Supramolecular Interaction of Gliclazide with Cucurbit[7]uril and its Analytical Application

2013 ◽  
Vol 66 (6) ◽  
pp. 701 ◽  
Author(s):  
Guang-Quan Wang ◽  
Yan-Fang Qin ◽  
Li-Ming Du ◽  
Yun-Long Fu
Keyword(s):  
Aqueous Solution ◽  
Fluorescence Intensity ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Therapeutic Monitoring ◽  
Stable Complex ◽  
Good Precision ◽  
Supramolecular Interaction ◽  
Pharmaceutical Dosage Forms ◽  
Fluorescent Probe Method

Gliclazide (GLZ) is non-fluorescent in aqueous solution. This property makes its determination through direct fluorescent methods impossible. Palmatine (PAL) exhibits very weak fluorescence emissions in aqueous solution. However, in acidic media at room temperature, PAL can react with cucurbit[7]uril (CB[7]) to form a stable complex and the fluorescence intensity of the complex is greatly enhanced. Dramatic quenching of the fluorescence intensity of the CB[7]–PAL complex was observed with the addition of GLZ. The competing reactions and the supramolecular interaction mechanisms between GLZ and PAL as they fight for occupancy of the CB[7] cavity were studied using spectrofluorimetry, 1H NMR spectroscopy, and molecular modelling calculations. The association constants of the complexes formed between the host and the guest were determined. Based on the significant quenching of the supramolecular complex fluorescence intensity, a fluorescent probe method of high sensitivity was developed to determine GLZ in its pharmaceutical dosage forms and in human plasma with good precision and accuracy. The linear range of the method was from 0.003 to 2.100 μg mL–1. The limit of detection was 0.001 μg mL–1. This shows that the proposed method has promising potential for therapeutic monitoring and pharmacokinetics and for clinical application.

scholarly journals Citric Acid Capped CdS Quantum Dots for Fluorescence Detection of Copper Ions (II) in Aqueous Solution

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 32 ◽  
Author(s):  
Zhezhe Wang ◽  
Xuechun Xiao ◽  
Tong Zou ◽  
Yue Yang ◽  
Xinxin Xing ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Quantum Dots ◽  
Citric Acid ◽  
Limit Of Detection ◽  
Copper Ions ◽  
High Sensitivity ◽  
Fluorescence Sensor ◽  
Cds Quantum Dots ◽  
Detection Range ◽  
Cds Qds

Citric acid capped CdS quantum dots (CA-CdS QDs), a new assembled fluorescent probe for copper ions (Cu2+), was synthesized successfully by a simple hydrothermal method. In this work, the fluorescence sensor for the detection of heavy and transition metal (HTM) ions has been extensively studied in aqueous solution. The results of the present study indicate that the obtained CA-CdS QDs could detect Cu2+ with high sensitivity and selectivity. It found that the existence of Cu2+ has a significant fluorescence quenching with a large red shifted (from greenish-yellow to yellowish-orange), but not in the presence of 17 other HTM ions. As a result, Cu2S, the energy level below the CdS conduction band, could be formed at the surface of the CA-CdS QDs and leads to the quenching of fluorescence of CA-CdS QDs. Under optimal conditions, the copper ions detection range using the synthesized fluorescence sensor was 1.0 × 10‒8 M to 5.0 × 10‒5 M and the limit of detection (LOD) is 9.2 × 10‒9 M. Besides, the as-synthesized CA-CdS QDs sensor exhibited good selectivity toward Cu2+ relative to other common metal ions. Thus, the CA-CdS QDs has potential applications for detecting Cu2+ in real water samples.

scholarly journals High-Performance Thin-Layer Chromatography with Densitometry for the Determination of Ciprofloxacin and Impurities in Drugs

2005 ◽  
Vol 88 (5) ◽  
pp. 1530-1536 ◽  
Author(s):  
Jan Krzek ◽  
Urszula Hubicka ◽  
Justyna Szczepańczyk
Keyword(s):  
Thin Layer ◽  
High Performance ◽  
Limit Of Detection ◽  
Degradation Products ◽  
Pharmaceutical Preparations ◽  
High Sensitivity ◽  
Good Precision ◽  
Relative Standard ◽  
Tlc Plates ◽  
Quantitative Analyses

Abstract A thin-layer chromatographic (TLC)-densitometric method has been developed for identification and quantification of ciprofloxacin (Rf = 0.61) and an ethylenediamine compound (Rf = 0.42), a desfluoro compound (Rf = 0.48), by-compound A (Rf = 0.53), and fluoroquinolonic acid (Rf = 0.68) as ciprofloxacin degradation products in pharmaceutical preparations. By using chloroform–methanol–25% ammonia (43 + 43 + 14, v/v/v) as the mobile phase and silica gel 60 F254 high-performance TLC plates as the stationary phase, it was possible to separate individual constituents that, when subjected to ultraviolet (UV) densitometric analysis at 330 nm for fluoroquinolonic acid and 277 nm for the other compounds, gave well developed peaks allowing easy qualitative and quantitative analyses. DMSO–methanol (1 + 1) was used to extract drug constituents. The method showed high sensitivity (limit of detection 10 to 44 ng), a wide linearity range (3 to 20 μg/mL), and good precision (2.32 to 6.46% relative standard deviation) and accuracy (percentage recoveries 98.62 to 101.52%) for individual constituents.

