scholarly journals Cholesteric Molecular Tweezer Artificial Receptor for Rapid and Highly Selective Detection of Ag+ in Food Samples

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6919
Author(s):  
Zhe Liu ◽  
Ying Ye ◽  
Hong Wang ◽  
Li-xia Luo
Keyword(s):  
Milk Powder ◽  
Food Samples ◽  
Buffer Solution ◽  
Red Color ◽  
Recognition Ability ◽  
Artificial Receptor ◽  
Novel Method ◽  
Molecular Tweezer ◽  
Mechanism Of Recognition

Chiral cholesteric molecular tweezer 7a was synthesized, and its recognition properties for Ag+, Al3+, Ca2+ etc., were investigated by UV and fluorescence spectra. The results showed that in ethanol/Tris (1/1, v/v, pH 7.0) buffer solution, the host molecular tweezer 7a had a specific recognition ability for Ag+, the detection limit was up to 1 × 10−6 mol/L, and other metal ions had little effect on Ag+ recognition. At the same time, the naked-eye detection of Ag+ was realized by the light red color of the complex solution. Furthermore, the mechanism of recognition of Ag+ by molecular tweezer 7a was studied by a nuclear magnetic titration test and computer molecular simulation, and a rapid detection method of Ag+ using host molecular tweezer 7a was established. Through the determination of Ag+ in milk powder, quinoa and other food samples, it was proved that this novel method had a good application prospect for the detection of Ag+ in food.

Fluorometric Determination of Selenium in Foods

1974 ◽  
Vol 57 (2) ◽  
pp. 368-372 ◽  
Author(s):  
Milan Ihnat
Keyword(s):  
Standard Deviation ◽  
Milk Powder ◽  
Skim Milk ◽  
Skim Milk Powder ◽  
Food Samples ◽  
Fluorometric Method ◽  
Fluorometric Determination ◽  
Relative Standard ◽  
The Mean

Abstract A fluorometric method using 2,3-diaminonaphthalene for estimating selenium has been evaluated with regard to its applicability to food samples. Charring of the sample during digestion appeared to result in losses of native and added selenium from some samples, so a modified wet digestion procedure was introduced. Digestion first in nitric acid followed by a mixture of nitric-perchloric-sulfuric acids substantially reduced the incidence of sample charring for a variety of foods. The mean apparent recovery of selenium added as selenite or selenate at 100 and 500 ng levels to 0.1 and 1.0 g corn cereal, skim milk powder, and meat and 0.1 g fish was 101.0%; the actual recovery of the same levels of selenium from standard solutions was 96.6%. For a variety of samples containing 5—750 ng native or added selenium, the standard deviation as 4.7 + 1.95 X 10-2W ng, where W = ng selenium in the sample taken for analysis. The relative standard deviation (RSD) as a function of selenium weight (ng) was 50% (10), 6.7% (100), 4.3% (200), 3.1% (400), 2.7% (600), and 2.5% (800). The detection limit (weight of selenium at which RSD = 50%) was 10 ng at a mean blank level of 25 ng.

A Simple and Sensitive Voltammetric Method for the Determination of Orange II Based on a Functionalized Graphene-Modified Electrode

2016 ◽  
Vol 99 (5) ◽  
pp. 1287-1294 ◽  
Author(s):  
Yudong Gao ◽  
Zhengkun Xie ◽  
Yulong Zhang ◽  
Lina Zou ◽  
Baoxian Ye
Keyword(s):  
Phosphate Buffer Solution ◽  
Linear Sweep Voltammetry ◽  
Food Samples ◽  
Orange Ii ◽  
Voltammetric Sensor ◽  
Functionalized Graphene ◽  
Modified Glassy Carbon Electrode ◽  
Buffer Solution ◽  
Accumulation Ability

Abstract A simple and sensitive voltammetric sensor for Orange II was developed, based on a poly(sodium p-styrenesulfonate)-functionalized graphene-modified glassy carbon electrode. This voltammetric sensor showed strong accumulation ability and an excellent voltammetric response for Orange II. The electrochemical behavior of Orange II was systematically investigated in a pH 7.0 phosphate buffer solution. By linear sweep voltammetry, under optimum conditions, a good linear relationship was obtained between peak currents and Orange II concentrations in the wider range of 3 × 10−8 to 5 × 10−6 mol/L, with an LOD of 1 × 10−8 mol/L. In addition, the proposed Orange II sensor was successfully applied to real food samples with satisfactory recovery.

scholarly journals A Novel Method for Determination of Protein in Human Serum Utilizing the Trihydroxylphenylfluorone-Molybdenum(VI) Complex as a Probe by Fluorescence Spectrometry

2007 ◽  
Vol 90 (1) ◽  
pp. 238-243 ◽  
Author(s):  
Qin Wei ◽  
Hongmin Ma ◽  
Caihong Duan ◽  
Jin Wang ◽  
Shuyuan Liu ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Detection Limit ◽  
Human Serum ◽  
Fluorescence Intensity ◽  
Acetate Buffer Solution ◽  
Buffer Solution ◽  
Protein Assay ◽  
Novel Method

