scholarly journals Comparative Analysis of Verification Parameters of Event-Specific Methods in GMO Maize

2018 ◽  
Vol 2 (1) ◽  
pp. 8
Author(s):  
Anesa Ahatović ◽  
Adaleta Durmić-Pašić
Keyword(s):  
Limit Of Detection ◽  
Certified Reference Materials ◽  
Simultaneous Detection ◽  
Specific Marker ◽  
The European Union ◽  
Gm Crop ◽  
Gm Maize ◽  
Absolute Limit ◽  
Multiplex Reaction

The second most dominant genetically modified (GM) crop is maize. Increasing number of GM maize events puts significant pressure on GMO testing laboratories to achieve the level of competence necessary to fulfill legal requirements. In the European Union, Polymerase Chain Reaction (PCR) is the method of choice for identification and quantification of GMOs. We performed verification of validated methods for identification of four GM maize events. Additionaly we aimed to explore the option of designing a method for simultaneous detection of these events in a multiplex PCR reaction. DNA was extracted from certified reference materials (CRM) using validated CTAB extraction protocol. Concentration of DNA was measured using Qubit dsDNA Broad Range Assay. Amplification of taxon specific marker for maize and all event-specific methods was performed according to the JRC Compendium of Reference Methods for GMO Analysis. Absolute limit of detection (LODabs) was determined for taxon specific and four event specific RealTime PCR based methods. DNA extracted from CRMs showed sufficient concentration for downstream analyses and preparation of dilutions for determination of LODabs. Determined LODabs for all tested methods meet acceptance criteria. As expected, the methods performance with respect to the repeatability and precision decline with the decrease in concentration of the target. Event-specific GA21 and NK603 methods show high Ct values at the determined LODabs. However, by adjusting the concentrations of primers and probes sensitivity of these two methods should be improved. Considering that the amplicons for all five methods are quite short (<120 bp) optimization of multiplex reaction conditions for simultaneous amplification should be feasible

scholarly journals Estimate of Uncertainty of Measurement from a Single-Laboratory Validation Study: Application to the Determination of Lead in Blood

2004 ◽  
Vol 50 (8) ◽  
pp. 1396-1405 ◽  
Author(s):  
Marina Patriarca ◽  
Marco Castelli ◽  
Federica Corsetti ◽  
Antonio Menditto
Keyword(s):  
Reference Materials ◽  
Certified Reference Materials ◽  
Electrothermal Atomic Absorption Spectrometry ◽  
Absorption Spectrometry ◽  
Environmental Pollutant ◽  
The European Union ◽  
Lead In Blood ◽  
Method Performance ◽  
Target Values

Abstract Background: Lead is an environmental pollutant, and human exposure is assessed by monitoring lead concentrations in blood. Because the main source of environmental exposure has been the use of leaded gasoline, its phase-out has led to decreased lead concentrations in the general population. Therefore, validated analytical methods for the determination of lower lead concentrations in blood (&lt;150 μg/L) are needed. In addition, new ISO standards require that laboratories determine and specify the uncertainty of their results. Methods: We validated a method to determine lead in blood at concentrations up to 150 μg/L by electrothermal atomic absorption spectrometry with Zeeman background correction according to EURACHEM guidelines. Blood samples were diluted (1:1 by volume) with 2 mL/L Triton X-100. NH4H2PO4 (5 g/L) and Mg(NO3)2 (0.5 g/L) were used as modifiers. Matrix-matched standards were used for calibration. Results: We determined the limits of detection (3.1 μg/L) and quantification (9.4 μg/L). Repeatability and intermediate imprecision within the range 35–150 μg/L were &lt;5.5% and &lt;6.0%, respectively. We assessed trueness by use of certified reference materials, by recovery tests, and by comparison with target values of other reference materials (candidate external quality assessment samples). The expanded uncertainty ranged from 20% to 16% (with a confidence level of 95%) depending on concentration. Conclusions: This study provides a working example of the estimate of uncertainty from method performance data according to the EURACHEM/CITAC guidelines. The estimated uncertainty is compatible with quality specifications for the analysis of lead in blood adopted in the US and the European Union.

