MEASUREMENT
·
2017
·
IF 2.359
Xuzhi Zhang,Mengshi Huang,Jun Zhao,Jingquan Liu,Wenrong Yang,Keming Qu
Herein, an approach for versatile titration by monitoring the chemical reaction process with a developed capacitively coupled contactless conductivity detector (C 4 D) was developed. A disposable glass reaction cell, in which sub-milliliter titrand was loaded, was inserted into the working head stage of the C 4 D. Upon addition of titrant, the ionic strength and/or mobility of components in the solution changed, causing consequently change of conductivity. The C 4 D monitored the change in real time. A V-shaped titration curve was gained, allowing an easy identification of the endpoint. Between the elapsed time and the initial concentration of titrand, linear relationships were found for classical acid-base, precipitation, complexation and redox reaction over certain ranges, enabling the establishment of quantitative determinations. The new approach had a few charming advantages (e.g. simplicity and cost effectiveness) over contact electrochemical methods because that the solution was isolated from the working electrodes. Therefore, a development of versatile and multifunctional platform for micro-titrations is promising.
研究领域:
分析化学
·
电化学
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DOI
高影响因子
TALANTA
·
2021
·
IF 6.057
Yue Sun,Zhenzi Xu,Feifang Zhang,Zongying Li,Bingcheng Yang
We describe a reagent-free acid-base titration method, in which only water is added and the titrant is online electrodialytically produced. Electrodialytic eluent generator, a well-established technique in ion chromatography to produce high purity base or acid eluent through precise control of an electric current, has been for the first time used for titration, termed as electrodialytic titrant generator (ETG). Three kinds of titrants produced by ETG have been demonstrated, including potassium hydroxide , methanesulfuric acid and sulfuric acid. A series of titrants with different concentration up to at least 140 mM (e.g. KOH) could be accurately and reproducibly obtained by manipulating current and the KOH titrant showed extremely high purity. The titration results achieved by ETG were in a good agreement with those obtained by the regular way and their ratio was in the range of 0.9918 and 1.0034. Good accuracy and precision were achieved for ETG titration, as indicated by 2.2% of relative error and 0.17% of relative standard error. Its utility was demonstrated to measure pKa-differentiated capacity of anion exchange resins .
研究领域:
分析化学
·
环境科学
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DOI
PubMed
高影响因子
CHEMICAL PAPERS
·
2023
·
IF 2.2
Zhang Lie-yuan,Liu Jie-guang,Han Ying,Zhang Shu-min,Jiang Long-fa,Zhan Chun-rui,Zeng Chen-hui,Wang Wen-jun
An automatic potentiometric setting dynamic pH titration method for the determination of sodium bicarbonate in compositions of smoke-type fireworks was developed. After wetting the sample with 0.1 mL ethanol, added 60 mL of deionized water for dissolution, ultrasound for 10 min, filtered and removed the insoluble matter, and then used a potentiometric titrator to drop 0.1 mol/L of hydrochloric acid. The experimental results showed that the limit of quantitation was 0.1%, the recoveries were 96.1–104.8% and the relative standard deviation was 0.56–3.11% when the sample weigh 0.2 g. The automatic potentiometric setting dynamic pH titration method is simple to operate and can accurately and quickly determine the content of sodium bicarbonate in compositions of smoke-type fireworks.
研究领域:
化学分析
·
烟花爆竹安全
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DOI
高影响因子
MICROCHEMICAL JOURNAL
·
2020
·
IF 3.594
Songyang Feng,Sheng Xiang,Xinchao Bian,Gao Li
In aqueous solutions of concentrated lactic acid (>30 wt%), oligomers of lactic acid can produce via the intermolecular esterification of lactic acid, and thus the amount of titratable acidity is often less than that of total acidity. In this paper, the hydrolysis of oligomers of lactic acid was investigated at different temperatures in detail. The experimental results showed that when the content of total acidity is lower than 30 wt% in aqueous lactic acid solutions, the oligomers of lactic acid can been completely hydrolyzed to give monomeric lactic acid and the monomeric lactic acid is stable at temperatures of 8–33 °C, thus the total acidity is equivalent to the titratable acidity and can be determined quantitatively by a direct potentiometric titration. The results for determining total acidities were in good agreement with those obtained from a back titration by a two tailed t -test. Compared with the back titration, the novel method's procedure is simpler and reducing sugars do not interfere with measurements. The relative standard deviation ( RSD ) was less than 0.7% and 1.1% for the direct potentiometric and back titrations, respectively, which indicated that the direct potentiometric titration has a higher precision.
