Analytical Chemistry
Luminescence Detection of Cr3+, Bi3+, and Acetone in Aqueous Solution by Core-Shell Tb-MOF
By using terephthalic acid 2 5-furandicarboxylic acid and terbium nitrate hexahydrate a Tb-MOF with a core-shell structure was successfully designed and prepared.
A one-pot method was employed to design and synthesize core-shell Tb-MOF. The morphology luminescence performance and stability were well characterized.
Tb-MOF demonstrated good water stability acid and alkali resistance and thermal stability. Tb-MOF was found to have high sensitivity to detect Cr3+ Bi3+ and acetone in an aqueous solution and the LOD of Cr3+ Bi3+ and acetone were calculated to be 0.18 μM 4.22 μM and 0.26% respectively. The sensing mechanism of Cr3+ and acetone was explained as energy-competitive absorption and the sensing mechanism of Bi3+ was explained as ion replacement.
The prepared Tb-MOF can be developed as a multifunctional light-emitting sensor with high selectivity.
Recent Advancement in the Development of Detection and Removal of Heavy Metal Ions by Deep Eutectic Solvents: A Review
Heavy metal pollution is one of the most serious environmental problems because of the non-degradable nature of heavy metals and their accumulation in the food chain which poses a severe threat to the environment and human health even at low concentrations. Most of these metal ions can coordinate with biological molecules and disturb their function. Exposure to heavy metals can cause different health threats such as endothelial dysfunction allergy infant mortality cancer neurological diseases respiratory diseases oxidative stress cardiovascular disorders and kidney diseases. Therefore the detection and removal of these toxic species are very important. Deep eutectic solvents (DESs) are green solvents and have excellent applications in many fields. They contain nonsymmetrical ions that have low lattice energy low vapor pressure dipolar nature non-flammability low volatility low melting points excellent thermal and chemical stability and high solubility. DESs are also better in terms of the availability of raw materials easy synthetic procedure low cost of their starting materials and their easy storage. DESs have an excellent ability for the detection and removal of heavy metal ions. In this review we discussed various DES-based spectrophotometric and fluorimetric chemosensors for the detection of heavy metal ions in different matrixes. Additionally we have also explored the capabilities of different DESs in removing heavy metals.
Recent Advancements in Biochar and its Composite for the Remediation of Hazardous Pollutants
Biochar has garnered considerable attention in recent times due to its potential uses in the environmental field. In this study we comprehensively examine and condense information on biochar production characteristics and adsorption mechanisms with a focus on its economic applications for remediating hazardous contaminants. Our assessment is based on over 200 publications from the past decade. Biochar a carbon-rich material can be derived from various organic waste sources such as food waste and urban sewage sludge. Researchers are particularly interested in biochar due to its high carbon content cation exchange capacity substantial specific surface area and stable structure. We investigate how the physical and chemical properties of biochar may vary based on the feedstock used providing a comprehensive overview of biochar and its composition for pollution remediation. The review also discusses common techniques such as gasification hydrothermal carbonization and pyrolysis used to produce biochar. We analyze current research on the mechanisms involved in pollutant treatment using biochar and its composites while also addressing future directions in biochar research.
Investigating the Effects of Urea-Zinc Sulfate-L Phenylalanine on the Corrosion Inhibition of Mild Steel Exposed to pH-4 Sulfuric Acid
Corrosion of mild steel is a risk to material and stability. The practice of corrosion inhibitors is a cost-effective corrosion modification method for mild steel. Organic inhibitors rich in electrons might have an excellent ability to prevent corrosion. This study aims to assess the inhibitory effect of the mixture of Urea Zinc Sulfate and L-Phenylalanine which has a high electron density.
MS corrosion was experimentally analyzed by dipping in H2SO4 solution at a pH – 4 for 24 hrs. Different gravimetric and conventional techniques such as polarization AC impedance AFM UV and fluorescence were used to examine the corrosion rate.
According to gravimetric measurements this combination produced 93% effective inhibition. The findings of the impedance test proved that the mixture of inhibitors that was adsorbed on the metal surface effectively prevented corrosion.
Likewise according to the Polarization measurements the inhibitor exhibits mixed-type performance with significant cathodic activity. UV Fluorescence and AFM findings showed that MS corrosion was suppressed because the inhibitor molecule adhered to the metal's surface and reduced.
