Chinese Journal of Analytical Chemistry最新文献

The green chemistry method for analyzing changes in the concentration of substances during a reaction process is an energy-saving and interesting experimental process. In this paper, the performance of electrolysis of methylene blue (MB) in NaCl electrolyte was studied using a smartphone-based paper microzones method (PMZs), and paper microzone platform was made by discarded label stickers. The linear range spanned from 1.25 to 15 mg/L for the concentration-absorbance correspondence measured via spectrophotometry, and from 1.25 to 17.5 mg/L for the concentration-R-value correspondence measured via the PMZs method. The findings revealed that the limit of detection (LOD) value of the PMZs method was 0.494 mg/L, and the limit of quantification (LOQ) value was 1.497 mg/L. Moreover, the accuracy ranking of the measured MB electrolytic change process across different channels was as follows: Red>Grey>Green>Blue. PMZs method also showed well reliability in measuring actual dye polluted wastewater. The results demonstrate the sensitivity and precision of the PMZs method, as indicated by the low LOD and LOQ values. Additionally, the accuracy ranking provides valuable insight into the performance of the method across different color channels, shedding light on the potential applications and limitations of the PMZs technique in color-based electrochemical analyses. The electrolysis reaction led to a red-shift in the absorption characteristics of MB in NaCl electrolyte, resulting in a notable change in its light absorption properties. This information is crucial for researchers and practitioners seeking to employ the PMZs method for accurate and reliable color measurements in various scientific and industrial settings.

Water pollution is currently a major problem worldwide. Given its detrimental effects on health, Hg(II) is considered an extremely hazardous heavy metal contaminant, even at low doses. Heterocyclic compounds have been thoroughly evaluated as the chemosensor agents for Hg(II) detection. However, they suffer from poor sensitivity. In this study, we prepared two fluorescence chemosensor agents from vanillin via several steps, i.e., etherification, Claisen–Schmidt, and cyclocondensation reactions to yield N-phenyl- and N-pyridine-pyrazoline compounds. Products characterization was accomplished via spectroscopic techniques. Chalcone, N-phenyl-, and N-pyridine-pyrazoline derivatives were successfully obtained at 87.04%, 90.91%, and 91.73% yields, with limits of detection of 156,840, 65.810, and 161.011 nM, respectively. These results show that the conversion of chalcone to pyrazoline structure improved the sensitivity for Hg(II) detection at the nanomolar level, which is 2384 times lower than that for chalcone. Further spectroscopic investigations through Job's plot, Fourier-transform infrared spectroscopy, and proton-nuclear magnetic resonance analyses revealed that Hg(II) ions were chelated with two nitrogen atoms of pyrazoline. Thus, this phenomenon can explain the considerable sensitivity enhancement for Hg(II) detection. N-Phenyl-pyrazoline is the more sensitive chemosensor to Hg(II) compared with N-pyridine-pyrazoline because the more nitrogen groups in the binding site, the less selective and sensitive the compound. This finding is also supported by the higher binding constant value of N-phenyl-pyrazoline (9.416 × 10² mol⁻¹) than N-pyridine-pyrazoline (1.771 × 10² mol⁻¹). Furthermore, N-phenyl-pyrazoline can be applied in the direct quantification of Hg(II) in tap and groundwater samples with a validity parameter in a range of 80.97%–103.54%.

To elucidate the concentrations of heavy metal elements in commercially available electronic cigarettes and improve quality assessment. Inductively coupled plasma-mass spectrometry (ICP-MS) coupled to chemometrics was used to determine the concentrations of Cr, Ni, As, Cd, Sn, Sb, Hg, and Pb in the e-liquids and aerosols derived from 32 electronic cigarettes sold commercially under six brand names. The e-liquids contained: 4.858 to 274.658 (Cr), 17.292 to 3068.375 (Ni), 3.217 to 29.867 (As), 0.225 to 24.717 (Cd), 0.783 to 17.042 (Sn), 0.658 to 36.033 (Sb), 0.658 to 187.592 (Hg), and 2.458 to 17.417 (Pb) ng g⁻¹. The aerosol samples contained: 276.075 to 3333.175 (Cr), 72.908 to 1150.183 (Ni), 4.567 to 86.958 (As), 0.400 to 12.842 (Cd), 1.092 to 32.142 (Sn), 0.976 to 10.633 (Sb), 3.483 to 234.708 (Hg), 27.833 to 849.100 (Pb) ng 100 puffs⁻¹. The recovery of heavy metals ranged from 99.1% to 112.4% in the e-liquids and from 87.3% to 116.6% in the aerosols, with RSD values below 10%. Hierarchical cluster analysis grouped the e-liquids into eight clusters, and the aerosols into five, indicating differences between products within brands and between different brands. Orthogonal partial least squares discriminant analysis coupled with variable importance in projection (VIP > 1) identified As and Sb as the primary heavy metals causing differences between the e-liquids, while differences between the aerosols were caused by Hg, As, Pb, Cd, and Cr. The use of chemometric methods yields a greater depth of information that will support improvements to the quality control of e-cigarette products and the assessment of their potential risk to human health.