scholarly journals Electrocatalytic determination of levodopa in presence of cabergoline using carbon paste electrode modified with graphene quantum dots/2-chlorobenzoyl ferrocene/ionic liquid

2021 ◽  
Author(s):  
Peyman Mohammadzadeh Jahani
Keyword(s):  
Quantum Dots ◽  
Ionic Liquid ◽  
Carbon Paste Electrode ◽  
Limit Of Detection ◽  
Graphene Quantum Dots ◽  
Simultaneous Detection ◽  
Phosphate Buffer Solution ◽  
Carbon Paste ◽  
Paste Electrode

The electrochemical sensor was fabricated for the simultaneous determination of levodopa and cabergoline using carbon paste electrode (CPE) modified with graphene quantum dots (GQD), 2-chlorobenzoyl ferrocene (2CBF) and ionic liquid (IL). Then, the electrochemical behavior of levodopa alone and simultaneously with cabergoline at the surface of GQDs/2CBF/IL/CPE was investigated in phosphate buffer solution (PBS). Under optimal PBS, pH=7 condition, oxidation peak current has been found proportional to levodopa concentration in the range between 0.07 μM and 500.0 μM, with the limit of detection (LOD) of 0.02 μM (S/N=3). Outputs showed that at GQDs/2CBF/IL/CPE surface, the levodopa and cabergoline oxidation peaks are separated by the potential difference of 200 mV. In addition, it was found that this modified electrode possesses acceptable sensitivity, selectivity, stability and repeatability. All these properties were sufficient to allow simultaneous detection of levodopa and cabergoline in real samples at the surface of GQDs/2CBF/IL/CPE. This was supported by the successful application of this electro­chemical sensor electrode for the determination of levodopa and cabergoline in urine, serum, and cabergoline tablets.

scholarly journals Determination of Florfenicol, Thiamfenicol and Chloramfenicol at Trace Levels in Animal Feed by HPLC–MS/MS

Antibiotics ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 59 ◽  
Author(s):  
Rosa Elvira Gavilán ◽  
Carolina Nebot ◽  
Ewelina Patyra ◽  
Beatriz Vazquez ◽  
Jose Manuel Miranda ◽  
...  
Keyword(s):  
Ethyl Acetate ◽  
Animal Feed ◽  
Simultaneous Detection ◽  
The European Union ◽  
European Regulation ◽  
Official Control ◽  
Liquid Chromatography Tandem Mass ◽  
Residue Levels ◽  
Low Levels

Administration of florfenicol and thiamfenicol through medicated feed is permitted within the European Union, always following veterinary prescription and respecting the withdrawal periods. However, the presence of low levels of florfenicol, thiamfenicol, and chloramfenicol in non-target feed is prohibited. Since cross-contamination can occur during the production of medicated feed and according to Annex II of the European Regulation 2019/4/EC, the control of residue levels of florfenicol and thiamfenicol in non-target feed should be monitored and avoided. Based on all the above, a sensitive and reliable method using liquid chromatography tandem mass spectrometry was developed for the simultaneous detection of chloramfenicol, florfenicol, and thiamfenicol at trace levels in animal feed. Analytes were extracted from minced feed with ethyl acetate. Then, the ethyl acetate was evaporated, the residue was resuspended in Milli-Q water and the extract filtered. The method was in-house validated at carryover levels, with concentration ranging from 100 to 1000 µg/kg. The validation was conducted following the European Commission Decision 2002/657/EC and all performance characteristics were successfully satisfied. The capability of the method to detect amfenicols at lower levels than any prior perspective regulation literature guarantees its applicability in official control activities. The developed method has been applied to non-compliant feed samples with satisfactory results.

scholarly journals New Method for Simultaneous Determination of Microcystins and Cylindrospermopsin in Vegetable Matrices by SPE-UPLC-MS/MS

Toxins ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 406 ◽  
Author(s):  
Leticia Díez-Quijada ◽  
Remedios Guzmán-Guillén ◽  
Ana Prieto Ortega ◽  
María Llana-Ruíz-Cabello ◽  
Alexandre Campos ◽  
...  
Keyword(s):  
Chemical Structure ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Simultaneous Detection ◽  
Ultra Performance Liquid Chromatography ◽  
Limit Of Quantification ◽  
Worldwide Distribution ◽  
Exposure Estimation ◽  
Liquid Chromatography Tandem Mass

