scholarly journals A Fluidics-Based Biosensor to Detect and Characterize Inhibition Patterns of Organophosphate to Acetylcholinesterase in Food Materials

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 397
Author(s):  
Dang Song Pham ◽  
Xuan Anh Nguyen ◽  
Paul Marsh ◽  
Sung Sik Chu ◽  
Michael P. H. Lau ◽  
...  
Keyword(s):  
Room Temperature ◽  
Current Flow ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Food Samples ◽  
Side Chain ◽  
Limit Of Quantification ◽  
Activity Inhibition ◽  
Lysine Side Chain ◽  
Sensing Platform

A chip-based electrochemical biosensor is developed herein for the detection of organophosphate (OP) in food materials. The principle of the sensing platform is based on the inhibition of dimethoate (DMT), a typical OP that specifically inhibits acetylcholinesterase (AChE) activity. Carbon nanotube-modified gold electrodes functionalized with polydiallyldimethylammonium chloride (PDDA) and oxidized nanocellulose (NC) were investigated for the sensing of OP, yielding high sensitivity. Compared with noncovalent adsorption and deposition in bovine serum albumin, bioconjugation with lysine side chain activation allowed the enzyme to be stable over three weeks at room temperature. The total amount of AChE was quantified, whose activity inhibition was highly linear with respect to DMT concentration. Increased incubation times and/or DMT concentration decreased current flow. The composite electrode showed a sensitivity 4.8-times higher than that of the bare gold electrode. The biosensor was challenged with organophosphate-spiked food samples and showed a limit of detection (LOD) of DMT at 4.1 nM, with a limit of quantification (LOQ) at 12.6 nM, in the linear range of 10 nM to 1000 nM. Such performance infers significant potential for the use of this system in the detection of organophosphates in real samples.

Catalytic activity of CuGHK peptide-based porous material

2021 ◽  
Author(s):  
Francisco G. Cirujano ◽  
Nuria Martin ◽  
Neyvis Almora-Barrios ◽  
Carlos Martí-Gastaldo
Keyword(s):  
Catalytic Activity ◽  
Porous Material ◽  
Active Sites ◽  
Room Temperature ◽  
Side Chain ◽  
Periodic Distribution ◽  
Lysine Side Chain ◽  
One Step

Room temperature one-step synthesis of the peptide-based porous material with a periodic distribution of pockets decorated with lysine side chain active sites behaves as a heterogeneous organocatalyst. The pockets are...

Core-shell Cu@C@ZIF-8 composite: a high-performance electrode material for electrochemical sensing of nitrite with high selectivity and sensitivity

2021 ◽  
Author(s):  
Feng Gao ◽  
Xiaolong Tu ◽  
Yongfang Yu ◽  
Yansha Gao ◽  
Jin Zou ◽  
...  
Keyword(s):  
High Performance ◽  
High Selectivity ◽  
Limit Of Detection ◽  
Metal Organic Framework ◽  
High Sensitivity ◽  
Electrochemical Sensing ◽  
Core Shell ◽  
Zeolitic Imidazolate Framework ◽  
Sensing Platform ◽  
The Difference

Abstract Herein, an efficient electrochemical sensing platform is proposed for selective and sensitive detection of nitrite on the basis of Cu@C@Zeolitic imidazolate framework-8 (Cu@C@ZIF-8) heterostructure. Core-shell Cu@C@ZIF-8 composite was synthesized by pyrolysis of Cu-metal-organic framework@ZIF-8 (Cu-MOF@ZIF-8) in Ar atmosphere on account of the difference of thermal stability between Cu-MOF and ZIF-8. For the sensing system of Cu@C@ZIF-8, ZIF-8 with proper pore size allows nitrite diffuse through the shell, while big molecules cannot, which ensures high selectivity of the sensor. On the other hand, Cu@C as electrocatalyst promotes the oxidation of nitrite, thereby resulting high sensitivity of the sensor. Accordingly, the Cu@C@ZIF-8 based sensor presents excellent performance for nitrite detection, which achieves a wide linear response range of 0.1 µM to 300.0 µM, and a low limit of detection (LOD) of 0.033 µM. In addition, the Cu@C@ZIF-8 sensor possesses excellent stability and reproducibility, and was employed to quantify nitrite in sausage samples with recoveries of 95.45-104.80%.

scholarly journals Development of the UV Spectrophotometric Method of Azithromycin in API and Stress Degradation Studies

2016 ◽  
Vol 68 ◽  
pp. 48-53 ◽  
Author(s):  
Sandip Bhimani ◽  
Gaurav Sanghvi ◽  
Trupesh Pethani ◽  
Gaurav Dave ◽  
Vishal Airao ◽  
...  
Keyword(s):  
Linear Relationship ◽  
Spectrophotometric Method ◽  
Phosphate Buffer ◽  
Macrolide Antibiotic ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Limit Of Quantification ◽  
Absorbance Maximum ◽  
Antibiotic Drug ◽  
Stress Degradation