In this study, Co-Ni nanomaterials were in situ synthesized on carbon fiber paper substrates, termed Co-Ni paper. Scanning electron microscopy characterization demonstrates fabricated flake-like Co-Ni nanocomposites uniformly distribute on carbon fibers, forming three-dimensional continuous network structure. The fabricated sample is determined to be a mixture of Co, Ni and C elements according to energy-dispersive X-ray spectrometer analysis. Without any pretreatments, Co-Ni paper exhibits excellent electro-oxidation capabilities towards H₂O₂, such as an excellent detecting performance in a wide linear range of 0‒11.5 mM of H₂O₂, fast amperometric responses within 1 s, and a low detection limit of 2.53 μM. Along with these intriguing properties, the in situ-synthesized Co-Ni paper has a good anti-interference towards Na₂SO₄, ZnCl₂, glucose and NaCl during H₂O₂ detection. Moreover, the H₂O₂ electro-chemical sensor on Co-Ni paper also possesses excellent reproducibility, long-term stability and high mechanical stability. This Co-Ni-paper-based sensor is effective to determine H₂O₂ in blood samples, thus it is promising for electrochemical H₂O₂ sensing.

Using terephthalic acid (BDC) as the organic ligand and zirconium chloride (ZrCl₄) as the metal source, a lanthanide metal-organic framework (Tb/Zr-UiO-66) with excellent luminescence properties was successfully prepared by introducing the lanthanide ion Tb³⁺ in situ through a simple one-pot hydrothermal reaction, which was designed as an optical biosensor for 2-thiothiazolidine-4-carboxylic acid (TTCA), the urinary biomarker of human exposure to carbon disulfide (CS₂). The fabricated Tb/Zr-UiO-66 exhibits high chemical and luminescent stability, making it competent for recognizing TTCA in aqueous environments. Significantly, its luminescence intensity change shows a good linearity relationship with the concentration of TTCA in the range of 0–110 μM, with a limit of detection (LOD) as low as 0.14 μM. Meanwhile, this sensor exhibits good selectivity and anti-interference ability towards TTCA among the various coexisting components in urine (Na⁺, K⁺, NH₄⁺, SO₄²⁻, Cl ⁻, creatine, creatinine, glucose, urea, etc.), and can quickly respond to TTCA within 2 min. The analysis results of powder X-ray diffraction (PXRD), fluorescence lifetime and ultraviolet–visible (UV–vis) spectrum demonstrate that the sensing mechanism can be ascribed to the competition absorption effect between TCAA and Tb/Zr-UiO-66. This biosensor with simple synthesis, stable framework, high sensitivity and selectivity, and rapid response has potential to become a powerful tool for diagnosing diseases associated with CS₂ exposure.

Microplastics (MPs) in the atmosphere have attracted global concern due to their potential threats to human health. However, the current rapid analytical method for airborne MPs is insufficient, which hinders a comprehensive understanding of their environmental risks. In recent years, the disposable face masks have emerged as a new source of airborne MPs. There are significant knowledge gaps regarding MPs from mask, including detection methods, formation mechanisms, and environmental abundance. This study presented a novel analytical approach for the rapid detection of airborne MPs using the electromagnetic heating-pyrolysis-mass spectrometry (Eh-Py-MS). To validate this method, surgical face masks were employed as an illustrative example. The mass-related quantification of MPs was realized based on the Eh-Py-MS. By employing a conversion model of mass, size, and density, simultaneous assessment of both mass and quantity of MPs was realized. The recovery rates were in the range of 86.6%–111.6% and the precision (RSD) was 8.4%, which was sufficient for rapid quantification. Results showed that the simultaneous tracing of mass and quantity of airborne microplastics could be successfully achieved through the developed method. Furthermore, the formation mechanism of MPs in surgical masks under UV exposure was also investigated to address the knowledge gap of masks MPs. Results indicated that surgical masks could be a neglected source of airborne microplastics in the environment. This study aims to provide valuable insights for the rapid assessment of airborne MPs in the environment.