Validated green chromatographic methods for determination of amlodipine and celecoxib in presence of methylacetophenone

Bioanalysis ◽  
2021 ◽  
Author(s):  
Marco M Z Sharkawi ◽  
Norhan R Mohamed ◽  
Mohammed T El-Saadi ◽  
Noha H Amin
Keyword(s):  
Aqueous Solution ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Amlodipine Besylate ◽  
Rapid Methods ◽  
Ich Guidelines ◽  
Layer Chromatography

Aim: Green, accurate and rapid methods, namely LC–MS/MS and thin layer chromatography-densitometric methods, were developed for determination of amlodipine besylate and celecoxib in presence of its process-related impurities, 4-methylacetophenone in pure and formulated tablets. Results: LC–MS/MS was achieved on ZORBAX Eclipse Plus C18 column using methanol: aqueous solution of 5 mM formic acid (95:5 v/v). High sensitivity with low limit of detection values 0.00028, 0.00027 and 0.0003 for amlodipine, celecoxib and 4-methylacetophenone, respectively were obtained. While, thin layer chromatography-densitometric was established using methanol: water: ammonia (70: 25: 1.5, by volume). Good linearity was obtained in the range of 0.1–10 μg/band, 1–150 μg/band and 0.01–2 μg/band for amlodipine, celecoxib and 4-methylacetophenone, respectively. Conclusion: The proposed method validation was achieved according to ICH guidelines. Those methods possess advantages of being ecofriendly methods which permit their application in quality control laboratories.

scholarly journals Torsemide Analysis Using Derivative Spectrophotometric Methods

2020 ◽  
Vol 11 (SPL4) ◽  
pp. 1847-1852
Author(s):  
Noon AA Kamil ◽  
Shaza W Shantier ◽  
Elrasheed A Gadkariem
Keyword(s):  
Aqueous Solution ◽  
Good Precision ◽  
Pharmaceutical Dosage Forms ◽  
Spectrophotometric Methods ◽  
New Methods ◽  
Stability Indicating Method ◽  
First Order Kinetics ◽  
Ich Guidelines ◽  
The Stability ◽  
Effect Of Light

An accurate stability-indicating method has been developed for the analysis of Torsemide (TOR) in bulk and pharmaceutical dosage forms. The methods used the zero-order spectrum (0D) of TOR aqueous solution (measured at 285 nm) and the instrumentally differentiated first (1D) and second (2D) derivative spectra (measured at 311 nm and 282 nm, respectively). The effect of light, acid (HCL) and alkali (NaOH) on the stability of TOR were studied using the new methods. ICH guidelines were used to validate the new methods. Regression analysis of Beer's plots showed a good correlation coefficient not less than 0.998. These methods reported great inter-day and intra-day precision. Excipients interference was not detected due to the achievement of good recovery percentages (97.60 - 101.45 ± 2.7 %, n=3). Good assay results ranged from 99.0 ± 1.7% to 100.0 ± 2.5%; the developed methods obtained n=3. The 2D model proved its ability to be used as a stability indication method of TOR analysis. TOR was unstable in acids and bases with or without heating. Its degradation follows the first-order kinetics. However, its aqueous solution was proved to be stable under sunlight. The established methods demonstrated good precision, sensitivity and accuracy at 95% confidence level.

Determination of Epsilon Aminocaproic Acid Based on Charge Transfer Complexation with p-Nitrophenlol by Spectrophotometry

2020 ◽  
Vol 16 ◽  
Author(s):  
Sheng-Yun Li ◽  
Fang Tian
Keyword(s):  
Charge Transfer ◽  
Aminocaproic Acid ◽  
Concentration Limit ◽  
Official Method ◽  
Good Precision ◽  
Pharmaceutical Dosage Forms ◽  
Relative Standard ◽  
A Charge ◽  
Epsilon Aminocaproic Acid

