scholarly journals A New Clark-Type Layered Double Hydroxides-Enzyme Biosensor for H2O2 Determination in Highly Diluted Real Matrices: Milk and Cosmetics

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1878
Author(s):  
Mauro Tomassetti ◽  
Riccardo Pezzilli ◽  
Giuseppe Prestopino ◽  
Francesco Di Biagio ◽  
Corrado Di Natale ◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Limit Of Detection ◽  
Gas Diffusion ◽  
Milk Samples ◽  
Low Concentrations ◽  
Enzyme Biosensor ◽  
H2o2 Determination ◽  
Double Hydroxides ◽  
Real Matrices

A new catalase amperometric biosensor for hydroperoxides detection has been built as part of research aimed at the development of biosensors based on layered double hydroxides (LDH) used as support for enzyme immobilization. The fabricated device differs from those developed so far, usually based on an LDH enzyme nanocomposite adsorbed on a glassy carbon (GC) electrode and cross-linked by glutaraldehyde, since it is based on an amperometric gas diffusion electrode (Clark type) instead of a GC electrode. The new biosensor, which still uses LDH synthesized by us and catalase enzyme, is robust and compact, shows a lower LOD (limit of detection) value and a linearity range shifted at lower concentrations than direct amperometric GC biosensor, but above all, it is not affected by turbidity or emulsions, or by the presence of possible soluble species, which are reduced to the cathode at the same redox potential. This made it possible to carry out accurate and efficient determination of H2O2 even in complex or cloudy real matrices, also containing very low concentrations of hydrogen peroxide, such as milk and cosmetic products, i.e., matrices that would have been impossible to analyze otherwise, using conventional biosensors based on a GC–LDH enzyme. An inaccuracy ≤7.7% for cosmetic samples and ≤8.0% for milk samples and a precision between 0.7 and 1.5 (as RSD%), according to cosmetic or milk samples analyzed, were achieved.

scholarly journals Determination of carcinogenic herbicides in milk samples using green non-ionic silicone surfactant of cloud point extraction and spectrophotometry

2018 ◽  
Vol 5 (4) ◽  
pp. 171500 ◽  
Author(s):  
N. I. Mohd ◽  
N. N. M. Zain ◽  
M. Raoov ◽  
S. Mohamad
Keyword(s):  
Cloud Point ◽  
Cloud Point Extraction ◽  
Limit Of Detection ◽  
Cost Effective ◽  
Silicone Surfactant ◽  
Extraction Solvent ◽  
Milk Samples ◽  
Relative Standard ◽  
Limit Of Quantitation

A new cloud point methodology was successfully used for the extraction of carcinogenic pesticides in milk samples as a prior step to their determination by spectrophotometry. In this work, non-ionic silicone surfactant, also known as 3-(3-hydroxypropyl-heptatrimethylxyloxane), was chosen as a green extraction solvent because of its structure and properties. The effect of different parameters, such as the type of surfactant, concentration and volume of surfactant, pH, salt, temperature, incubation time and water content on the cloud point extraction of carcinogenic pesticides such as atrazine and propazine, was studied in detail and a set of optimum conditions was established. A good correlation coefficient ( R 2 ) in the range of 0.991–0.997 for all calibration curves was obtained. The limit of detection was 1.06 µg l −1 (atrazine) and 1.22 µg l −1 (propazine), and the limit of quantitation was 3.54 µg l −1 (atrazine) and 4.07 µg l −1 (propazine). Satisfactory recoveries in the range of 81–108% were determined in milk samples at 5 and 1000 µg l −1 , respectively, with low relative standard deviation, n  = 3 of 0.301–7.45% in milk matrices. The proposed method is very convenient, rapid, cost-effective and environmentally friendly for food analysis.

Sorption Catalytic Determination of Copper(II) and L-α-alanine on Mg-, Al-Layered Double Hydroxides

2016 ◽  
Vol 50 (6) ◽  
pp. 964-981 ◽  
Author(s):  
Yuliya Yu. Petrova ◽  
Ekaterina V. Sevast’yanova ◽  
Elena V. Bulatova ◽  
Marina I. Makhanova
Keyword(s):  
Layered Double Hydroxides ◽  
Catalytic Determination ◽  
Double Hydroxides ◽  
Determination Of Copper

scholarly journals Determination of Ultratrace Bismuth in Milk Samples by Atomic Fluorescence Spectrometry

2003 ◽  
Vol 86 (4) ◽  
pp. 815-822 ◽  
Author(s):  
Patricia Cava-Montesinos ◽  
M Luisa Cervera ◽  
Agustín Pastor ◽  
Miguel de la Guardia
Keyword(s):  
Inductively Coupled Plasma ◽  
Limit Of Detection ◽  
Hydride Generation ◽  
Fluorescence Spectrometry ◽  
Cow Milk ◽  
Atomic Fluorescence Spectrometry ◽  
Atomic Fluorescence ◽  
Microwave Assisted ◽  
Milk Samples