Cyanotoxins are a large group of noxious metabolites with different chemical structure and mechanisms of action, with a worldwide distribution, producing effects in animals, humans, and crop plants. When cyanotoxin-contaminated waters are used for the irrigation of edible vegetables, humans can be in contact with these toxins through the food chain. In this work, a method for the simultaneous detection of Microcystin-LR (MC-LR), Microcystin-RR (MC-RR), Microcystin-YR (MC-YR), and Cylindrospermopsin (CYN) in lettuce has been optimized and validated, using a dual solid phase extraction (SPE) system for toxin extraction and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for analysis. Results showed linear ranges (5–50 ng g−1 f.w.), low values for limit of detection (LOD) (0.06–0.42 ng g−1 f.w.), and limit of quantification (LOQ) (0.16–0.91 ng g−1 f.w.), acceptable recoveries (41–93%), and %RSDIP values for the four toxins. The method proved to be robust for the three variables tested. Finally, it was successfully applied to detect these cyanotoxins in edible vegetables exposed to cyanobacterial extracts under laboratory conditions, and it could be useful for monitoring these toxins in edible vegetables for better exposure estimation in terms of risk assessment.

Rapid Determination of Fumonisin B1 in Food Samples by a Clean-Up Tandem Immunoassay Column

2012 ◽  
Vol 488-489 ◽  
pp. 1568-1573 ◽  
Author(s):  
Yan Wang ◽  
Guang He Wu ◽  
Wei Sheng ◽  
Yan Zhang ◽  
Meng Yuan ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Rapid Determination ◽  
Enzymatic Reaction ◽  
Simultaneous Detection ◽  
Fumonisin B1 ◽  
Food Samples ◽  
Promising Tool ◽  
Pre Treatment ◽  
Treatment Procedures

An immunochemistry-based assay for non-instrumental simultaneous detection of fumonisins in food was developed. The method was based upon the direct competitive immuno-reaction and the horse radish peroxidase enzymatic reaction. The assay was developed to show a visual detection result, according to a yes/no response to the LOD of fumonisins. The limit of detection (LOD) was 40 μg L-1. The assay could be accomplished within 15 min in all and 4 min for chromogenic substrate application. The fumonisin contaminations in different kinds of food were analyzed by the proposed method and the results were confirmed by ELISA. Avoiding time-consuming reaction steps and complicated pre-treatment procedures, this assay was demonstrated as a promising tool for on-site sample detections.

scholarly journals In-Situ Formation of Modified Nickel–Zinc-Layered Double Hydroxide Followed by HPLC Determination of Neonicotinoid Insecticide Residues

Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 43
Author(s):  
Jitlada Vichapong ◽  
Rawikan Kachangoon ◽  
Rodjana Burakham ◽  
Yanawath Santaladchaiyakit ◽  
Supalax Srijaranai
Keyword(s):  
Limit Of Detection ◽  
Sodium Dodecyl ◽  
The European Union ◽  
Precipitate Phase ◽  
Insecticide Residues ◽  
Nickel Zinc ◽  
Neonicotinoid Insecticide ◽  
In Situ Formation

A single-step preconcentration procedure using the in-situ formation of modified nickel–zinc-layered double hydroxides (LDHs) prior to high-performance liquid chromatography (HPLC) is investigated for the determination of neonicotinoid insecticide residues in honey samples. The LDHs could be prepared by the sequential addition of sodium hydroxide, sodium dodecyl sulfate, nickel nitrate 6-hydrate and zinc nitrate 6-hydrate, which were added to the sample solution. The co-precipitate phase and phase separation were obtained by centrifugation, and then the precipitate phase was dissolved in formic acid (concentrate) prior to HPLC analysis. Various analytical parameters affecting extraction efficiency were studied, and the characterization of the LDHs phase was performed using Fourier-transformed infrared spectroscopy and scanning electron microscopy. Under optimum conditions, the limit of detection of the studied neonicotinoids, in real samples, were 30 μg L−1, for all analytes, lower than the maximum residue limits established by the European Union (EU). The developed method provided high enrichment, by a factor of 35. The proposed method was utilized to determine the target insecticides in honey samples, and acceptable recoveries were obtained.

