scholarly journals Determination of bacterial contamination of milk using fluorometry

2011 ◽  
Vol 8 (3) ◽  
pp. 745-750
Author(s):  
Baghdad Science Journal
Keyword(s):  
Bacterial Contamination ◽  
Laser Light ◽  
Low Cost ◽  
Emission Spectra ◽  
High Sensitivity ◽  
Excitation Wavelength ◽  
Milk Samples ◽  
Good Differentiation ◽  
Auto Fluorescence

The aim of this paper is to determine the feasibility of using fluorometric methods as an indicator for quality and contamination of milk with E.coli bacteria, and selection the suitable wavelength to be used with laser induced auto fluorescence. Three groups of milk samples were used in this study: Fresh pasteurized milk samples, milk samples containing different concentration of E.coli bacteria which were added artificially, and milk samples that were kept in refrigerator for 3-5 days. Thirteen excitation wavelengths were used to get the emission spectra for all milk samples using spectroflourometer .The results showed that the emission spectra at 275nm excitation wavelength gave a good differentiation between these three groups. The data analysis demonstrated that the proposed method can bring progress in identification of milk quality and contamination with rapidness, high sensitivity and low cost diagnostic tool. Laser light at this wavelength that transmitted by optical fiber can be used for milk samples examination in situe and for more precise results.

scholarly journals Simultaneous Determination of C18 Fatty Acids in Milk by GC-MS

Separations ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 118
Author(s):  
Meiqing Chen ◽  
Yangdong Zhang ◽  
Fengen Wang ◽  
Nan Zheng ◽  
Jiaqi Wang
Keyword(s):  
Fatty Acids ◽  
High Sensitivity ◽  
Raw Milk ◽  
Uht Milk ◽  
Milk Samples ◽  
Accuracy And Precision ◽  
Different Temperatures ◽  
Chromatographic Resolution ◽  
Commercial Milk

The determination of C18 fatty acids (FAs) is a key and difficult aspect in FA profiling, and a qualified method with good chromatographic separation and high sensitivity, as well as easy methylation, is required. A GC-MS method was established to simultaneously determine C18 FAs in milk. To simplify the methylation protocol for milk samples, besides a base-catalyzation methylation (50 °C for 20 min), the necessity of an additional acid-catalyzation was also studied using different temperatures (60 °C, 70 °C, 80 °C, and 90 °C) and durations (90 min and 150 min). The results showed that the chromatographic resolution was improved, although three co-eluted peaks existed. The base-catalyzation was sufficient, and an additional acid-catalyzation was not necessary. The proposed method was validated with good sensitivity, linearity, accuracy, and precision, and then applied in determining C18 FAs in 20 raw milk and 30 commercial milk samples. UHT milk presented a different profile of C18 FAs from raw milk and PAS milk samples, which indicated that excessive heating could change the profile. Overall, the proposed method is a high-throughput and competent approach for the determination of C18 FAs in milk, and which presents an improvement in chromatographic resolution and sensitivity, as well as a simplification of methylation.

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.

scholarly journals Concentration Quantification of Oil Samples by Three-Dimensional Concentration-Emission Matrix (CEM) Spectroscopy

2019 ◽  
Vol 10 (1) ◽  
pp. 315
Author(s):  
Yunan Chen ◽  
Ruifang Yang ◽  
Nanjing Zhao ◽  
Wei Zhu ◽  
Yao Huang ◽  
...  
Keyword(s):  
Oil Spill ◽  
Three Dimensional ◽  
Emission Spectra ◽  
Quantitative Detection ◽  
Excitation Wavelength ◽  
Detection Technology ◽  
Shift Behavior ◽  
Relative Errors ◽  
Matrix Similarity

Developing fast and accurate fluorescence detection technology of oil spill is significant for quantitative analysis in unexpected oil spill events. As the oil sample concentration increases, the fluorescence spectrum produces red-shift behavior, which seriously affects the quantitative detection of concentration. In this work, a three-dimensional concentration-emission matrix (CEM) was constructed by using a series of emission spectra with different levels of concentration at the excitation wavelength of 266 nm. The database is the interpolated CEM of six samples using bicubic interpolation in the concentration dimension. With matrix similarity matching, the database was used to achieve quantification of the concentration of oil samples. The recovery rates of prediction for test samples and weathering samples of six oil samples were between 86.8% and 116.11%, with relative errors of predictions ranging from 2.09% to 15.2%. The results show that this method can provide accurate quantitative determination of the concentration of different oil samples.

