scholarly journals A Simple, Rapid, Fluorometric Assay for Dopamine by In Situ Reaction of Boronic Acids and cis-Diol

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaoxia Liu ◽  
Miaomiao Tian ◽  
Wenmei Gao ◽  
Jinzhong Zhao
Keyword(s):  
Low Cost ◽  
Boronic Acids ◽  
Emission Peak ◽  
Excitation Wavelength ◽  
Fluorescence Sensing ◽  
Serum Samples ◽  
Turn On ◽  
Rapid Reaction

An efficient, sensitive, and low-cost method has been developed for turn-on fluorescence sensing of dopamine (DA). The method relies on the rapid reaction of DA and 3-Hydroxyphenylboronic acid (3-HPBA) via specific recognition between boronic acids and cis-diol of DA in alkaline solution. The reaction product shows an excitation wavelength of 417 nm and the maximum emission peak at 470 nm. The proposed method allows the determination of DA in the range of 50 nM–25 μM, and the whole detection can be completed within 5 minutes. Furthermore, the presented approach has good selectivity and has been successfully applied to DA sensing in human serum samples, showing great potential in clinical diagnosis.

A “turn-on” small molecule fluorescent sensor for the determination of Al3+ ion in real samples: theoretical calculations, and photophysical and electrochemical properties

2021 ◽  
Vol 45 (39) ◽  
pp. 18400-18411
Author(s):  
Süreyya Oğuz Tümay ◽  
Ahmet Şenocak ◽  
Arif Mermer
Keyword(s):  
Small Molecule ◽  
Fluorescent Sensor ◽  
Theoretical Calculations ◽  
Sample Analysis ◽  
Fluorescence Sensing ◽  
Paper Test ◽  
Real Samples ◽  
Real Sample Analysis ◽  
Turn On

The fluorescence sensing properties of a naphthalene-based acetohydrazide (3) were investigated. A highly selective “turn-on” response was obtained towards Al3+ ions, and this was used for real sample analysis and development of paper test strips.

scholarly journals Preparation of Cerium Oxide-MWCNTs Nanocomposite Bulk Modified Carbon Ceramic Electrode: A Sensitive Sensor for Tamoxifen Determination in Human Serum Samples

2021 ◽  
Author(s):  
Sepideh Shafaei ◽  
Elyas Hosseinzadeh ◽  
Gulsah Saydan Kanberoglu ◽  
Balal Khalilzadeh ◽  
Rahim Mohammad-Rezaei
Keyword(s):  
Cerium Oxide ◽  
Limit Of Detection ◽  
Low Cost ◽  
High Electron ◽  
Range Limit ◽  
Serum Samples ◽  
Important Species ◽  
Carbon Ceramic Electrode ◽  
Carbon Ceramic

Abstract In this study, cerium oxide and multi-walled carbon nanotubes nanocomposite was incorporated into the carbon ceramic electrode (CeO2-MWCNTs/CCE) as a renewable electrode for the electrocatalytic purposes. To demonstrate capability of the fabricated electrode, determination of Tamoxifen as an important anticancer drug with differential pulse voltammetry technique was evaluated. Linear range, limit of detection and sensitivity of the developed sensor were found to be 0.2-40 nM, 0.132 nM and 1.478 µA nM-1 cm-2, respectively. Ease of production, low cost and high electron transfer rate of CeO2-MWCNTs/CCE promise it as a novel electro-analytical tool for determination of important species in real samples.

4-Amino-Benzo[F]Isoindole-1,3-Dione Derivatives As Turn-On Fluorescent Indicators For Water Determination In Acetonitrile

2018 ◽  
pp. 183-191
Author(s):  
R. Linnik ◽  
I. Levkov ◽  
A. Chemnyi ◽  
O. Radchenko ◽  
Z. Voitenko ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Linear Response ◽  
Emission Peak ◽  
Water Determination ◽  
Fluorescent Indicators ◽  
Turn On ◽  
Peak Intensity ◽  
Relative Standard ◽  
Acetonitrile Solutions

4-Amino-9-(2,5-dioxo-pyrrolidin-1-phenyl-3-yl)-1-phenyl-benzo[f]isoindole-1,3-dione (1) and 4-amino-9-(2,5- dioxo-1-(4-methylphenyl)-pyrrolidin-3-yl)-1-(4-methylphenyl)-benzo[f]isoindole-1,3-dione (2) were studied as fluorescent indicators for water determination in acetonitrile. The intensity of fluorescence of these compounds in acetonitrile solutions increases in presence of water along with red shift of the emission peak. Intensity-based and wavelength-based procedures of water determination in acetonitrile are suggested with detection limit of 0.2 % (v/v) H2O in both cases. The linear response covers a concentration range of 0.2–20 % (v/v). The relative standard deviation at 1 % (v/v) water content is 0.20. The interferences of acetic acid, ammonia and metal ions have been studied. Ammonia and acetic acid don’t interfere with the determination of water by wavelength-based fluorescence technique. In intensity-based mode the determination of water is possible at concentration of these impurities up to 0.25 and 0.02 mol·L -1, respectively. Cu(II) ions have almost no effect on fluorescence of indicators up to 1·10 -5 mol·L -1 ; Zn (II) ions enhance fluorescence of 1 at concentration ≥ 5·10-6 mol·L-1 . The 4-amino-benzo[f]- isoindole-1,3-dione-based fluorescent indicators are pH-insensitive.

scholarly journals Development and application of a portable instrument for drugs analysis in pharmaceutical preparations