Developing an effective method for monitoring of tetracycline (TC) concentrations is extremely crucial due to its adverse effects on both ecosystems and human health. In this study, we developed a novel glutathione-protected nickel nanoclusters (GSHNiNCs) fluorescent (FL) sensing platform to detect TC. The GSHNi NCs were synthesized by a facile one-pot route with GSH as a stabilizer and ascorbic acid (AA) as reducing agent. The experimental results confirmed that the FL of GSHNiNCs was quenched in the presence of TC based on both of the inner-filter effect (IFE) and photoinduced electron transfer (PET) mechanisms to achieve high sensitivity. Under the optimal conditions, excellent linear relationships existed between the FL intensities of GSHNiNCs and the logarithmic TC concentrations in the range of 0.5–120.0 and 120.0–300.0 μM. Even in the absence of surface modification or any complex signal amplification techniques, the proposed FL sensing platform for TC detection showed a low limit of detection of 58 nM (3σ/k). Thus, this approach provides considerable simplicity, low-cost, timesaving and flexibility for the construction of a TC sensor. Most remarkably, we could selectively analyze TC in milk samples without the need for tedious or time-consuming pretreatment processes. This work expands the FL analysis platform for TC detection, and facilitates the design and development of NiNC-based FL sensors for the monitoring of antibiotics.

Chirality, also known as handedness, is one of the most widespread and intriguing properties in nature, touching upon various fields including physics, chemistry, biology, medicine and beyond. Chiral interface is the place where chirality related process occurs. The development of synthetic chiral interface not only deepens the understanding of chiral mechanism, but also provides the basis for the application of chiral phenomenon. In this review, we provide a summary of the various types of chiral interfaces, their construction methods, and the recent process of their application in chiral recognition, chiral separation, and chiral catalysis, as well as a prospect for further direction.

Wastewater contaminated with antibiotics requires innovative solutions to remove such pollutants efficiently. In this work, Zn-Al layered double hydroxide (LDH) adsorbent supported on polyurethane (PU) (Zn-Al LDH/PU) was synthesized using a simple co-precipitation method. The synthesized material was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), zeta potential, and hydrodynamic size. This adsorbent was investigated for the removal of cefixime (CFX), which is a model third-generation cephalosporin antibiotic. The LDH phase showed a typical hexagonal layered morphology with layer sizes larger than 200 nm in diameter. CFX adsorption on PU, Zn-Al LDH and Zn-Al LDH/PU showed a maximum adsorption capacity of 94.43, 57.17, and 115.69 mg/g, respectively. The Redlich-Peterson and Baudu isotherm models were found to be the best fit models for CFX adsorption of Zn-Al LDH and Zn-Al/PU, respectively. The equilibrium time was found to be 175 and 250 min for CFX adsorption of Zn-Al LDH and Zn-Al/PU, respectively. CFX adsorption kinetics on Zn-Al LDH/PU best fitted the pseudo-second order model indicating chemisorption and diffusion limited adsorption process. Numerous types of bonding between functional groups of CFX and both Zn-Al LDH and PU could explain the adsorption mechanism. The selectivity study of CFX adsorption on Zn-Al LDH/PU using Sulfamethoxazole and Ciprofloxacin with different concentrations was investigated and discussed. The recyclability of this Zn-Al LDH/PU was also studied. Also, the effect of temperature was investigated at (23, 35, 45, 55 °C) and the thermodynamic parameters (∆H°, ∆S° and ∆G°) were calculated showing exothermic and spontaneous adsorption process.The methyl thiazolyl tetrazolium (MTT) assay indicated that the biocompatibility of Zn-Al LDH nanostructures was enhanced following modification with PU, demonstrating regulated and minimal cytotoxic effects towards normal liver cell line (WRL-68). The Zn-Al LDH/PU can be considered as a promising low-cost adsorbent for CFX antibiotic from wastewater streams.

In this work, silver-carbon composite semitransparent hollow spheres (Ag/HCSs) have been successfully synthesized via hydrothermal carbonization (HTC) with trioctylamine (TOA) as a stabilizer and soft template. Furthermore, silver-carbon composites with core-shell structure (Ag@CSs) and carbon films loaded with silver nanoparticles composites with lamellar structure (Ag/CFs) were prepared by adjusting the amount of TOA. The Ag/HCSs were composed of a matrix of ultrathin translucent hydrothermal hollow carbon microspheres with Ag nanoclusters embedded, and numbers of Ag@CSs inside and outside of the hollow carbon microspheres. We further investigated the growth mechanism and morphology evolution, on the basis of the properties of Ag and HCSs, explored the application of the Ag/HCSs for surface-enhanced Raman scattering (SERS). SERS activity was investigated using Rhodamine 6 G (R6G) and crystal violet (CV) as the SERS probe molecules. Ag/HCSs exhibit the best SERS performance among three products. The semitranslucent carbon shell, localized surface plasmon resonances of AgNPs and the effect of charge transfer arising from oxygen-containing moieties make the Ag/HCSs to exhibit good SERS performance, which may give a little inspiration to prepare novel SERS substrates.