Application of Time-of-flight Secondary Ion Mass Spectrometry in Lithium-ion Batteries
Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is becoming a powerful tool in the Lithium-Ion Batteries (LIBs) field due to its excellent resolution and sensitivity as well as its ability to provide spectrally and depth-resolved information. The perspective comprehensively delves into the application of ToF-SIMS in two major areas of LIBs research. Firstly the article elucidates how ToF-SIMS has been instrumental in deciphering the Solid Electrolyte Interphase (SEI) composition and analyzing electrolyte aging. The insights gleaned from such studies have paved the way for enhancing the longevity and safety of LIBs. Secondly we explore the role of ToF-SIMS in scrutinizing the distribution of interface reactions which are critical for understanding charge and discharge mechanisms. The analysis aids in optimizing the interface properties thereby improving battery performance. Such detections are paramount in ensuring the safety and operational stability of batteries. Overall the integration of ToF-SIMS in LIBs research offers a promising avenue for the development of advanced and safer energy storage systems.
A Typology and Lead Isotope and Cultural Exchange Study on Bronze Knives from Shuangyuan Cemetery, Chengdu City, Southwest China
Background: Bronze knives which have been excavated in large quantities and acquired hierarchical significance are essential artifacts in Shu State in Southwest China. Building upon previous typological analyses of bronze knives it is hypothesized that Shu culture may have imported foreign-style bronze knives. However further demonstration of the provenance of metal materials the types of knives and the cultural exchange necessitates a comprehensive examination through the lens of scientific analysis. The purpose of this study is to investigate the differences in the manufacturing processes and metal resources of Shu bronze knives with various cultural styles and whether bronze knives in the foreign styles were imported or locally imitated. Methods: In this study the typology portable X-ray fluorescence spectrometry and multi-collector inductively coupled plasma mass spectrometry were used to analyze twenty-four bronze knives unearthed from Shuangyuan Cemetery a cemetery of the Eastern Zhou Dynasty in Chengdu City Sichuan Province Southwest China. Results: The results of the study show that the knives of Shuangyuan Cemetery can be classified typologically into five types encompassing both local and foreign styles. The predominant alloy composition of these knives is lead-tin bronze characterized by a notably high tin content. Lead isotope ratios indicate that metal materials from the South China geochemical province and the Yangtze geochemical province were mainly used to manufacture the bronze knives unearthed from the Shu state. Conclusion: While the majority of foreign-style knives with ring-shaped heads were likely imported from neighboring regions like Chu state distinctively styled type D and type E bronze knives appear to have been locally imitated by the Shu showcasing a blend of external influences and indigenous innovation. The combination of typology and scientific analysis of the bronze knife may shed new light on the study of the Shu culture of the Eastern Zhou period.
Studies on Quantitative Determination of Polyphenols in Seven Harvesting Times of Salvia deserta Schang Leaves and its Stability Evaluation
Introduction: Leaves of Salvia deserta Schang at seven harvesting times in the same year were collected as the materials. Method: The polyphenols were determined by the Folin–Ciocaileu method and High-Performance Liquid Chromatography (HPLC) to compare the quality of samples. The stability of polyphenols was studied under different conditions (light temperature pH common additives). Results: The results showed that the established method is fast simple and reliable which is fully validated in terms of outstanding validation data. High Performance Liquid Chromatography (HPLC) for the determination of total polyphenol content can be quickly and accurately detected reducing the error of manual determination of the content. The study of polyphenol stability was carried out using a UV spectrophotometer (UV) in order to explore the potential factors affecting polyphenol stability as much as possible and to make the study as scientific and rigorous as possible. The results of quantitative determination showed that there are obvious differences in the content of polyphenols in seven samples. The contents of total polyphenols rosmarinic acid (RA) and caffeic acid (CA) in the samples harvested in July reached the highest level of 41.37 26.73 and 1.05 mg/g. Conclusion: The results of the stability assay found that light could damage the stability of polyphenols in samples especially UV light. Polyphenols are quite sensitive to high temperatures. While polyphenols are less stable when exposed to high alkali conditions and salt treatment they are much more stable when subjected to low concentrations of redox agents carbohydrates and preservatives. The developed methods and stability evaluation provide valuable basis information for quality evaluation and the following use of polyphenols in S. deserta Schang leaves.
