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
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生物材料学
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产品关联
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
✓ 已验证
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
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2019
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IF 4.046
Bo Liang,Kai Shi,Yanfang Niu,Zhengchun Liu,Jianlong Zheng
Styrene-butadiene-styrene (SBS)-modified asphalt plays an integral role in asphalt pavements. To facilitate the understanding of the correlations between the physical and chemical properties of asphalt cement and SBS , a method for the direct quantitative determination of the SBS modification mechanism via potentiometric titration is proposed. This method will theoretically guide the processing design of SBS-modified asphalts. Potentiometric titration is applied to investigate the unsaturation of SBS-mixed, SBS-modified, and SBS/sulfur-modified asphalts with different SBS dosages ranging from 0% to 10%. The unsaturation of SBS-mixed asphalt exhibits a good linear increase with an increase in SBS dosage. A noticeable loss of SBS unsaturation occurs in SBS- and SBS/sulfur-modified asphalts after undergoing complete modification. In addition, unsaturation presents an evident inflection point at approximately 5 wt% SBS with an increase in SBS dosage. This finding indicates SBS changing from a dispersed phase to a continuous phase in the modified asphalts. Remarkably, the addition of sulfur can accelerate the emergence of an inflection point. Results corroborate that various types of virgin asphalt exhibit different inflection points. SBS/sulfur-modified asphalt demonstrates stronger chemical cross-linking than SBS-modified asphalt. These findings are further confirmed via fluorescence imaging, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Potentiometric titration potentially provides a direct quantitative method for probing the modification mechanism of and designing customized processing for SBS-modified asphalts.
研究领域:
材料科学
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化学工程
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DOI
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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产品关联
DOI
高影响因子
JOURNAL OF PHYSICAL CHEMISTRY B
·
2016
·
IF 3.187
Bijun Liu,Lan Dong,Qianhong Yu,Xingliang Li,Fengchang Wu,Zhaoyi Tan,Shunzhong Luo
Glyphosate [N-(phosphonomethyl)glycine] has been described as the ideal herbicide because of its unique properties. There is some conflicting information concerning the structures and conformations involved in the protonation process of glyphosate. Protonation may influence the chemical and physical properties of glyphosate, modifying its structure and the chemical processes in which it is involved. To better understand the species in solution associated with changes in pH, thermodynamic study (potentiometry, calorimetry and NMR spectroscopy) about the protonation pathway of glyphosate is performed. Experimental results confirmed that the order of successive protonation sites of totally deprotonated glyphosate is phosphonate oxygen, amino nitrogen, and finally carboxylate oxygen. This trend is in agreement with the most recent theoretical work in the literature on the subject ( J. Phys. Chem. A 2015,, 119, 5241−5249). The result is important because it confirms that the protonated site of glyphosate in pH range 7–8, is not on the amino but on the phosphonate group instead. This corrected information can improve the understanding of the glyphosate chemical and biochemical action.
研究领域:
化学
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环境科学
·
生物学
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产品关联
DOI
PubMed
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2015
·Vol. 25
·期 30
·4867-4873
·
IF 11.805
Yunlong Li,Weihai Sun,Weibo Yan,Senyun Ye,Haitao Peng,Zhiwei Liu,Zuqiang Bian,Chunhui Huang
Solution-processable hybrid perovskite solar cells are a new member of next generation photovoltaics. In the present work, a low-temperature two-step dipping method is proposed for the fabrication of CH 3 NH 3 PbI 3- x Cl x perovskite films on the indium tin oxide glass/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) substrate. The bandgaps of the CH 3 NH 3 PbI 3- x Cl x perovskite films are tuned in the range between 1.54 and 1.59 eV by adjusting the PbCl 2 mole fraction ( n Cl /( n Cl + n I )) in the initial mixed precursor solution from 0.10 to 0.40. The maximum chlorine mole fraction measured by a unique potentiometric titration method in the produced CH 3 NH 3 PbI 3- x Cl x films can be up to 0.220 ± 0.020 ( x = 0.660 ± 0.060), which is much higher than that produced by a one-step spin-coating method (0.056 ± 0.015, x = 0.17 ± 0.04). The corresponding solar cell with the CH 3 NH 3 PbI 2.34±0.06 Cl 0.66±0.06 perovskite film sandwiched between PEDOT:PSS and C 60 layers exhibits a power conversion efficiency as high as 14.5%. Meanwhile, the open-circuit potential ( V oc ) of the device reaches 1.11 V, which is the highest V oc reported in the perovskite solar cells fabricated on PEDOT:PSS so far.
