scholarly journals A Colorimetric Dip Strip Assay for Detection of Low Concentrations of Phosphate in Seawater

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3125
Author(s):  
Hojat Heidari-Bafroui ◽  
Amer Charbaji ◽  
Constantine Anagnostopoulos ◽  
Mohammad Faghri
Keyword(s):  
Limit Of Detection ◽  
Storage Conditions ◽  
Ammonium Molybdate ◽  
Sargasso Sea ◽  
Detection Zone ◽  
Liquid Form ◽  
Limits Of Detection ◽  
Low Concentrations ◽  
Phosphate Detection ◽  
Detection And Quantification

Nutrient pollution remains one of the greatest threats to water quality and imposes numerous public health and ecological concerns. Phosphate, the most common form of phosphorus, is one of the key nutrients necessary for plant growth. However, phosphate concentration in water should be carefully monitored for environmental protection requirements. Hence, an easy-to-use, field-deployable, and reliable device is needed to measure phosphate concentrations in the field. In this study, an inexpensive dip strip is developed for the detection of low concentrations of phosphate in water and seawater. In this device, ascorbic acid/antimony reagent was dried on blotting paper, which served as the detection zone, and was followed by a wet chemistry protocol using the molybdenum method. Ammonium molybdate and sulfuric acid were separately stored in liquid form to significantly improve the lifetime of the device and enhance the reproducibility of its performance. The device was tested with deionized water and Sargasso Sea seawater. The limits of detection and quantification for the optimized device using a desktop scanner were 0.134 ppm and 0.472 ppm for phosphate in water and 0.438 ppm and 1.961 ppm in seawater, respectively. The use of the portable infrared lightbox previously developed at our lab improved the limits of detection and quantification by a factor of three and were 0.156 ppm and 0.769 ppm for the Sargasso Sea seawater. The device’s shelf life, storage conditions, and limit of detection are superior to what was previously reported for the paper-based phosphate detection devices.

scholarly journals Optimized HPLC -UV Method for Separation, Detection and Quantification of Endocrine Disrupting Estrogens in Low Quality Water

2017 ◽  
Vol 9 (3) ◽  
pp. 19
Author(s):  
Sijaona Cassian Msigala ◽  
Faith P Mabiki ◽  
Bjarne Styrishave ◽  
Robinson H Mdegela
Keyword(s):  
Emerging Contaminants ◽  
Limit Of Detection ◽  
Health Effect ◽  
Low Concentrations ◽  
Routine Monitoring ◽  
Relative Standard ◽  
Endocrine Disrupting ◽  
Quality Water ◽  
Living Organisms ◽  
Detection And Quantification

Endocrine disrupting estrogens are emerging contaminants in aquatic ecosystems and environment in general. There are no guidelines for routine monitoring of these chemicals, despite the existing evidences of their adverse health effect to living organisms at low concentrations. This study aimed at developing and validating an optimized HPLC-UV method for detection and quantification of estradiol and ethinylestradiol. Isocratic elution was used for separation and detection of ethinylestradiol and estradiol. The mobile phase was applied with A; water B; acetonitrile (50:50) at flow rate of 0.7mL/min and injection volume 10mL. The precision and accuracy of the method were within the acceptable range. Relative standard deviation of peak area for E2 ranged from 1.373 to 3.668%, and for EE2 ranged from 0.829 to 6.495 %. The percentage recovery for E2 ranged from 82.3 to 99.84 %, and for EE2 ranged from 84.6 to 103.52 %. Linearity of the method was realized at range of 2.5 to 50 ng/mL and 100 to 1000 ng/mL for both E2 and EE2. The linear regression coefficients were 0.9979 and 0.9973 for E2 whereas for EE2 were 0.9983 and 0.9976. Limit of detection were found to be 0.05 ng/mL and 0.08 ng/mL for E2 and EE2 respectively. The obtained limits of quantification were 0.18 and 0.28 ng/mL for E2 and EE2 respectively. In untreated sewage the concentrations of E2 and EE2 were 0.28 ng/ml and 0.18 ng/ml respectively. But in subsequent wastewater stabilization ponds the concentrations were below detection limit. Therefore, the optimized HPLC-UV method is suitable for detection and quantification of endocrine disrupting estrogens when a level of pollution is at least 0.15 ng/ml. At low extent of pollution would require use of the method in conjunction with ELISA technique.

Micro-Extraction of Commonly Abused Benzodiazepines for Urinary Screening by Liquid Chromatography

1997 ◽  
Vol 34 (1) ◽  
pp. 61-67 ◽  
Author(s):  
Kim Wolff ◽  
Deborah Garretty ◽  
Alastair W M Hay
Keyword(s):  
Liquid Chromatography ◽  
Coefficient Of Variation ◽  
Limit Of Detection ◽  
Extraction Procedure ◽  
Sample Processing ◽  
Sample Handling ◽  
Urinary Screening ◽  
Low Concentrations ◽  
Coefficients Of Variation ◽  
Detection And Quantification

We have developed a micro-extraction procedure for the analysis of seven commonly prescribed benzodiazepines (chlordiazepoxide, diazepam, lorazepam, nitrazepam, nordiazepam, oxazepam, and temazepam) in urine using liquid chromatography. The method is reliable and sensitive, uses small volumes (100μL) of urine and is suitable for the detection and quantification of low concentrations of benzodiazepines. The micro-extraction procedure allowed rapid sample processing, which is important for routine sample handling. The limit of detection for the seven benzodiazepines ranged from 0·10–0·71 mg/L and recovery of the different benzodiazepines was good, ranging from 70–105%. Between-and within-assay coefficients of variation ranged from 6·3% to 13·8%, and 2% to 3·5%, respectively. Chlordiazepoxide chromatographed poorly (between assay coefficient of variation 35·4%, within-assay 7%), and we set the cut-off value for this compound at 5·0 mg/L.