scholarly journals A general strategy for the voltammetric trace determination of tellurium in geochemical and environmental matrices after arsenic coprecipitation and critical assessment of digestion schemes

2020 ◽  
Vol 17 (2) ◽  
pp. 85 ◽  
Author(s):  
Marc Biver ◽  
Montserrat Filella
Keyword(s):  
Reference Materials ◽  
Limit Of Detection ◽  
Chemical Elements ◽  
Certified Reference Materials ◽  
Anodic Stripping Voltammetry ◽  
General Strategy ◽  
Environmental Matrices ◽  
Hypophosphorous Acid ◽  
Sample Digestion

Environmental contextAmong chemical elements classified as elements of strategic importance, tellurium is rapidly becoming an emergent contaminant. There is, however, no accurate and sensitive method for measuring tellurium concentrations in environmental and geological samples (e.g., soils, sediments), and thus it is not possible to determine whether an ecosystem is being polluted by human activities. This study provides a reliable answer to this problem. AbstractA general method is proposed for the determination of tellurium in environmental and geochemical samples. Samples may be digested by any technique (acid or fusion digestion). The tellurium in the resulting solution is reductively coprecipitated with added arsenite by hypophosphorous acid, and the precipitate is redissolved and analysed by catalytic anodic stripping voltammetry. Several sample digestion techniques (acid and fusion digestions) are critically assessed. The method is applied to ore certified reference materials, with tellurium concentrations spanning three orders of magnitude, and sediment certified reference materials (ocean, lake and estuarine). An overall limit of detection (LOD) of 5 ppb is achieved. Acid digestion by H2SO4 and by HClO4 or sintering with Na2O2 in glassy carbon crucibles are shown to be the most adequate sample digestion techniques.

scholarly journals A two-colour multiplexed lateral flow immunoassay system to differentially detect human malaria species on a single test line

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Jinsu Kim ◽  
Xiangkun Elvis Cao ◽  
Julia L. Finkelstein ◽  
Washington B. Cárdenas ◽  
David Erickson ◽  
...  
Keyword(s):  
Test Line ◽  
Limit Of Detection ◽  
Simultaneous Detection ◽  
Lateral Flow ◽  
Lateral Flow Immunoassay ◽  
Specific Marker ◽  
Single Test ◽  
Simple Method ◽  
Human Malaria ◽  
Malaria Species

Abstract Background Malaria continues to impose a tremendous burden in terms of global morbidity and mortality, yet even today, a large number of diagnoses are presumptive resulting in lack of or inappropriate treatment. Methods In this work, a two-colour lateral flow immunoassay (LFA) system was developed to identify infections by Plasmodium spp. and differentiate Plasmodium falciparum infection from the other three human malaria species (Plasmodium vivax, Plasmodium ovale, Plasmodium malariae). To achieve this goal, red and blue colours were encoded to two markers on a single test line of strips, for simultaneous detection of PfHRP2 (red), a marker specific for P. falciparum infection, and pLDH (blue), a pan-specific marker for infections by all species of Plasmodium. The assay performance was first optimized and evaluated with recombinant malarial proteins spiked in washing buffer at various concentrations from 0 to 1000 ng mL−1. The colour profiles developed on the single test line were discriminated and quantified: colour types corresponded to malaria protein species; colour intensities represented protein concentration levels. Results The limit of detection (the lowest concentrations of malaria antigens that can be distinguished from blank samples) and the limit of colour discrimination (the limit to differentiate pLDH from PfHRP2) were defined for the two-colour assay from the spiked buffer test, and the two limits were 31.2 ng mL−1 and 7.8 ng mL−1, respectively. To further validate the efficacy of the assay, 25 human whole blood frozen samples were tested and successfully validated against ELISA and microscopy results: 15 samples showed malaria negative; 5 samples showed P. falciparum positive; 5 samples showed P. falciparum negative, but contained other malaria species. Conclusions The assay provides a simple method to quickly identify and differentiate infection by different malarial parasites at the point-of-need and overcome the physical limitations of traditional LFAs, improving the multiplexing potential for simultaneous detection of various biomarkers.