Abstract The fluorescence intensity of the trihydroxylphenylfluorone-molybdenum(VI) Mo(VI) complex is quenched by protein. Based on this, a novel method for protein assay in aqueous solution was developed. With pH 3.75 acetic acidsodium acetate buffer solution, in the presence of p-octyl polyethylene glycol phenyl ether microemulsion, the quenched fluorescence intensity is proportional to the concentration of bovine serum albumin (BSA) in the range of 07.00 μg/mL, and the detection limit of BSA is 5.65 ng/mL. There is no interference from amino acids and most metal ions. The method developed in this paper has been used for the successful determination of protein in human serum.

scholarly journals Modulating Linker Composition of Haptens Resulted in Improved Immunoassay for Histamine

Biomolecules ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 597 ◽  
Author(s):  
Lin Luo ◽  
Xiao-Qun Wei ◽  
Bao-Zhu Jia ◽  
Jin-Yi Yang ◽  
Yu-Dong Shen ◽  
...  
Keyword(s):  
Small Molecules ◽  
Limit Of Detection ◽  
Food Samples ◽  
Important Food ◽  
Buffer Solution ◽  
Protein Conjugates ◽  
Inhibition Concentration ◽  
Hapten Design ◽  
Direct Derivatization

Histamine (HA) is an important food contaminant generated during food fermentation or spoilage. However, an immunoassay for direct (derivatization free) determination of HA has rarely been reported due to its small size to induce the desired antibodies by its current hapten-protein conjugates. In this work, despite violating the classical hapten design criteria which recommend introducing a linear aliphatic (phenyl free) linker into the immunizing hapten, a novel haptens, HA-245 designed and synthesized with a phenyl-contained linker, exhibited significantly enhanced immunological properties. Thus, a quality-improved monoclonal antibody (Mab) against HA was elicited by its hapten-carrier conjugates. Then, as the linear aliphatic linker contained haptens, Hapten B was used as linker-heterologous coating haptens to eliminate the recognition of linker antibodies. Indirect competitive ELISA (ic-ELISA) was developed with a 50% inhibition concentration (IC50) of 0.21 mg/L and a limit of detection (LOD) of 0.06 mg/L in buffer solution. The average recoveries of HA from spiked food samples for this ic-ELISA ranged from 84.1% and 108.5%, and the analysis results agreed well with those of referenced LC-MS/MS. This investigation not only realized derivatization-free immunoassay for HA, but also provided a valuable guidance for hapten design and development of immunoassay for small molecules.

scholarly journals Determination of Protein in Milk Powder Using 2-Sulfophenylazo-Rhodanine as a Probe by the Enhanced Resonance Rayleigh Light-Scattering Technique

2006 ◽  
Vol 89 (5) ◽  
pp. 1353-1359
Author(s):  
Qin Wei ◽  
Yan Li ◽  
Wenying Dong ◽  
Bin Du
Keyword(s):  
Light Scattering ◽  
Serum Albumin ◽  
Milk Powder ◽  
Buffer Solution ◽  
Protein Determination ◽  
Rayleigh Light Scattering ◽  
Scattering Technique ◽  
Light Scattering Technique ◽  
Rayleigh Light

Abstract In this paper, the interaction between 2-sulfophenylazo-rhodanine and protein was investigated by Rayleigh light-scattering technique. Based on this, a novel method for the determination of protein was developed. The effects of different conditions, such as acidity and media, were investigated thoroughly, and the optimum conditions were confirmed. Bis(2-ethylhexyl)sulfosuccinate (AOT) microemulsion, which is introduced into the protein determination, markedly increased the sensitivity of the system by changing the microenvironment. In pH 2.80 Britton-Robinson buffer solution in the presence of AOT microemulsion, the detection limits of bovine serum albumin, human serum albumin, ovalbumin, and -globulin are 5.4, 4.5, 9.8, and 10.1 ng/mL, respectively. The method developed in this paper has been applied to the determination of protein in milk powder with satisfactory results.

scholarly journals Solidified Floating Organic Drop Microextraction for the Detection of Trace Amount of Lead in Various Samples by Electrothermal Atomic Absorption Spectrometry

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Oya Aydın Urucu ◽  
Şeyda Dönmez ◽  
Ece Kök Yetimoğlu
Keyword(s):  
Standard Deviation ◽  
Electrothermal Atomic Absorption Spectrometry ◽  
Chelating Agent ◽  
Absorption Spectrometry ◽  
Food Samples ◽  
Lead Ion ◽  
Optimum Conditions ◽  
Relative Standard ◽  
Novel Method

A novel method was developed for determination of trace amounts of lead in water and food samples. Solidified floating organic drop microextraction was used to preconcentrate the lead ion. After the analyte was complexed with 1-(2-pyridylazo)-2-naphthol, undecanol and acetonitrile were added as extraction and dispersive solvent, respectively. Variables such as pH, volumes of extraction and dispersive solvents, and concentration of chelating agent were optimized. Under the optimum conditions, the detection limit of Pb (II) was determined as 0.042 µg L−1 with an enrichment factor of 300. The relative standard deviation is <10%. Accuracy of the developed procedure was evaluated by the analysis of certified reference material of human hair (NCS DC 73347) and wastewater (SPS-WW2) with satisfactory results. The developed procedure was then successfully applied to biscuit and water samples for detection of Pb (II) ions.