Azithromycin (AZI) is a semi-synthetic macrolide antibiotic drug, effective against a wide variety of bacteria. The present study describes a simple, accurate, reproducible and precise UV Spectrophotometric method for the estimation of AZI (pH 6.8 Phosphate buffer). The absorbance maximum (λmax) for AZI was found to be 208nm. The method reveals high sensitivity, with linearity in the 10 µg/ml to 50 µg/ml range. The lower limit of detection was found to be 1.6µg/ml and the limit of quantification was found to be 5µg/ml. All the calibration curves demonstrated a linear relationship between the absorbance and concentration, with the correlation coefficient higher than 0.99. The % recovery was found to be 99.72%. AZI was also subjected to stress degradation under different conditions recommended by the International Conference on Harmonization (ICH).

scholarly journals Greener Monolithic Solid Phase Extraction Biosorbent Based on Calcium Cross-Linked Starch Cryogel Composite Graphene Oxide Nanoparticles for Benzo(a)pyrene Analysis

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6163
Author(s):  
Aree Choodum ◽  
Nareumon Lamthornkit ◽  
Chanita Boonkanon ◽  
Tarawee Taweekarn ◽  
Kharittha Phatthanawiwat ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Solid Phase Extraction ◽  
Limit Of Detection ◽  
Solid Phase ◽  
High Sensitivity ◽  
Rice Flour ◽  
Oxide Nanoparticles ◽  
Phase Extraction ◽  
Limit Of Quantification ◽  
Significant Difference

Benzo(a)pyrene (BaP) has been recognized as a marker for the detection of carcinogenic polycyclic aromatic hydrocarbons. In this work, a novel monolithic solid-phase extraction (SPE) sorbent based on graphene oxide nanoparticles (GO) in starch-based cryogel composite (GO-Cry) was successfully prepared for BaP analysis. Rice flour and tapioca starch (gel precursors) were gelatinized in limewater (cross-linker) under alkaline conditions before addition of GO (filler) that can increase the ability to extract BaP up to 2.6-fold. BaP analysis had a linear range of 10 to 1000 µgL−1 with good linearity (R2 = 0.9971) and high sensitivity (4.1 ± 0.1 a.u./(µgL−1)). The limit of detection and limit of quantification were 4.21 ± 0.06 and 14.04 ± 0.19 µgL−1, respectively, with excellent precision (0.17 to 2.45%RSD). The accuracy in terms of recovery from spiked samples was in the range of 84 to 110% with no significant difference to a C18 cartridge. GO-Cry can be reproducibly prepared with 2.8%RSD from 4 lots and can be reused at least 10 times, which not only helps reduce the analysis costs (~0.41USD per analysis), but also reduces the resultant waste to the environment.

scholarly journals Impedance Sensing Platform for Detection of the Food Pathogen Listeria monocytogenes

Electronics ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 347 ◽  
Author(s):  
Maria Chiriacò ◽  
Ilaria Parlangeli ◽  
Fausto Sirsi ◽  
Palmiro Poltronieri ◽  
Elisabetta Primiceri
Keyword(s):  
Listeria Monocytogenes ◽  
Foodborne Pathogens ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Foodborne Pathogen ◽  
High Sensitivity ◽  
Primary Objective ◽  
Field Application ◽  
Impedance Sensing ◽  
Sensing Platform

A great improvement in food safety and quality controls worldwide has been achieved through the development of biosensing platforms. Foodborne pathogens continue to cause serious outbreaks, due to the ingestion of contaminated food. The development of new, sensitive, portable, high-throughput, and automated platforms is a primary objective to allow detection of pathogens and their toxins in foods. Listeria monocytogenes is one common foodborne pathogen. Major outbreaks of listeriosis have been caused by a variety of foods, including milk, soft cheeses, meat, fermented sausages, poultry, seafood and vegetable products. Due to its high sensitivity and easy setup, electrochemical impedance spectroscopy (EIS) has been extensively applied for biosensor fabrication and in particular in the field of microbiology as a mean to detect and quantify foodborne bacteria. Here we describe a miniaturized, portable EIS platform consisting of a microfluidic device with EIS sensors for the detection of L. monocytogenes in milk samples, connected to a portable impedance analyzer for on-field application in clinical and food diagnostics, but also for biosecurity purposes. To achieve this goal microelectrodes were functionalized with antibodies specific for L. monocytogenes. The binding and detection of L. monocytogenes was achieved in the range 2.2 × 103 cfu/mL to 1 × 102 with a Limit of Detection (LoD) of 5.5 cfu/mL.