Recent Electrochemical Assays on Cephalosporins

2020 ◽  
Vol 16 (4) ◽  
pp. 337-349
Author(s):  
Leyla Karadurmus ◽  
Kaan Eşme ◽  
Nurgul K. Bakirhan ◽  
Sibel A. Ozkan
Keyword(s):  
Low Cost ◽  
Linear Sweep Voltammetry ◽  
High Sensitivity ◽  
Differential Pulse ◽  
Electroanalytical Methods ◽  
Antibiotic Drugs ◽  
Short Time ◽  
Advanced Generation ◽  
Antibacterial Spectrum

: Antibiotics are an important class among drugs because they are a significant agent to deal with infections. Cephalosporins are a very important group of antibiotics in the β-lactam class. The cephalosporins are semisynthetic antibiotics derived from products of the fungus Cephalosporium. Cephalosporins are classified as first, second, third, fourth, and advanced generation, based largely on their antibacterial spectrum and stability to β-lactamases. Electrochemical methods have been used for the determination of cephalosporin just as used in the determination of many antibiotic drugs. Electroanalytical methods present generally high sensitivity, low cost, low requirements, ease of preparation of the samples in a very short time, and a short analysis time. The most commonly used types are cyclic voltammetry, differential pulse voltammetry, square wave voltammetry and linear sweep voltammetry. The aim of this review is to evaluate the advantages and uses of electroanalytical methods used in the determination of cephalosporins. In addition, current applications of the methods to the pharmaceutical analysis of cephalosporins will also be summarized in a table.

Development of a Novel Fluorimeter Based on Superluminescent Light-Emitting Diodes and Acousto-Optic Tunable Filter and its Application in the Determination of Chlorophylls a and b

1997 ◽  
Vol 51 (11) ◽  
pp. 1603-1606 ◽  
Author(s):  
Troy A. Alexander ◽  
Guan-Hong Gao ◽  
Chieu D. Tran
Keyword(s):  
Light Emitting Diodes ◽  
Light Emitting Diode ◽  
Emission Spectra ◽  
High Sensitivity ◽  
Tunable Filter ◽  
Excitation Spectra ◽  
Excitation Light ◽  
Light Emitting ◽  
Chlorophylls A And B

A novel, compact, inexpensive fluorimeter that has high sensitivity and no moving parts has been developed by using super luminescent (bright-blue) light-emitting diodes (SLEDs) and an acousto-optic tunable filter (AOTF). In this instrument, the recently developed gallium nitride SLEDs were used in a counterpropagating configuration to provide excitation light. These SLEDs provide not only high intensity (several milliwatts) but also wide spectral bandwidth in the blue region (from 370 to 570 nm). The AOTF can be placed before the sample to facilitate the measurements of excitation spectra or after the sample for the emission spectra measurements. This fluorimeter is suitable for the sensitive and general fluorescent analysis of a variety of compounds. It has been used, as an example, for the sensitive and simultaneous determination of chlorophylls a and b. Detection limits of 2.30 × 10−9 and 1.10 × 10−9 M have been achieved for chlorophyll a and chlorophyll b, respectively. Index Headings: Superluminescent light-emitting diode; Acousto-optic tunable filter; Fluorescence; Chlorophyll.

Quantitative Determination of Triglyceride by Photoactivated CdSe/ZnS Quantum Dots Through Fluorescence Assay

2008 ◽  
Vol 8 (7) ◽  
pp. 3434-3438 ◽  
Author(s):  
Chin-Ping Huang ◽  
Yaw-Kuen Li ◽  
Teng-Ming Chen
Keyword(s):  
Quantum Dots ◽  
Color Change ◽  
Low Cost ◽  
High Sensitivity ◽  
Assay System ◽  
Oil Refining ◽  
Quantitative Detection ◽  
Multiple Reactions ◽  
High Flexibility