: A spectrophotometry was investigated for the determination of epsilon aminocaproic acid (EACA) with p-nitrophenol (PNP). The method was based on a charge transfer (CT) complexation of this drug as n-electron donor with π-acceptor PNP. Experiment indicated that the CT complexation was carried out at room temperature for 10 minutes in dimethyl sulfoxide solvent. The spectrum obtained for EACA/PNP system showed the maximum absorption band at wavelength of 425 nm. The stoichiometry of the CT complex was found to be 1:1 ratio by Job’s method between the donor and the acceptor. Different variables affecting the complexation were carefully studied and optimized. At the optimum reaction conditions, Beer’s law was obeyed in a concentration limit of 1～6 µg mL-1. The relative standard deviation was less than 2.9%. The apparent molar absoptivity was determined to be 1.86×104 L mol-1cm-1 at 425 nm. The CT complexation was also confirmed by both FTIR and 1H NMR measurements. The thermodynamic properties and reaction mechanism of the CT complexation have been discussed. The developed method could be applied successfully for the determination of the studied compound in its pharmaceutical dosage forms with a good precision and accuracy compared to official method as revealed by t- and F-tests.

scholarly journals A Novel Thiosemicarbazide-Based Fluorescent Chemosensor for Hypochlorite in Near-Perfect Aqueous Solution and Zebrafish

Chemosensors ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 65
Author(s):  
Minji Lee ◽  
Donghwan Choe ◽  
Soyoung Park ◽  
Hyeongjin Kim ◽  
Soomin Jeong ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Reactive Oxygen Species ◽  
Aqueous Solution ◽  
Fluorescence Quenching ◽  
Limit Of Detection ◽  
Fluorescent Sensor ◽  
Ionization Mass ◽  
Oxygen Species ◽  
Marked Selectivity ◽  
Uv Visible

A novel thiosemicarbazide-based fluorescent sensor (AFC) was developed. It was successfully applied to detect hypochlorite (ClO−) with fluorescence quenching in bis-tris buffer. The limit of detection of AFC for ClO− was analyzed to be 58.7 μM. Importantly, AFC could be employed as an efficient and practical fluorescent sensor for ClO− in water sample and zebrafish. Moreover, AFC showed a marked selectivity to ClO− over varied competitive analytes with reactive oxygen species. The detection process of AFC to ClO− was illustrated by UV–visible and fluorescent spectroscopy and electrospray ionization–mass spectrometry (ESI–MS).

scholarly journals Highly sensitive detection of nitrobenzene by a series of fluorescent 2D zinc(ii) metal–organic frameworks with a flexible triangular ligand

RSC Advances ◽  
2021 ◽  
Vol 11 (39) ◽  
pp. 23975-23984
Author(s):  
Xue Yang ◽  
Yixia Ren ◽  
Hongmei Chai ◽  
Xiufang Hou ◽  
Zhixiang Wang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Metal Organic Frameworks ◽  
High Sensitivity ◽  
Fluorescent Sensors ◽  
Sensitive Detection ◽  
Donor Ligands ◽  
Highly Sensitive ◽  
Metal Organic ◽  
Highly Sensitive Detection

Four fluorescent 2D Zn-MOFs based on a flexible triangular ligand and linear N-donor ligands are hydrothermally prepared and used to detect nitrobenzene in aqueous solution with high sensitivity, demonstrating their potential as fluorescent sensors.

scholarly journals Ratiometric Fluorescent Biosensors for Glucose and Lactate Using an Oxygen-Sensing Membrane

Biosensors ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 208
Author(s):  
Hong Dinh Duong ◽  
Jong Il Rhee
Keyword(s):  
Limit Of Detection ◽  
Oxygen Sensing ◽  
High Sensitivity ◽  
Glucose Sensing ◽  
Oxidation Reactions ◽  
Lactate Oxidase ◽  
Lactate Oxidation ◽  
Detection Range ◽  
Quenching Effect ◽  
Sensing Membrane

In this study, ratiometric fluorescent glucose and lactate biosensors were developed using a ratiometric fluorescent oxygen-sensing membrane immobilized with glucose oxidase (GOD) or lactate oxidase (LOX). Herein, the ratiometric fluorescent oxygen-sensing membrane was fabricated with the ratio of two emission wavelengths of platinum meso-tetra (pentafluorophenyl) porphyrin (PtP) doped in polystyrene particles and coumarin 6 (C6) captured into silica particles. The operation mechanism of the sensing membranes was based on (i) the fluorescence quenching effect of the PtP dye by oxygen molecules, and (ii) the consumption of oxygen levels in the glucose or lactate oxidation reactions under the catalysis of GOD or LOX. The ratiometric fluorescent glucose-sensing membrane showed high sensitivity to glucose in the range of 0.1–2 mM, with a limit of detection (LOD) of 0.031 mM, whereas the ratiometric fluorescent lactate-sensing membrane showed the linear detection range of 0.1–0.8 mM, with an LOD of 0.06 mM. These sensing membranes also showed good selectivity, fast reversibility, and stability over long-term use. They were applied to detect glucose and lactate in artificial human serum, and they provided reliable measurement results.