研究领域:
分析化学
·
食品科学
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DOI
高影响因子
ADVANCES IN COLLOID AND INTERFACE SCIENCE
·
2023
·
IF 15.6
Marek Kosmulski
Surfaces are often characterized by their points of zero charge (PZC) and isoelectric points (IEP). Different authors use these terms for different quantities, which may be equal to the actual PZC under certain conditions. Several popular methods lead to results which are inappropriately termed PZC. This present review is limited to zero-points obtained in the presence of inert electrolytes (halides, nitrates, and perchlorates of the 1st group metals). IEP are reported for all kinds of materials. PZC of metal oxides obtained as common intersection points of potentiometric curves for 3 or more ionic strengths (or by means of equivalent methods) are also reported, while the apparent PZC obtained by mass titration, pH-drift method, etc. are deliberately neglected. The results published in the recent publications and older results overlooked in the previous compilations by the same author are reported. The PZC/IEP are accompanied by information on the temperature and on the nature and concentration of supporting electrolyte (if available). The references to previous reviews by the same author allow to compare the newest results with the PZC/IEP of similar materials from the older literature.
研究领域:
表面化学
·
胶体科学
·
材料科学
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DOI
PubMed
高影响因子
POLYMER TESTING
·
2019
·
IF 2.943
Ning Yan,Xiao-Fang Wan,Xin-Sheng Chai
This paper reports on a novel method for rapid determination of the degree of deacetylation (DD) of chitosan samples by headspace gas chromatography (HS-GC). In this method, overdose of an acid is added to protonate the free amino groups in chitosan, which further reacts with bicarbonate (as an alkali titrant) in a close vial. Based on measuring the HS-GC signal for CO 2 vs. the volume of HCO 3 − added by a stepwise titration, two transition points can be obtained. The DD value is calculated by net volume of HCO 3 − consumed, i.e., by the R NH 3 + groups in chitosan. The results showed that the present method has a good measurement precision (RSD < 0.82%) and accuracy (relative differences < 6.46% when compared with the results measured by a reference method). Since the HS-GC can perform an automated sample reaction equilibration and measurement, it could be much more efficient than the existing methods in the batch sample analysis.
研究领域:
分析化学
·
生物材料学
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产品关联
DOI
高影响因子
MICROCHEMICAL JOURNAL
·
2023
·
IF 4.8
Luo lixia,Ye ying,Wang hong,Liu zhe,Li Jiqian
A cholesteric chiral artificial receptor L5 was synthesized, which recognized and cooperated with Ag + in metal ions, and a rapid method for detecting Ag + was established in food. It was found by fluorescence spectroscopy analysis that the L5 could recognize Ag + in DMSO solution; with the help of fluorescence and UV titration, job test and interference test to verify its recognition pattern, and founded that the L5 and guest Ag + were combined with 1:1 coordination ratio. Then, the recognition mechanism between L5 and guest Ag + was explored by measures of nuclear magnetic titration, infrared spectroscopy, electron microscopy and computer molecular simulation. It was speculated that the carbonyl oxygen atom near the amide of the MeO-PhCONH group and the carbonyl oxygen atom of the –COOCH 3 group cooperated with Ag + throµgh electrostatic gravitational interaction. This method was used to establish the detection of Ag + in food in which the detection limit of L5 for Ag + was derived as 0.13 µmol/L, and the silver ions in wolfberry, milk powder,wheat flour, tea leaf and soybean were accurately detected. This method can be used to quantify Ag + content in actual samples accurately and efficiently.
研究领域:
化学
·
食品安全
·
分析化学
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DOI
高影响因子
Analytical Methods
·
2023
·Vol. 15
·期 24
·2971-2978
·
IF 3.1
Muhammad Idrees Khan,Qiang Zhang,Youli Tian,Shah Saud,Yiren Cao,Jicun Ren,Weiwen Liu,Chengxi Cao
Cholesterol (CHO) in human blood is one of the most frequently and crucially quantified substances in diagnostic laboratories. However, visual and portable point of care testing (POCT) methods have been rarely developed for the bioassay of CHO in blood samples. Here, we developed an electrophoresis titration (ET) model, a chip device of ∼60 grams, and a quantification method for the POCT of CHO in blood serum based on a moving reaction boundary (MRB). In this model, the selective enzymatic reaction is integrated with an ET chip for visual and portable quantification. At first, CHO reacted with cholesterol oxidase (CHOx) in the anode well, producing H2O2 and cholest-4-en-3-one in the solution. H2O2 further oxidized the colorless and chargeless leucocrystal violet (LCV) dye into violet colored positively charged crystal violet (CV+) and, under the influence of the electric field, the CV+ migrates in the ET channels and is titrated by the alkali of sodium hydroxide immobilized in the ET channels. The length covered by the MRB was measured as a function of the CHO content. The relevant experiments validated the feasibility of the model and method. Furthermore, the experiments revealed the high selectivity, portability, and visuality of the ET-MRB model, device, and method. Finally, the experiments showed a fair sensitivity of LOD of 5 μM, good linearity of 10–1000 μM (r2 = 0.9919), fair stability (intra-day RSD of less than 5.09% and an inter-day RSD of less than 6.36%), and high recovery (99.4–105%). All the data and results indicate the potential of the ET-MRB model, chip device, and method for POCT of CHO in human blood samples.