scholarly journals SaQuant: a real-time PCR assay for quantitative assessment of Staphylococcus aureus

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Colin Wood ◽  
Jason Sahl ◽  
Sara Maltinsky ◽  
Briana Coyne ◽  
Benjamin Russakoff ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Sensitivity And Specificity ◽  
Pathogen Detection ◽  
Limit Of Detection ◽  
Future Research ◽  
Limit Of Quantification ◽  
Pathogen Prevalence ◽  
Single Well ◽  
Effective Public Health ◽  
Detection And Quantification

Abstract Background Molecular assays are important tools for pathogen detection but need to be periodically re-evaluated with the discovery of additional genetic diversity that may cause assays to exclude target taxa or include non-target taxa. A single well-developed assay can find broad application across research, clinical, and industrial settings. Pathogen prevalence within a population is estimated using such assays and accurate results are critical for formulating effective public health policies and guiding future research. A variety of assays for the detection of Staphylococcus aureus are currently available. The utility of commercial assays for research is limited, given proprietary signatures and lack of transparent validation. Results In silico testing of existing peer-reviewed assays show that most suffer from a lack of sensitivity and specificity. We found no assays that were specifically designed and validated for quantitative use. Here we present a qPCR assay, SaQuant, for the detection and quantification of S. aureus as might be collected on sampling swabs. Sensitivity and specificity of the assay was 95.6 and 99.9 %, respectively, with a limit of detection of between 3 and 5 genome equivalents and a limit of quantification of 8.27 genome equivalents. The presence of DNA from non-target species likely to be found in a swab sample, did not impact qualitative or quantitative abilities of the assay. Conclusions This assay has the potential to serve as a valuable tool for the accurate detection and quantification of S. aureus collected from human body sites in order to better understand the dynamics of prevalence and transmission in community settings.

scholarly journals A Novel Niosome-Encapsulated Essential Oil Formulation to Prevent Aspergillus flavus Growth and Aflatoxin Contamination of Maize Grains During Storage

Toxins ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 646 ◽  
Author(s):  
García-Díaz ◽  
Patiño ◽  
Vázquez ◽  
Gil-Serna
Keyword(s):  
Aspergillus Flavus ◽  
Fungal Growth ◽  
Storage Conditions ◽  
Aflatoxin Contamination ◽  
Small Scale ◽  
Low Concentrations ◽  
Oil Formulation ◽  
Scale Test ◽  
Encapsulation Method

Aflatoxin (AF) contamination of maize is a major concern for food safety. The use of chemical fungicides is controversial, and it is necessary to develop new effective methods to control Aspergillus flavus growth and, therefore, to avoid the presence of AFs in grains. In this work, we tested in vitro the effect of six essential oils (EOs) extracted from aromatic plants. We selected those from Satureja montana and Origanum virens because they show high levels of antifungal and antitoxigenic activity at low concentrations against A. flavus. EOs are highly volatile compounds and we have developed a new niosome-based encapsulation method to extend their shelf life and activity. These new formulations have been successfully applied to reduce fungal growth and AF accumulation in maize grains in a small-scale test, as well as placing the maize into polypropylene woven bags to simulate common storage conditions. In this latter case, the antifungal properties lasted up to 75 days after the first application.

Simultaneous quantification of vitamin E and vitamin E metabolites in equine plasma and serum using LC-MS/MS

2021 ◽  
pp. 104063872110054
Author(s):  
Hadi Habib ◽  
Carrie J. Finno ◽  
Ingrid Gennity ◽  
Gianna Favro ◽  
Erin Hales ◽  
...  
Keyword(s):  
Vitamin E ◽  
Normal Growth ◽  
Alpha Tocopherol ◽  
Limits Of Detection ◽  
Phase Gradient ◽  
Equine Plasma ◽  
Accuracy And Precision ◽  
Low Concentrations ◽  
Liquid Chromatography Tandem Mass ◽  
Acquity Uplc

Vitamin E deficiencies can impact normal growth and development in humans and animals, and assessment of circulating levels of vitamin E and its metabolites may be an important endpoint for evaluation. Development of a sensitive method to detect and quantify low concentrations of vitamin E and metabolites in biological specimens allows for a proper diagnosis for patients and animals that are deficient. We developed a method to simultaneously extract, detect, and quantify the vitamin E compounds alpha-tocopherol (α-TP), gamma-tocopherol (γ-TP), alpha-tocotrienol (α-TT), and gamma-tocotrienol (γ-TT), and the corresponding metabolites formed after β-oxidation of α-TP and γ-TP, alpha-carboxymethylbutyl hydroxychroman (α-CMBHC) and alpha- or gamma-carboxyethyl hydroxychroman (α- or γ-CEHC), respectively, from equine plasma and serum. Quantification was achieved through liquid chromatography–tandem mass spectrometry. We applied a 96-well high-throughput format using a Phenomenex Phree plate to analyze plasma and serum. Compounds were separated by using a Waters ACQUITY UPLC BEH C18 column with a reverse-phase gradient. The limits of detection for the metabolites and vitamin E compounds were 8–330 pg/mL. To validate the method, intra-day and inter-day accuracy and precision were evaluated along with limits of detection and quantification. The method was then applied to determine concentrations of these analytes in plasma and serum of horses. Alpha-TP levels were 3–6 µg/mL of matrix; the metabolites were found at much lower levels, 0.2–1.0 ng/mL of matrix.

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