A New Modified Carbon Paste Electrode for Selective Determination of Chromium(III) in Pharmaceutical Drugs and Food Samples
Background and Objective: This study presents a novel potentiometric method for the precise accurate selective and rapid determination of Cr(III) ion concentration in different samples. Methods: A new ionophore namely macrocyclic tetramide ionophore (MCTA) was synthesized through an inexpensive and straightforward approach yielding a high-quality product. The (MCTA) ionophore was utilized as the active center in the preparation of modified carbon paste electrodes (MCPEs) to quantify the Cr(III) ion. The paste was made by adding graphite MCTA and plasticizer and mixing them in varying weight percent ratios. Results: The proposed electrodes I and II exhibited a trivalent Nernstian response of 20.029 ±0.57 and 20.3±0.56 mV decade-1 respectively with linearity of 1.0x10-7 – 1.0x10-2 and 1.0x10-5 – 1.0x10-2 mol L-1. Electrodes I and II were examined for their pH response time and thermal stability. In comparison to other mono- bi- and trivalent cations starch and sugars the electrodes demonstrated a high degree of selectivity for Cr(III). The modified electrodes were used to determine the concentration of Cr(III) in various real samples including drug tablets juice extractions and tap water with acceptable recovery values. Conclusion: The results were compared with those obtained using the previously reported method with no significant difference observed between them as indicated by the F and t-test values. The data showed good accuracy and precision as well as a high percentage of recovery. The adsorption capacity of the MCTA ionophore towards Cr(III) ions was also examined.
Study on 13C MultiCP/MAS ssNMR Analysis of Tobacco Pectin
Background: As one of the most important economic crops tobacco products have a long history and dominate the development of the world economy. Pectin as a complex colloidal substance widely present in plant cell walls its content is an important factor affecting the safety of tobacco smoking. Objective: This study aimed to analyze the content and structure of pectin in tobacco samples. Methods: In this study tobacco pectin was extracted by ultrasonic-assisted ionic liquid extraction and the 13C MultiCP/MAS NMR spectral analysis of pectin was conducted. Results: The type of extractant duration of ultrasonication extraction temperature and solid-liquid ratio were optimized. Under the conditions of using 1-Butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) as the extractant the solid-liquid ratio of 1:20 g/mL and the ultrasonic power of 600 w for 30 min at 30°C the yield of 23.7% of tobacco stem pectin and the purity of 54.2% could be obtained. The optimized MultiCP sequence parameters with 10 CP cycles of 1.0 ms and the repolarization time of 50 ms could obtain high-resolution spectra within a time of 1.0 h. The C-6 peaks of the pectin in spectra were fitted using the spectral deconvolution technique and calculated the methylesterification (DM) of the tobacco pectin which was generally less than 50% and belonged to the low methyl esterification pectin. The pectin content of the tobacco sample was calculated using the standard curve method with the addition of dimethyl sulfone (DMS) as an internal reference. The results of this method were consistent with the colorimetric method. Conclusion: The 13C MultiCP/MAS NMR method has the advantages of being green fast and accurate and provides a new technical tool for quantitative and qualitative studies of cell wall substances in tobacco samples.