scholarly journals Dissolved Carbon Dioxide Sensing Platform for Freshwater and Saline Water Applications: Characterization and Validation in Aquaculture Environments

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5513
Author(s):  
J.P. Mendes ◽  
L. Coelho ◽  
B. Kovacs ◽  
J.M.M.M. de Almeida ◽  
C.M. Pereira ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Limit Of Detection ◽  
Saline Water ◽  
Light Emitting Diode ◽  
Limit Of Quantification ◽  
Acid Media ◽  
Dissolved Carbon ◽  
Sensing Platform ◽  
Dissolved Carbon Dioxide ◽  
Colorimetric Indicator

A sensing configuration for the real-time monitoring, detection, and quantification of dissolved carbon dioxide (dCO2) was developed for aquaculture and other applications in freshwater and saline water. A chemical sensing membrane, based on a colorimetric indicator, is combined with multimode optical fiber and a dual wavelength light-emitting diode (LED) to measure the dCO2-induced absorbance changes in a self-referenced ratiometric scheme. The detection and processing were achieved with an embeded solution having a mini spectrometer and microcontroller. For optrode calibration, chemical standard solutions using sodium carbonate in acid media were used. Preliminary results in a laboratory environment showed sensitivity for small added amounts of CO2 (0.25 mg·L−1). Accuracy and response time were not affected by the type of solution, while precision was affected by salinity. Calibration in freshwater showed a limit of detection (LOD) and a limit of quantification (LOQ) of 1.23 and 1.87 mg·L−1, respectively. Results in saline water (2.5%) showed a LOD and LOQ of 1.05 and 1.16 mg·L−1, respectively. Generally, performance was improved when moving from fresh to saline water. Studies on the dynamics of dissolved CO2 in a recirculating shallow raceway system (SRS+RAS) prototype showed higher precision than the tested commercial sensor. The new sensor is a compact and robust device, and unlike other sensors used in aquaculture, stirring is not required for correct and fast detection. Tests performed showed that this new sensor has a fast accurate detection as well as a strong potential for assessing dCO2 dynamics in aquaculture applications.

Red-Excitation Dispersive Raman Spectroscopy is a Suitable Technique for Solid-State Analysis of Respirable Pharmaceutical Powders

2005 ◽  
Vol 59 (3) ◽  
pp. 286-292 ◽  
Author(s):  
Reinhard Vehring
Keyword(s):  
Raman Spectroscopy ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Instrument Design ◽  
Background Suppression ◽  
Pharmaceutical Powders ◽  
Limit Of Quantification ◽  
Mass Fractions ◽  
Suitable Technique ◽  
Spray Dried

Dispersive Raman spectroscopy with excitation by a red diode laser is suitable for quantitative crystallinity measurements in powders for pulmonary drug delivery. In spray-dried mixtures of salmon calcitonin and mannitol, all three crystalline polymorphs of mannitol and amorphous mannitol were unambiguously identified and their mass fractions were measured with a limit of quantification of about 5%. The instrument design offered high sensitivity and adequate background suppression, resulting in a low limit of detection in the range of 0.01% to 1%. This spectroscopy method has significant advantages over established techniques regarding specificity, sensitivity, and sample requirements.

scholarly journals Electrochemical Applications for the Antioxidant Sensing in Food Samples Such as Citrus and Its Derivatives, Soft Drinks, Supplementary Food and Nutrients

2021 ◽  
Author(s):  
Ersin Demir ◽  
Hülya Silah ◽  
Nida Aydogdu
Keyword(s):  
Antioxidant Capacity ◽  
Analytical Methods ◽  
High Sensitivity ◽  
Differential Pulse ◽  
Food Samples ◽  
Electrochemical Methods ◽  
General Description ◽  
Range Limit ◽  
Healthy Individuals ◽  
Limit Of Quantification

Although there are many definitions of antioxidants, the most general description; antioxidants are carried a phenolic function in their structure and prevent the formation of free radicals or intercept from damage to the cell by scavenging existing radicals. Moreover, they are one of the most effective substances that contain essential nutrients for healthy individuals. The importance of these antioxidants, which have an incredible effect on the body and increase the body’s resistance, is increasing day by day for healthy individuals. Numerous studies have been carried out for antioxidants with excellent properties and however new, reliable, selective, sensitive and green analytical methods are sought for their determination at trace levels in food samples. Along with the latest developments, electrochemical methods are of great interest in the world of science because they are fast, reliable, sensitive and environmentally friendly. Electrochemical methods have been frequently applied to analyze antioxidant capacity in many nutrients samples found in different forms such as solid, liquid without any pretreatment applications in the last decade. Furthermore, these methods are preferred because of the short analysis time, the ability to lower detection limits, reduction in a solvent, high sensitivity, portability, low sample consumption, wide working range, and more economical than existing other traditional analytical methods. The antioxidant sensing applications by modern electrochemical methods such as cyclic, square wave, differential pulse, and combined with stripping voltammetric techniques were used to deduce antioxidant capacity (AC) in critical nutrients. Moreover, this chapter includes a description of the classification of electrochemical methods according to the working electrode type, dynamic working range, limit of determination (LOD), limit of quantification (LOQ), sample type, and using standard analyte and so forth for each voltammetric methods. While many articles applied for the determination of antioxidant sensing by electrochemistry have gained momentum in the last two decades, we focused on the studies conducted over the last 4 years in this chapter.