scholarly journals Simultaneous Determination of Penicillin G and Chloramphenicol in Milk by a Magnetic Nanoparticle-Based Fluorescent Immunoassay

2020 ◽  
Vol 14 (1) ◽  
pp. 59-69
Author(s):  
Milka Atanasova ◽  
Yavor Ivanov ◽  
Elena Zvereva ◽  
Anatoly Zherdev ◽  
Tzonka Godjevargova
Keyword(s):  
Magnetic Nanoparticles ◽  
Simultaneous Determination ◽  
Magnetic Nanoparticle ◽  
Limit Of Detection ◽  
Animal Health ◽  
Simultaneous Detection ◽  
Penicillin G ◽  
Frequent Use ◽  
Simultaneous Immunoassay

Background: Antibiotic residues are a problem of increasing importance and have direct consequences for human and animal health. The frequent use of antibiotics in veterinary practice causes their excretion in milk in dairy cattle. This way, they can easily enter the human body through the consumption of milk and dairy products. Objectives: This induces the need for accurate and sensitive methods to monitor antibiotic levels in milk. The aim of this study was to develop a rapid and sensitive magnetic nanoparticle-based fluorescence immunoassay for the simultaneous detection of chloramphenicol and penicillin G in milk. Methods: Magnetic nanoparticles were synthesized and functionalized with (3-aminopropyl)triethoxysilane. Chloramphenicol-Ovalbumin and Chloramphenicol-Ovalbumin-Fluorescein-5-isothiocyanate conjugates were prepared. Penicillin G – ATTO 633 fluorescent conjugate was synthesized. Antibodies against chloramphenicol and penicillin G were immobilized onto the magnetic nanoparticles. The competitive fluorescent immunoassay was developed. The optimal concentration of the antibody-magnetic nanoparticles and the fluorescent conjugates for the assay was determined. The calibration curves for the antibiotics in buffer and milk were plotted. Fluorescent immunoassay for the simultaneous determination of chloramphenicol and penicillin G in milk was developed. Results: The limit of detection by the simultaneous immunoassay of chloramphenicol and penicillin G in milk was 0.85 ng/mL and 1.6 ng/mL, respectively. The recovery of different concentrations of chloramphenicol and penicillin G in milk samples varied from 98% to 106%. Conclusions: A rapid and sensitive magnetic nanoparticle-based immunofluorescent assay for the simultaneous determination of chloramphenicol and penicillin G in milk was developed. The magnetic nanoparticles ensured rapid and easy procedure.

scholarly journals DESENVOLVIMENTO DE METODOLOGIA EM SISTEMA EM FLUXO PARA DETERMINAÇÃO DE CD USANDO ERVA MATE E CHÁ PRETO COMO ADSORVENTE E ESPECTROMETRIA DE ABSORÇÃO ATÔMICA EM CHAMA

2014 ◽  
Vol 39 (1) ◽  
pp. 68
Author(s):  
Renata Mior ◽  
Joyce Nunes Bianchin ◽  
Edmar Martendal ◽  
Eduardo Carasek
Keyword(s):  
Limit Of Detection ◽  
Certified Reference Materials ◽  
Absorption Spectrometry ◽  
Black Tea ◽  
New Methods ◽  
Sample Flow Rate ◽  
Flame Atomic Absorption ◽  
On Line ◽  
Ph Buffer

In this study new methods for determination of cadmium in certified biological samples using mate (llex paraguariensis) and black tea (Camellia sinensis, L.) as biosorbents in an on-line preconcentration system coupled to flame atomic absorption spectrometry was developed. Flow and chemical variables of the proposed system were optimized through multivariate designs. Sample pH, buffer concentration, sample flow rate and biosorbents mass were the selected variables. The limit of detection for cadmium was 0.98 μg L-1 with a precision below 3.6% (35 μg L-1, n=6) for mate biosorbent and 0.97 μg L-1 with a precision below 4.4% (35 μg L-1, n=7) for black tea biosorvent. For both biosorbents the analytical curves were linear from 5 to 50 μg L-1, with a correlation coefficient of 0.9995. The developed methods were successfully applied to certified reference materials (pig kidney and human hair).

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