Development and Validation of 1H Nuclear Magnetic Resonance Quantitative Method for Efavirenz API Quality Control
Background: The pharmaceutical industry is constantly looking for a better way to ensure and improve its products' safety quality and effectiveness. Since there are many attributes of the drug substance and excipients that could potentially affect the Critical Quality Attributes (CQAs) of the intermediates and the final product the evaluation of the raw material's physicochemical characteristics is crucial as they directly affect the quality safety efficacy and lot-to-lot consistency. Scientists rely on methods like HPLC HPTLC LC-MS GC-MS and NMR to analyze these substances. The advantage of NMR is that it is considered a primary analytical method compared to other analytical techniques. Objective: This work aimed to present a simple rapid specific and accurate method by proton Nuclear Magnetic Resonance spectroscopy (1H-NMR) developed to determine the activity of the antiretroviral Efavirenz’s (EFZ) Active Pharmaceutical Ingredient (API). The method was based on quantitative NMR spectroscopy (qNMR). Methods: A Bruker Avance spectrometer (11.7 Tesla 500 MHz for 1H) with a 5mm probe was used. The 1H-NMR signal at 7.54 ppm corresponding to the analyte of interest was employed to quantify the drug. The method was validated for specificity selectivity intermediate precision linearity range of work accuracy and robustness. Results: The method developed was specific and linear (r2 = 0.9998) with a value between 4.30 mg/mL and 12.40 mg/mL. The relative standard deviation for accuracy and precision was 0.4% or less. The method's robustness was demonstrated by changing four different parameters and the difference among each was 1.2% or less. The results of this work have been found to be in agreement with those obtained from High-performance Liquid Chromatography (HPLC) analysis. Conclusion: The proposed method has been found to be a valuable and practical tool for quality control. Its applicability to determining many APIs and saving solvent use and time is highlighted.
Layer-by-layer Fabrication of Gold Nanoparticles/Polyaniline Modified Gold Electrodes for Direct Non-enzymatic Oxidation of Glucose
Background: Non-enzymatic direct glucose biofuel cell is a promising technology to harness sustainable renewable energy. Furthermore monitoring glucose levels is essential for human lives with age. Thus there is an increasing need to develop highly efficient and stable modified electrodes. Methods: This study reported the manufacture of gold nanoparticles/polyaniline/modified gold electrodes (Au NPs/PANI/Au electrode) based on the electrochemical polymerization method followed by the deposition of gold nanoparticles. The shapes and chemical constitution of the electrodes were examined by using different techniques including SEM FTIR XRD EDS and Raman spectroscopy techniques. The electrocatalytic efficiency of the present electrodes toward direct glucose oxidation was evaluated by applying cyclic voltammetry linear sweep voltammetry and square wave voltammetry techniques. Results: The results exhibited high electrocatalytic performance for direct glucose electrooxidation in alkaline media. The modified electrodes show the ability to electrooxidation of various glucose concentrations (1 μM 100 μM) with a limit of detection and limit of quantitation of 140 nM and 424 nM respectively. Furthermore the Au NPs/PANI/Au electrode showed higher durability sensitivity and selectivity toward glucose oxidation than the Au NPs/ Au electrode which confirmed the role of the PANI layer in enhancing the stability of the modified electrode. Conclusion: Moreover the molar fraction of glucose to KOH has a crucial role in the output current. Hence the modified electrodes are great candidates for direct glucose biofuel cell application.
Deep Learning-enhanced Hyperspectral Imaging for the Rapid Identification and Classification of Foodborne Pathogens
Background: Bacterial cellulose (BC) is a versatile biomaterial with numerous applications and the identification of bacterial strains that produce it is of great importance. This study explores the effectiveness of a Stacked Autoencoder (SAE)-based deep learning method for the classification of bacterial cellulose-producing bacteria. Objective: The primary objective of this research is to assess the potential of SAE-based classification models in accurately identifying and classifying bacterial cellulose-producing bacteria with a particular focus on strain GZ-01. Methods: Strain GZ-01 was isolated and subjected to a comprehensive characterization process including morphological observations physiological and biochemical analysis and 16S rDNA sequencing. These methods were employed to determine the identity of strain GZ-01 ultimately recognized as Acetobacter Okinawa. The study compares the performance of SAE-based classification models to traditional methods like Principal Component Analysis (PCA). Results: The SAE-based classifier exhibits outstanding performance achieving an impressive accuracy of 94.9% in the recognition and classification of bacterial cellulose-producing bacteria. This approach surpasses the efficacy of conventional PCA in handling the complexities of this classification task. Conclusion: The findings from this research highlight the immense potential of utilizing nanotechnology- driven data analysis methods such as Stacked Autoencoders in the realm of bacterial cellulose research. These advanced techniques offer a promising avenue for enhancing the efficiency and accuracy of bacterial cellulose-producing bacteria classification which has significant implications for various applications in biotechnology and materials science.