研究领域:
材料科学
·
能源科学
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DOI
高影响因子
JOURNAL OF CHEMICAL THERMODYNAMICS
·
2020
·
IF 2.888
Minghui Xu,Valeri Smolenski,Qi Liu,Alena Novoselova,Kewei Jiang,Jing Yu,Jingyuan Liu,Rongrong Chen,Hongsen Zhang,Milin Zhang,Jun Wang
The interaction of oxygen and cerium-free ions in molten 3LiCl-2KCl eutectic in the temperature range of (723–823) K was studied by the method of potentiometric titration using YZME electrodes. Stable states of cerium compounds in the Ce–O system and the mechanism of interaction of Ce 3+ with O 2− ions have been established. The solubility constants of cerium oxychloride and oxide compounds at different temperatures were determined. Principal thermodynamic data of CeOCl and Ce 2 O 3 were calculated. The Pourbaix (potential-pO 2− ) diagram was drawn and summarizes the properties of stable cerium species in the melt.
研究领域:
化学
·
材料科学
✓ 已验证
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2023
·Vol. 47
·期 18
·8499-8506
·
IF 3.3
Huanhuan Liu,Qian Liu,Youshi Lan,Di Wang,Lifeng Zhang,Xian Tang,Suliang Yang,Zhifu Luo,Guoxin Tian
The speciation of borate has been studied by potential titration in 0.5 M NaClO4 and Raman spectroscopic titration at 25 °C. Five borate species including B(OH)4−, B3O3(OH)4−, B5O6(OH)4−, B3O3(OH)52−, and B4O5(OH)42− along with boric acid, H3BO3, are identified, and the corresponding formation constants are determined accordingly in the solutions with initial boron concentrations between 0.01 and 0.7 M. The attributions for the Raman shifts of the spectra at 874 cm−1 to the ν1 vibrational mode of B(OH)3, 741 cm−1 to ν1 of B(OH)4−, 610 cm−1 to ν1 of B3O3(OH)4−, 525 cm−1, 760 cm−1, 915 cm−1, and 994 cm−1 to ν1, ν2, ν4, and ν3 of B5O6(OH)4−, 612 cm−1 to ν1 of B3O3(OH)52−, and 563 cm−1 (ν1a) and 938 cm−1 (ν1b) to B4O5(OH)42− are made by combining the speciation from potential titrations and deconvolution of Raman spectra with DFT calculations.
研究领域:
分析化学
·
物理化学
·
计算化学
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产品关联
DOI
高影响因子
Current Research in Food Science
·
2022
·
IF 6.269
Mang-Mang Li,Yi-Ting Chen,Jin-Cang Ruan,Wen-Jun Wang,Ji-Guang Chen,Qing-Feng Zhang
Lipase is a very important digestive enzyme for triglyceride absorption in vivo. The inhibitory activities of 26 dietary flavonoids, including flavone, flavanone, isoflavone and flavanol, on lipase were determined. Flavone exhibited stronger inhibitory activity than other types of flavonoids. Among them, luteolin exhibited the strongest inhibitory activity with IC50 value of 99 ± 11 μM, followed by quercetin and baicalein. The binding affinity of these flavonoids with lipase was investigated by fluorescence titration method. The binding affinity of flavones was stronger than flavanones, and was linearly positively correlated with their inhibitory activity. The binding of flavones on lipase caused the blue-shift of fluorescence, while flavanones caused red-shift. The analysis of structure-activity relationship of flavonoids on lipase revealed that the structure of C ring is very crucial. The hydrogenation of C2=C3 bond and the absence of C=O group in C ring both caused significant decrease of inhibitory activity. Besides, the hydroxylation on ring A and B of flavones increased the activity, while glycosylation weakened the activity. Molecular docking analysis confirmed that C2=C3 bond in C ring of flavones increases the π-conjugation and contributes to maintaining the planarity of flavonoid structure, which favour its Pi-Pi interaction with lipase.
研究领域:
药理学
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生物化学
·
营养学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF CHROMATOGRAPHY A
·
2012
·
IF 4.531
Jin-Feng Zhong,Xin-Sheng Chai,Hui-Chao Hu,Shi-Yu Fu
This paper reports on a headspace gas chromatographic method (HS-GC) for rapid determination of degree of substitution in succinic anhydride (SA) modified celluloses. The method is based on the reaction between the carboxyl groups in SA modified cellulose and bicarbonate solution in a closed headspace sample vial. The CO 2 released from the reaction was measured by HS-GC. The completion of the reaction was achieved within 25 min at 80 °C when a small sample size (<20 mg) was used. The relative standard deviation (RSD) measurement of precision was less than 4.1%, and the results were within 8.0% of those obtained with the traditional titration for determining the degree of substitution. The present method is simple, practical, automated, and suitable for use in anhydride modified cellulose research.
研究领域:
分析化学
·
材料科学
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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
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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