scholarly journals Multiple Mycotoxins Determination in Food by LC-MS/MS: An International Collaborative Study

Toxins ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 658 ◽  
Author(s):  
Thomas Bessaire ◽  
Claudia Mujahid ◽  
Pascal Mottier ◽  
Aurélien Desmarchelier
Keyword(s):  
Collaborative Study ◽  
Milk Powder ◽  
Food Samples ◽  
Relative Standard ◽  
Liquid Chromatography Tandem Mass ◽  
Mycotoxin Analysis ◽  
Repeatability And Reproducibility ◽  
Iso 5725 ◽  
Infants And Young Children

An intercollaborative study was organized to evaluate the performance characteristics of a liquid chromatography tandem mass spectrometry procedure for the simultaneous determination of 12 mycotoxins in food, which were ochratoxin A, aflatoxins B1, B2, G1, G2, and M1, deoxynivalenol, zearalenone, fumonisins B1 and B2, and T-2 and HT-2 toxins. The method combined the simplicity of the QuEChERS (Quick, Easy, Cheap, Efficient, Rugged and Safe) approach with the efficiency of immunoaffinity column cleanup (the step used to enhance sensitivity and sample cleanup for some matrices only). Twenty-three entities were enrolled and were European reference laboratories for mycotoxin analysis, U.S. and European service laboratories, and Nestlé laboratories. Each participant analyzed 28 incurred and/or spiked blind samples composed of spices, nuts, milk powder, dried fruits, cereals, and baby food using the protocol given. Method performances were assessed according to ISO 5725-2. Relative standard deviations of repeatability and reproducibility and trueness values for each of the 115 mycotoxin/sample combinations ranged from 5% to 23%, 7% to 26%, and 85% to 129%, respectively, in line with requirements defined in EC 401/2006. The overall set of data gathered demonstrated that the method offered a unique platform to ensure compliance with EC 1881/2006 and EC 165/2013 regulations setting maximum limits for mycotoxins in food samples, even at low regulated levels for foods intended for infants and young children. The method was applicable regardless of the food, the regulated mycotoxin, and the concentration level, and thus is an excellent candidate for future standardization.

Discrimination and Simultaneous Determination of 6-BA and KT by Polarized Synchronous Light Scattering and Synchronous Light Scattering Spectrum

2013 ◽  
Vol 634-638 ◽  
pp. 81-86
Author(s):  
Xiao Hui Zhao ◽  
Qian Hua Zhu ◽  
Qiong Yang ◽  
Wei He ◽  
Shang Zhou ◽  
...  
Keyword(s):  
Light Scattering ◽  
Simultaneous Determination ◽  
Buffer Solution ◽  
Standard Curve ◽  
Scattering Spectrum ◽  
Curve Method ◽  
Standard Curve Method ◽  
Novel Method ◽  
Light Scattering Spectrum

In pH=5.70 B-R buffer solution, Na2WO4 and rhodamine 6G（R6G） could react with natural cytokinins of 6-benzylaminourine (6-BA) and kinetin (KT) and resulted in a great enhacement of synchronous light scattering (SLS) signals. This article first established the degree of polarized synchronous light scattering (P) based on the measurements of the polarized synchronous light scattering signals to distinguish two natural cytokinins of 6-BA and KT. Simultaneously based on the synchronous scattering spectrum and the double standard curve method, a novel method for simultaneous determination of 6-BA and KT was developed by SLS spectralmethod. The method was applied to simultaneous determination of 6-BA and KT in balsam pear skin and tomato skin with satisfactory results.

Determination of Radiochemical Purity and Pharmacokinetic Parameters of 99mTc-Sulphur Colloid and 99mTc-Tin Colloid

1981 ◽  
Vol 20 (06) ◽  
pp. 279-282 ◽  
Author(s):  
D. Konstantinovska ◽  
K. Milivojević ◽  
J. Bzenić ◽  
V. Jovanović
Keyword(s):  
Radiochemical Purity ◽  
Slow Component ◽  
Pharmacokinetic Parameters ◽  
Optimum Size ◽  
Buffer Solution ◽  
Chromatography Method ◽  
Fast Phase ◽  
Biodistribution Studies ◽  
Biological Half Time

Labelling yield and radiochemical purity, higher than 95%, of 99mTc-colloid preparations were determined by using the paper chromatography method. Less than 3% of labelled citric acid, added to the preparation as a buffer solution, has been found in 99mTc-sulphur colloid. High radiochemical purity and optimum size of colloid particles has also been proved by biodistribution studies on experimental animals. The analysis performed has shown that more than 50% of 99mTc-colloid preparations excreted by urine is 99mTcO–, the remaining past 50% being protein bound 99mTc. Biological half-time of excretion of the fast phase is the same for both preparations, i.e. 10 min, while for the slow component it is 120 min in 99mTc-S-colloid and 160 min in 99mTc-Sn colloid.

Sign in / Sign up

Export Citation Format

Share Document