研究领域:
医学诊断
·
生物化学
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产品关联
DOI
PubMed
高影响因子
ANALYTICAL CHEMISTRY
·
2025
·
IF 6.7
Yu Kang,Yuan Zheng,Zi-Yi Zhang,Bin Li,Yao-Yang Liu,Yun-Hong Xie,Zhong-Feng Li,Xiao-Yan Tang,Jing Chen,Li Wang,Chao Xu
In situ characterization of coordination species and their evolution are crucial for effective lanthanide separation and recycling. Current technical approaches often operate under constrained conditions, requiring complex equipment, experimental setups, and sometimes intricate data interpretation. Herein, we demonstrate that carbon NMR titrations offer a valuable approach for in situ coordination analysis of lanthanides, particularly for highly fused preorganized ligands that offer more NMR-active carbons than traditional proton NMR. Two representative ligands of both lipophilic and hydrophilic in nature were investigated, and the resulting carbon NMR titration data were analyzed. Comparisons with IR and single-crystal data showed that NMR provided insights not only into the evolution of coordination species but also into changes in the electron distribution during complex formation. Additionally, we discussed inconsistencies between atomic charge populations obtained from carbon NMR and those from Mulliken and Hirshfeld calculations. With advancements in NMR technology and the availability of higher-field NMR instruments, we believe NMR titrations will play an increasingly significant role in unravelling the complex solution coordination chemistry of f-block elements.
研究领域:
化学
·
配位化学
·
材料科学
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DOI
PubMed
高影响因子
JOURNAL OF SOLUTION CHEMISTRY
·
2018
·Vol. 47
·期 4
·705-714
·
IF 1.401
Li Qiang,Liu Bijun,Mu Wanjun,Yu Qianhong,Tian Yin,Liu Guoping,Yang Yuchuan,Li Xingliang,Luo Shunzhong
Glufosinate, an analogue of glutamic acid (also known as phosphinothricin), is an important herbicide. The protonation constants of glufosinate were determined by means of potentiometric titrations at variable temperatures with ionic strength 0.5 mol·L −1 (NaCl solution). The heat effects of the protonation reactions of glufosinate were measured by direct calorimetry. NMR spectroscopies have demonstrated that the first protonation site occurs on the nitrogen atom in the amino group, followed by one of the oxygen atoms in the phosphono group, and finally the carboxyl oxygen atom. This trend is in good agreement with the enthalpy of protonation and crystal structure results. These data will help to predict the speciation of glufosinate in physiological systems.
研究领域:
植物学
·
化学
·
环境科学
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DOI
高影响因子
Analytical Methods
·
2018
·Vol. 10
·期 28
·3552-3556
·
IF 2.073
Zhe-Xuan Mu,Chuan-Shu He,Jian-Kai Jiang,Yang Mu
High ammonia nitrogen concentrations inhibit methanogenic activity and induce digester upset or failure. Therefore, it is essential to monitor the ammonium concentration in anaerobic systems. In this work, a fixed-point titration method was established to determine the ammonium concentration. This method was demonstrated to be effective with standard ammonium solutions, synthetic and practical reactor effluents, respectively. In addition, the effects of phosphate and ionic strength on titration accuracy were weak, while the interference of volatile fatty acids was inconspicuous. Considering its simplicity, accuracy and cost-effectiveness, the proposed titration method shows great potential for monitoring the ammonium concentration in practical applications.
研究领域:
环境科学
·
生物化学
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DOI
高影响因子
Journal of Sulfur Chemistry
·
2018
·
IF 1.32
Yanmei Chen,Xuefang Shang,Xing Zhao,Jie Li,Jianmei Yuan,Hongli Chen,Jinlian Zhang,Tianyun Wang
Two probes based on novel Copper(II) complexes were developed in order to obtain H2S molecular probes with higher selectivity. The molecular structures of the complexes were characterized by 1H NMR, HRMS, IR and elemental analysis. The interaction of the compounds with biologically important anions and amino acids was determined by UV-vis and Fluorescence titration experiments. Results indicated that the compounds showed the highest binding ability for HS− among studied anions (AcO−, H2PO4−, F−, Cl−, Br− and I−) and amino acids (GSH, HCys and Cys) accompanied by blue shift phenomenon in pure DMSO and aqueous solution. The possible mechanism of host–guest interaction may be that the Copper(II) ion of complex was captured by HS− and free ligand released which showed a remarkable changes in UV-vis absorption. In addition, cytotoxicity of the synthesized compounds was studied on MCF-7 cells. Results indicated that the synthesized compounds had low cytotoxicity over a concentration range of 0–150 µg⋅mL−1, which exhibited that the synthesized probes could be used to detect H2S in vivo.The probes based on novel copper(II) complexes were synthesized and obtained by the reaction of substituent salicylaldehyde with amine derivatives, and then reacted with Cu(CH3COO)2·H2O, respectively. Investigation on the interference from other species suggested that copper(II) complexes have high selectivity for HS− over other anions (AcO−, , F−, Cl−, Br− and I−), followed by the release of the copper ion to give a remarkable increase in UV–VIS absorption in pure DMSO solution and aqueous solution.
研究领域:
分析化学
·
生物化学
·
医学
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DOI
高影响因子
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