Analysis of Seven Terpenoids by HS-SPME Coupled with GC-MS for the Identification and Classification of Different Teas
Background: Terpenoids are essential aroma substances in teas and their concentration brings various characteristics to different teas. Therefore developing a simple and stable method is necessary for distinguishing tea categories. Objective: In previous studies more attention was paid to non-chiral isomers of terpenes due to the challenges of separating chiral isomers. So this paper aims to present a method for effectively separating seven terpenoid substances including chiral isomers and non-chiral isomers to facilitate the classification and identification of teas. Methods: A method utilizing headspace solid-phase microextraction coupled with gas chromatography- mass spectrometry was used to isolate and analyze 7 terpenoid compounds. After optimized conditions the BGB-176 chiral column and the PDMS/DVB fiber were selected for subsequent analysis. Results: This method has a good linear range of 0.1-200 mg/L and its linear correlation coefficients are between 0.9974 and 0.9994 and the limit of detection and the limit of quantification is 0.02–0.03 and 0.06–0.09 mg/L respectively. Only five terpenoid substances were detected in a total of 15 tea samples. Furthermore In the detection of carvon and α-ionone optical isomers the S isomer was mainly detected. Conclusions: An effective approach was developed to separate and analyze 7 terpenoid compounds in natural and synthetic teas. Meanwhile 15 tea samples can be identified and classified using principal component analysis.
Identification of Volatile Organic Compounds (Distinct Biomarkers) Emitted by Cancer Cells Using Gas Chromatography-mass Spectrometry – A Review
The utilization of Gas Chromatography-Mass Spectrometry (GC-MS) for the detection of Volatile Organic Compounds (VOCs) as potential biomarkers in cancer diagnostics is an evolving and promising field. This review outlines current exploratory and pilot studies that lay a fundamental groundwork for future research. Due to the complexity of the fecal and respiratory volatilome influenced by a myriad of biological and environmental factors it is crucial to expand research demographics to enhance data robustness and ensure the applicability of findings across diverse populations. We have also herein highlighted the dual capability of VOC analysis to detect cancer and differentiate between its stages which is vital for customizing patient treatment plans and monitoring therapeutic efficacy. Furthermore establishing quantifiable thresholds for VOC concentrations is essential for their clinical adoption as reliable indicators of cancer. The integration of GC-MS with machine learning and Artificial Intelligence (AI) could be useful for comprehensive metabolic profiles and facilitating the development of non-invasive and real-time diagnostic tools. The adoption of multi-omics approach promises a deeper understanding of cancer biology potentially leading to personalized medicine and strategies finely tuned to individual molecular profiles. Hence the research on VOCs as cancer biomarkers is set to offer transformative advancements in diagnostic technologies ultimately improving patient outcomes through tailored therapeutic interventions.
Spectrophotometric Determination of 4-n-butylresorcinol in Cosmetics by Decolorization of Oxidized 3,3',5,5'-tetramethylbenzidine
4-n-butylresorcinol (4nBR) was widely used in the treatment of chloasma and skin whitening cosmetics. As a decolorizing agent it can effectively control the activity of tyrosinase. Market regulatory authorities require truthful labeling of ingredients in cosmetics. Therefore the quantitative determination of 4nBR is of great practical significance.
At present the main detection method of 4nBR reported in the literature is HPLC.Compared with the HPLC method optical methods offer several advantages including low cost and simplicity which make them suitable for on-field detection applications. A convenient spectrophotometric method was established for 4nBR detection.
Fe3+ can oxidize the common colorless chromogenic substrate 33'55'-tetramethylbenzidine (TMB) to blue oxTMB. Based on the fact that 4-n-butyl resorcinol (4nBR) can reduce oxTMB a convenient and rapid spectrophotometric method for the determination of 4nBR was proposed.
Under the optimum conditions the absorbance at 652 nm has a good linear relationship with the concentration of 4nBR in the range of 1.2 - 16 μM. The linear equation for the detection of 4nBR was ΔA = 0.0546 c (μM) - 0.0026 (r2=0.9962) and the detection limit was 0.33 μM. The accuracy of this method is comparable to that of HPLC.
This method has good selectivity for 4nBR and good anti-interference ability for common additives in cosmetics. The proposed method can be applied to the determination of 4nBR in thereal samples.
