Ni2+, and the extractant was uniformly dispersed in the sample solution under the action of CO2 and fully in contact with Ni-PAN, which enabled efficient extraction of Ni2+. The color changes of the extraction phase were captured by smartphone, then a quantitative relationship between the concentrations of Ni2+ and color intensity of images captured using a smartphone was established by customized applet WASDIC, which realized quantitative analysis of Ni2+ in different samples. Under optimal conditions, the enhancement factor (EF) of the proposed method was 65.1, the limit of detection (LOD) and limit of quantification (LOQ) were 1.69 and 5.64 μg L-1, respectively. The developed method was successfully applied to the detection of trace Ni2+ in the environmental samples and natural medicines. And the applicability of the method for use in field analysis was validated.

Switchable metal extractant integrated miniaturized 3D-printed device: A semi-online multi-metal separation system for matrix-free ICP-MS analysis

BACKGROUND

This study tackles the critical challenges in metal analysis by presenting an innovative miniaturized metal extraction device prototype. This device features a functional nanocomposite (FNC) enhanced 3D-printed polylactic acid (PLA) metal extractant (FNC@3D PLA). The research is motivated by the constraints of traditional solid-phase extraction (SPE) methods, specifically their limitations in handling competitive metal ion environments and matrix interference during inductively coupled plasma mass spectrometry (ICP-MS) analysis. The designed prototype aims to overcome these challenges and enhance the extraction efficiency of diverse metals.

RESULTS

The FNC, designed to incorporate various functional groups critical for metal ion extraction efficiency, was meticulously engineered through the reaction of acid-treated and delaminated graphitic carbon nitride nanosheets (Thiol-gCN NSs) with 3-mercaptopropyl trimethoxysilane (MPTMS). The competitive metal ion extraction efficiency of FNC@3D PLA was demonstrated, showcasing notable limit of detection values of 3.2 ± 0.7 ng mL-1 and 8.57 ± 3.05 ng mL-1 for Cu and Ag, respectively. Furthermore, the miniaturized 3D-printed metal-preconcentration setup incorporating FNC@3D PLA exhibited favorable intraday relative standard deviation (RSD) percentage (%) values ranging from 1.23 to 8.6 for both Cu and Ag. Interday RSD % between 1.41 and 8.14 were observed under spiked real urine sample conditions. The sustainability and robustness of the proposed approach were underscored by substantial recovery % values exhibited by FNC@3D PLA, even after eight consecutive regeneration processes.

SIGNIFICANCE

This study significantly contributes to the advancement of analytical methodologies by providing a reliable and efficient platform for metal extraction and preconcentration in practical metal analysis applications. Developed FNC@3D PLA system demonstrates its potential to address the challenges associated with SPE in metal analysis, especially in complex sample matrices. We believe implications of this research can be extended to various fields, from environmental monitoring to clinical diagnostics, where accurate and reliable metal analysis is paramount.

Ultra-sensitive photoelectrochemical sensor for copper ion detection based on ITO/BiVO4 photoelectrode

In this work, a photoelectrochemical sensor for Cu2+ trace detection was prepared based on the excellent semiconductor material BiVO4 modified ITO electrode. It was found that Cu2+ formed a doping effect by adsorption on the surface of ITO/BiVO4 electrode, which inhibited the photogenerated electron complex and thus caused an increase in photocurrent. In addition, due to the complexation effect of EDTA on Cu2+, the Cu2+ adsorbed on the electrode surface is desorbed and the photocurrent returns to the blank value, making it possible to reuse electrodes. Under optimal conditions, the linearity range was measured between 0.1 pM and 0.1 μM and the detection limit was 0.063 pM. The PEC sensor exhibits the advantages of high sensitivity and reusability for Cu2+ detection. This provides a novel PEC detection platform for Cu2+ monitoring in environmental water samples.

An Eco-Friendly, Interference, and Solvent Free Surfactant-Assisted Dual-Wavelength β-CorrectionSpectrometric Method for Total Determination and Speciation of Cu2+ Ions in Water

Spectral interference through the presence of uninformative variables, excess reagents, and complications in the refinement of the analyte signal is common in the quest to identify complex species in real samples. Therefore, an economical green, facile, and sensitive strategy has been developed for Cu2+ detection using the anionic surfactant sodium dodecylsulphate- (SDS-) assisted dual-wavelength β-correction spectrophotometric strategy combined with the chromogenic reagent zincon (ZI). The low limits of detection (LOD) and quantification (LOQ) of Cu2+ using ordinary (single wavelength) spectrophotometry were 0.19 (3.02) and 0.63 (10.0) μgmL-1, and these values were improved to 0.08 (1.27) and 0.26 μgmL-1 (4.12 μM)) using β-correction (dual wavelength) spectrophotometry, respectively. The LOD and LOQ were improved from 0.08 (1.27) and 0.26 (4.12) μgmL-1 to 0.02 (0.32) and 0.08 μgmL-1 (1.27 μM) using SDS-assisted dual-β-correction spectrometry, respectively. Ringbom, s, and the corrected absorbance (Ac) versus Cu2+ concentration plots were linear over the concentration range 1.10-2.4 (17.4-38.1) and 0.50-2.40 μgmL-1 (7.94-38.1 μM), respectively. Sandell's sensitivity index of 3.0 × 10-3 μg/cm2 was achieved. The selectivity was further confirmed via monitoring the impact of common diverse ions and surfactants on the corrected absorbance. Total determination and Cu2+ speciation in water were favorably implemented and validated by ICP-OES at 95% (P=0.05). Satisfactory Cu2+ recoveries in tap (92.2-98.0%) and mineral (105-111.0%) water samples were achieved. The sensing system is simple, reliable, sensitive, and selective for Cu2+ detection.