scholarly journals Development and Application of a New QuEChERS Method in UHPLC-QqQ-MS/MS to Detect Seven Biogenic Amines in Chinese Wines

Foods ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 552
Author(s):  
Shun-Yu Han ◽  
Lan-Lan Hao ◽  
Xiao Shi ◽  
Jian-Ming Niu ◽  
Bo Zhang
Keyword(s):  
Biogenic Amines ◽  
Storage Time ◽  
Limit Of Detection ◽  
Pearson Correlation ◽  
High Sensitivity ◽  
Gansu Province ◽  
Grape Variety ◽  
Limit Of Quantification ◽  
Toxic Dose ◽  
Relative Standard

The aim of this study was to develop and validate an improved, simple, and sensitive method for the simultaneous determination of seven types (cadaverine, CAD; hexylamine, HEX; histamine, HIS; phenylethylamine, PEA; putrescine, PUT; tyramine, TYR) of biogenic amines (BAs) in wine matrices. For this reason, a modified QuEChERS combined with ultra-performance liquid chromatography coupled to a triple quadrupole mass spectrometry (UHPLC-QqQ-MS/MS) method was investigated. The optimization of UHPLC-QqQ-MS/MS separation and QuEChERS procedure was performed. Under optimum conditions, the excellent chromatographic performance of the whole separation was accomplished within 6.3 min analyzing time. Meanwhile, the recoveries ranged from 77.2% to 101.7%, while relative standard deviation (RSD) remained between 0.0% and 9.4%. The limit of detection (LOD, 0.50–1.00 µg/L) and the limit of quantification (LOQ, 1.65–3.30 µg/L) were lower than those permitted by legislation in food matrices, which demonstrated the high sensitivity and applicability of this efficient method. This validated method was also applied in a pilot study to analyze BAs in 81 wine samples from Hexi Corridor Region (Gansu Province, Northwest China), CAD, HEX, HIS, PEA, PUT, and TYR were detected to varying degrees in the samples. However, when compared with the existing standards, the BAs in all 81 wine samples did not exceed the prescribed limit value or toxic dose (2–40 mg/L). Moreover, a statistical approach was also conducted using Pearson correlation analysis, and to evaluate their concentrations in terms of wine parameters (storage time, grape variety, wine type, and basic physicochemical index). The results showed that, among the seven kinds of BAs, the concentration of HIS had a certain correlation with alcoholic degree and grape variety. In addition, the level of PEA had a certain correlation with the wine pH and wine storage time. It is worth noting that this seems to be the first report regarding the application of QuEChERS-UHPLC-QqQ-MS/MS in the analysis of BAs in wine in this region.

scholarly journals Development of the High Sensitivity and Selectivity Method for the Determination of Histamine in Fish and Fish Sauce from Vietnam by UPLC-MS/MS

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Quang Hieu Tran ◽  
Thanh Tan Nguyen ◽  
Kim Phuong Pham
Keyword(s):  
Limit Of Detection ◽  
High Sensitivity ◽  
Fish Sauce ◽  
Limit Of Quantification ◽  
Fish Samples ◽  
The Matrix ◽  
Liquid Chromatography Tandem Mass ◽  
Sensitivity And Selectivity ◽  
Liquid Chromatographic

A selective, sensitive, and rapid method by using ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the determination of histamine in fish and fish sauce was developed. The optimal conditions of liquid chromatographic separation and mass spectroscopy of histamine have also been investigated. The linear ranges of the method were 20.0 ÷ 1000 ng/mL, and the corresponding correlation coefficient was 0.9993. Mean recoveries of the analyte at three spike levels (low, medium, and high) were within the range of 98.5% ÷ 102.5% (n = 7). The limit of detection (LOD) and limit of quantification (LOQ) values were 3.83 and 11.50 ng/mL for the fish sauce sample and 4.71 and 14.12 ng/mL for the fish sample, respectively. The influence of the matrix effect on the accuracy, repeatability, and recovery of the method was negligible. The recommended method was applied to determine the content of this substance in 21 fish sauce samples and 4 kinds of fish samples, which were collected from Ho Chi Minh City, Vietnam, in 2019.

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