Study on the Influence of Curing Conditions on the Inhomogeneity of Lightweight Ceramsite Concrete Wallboard
Due to the segregation of lightweight aggregate concrete there is a phenomenon of uneven distribution of ceramsite (aggregate) in commercial ceramsite concrete lightweight wallboard which the specific performance of wallboard can reflect.
In this paper the non-uniformity of six commercial ceramsite concrete wallboards with different curing conditions was analyzed. Six wallboards were cut into 648 samples and photographed and ImageJ image analysis technology was combined to analyze the non-uniformity of the ceramsite concrete wallboard under different curing conditions in terms of the proportion of ceramsite particle area density compressive strength and ultrasonic velocity. At the same time the reasons for the difference in wallboard performance under different curing methods were explained from the microscopic perspective by investigating the ITZ interface.
Compared with natural curing sealing curing can significantly optimize the performance distribution of the wallboard and effectively improve the inhomogeneity of the wallboard. The average density of the specimen is increased by about 13% and the average compressive strength by about 20%. The maximum density of the wallboard samples is increased by 105 kg/m3 which is about 15% higher than that of the naturally cured wallboard.
This paper quantifies the magnitude of the effect of sealing curing on wallboards and provides a basis for the selection of curing methods for ceramsite concrete wallboards.
A Method to Determine Metoclopramide Hydrochloride in Oral Dosage Forms by Micellar Liquid Chromatography
Metoclopramide is a widely prescribed antiemetic drug. Its analysis in pharmaceutical formulations often involves procedures using high amounts of toxic chemicals.
A method based on micellar liquid chromatography to determine metoclopramide hydrochloride in several oral dosage forms has been developed.
The drug was resolved from matrix compounds within 6 min using a C18 column with isocratic elution at 1 mL/min utilizing a solution of 0.10 mol/L sodium dodecyl sulfate – 6% 1-pentanol phosphate buffered at pH 7 as mobile phase and detection by absorbance at 210 nm. Samples were dissolved or diluted in the mobile phase and directly injected; thus only one solution had to be prepared for the entire procedure. Besides it contained mainly harmless chemicals and a minimal amount of organic solvent. Results The procedure was validated by the International Council of Harmonization guidelines and the results were: specificity calibration range (0.5 – 5.0 mg/L) linearity (r2 > 0.9990) trueness (98.1 – 100.3%) precision (< 0.7%) robustness carry-over effect and system suitability. It was used to analyze commercial samples. Otherwise it was found the influence of the surfactant on elution strength was nearly three times stronger than that of 1-pentanol.
The procedure was reliable easy-to-conduct safe eco-friendly short-time widely available and highly sample-throughput and then useful for routine analysis of metoclopramide-based dosage forms in pharmaceutical quality control.
Isolation, Development and Validation of Chromatographic Methods for the Estimation of Linoleic Acid from Different Parts of Euphorbia Neriifolia Linn.
This is the first report on the development and validation of thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC)-densitometric methods for the identification of linoleic acid (LA) in petroleum ether extract (PEE) of Euphorbia neriifolia (EN) stem (ST) latex (LX) and bark (BA).
Chromatographic analyses were performed on silica gel-G and silica gel 60 F254 plates and the antioxidant activities of isolated compounds were investigated by 22-diphenyl-1-picrylhydrazyl (DPPH) spectrophotometric assay.
The chromatographic analyses revealed better spots and well-separated peaks of LA with retention factor (Rf) values at 0.54 (ST) 0.40 (LX) and 0.64 (BA) respectively. The linearity of the calibration curve ranges from 10-50 ng/spot (ST) 10-100 ng/spot (LX) and 50-200 ng/spot (BA). The proposed method was characterized by better accuracy better robustness and good precision ranging from 0.173 to 0.372% (intra-day) and 0.185 to 0.205% (inter-day). The value of the limit of detection and quantification equal to 1.04 and 3.16 ng/spot in ST 0.87 and 2.64 ng/spot in LX and 0.177 and 0.53 ng/spot in BA determined the sensitivity of the method. In the obtained chromatogram no peak was observed other than the LA which determined the specificity of the method. The % RSD of < 2% after periods of 12 24 36 48 and 72 h determined the stability of standard LA.
Thus the fingerprinting method is valuable in determining the adulterants and in routine quality control of formulations and herbal drugs.