2015 ◽  
Vol 51 (3) ◽  
pp. 699-708
Author(s):  
Paulo Roberto da Silva Ribeiro ◽  
Helena Redigolo Pezza ◽  
Leonardo Pezza ◽  
Liliane Spazzapam Lima ◽  
Matthieu Tubino
Keyword(s):  
Low Cost ◽  
Pharmaceutical Preparations ◽  
Pharmaceutical Products ◽  
Ammonium Molybdate ◽  
Quantitative Studies ◽  
Significant Difference ◽  
Drugs Analysis ◽  
And Performance

This article describes the application and performance of an inexpensive, simple and portable device for colorimetric quantitative determination of drugs in pharmaceutical preparations. The sensor is a light detector resistor (LDR) incorporated into a black PTFE cell and coupled to a low-cost multimeter (Ohmmeter). Quantitative studies were performed with captopril/p-chloranil/H2O2 and methyldopa/ammonium molybdate systems. Calibration curves were obtained by plotting the electrical resistance of the LDR against the concentration of the colored species in the ranges 1.84 × 10-4 to 1.29 × 10-3mol L-1 and 5.04 × 10-4 to 2.52 × 10-3 mol L-1 for captopril/p-chloranil/H2O2 and methyldopa/ammonium molybdate systems, respectively, exhibiting good coefficients of determination. Statistical analysis of the results obtained showed no significant difference between the proposed methodologies and the official reported methods, as evidenced by the t-test and variance ratio at a 95% confidence level. The results of this study demonstrate the applicability of the instrument for simple, accurate, precise, fast,in situ and low-cost colorimetric analysis of drugs in pharmaceutical products.

scholarly journals In Situ Determination of Urea in Milk Employing a Portable and Low-Cost LED Photometer

2017 ◽  
Vol 11 (4) ◽  
pp. 1149-1154
Author(s):  
Willian Toito Suarez ◽  
Benedito Roberto de Alvarenga Junior ◽  
Mathews de Oliveira Krambeck Franco ◽  
Wesley Lira Gabriel ◽  
Denílson Mendes de Oliveira ◽  
...  
Keyword(s):  
Low Cost ◽  
Led Photometer

CdS-Intercalated Bentonite/Carbon Composite as Electrode for Sulfide Ion

2010 ◽  
Vol 663-665 ◽  
pp. 690-693 ◽  
Author(s):  
Kemawadee Udomphan ◽  
Atchana Wongchaisuwat ◽  
Ladda Meesuk
Keyword(s):  
Aqueous Solution ◽  
Low Cost ◽  
Carbon Composite ◽  
Good Precision ◽  
Solid Reaction ◽  
Artificial Graphite ◽  
Bright Yellow ◽  
Photochemical Properties

CdS, a bright yellow precipitate is well known for its optical, electrical, electro-optical and photochemical properties. CdS has also been prepared in the interlayer spaces of layered materials such as laponite and montmorillonite (bentonite). Several properties of intercalated CdS have been studied, but for the best of our knowledge there is no reports on its use. In this work, we applied CdS-intercalated bentonite / carbon composite as an electrode for determination of S2- ion in aqueous solution. CdS- intercalated bentonite was prepared by the in situ solid-solid reaction between Cd(II)-bentonite and Na2S. To construct a potentiometric electrode, CdS-intercalated bentonite was mixed with artificial graphite, polytetrafluoroethylene (PTFE) and carboxymethylcellulose (CMC) in an appropriate ratio. The electrode was used to determine S2- in aqueous solution, graphs of log [S2-] vs measured voltage (mv) gave linear relation up to 3 orders of ion concentrations. Apart from the reproducibility and good precision, the electrode is good for its selectivity, durability and low cost.

Dual enzyme-responsive “turn-on” fluorescence sensing systems based on in situ formation of 7-hydroxy-2-iminocoumarin scaffolds

2015 ◽  
Vol 13 (41) ◽  
pp. 10348-10361 ◽  
Author(s):  
Sylvain Debieu ◽  
Anthony Romieu
Keyword(s):  
Domino Reactions ◽  
Fluorescence Sensing ◽  
Turn On ◽  
Sensing Systems ◽  
Fluorogenic Probes ◽  
In Situ Formation

We herein report a novel class of dual enzyme-responsive fluorogenic probes based on two orthogonal deprotection reactions via the “covalent assembly” principle. Sensing of two different enzymes (hydrolase and nitroreductase) through domino reactions, producing the push–pull backbone of a fluorescent 3-substituted 7-hydroxy-2-iminocoumarin dye, is reported.

scholarly journals Influential Factors and Determination of strength of in-situ concrete, using twist-off method.

2019 ◽  
Vol 7 (2) ◽  
Author(s):  
Pooria Najarbashi ◽  
Mahmoud Naderi
Keyword(s):  
Low Cost ◽  
Concrete Strength ◽  
Influential Factors ◽  
Laboratory Methods ◽  
Significant Difference ◽  
Site Evaluation ◽  
In Situ Methods ◽  
Very High

Concrete strength represents by far the most critical property of concrete. It represents the mechanical properties of concrete. On-site evaluation of concrete strength remains the fundamental challenge in the condition assessment of existing infrastructure. Although standard laboratory methods can be typically used but most of these testing methods are costly and time-consuming. Among the in-situ methods, the “twist-off ” method with very slight damage is genuinely a convenient, fast and also low-cost technique that provides accurate results for engineers. In this study, the twist-offmethod has been used for the assessment of in-situ strength of the 30 concrete structures in Qazvin in Iran. The results showed structures studied had a strength of 45 to 600 kg/cm2 and the average is about 200 kg/cm2. The observed variation is very high, as well as a significant difference between the compressive strength of the columns, and the floors of the buildings that all indicate non-standard concrete mixing and inadequate control over construction. However, according to the past experience and results of the samples, some recommendations in this regard have been suggested.

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