The quantitative detection of triglycerides is an important issue for health inspection of metabolic disorders and for food and oil-refining industries. Many methods have been designed to approach this target, in which multiple reactions catalyzed by enzymes are normally coupled consecutively. In this study, we demonstrated a simple assay system containing lipase and photoactivated luminescent CdSe/ZnS quantum dots (QDs) for the quantitative detection of triglycerides. Photoactivated CdSe/ZnS QDs function as a sensitive "indicator" to reveal the minute acidity change of the assay system resulting from the enzymatic hydrolysis of triglycerides. By controlling the initial buffer condition of the assay system at 5, 10, or 20 mM phosphate buffer at pH 8.0, respectively, the quenching ratio of the QDs fluorescence intensity monitored at the maximum photoluminescence showed a linear correlation with the concentration of the examined triglyceride in the range of 0.02–6, 0.2–10, or 2–20 mM, respectively. The assay system also provides a convenient way to estimate triglyceride concentration by visualizing the color change of the QDs fluorescence. As compared to most of the existing methods, the system reported herein possessed many advantages, including simplicity, low cost, high flexibility, and high sensitivity. Furthermore, no complicated chemical modification or enzyme immobilization is needed.

scholarly journals Electrochemical Sensor for Rapid and Sensitive Detection of Tryptophan by a Cu2O Nanoparticles-Coated Reduced Graphene Oxide Nanocomposite

Biomolecules ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 176 ◽  
Author(s):  
Quanguo He ◽  
Yaling Tian ◽  
Yiyong Wu ◽  
Jun Liu ◽  
Guangli Li ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Low Cost ◽  
Supporting Electrolyte ◽  
Modified Electrodes ◽  
High Sensitivity ◽  
Experimental Conditions ◽  
Reduced Graphene ◽  
Electrochemically Reduced Graphene Oxide

In this paper, a nanocomposite of cuprous oxide and electrochemically reduced graphene oxide (Cu2O–ERGO) was prepared by a simple and low-cost method; hereby, a new method for the electrochemical determination of tryptophan (Trp) by this composite modified glassy carbon electrode (GCE) is proposed. The prepared materials and modified electrodes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and cyclic voltammetry (CV). The results showed that Cu2O–ERGO/GCE had good electrocatalytic activity for Trp. The effects of supporting electrolyte, scanning rate, accumulation potential, and accumulation time on the determination of Trp were studied. Under the optimum experimental conditions, Trp was quantitatively analyzed by square-wave voltammetry (SWV). The oxidation peak current of Trp had a good linear relationship with its concentration in the range of 0.02–20 μM, and the detection limit was 0.01 μM (S/N = 3). In addition, the modified electrode has high sensitivity, good repeatability, and long-term stability. Finally, the proposed method has been successfully applied in the determination of Trp concentration in practical samples.

Determination of trace uranium by a photo-catalytic resonance fluorescence method coupled with dual cloud point extraction

2016 ◽  
Vol 8 (30) ◽  
pp. 5984-5993 ◽  
Author(s):  
Guirong Li ◽  
Jiekang Li ◽  
Qian Han
Keyword(s):  
Cloud Point ◽  
High Selectivity ◽  
Cloud Point Extraction ◽  
Low Cost ◽  
High Sensitivity ◽  
Fluorescence Method ◽  
Resonance Fluorescence ◽  
Complex Samples ◽  
Resonance Fluorescence Method

(1) Extracting and purifying uranium in complex samples by dCPE with [UO22+–SA1]. (2) Detecting uranium super sensitively by a photocatalytic RF method with [UO22+–SA2]. (3) Coupling with separation, purification and analysis procedures exhibited a number of advantages, including high selectivity, high sensitivity and low cost.

scholarly journals Electrochemical Biosensors for Detection of Foodborne Pathogens

Micromachines ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 222 ◽  
Author(s):  
Zhenguo Zhang ◽  
Jun Zhou ◽  
Xin Du
Keyword(s):  
Foodborne Pathogens ◽  
Low Cost ◽  
Public Health Problem ◽  
High Sensitivity ◽  
Global Public Health ◽  
Real Time Analysis ◽  
Electrochemical Biosensing ◽  
Recent Developments ◽  
Global Public Health Problem

Foodborne safety has become a global public health problem in both developed and developing countries. The rapid and precise monitoring and detection of foodborne pathogens has generated a strong interest by researchers in order to control and prevent human foodborne infections. Traditional methods for the detection of foodborne pathogens are often time-consuming, laborious, expensive, and unable to satisfy the demands of rapid food testing. Owing to the advantages of simplicity, real-time analysis, high sensitivity, miniaturization, rapid detection time, and low cost, electrochemical biosensing technology is more and more widely used in determination of foodborne pathogens. Here, we summarize recent developments in electrochemical biosensing technologies used to detect common foodborne pathogens. Additionally, we discuss research challenges and future prospects for this field of study.

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