Abstract A sensitive procedure was developed for determination of bismuth (Bi) in milk samples by hydride generation atomic fluorescence spectrometry (HG–AFS) after microwave-assisted sample digestion with HNO3 and H2O2. The method provides a sensitivity of 1832 fluorescence units (ng/mL) with a detection limit of 0.01 ng/mL, which corresponds to 20 pg absolute limit of detection, equivalent to 0.50 ng/g in the original sample. Application of the methodology to cow milk samples from the Spanish market showed the presence of Bi at a concentration of 11.8–28.8 ng/g, which compared well with data obtained after dry ashing of samples and with data obtained by inductively coupled plasma–mass spectrometry after microwave-assisted digestion.

scholarly journals New Poly(Ionic Liquid) Based Fiber for Determination of Oxytetracycline in Milk Samples by Application of SPME-CE Technique

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 430 ◽  
Author(s):  
T. Alexandra Ferreira ◽  
J. Francisco Flores-Aguilar ◽  
Eva M. Santos ◽  
Jose A. Rodriguez ◽  
Israel S. Ibarra
Keyword(s):  
Capillary Electrophoresis ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Ionic Exchange ◽  
Imidazolium Chloride ◽  
Milk Samples ◽  
Multi Stage ◽  
Pre Treatment ◽  
Poly Ionic Liquid

In this work, a procedure using solid phase microextraction in combination with capillary electrophoresis was developed for the determination of oxytetracycline in milk samples. The method involves the synthesis of poly(1-allyl-3-methyl imidazolium) chloride film on a stainless-steel bar via electropolymerization and its use as an adsorbent for oxytetracycline (OT) by an ionic exchange mechanism. The coated fiber is then immersed in milk samples for retention of oxytetracycline residues, followed by elution, drying, and reconstitution before analysis with capillary electrophoresis. The proposed method achieves a limit of detection of 70 µg L–1 with adequate precision and uncertainty, making this methodology appropriate for the determination of OT in milk samples. The method was applied to the pre-concentration and quantification of oxytetracycline in ten commercial milk samples. Two tested samples were positive for the presence of oxytetracycline but the concentration was below the maximum residue limit according to the international normative standard. The proposed methodology was evaluated according to the Eco-Scale approach, and the total score of 51 indicated that the methodology proposed is both green and acceptable despite the multi-stage character. SPME-CE methodology allows us to perform the sample pre-treatment and determination of OT in an effective and greener way, decreasing the number of steps during the analysis and the generation of waste.

Determination of Sulfite in Food by Flow Injection Analysis

1986 ◽  
Vol 69 (3) ◽  
pp. 542-546 ◽  
Author(s):  
John J Sullivan ◽  
Thomas A Hollingworth ◽  
Marleen M Wekell ◽  
Richard T Newton ◽  
Jack E Larose
Keyword(s):  
Flow Injection ◽  
Flow Injection Analysis ◽  
Extraction Procedure ◽  
Food Product ◽  
Food Products ◽  
Peak Height ◽  
Gas Diffusion ◽  
Diffusion Cell ◽  
Low Concentrations

Abstract A method is described for the determination of sulfite levels in food products by flow injection analysis (FIA). The method is based on the decolorization of malachite green by S02, which is isolated from the flowing sample stream by means of a gas diffusion cell. The FIA method has a detection limit in food sample extracts of 0.1 ppm S02 (3 times peak height of blank), which corresponds to 1-10 ppm S02 in a food product, depending on the extraction procedure used. At the 5 ppm SO2 level in a food extract, the precision of replicate injections is ± 1-2%. The method was tested on a variety of both sulfite-treaied and untreated food products and the results compared favorably with those obtained by the Monier-Williams, colorimetric (pararosaniline), and enzymatic (sulfite oxidase) methods. The average differences from the FIA results were 19, 11, and 12%, respectively, for those samples (n = 12) above SO ppm S02. At lower levels the results were somewhat more erratic due to inaccuracies of the various methods at low concentrations.

Determination of Phenicols Using a Fast and Reliable HPLC Method Developed on Hypercarb Stationary Phase

2017 ◽  
Vol 68 (3) ◽  
pp. 545-548
Author(s):  
Georgeta Simona Stan ◽  
Florentina Moldovanu ◽  
Irinel Adriana Badea
Keyword(s):  
Stationary Phase ◽  
Mobile Phase ◽  
Reliable Method ◽  
Limit Of Detection ◽  
Hplc Method ◽  
Detection Capability ◽  
Milk Samples ◽  
Precision And Accuracy ◽  
Detection And Quantification

Hypercarb porous graphitic stationary phase was used to develop a fast and reliable method for simultaneous determination of chloramphenicol, thiamphenicol and florfenicol. The separation was achieved in 7 min elution being made isocratic using water modified with acetonitrile as mobile phase. The method was fully validated and showed good linearity, precision and accuracy. Limit of detection and quantification together with decision limit and detection capability were established. This method was applied for analysis of milk samples.

Sign in / Sign up

Export Citation Format

Share Document