scholarly journals Ag nanoparticles outperform Au nanoparticles for the use as label in electrochemical point-of-care sensors

2021 ◽  
Author(s):  
Franziska Beck ◽  
Carina Horn ◽  
Antje J. Baeumner
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Automatic Measurement ◽  
High Sensitivity ◽  
Differential Pulse ◽  
Small Sample ◽  
Blood Protein ◽  
User Friendliness ◽  
Response Curves ◽  
Assay Protocol

AbstractElectrochemical immunosensors enable rapid analyte quantification in small sample volumes, and have been demonstrated to provide high sensitivity and selectivity, simple miniaturization, and easy sensor production strategies. As a point-of-care (POC) format, user-friendliness is equally important and most often not combinable with high sensitivity. As such, we demonstrate here that a sequence of metal oxidation and reduction, followed by stripping via differential pulse voltammetry (DPV), provides lowest limits of detection within a 2-min automatic measurement. In exchanging gold nanoparticles (AuNPs), which dominate in the development of POC sensors, with silver nanoparticles (AgNPs), not only better sensitivity was obtained, but more importantly, the assay protocol could be simplified to match POC requirements. Specifically, we studied both nanoparticles as reporter labels in a sandwich immunoassay with the blood protein biomarker NT-proBNP. For both kinds of nanoparticles, the dose-response curves easily covered the ng∙mL−1 range. The mean standard deviation of all measurements of 17% (n ≥ 4) and a limit of detection of 26 ng∙mL−1 were achieved using AuNPs, but their detection requires addition of HCl, which is impossible in a POC format. In contrast, since AgNPs are electrochemically less stable, they enabled a simplified assay protocol and provided even lower LODs of 4.0 ng∙mL−1 in buffer and 4.7 ng∙mL−1 in human serum while maintaining the same or even better assay reliability, storage stability, and easy antibody immobilization protocols. Thus, in direct comparison, AgNPs clearly outperform AuNPs in desirable POC electrochemical assays and should gain much more attention in the future development of such biosensors.

Analytical assessment of ortho clinical diagnostics high-sensitivity cardiac troponin I assay

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Peter A. Kavsak ◽  
Tara Edge ◽  
Chantele Roy ◽  
Paul Malinowski ◽  
Karen Bamford ◽  
...  
Keyword(s):  
Cardiac Troponin ◽  
Troponin I ◽  
Limit Of Detection ◽  
Clinical Performance ◽  
Characteristic Curve ◽  
Area Under The Curve ◽  
High Sensitivity ◽  
Cardiac Troponin I ◽  
Clinical Diagnostics ◽  
Ortho Clinical Diagnostics

AbstractObjectivesTo analytically evaluate Ortho Clinical Diagnostics VITROS high-sensitivity cardiac troponin I (hs-cTnI) assay in specific matrices with comparison to other hs-cTn assays.MethodsThe limit of detection (LoD), imprecision, interference and stability testing for both serum and lithium heparin (Li-Hep) plasma for the VITROS hs-cTnI assay was determined. We performed Passing-Bablok regression analyses between sample types for the VITROS hs-cTnI assay and compared them to the Abbott ARCHITECT, Beckman Access and the Siemens ADVIA Centaur hs-cTnI assays. We also performed Receiver-operating characteristic curve analyses with the area under the curve (AUC) determined in an emergency department (ED)-study population (n=131) for myocardial infarction (MI).ResultsThe VITROS hs-cTnI LoD was 0.73 ng/L (serum) and 1.4 ng/L (Li-Hep). Stability up to five freeze-thaws was observed for the Ortho hs-cTnI assay, with the analyte stability at room temperature in serum superior to Li-Hep with gross hemolysis also affecting Li-Hep plasma hs-cTnI results. Comparison of Li-Hep to serum concentrations (n=202), yielded proportionally lower concentrations in plasma with the VITROS hs-cTnI assay (slope=0.85; 95% confidence interval [CI]:0.83–0.88). In serum, the VITROS hs-cTnI concentrations were proportionally lower compared to other hs-cTnI assays, with similar slopes observed between assays in samples frozen <−70 °C for 17 years (ED-study) or in 2020. In the ED-study, the VITROS hs-cTnI assay had an AUC of 0.974 (95%CI:0.929–0.994) for MI, similar to the AUCs of other hs-cTn assays.ConclusionsLack of standardization of hs-cTnI assays across manufacturers is evident. The VITROS hs-cTnI assay yields lower concentrations compared to other hs-cTnI assays. Important differences exist between Li-Hep plasma and serum, with evidence of stability and excellent clinical performance comparable to other hs-cTn assays.

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