Deep Eutectic Solvent Based Reversed-Phase Dispersive Liquid-Liquid Microextraction and High-Performance Liquid Chromatography for the Determination of Free Tryptophan in Cold-Pressed Oils

A fast and straightforward reversed-phase dispersive liquid-liquid microextraction (RP-DLLME) using a deep eutectic solvent (DES) procedure to determine free tryptophan in vegetable oils was developed. The influence of eight variables affecting the RP-DLLME efficiency has been studied by a multivariate approach. A Plackett-Burman design for screening the most influential variables followed by a central composite response surface methodology led to an optimum RP-DLLME setup for a 1 g oil sample: 9 mL hexane as the diluting solvent, vortex extraction with 0.45 mL of DES (choline chloride-urea) at 40 °C, without addition of salt, and centrifugation at 6000 rpm for 4.0 min. The reconstituted extract was directly injected into a high-performance liquid chromatography (HPLC) system working in the diode array mode. At the studied concentration levels, the obtained method detection limits (MDL) was 11 mg/kg, linearity in matrix-matched standards was R² ≥ 0.997, relative standard deviations (RSD) was 7.8%, and average recovery was 93%. The combined use of the recently developed DES -based RP-DLLME and HPLC provides an innovative, efficient, cost-effective, and more sustainable method for the extraction and quantification of free tryptophan in oily food matrices. The method was employed to analyze cold-pressed oils from nine vegetables (Brazil nut, almond, cashew, hazelnut, peanut, pumpkin, sesame, sunflower, and walnut) for the first time. The results showed that free tryptophan was present in the range of 11-38 mg/100 g. This article is important for its contributions to the field of food analysis, and for its development of a new and efficient method for the determination of free tryptophan in complex matrices, which has the potential to be applied to other analytes and sample types.

Green Analytical Toxicology for the Determination of Cocaine Metabolites

Brazil is the third largest contributor to Green Analytical Chemistry, and there is significant participation of toxicologists in the development and improvement of environmental techniques. Currently, toxicologists have their own strategies and guidelines to promote the reduction/replacement or elimination of solvents, reduce the impacts of derivatization and save time, among other objectives, due to the peculiarities of toxicological analysis. Thus, this review aims to propose the concept of Green Analytical Toxicology and conduct a discussion about its relevance and applications specifically in forensic toxicology, using the microextraction methods developed for the determination of cocaine and its metabolites as examples.

Accurate and sensitive determination of Sb(III) in water samples using UV-VIS spectrophotometry after simultaneous complexation and preconcentration with deep eutectic solvent/DTZ probe-based liquid-liquid microextraction

This study describes the determination of trace levels of antimony(III) by UV-Vis spectrophotometer after preconcentration by the deep eutectic solvent/dithizone probe-based liquid-liquid microextraction method. Ditizone was used as a ligand to form the coordinated antimony complex before extraction in the preconcentration process. In the microextraction method developed in the study, deep eutectic solvent was used to dissolve the complexing agent; thus, the complexation was performed at the same time as the extraction of antimony complex by deep eutectic solvent. All variables likely to affect the ligand-antimony(III) complex, extraction efficiency, and spectroscopic measurement were optimized to lower the detection limit. Under the determined optimum conditions, the detection limit for Sb was calculated as 1.6 × 10^-3 mg/L. The detection limit obtained with the method is much lower than the value obtained in the Uv-Vis spectrophotometer with the traditional method. In this study, the percent relative standard deviation for the lowest concentration was calculated as 3.12% (n = 8). This value indicates that the analysis performed has high precision. The applicability of the method was determined by performing spiked recovery tests on tap water taken from different regions. Satisfactory recovery results were obtained between 91 and 105% at three different concentrations.

Advanced Methodologies for Trace Elements in Edible Oil Samples: A Review

Advanced methodologies were applied for the detection of some elements at trace levels in edible oils. Trace elements play a role in oil stability, quality of edible oils and fats. In the present study, problems were addressed related to simple, cheap, less time consuming and suitable pretreatment advanced methods for suitable sample introduction and calibrations as well as the strategies and techniques are discussed. The present review is aimed to discuss the significance of simplifying sample treatments are offered for trace elements in oils. The period covered by this review is last twenty years. However, the various applications of advanced methodologies including extraction and microextraction. The scope of spectrometric techniques used for the analysis of trace elements in edible oils was discussed by new instrumental development trends.

Sustainable green solvents for microextraction techniques: Recent developments and applications

The development and application of alternative green solvents in analytical techniques consist of trends in sample preparation, since this subject represents an important step toward sustainability in experimental procedures. This review is focused on the main theoretical aspects related to deep eutectic solvents (DES), switchable hydrophilicity solvents (SHS) and supramolecular solvents (SUPRAS). Recent applications are highlighted, particularly for the extraction of different analytes from environmental, biological and food matrices. Moreover, novel configurations are emphasized, aiming for efficient, automated and high-throughput procedures. This review also provides some critical points regarding the use of these solvents and their green aspects.