scholarly journals Monitoring of cyanobacteria using derivative spectrophotometry and improvement of the method detection limit by changing pathlength

2021 ◽  
Author(s):  
Amitesh Malhotra ◽  
Banu Örmeci
Keyword(s):  
Detection Limit ◽  
Derivative Spectrophotometry ◽  
Method Detection Limit ◽  
Toxigenic Strain ◽  
Adverse Health Effects ◽  
First Derivative ◽  
Monitoring Tools ◽  
Wide Range ◽  
Low Probability ◽  
Who Guideline

Abstract Effective monitoring tools and methods are needed for the early detection and management of cyanobacteria in water bodies to minimize their harmful impacts on the environment and public health. This research investigated changing the cuvette pathlength (10-, 50-, and 100-mm) to improve the detection of cyanobacteria using UV-Vis spectrophotometry with subsequent application of derivative spectrophotometry and Savitzky-Golay (S-G) transformation. A non-toxigenic strain of blue-green cyanobacteria, Microcystis aeruginosa (CPCC 632), and a green algae strain for comparison, Chlorella vulgaris (CPCC 90), were studied in a wide range of concentrations (955,000–1,855 cells/mL). In each concentration range, method detection limits were established with absorbance measurements and S-G first derivative of absorbance using 10-, 50-, and 100-mm cuvette pathlengths. Increasing the cuvette pathlength from 10 to 100 mm resulted in a 15-fold improvement in sensitivity with absorbance and a 13-fold improvement with S-G first derivative of absorbance for M. aeruginosa. Overall, adoption of 100 mm pathlength and application of S-G derivative spectra improved the method detection limit for M. aeruginosa from 337,398 cells/mL to 4,916 cells/mL, which is below the WHO guideline for low probability of adverse health effects (<20,000 cells/mL). Similarly, the detection limit for C. vulgaris was improved from 650,414 cells/mL to 11,661 cells/mL. The results also showed that spectrophotometry could differentiate M. aeruginosa from C. vulgaris based on the variations in their pigment absorbance peaks.

scholarly journals Monitoring of Cyanobacteria in Water Using Spectrophotometry and First Derivative of Absorbance

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 124 ◽  
Author(s):  
Adogbeji Valentine Agberien ◽  
Banu Örmeci
Keyword(s):  
Detection Limit ◽  
Surface Water ◽  
Microcystis Aeruginosa ◽  
Negative Impact ◽  
Quality Parameters ◽  
Deionized Water ◽  
Derivative Spectrophotometry ◽  
First Derivative ◽  
Promising Tool ◽  
Low Concentrations

Management of cyanobacteria blooms and their negative impact on human and ecosystem health requires effective tools for monitoring their concentration in water bodies. This research investigated the potential of derivative spectrophotometry in detection and monitoring of cyanobacteria using toxigenic and non-toxigenic strains of Microcystis aeruginosa. Microcystis aeruginosa was quantified in deionized water and surface water using traditional spectrophotometry and the first derivative of absorbance. The first derivative of absorbance was effective in improving the signal of traditional spectrophotometry; however, it was not adequate in differentiating between signal and noise at low concentrations. Savitzky-Golay coefficients for first derivative were used to smooth the derivative spectra and improve the correlation between concentration and noise at low concentrations. Derivative spectrophotometry improved the detection limit as much as eight times in deionized water and as much as four times in surface water. The lowest detection limit measured in surface water with traditional spectrophotometry was 392,982 cells/mL, and the Savitzky-Golay first derivative of absorbance was 90,231 cells/mL. The method provided herein provides a promising tool in real-time monitoring of cyanobacteria concentrations and spectrophotometry offers the ability to measure water quality parameters together with cyanobacteria concentrations.

A novel 3D Zn-coordination polymer based on a multiresponsive fluorescent sensor demonstrating outstanding sensitivities and selectivities for the efficient detection of multiple analytes

2021 ◽  
Author(s):  
Yu Liu ◽  
Yan Wang ◽  
Xiao-Sa Zhang ◽  
Yu-Shu Sheng ◽  
Wen-Ze Li ◽  
...  
Keyword(s):  
Detection Limit ◽  
Coordination Polymer ◽  
Fluorescent Sensor ◽  
Lower Detection Limit ◽  
Ph Values ◽  
Efficient Detection ◽  
Wide Range ◽  
Lower Detection ◽  
Multiple Analytes

A Zn-CP exhibits remarkable fluorescence behaviours and stability in a wide range of pH values. It can become an outstanding candidate in the selective sensing of Fe3+, Mg2+, Cr2O72−, MnO4−, NB and NM at a lower detection limit.

scholarly journals Comparative Assessment of Tungsten Toxicity in the Absence or Presence of Other Metals

Toxics ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 66 ◽  
Author(s):  
Ola Wasel ◽  
Jennifer Freeman
Keyword(s):  
Human Exposure ◽  
Potable Water ◽  
Comparative Assessment ◽  
Tungsten Alloy ◽  
Tungsten Alloys ◽  
Mechanisms Of Toxicity ◽  
Adverse Health Effects ◽  
Current State ◽  
Wide Range ◽  
Military Applications

Tungsten is a refractory metal that is used in a wide range of applications. It was initially perceived that tungsten was immobile in the environment, supporting tungsten as an alternative for lead and uranium in munition and military applications. Recent studies report movement and detection of tungsten in soil and potable water sources, increasing the risk of human exposure. In addition, experimental research studies observed adverse health effects associated with exposure to tungsten alloys, raising concerns on tungsten toxicity with questions surrounding the safety of exposure to tungsten alone or in mixtures with other metals. Tungsten is commonly used as an alloy with nickel and cobalt in many applications to adjust hardness and thermal and electrical conductivity. This review addresses the current state of knowledge in regard to the mechanisms of toxicity of tungsten in the absence or presence of other metals with a specific focus on mixtures containing nickel and cobalt, the most common components of tungsten alloy.

CONTINUOUS BACKGROUNDS IN PIXE

1990 ◽  
Vol 01 (01) ◽  
pp. 1-29 ◽  
Author(s):  
KEIZO ISHII ◽  
SUSUMU MORITA
Keyword(s):  
Detection Limit ◽  
Heavy Ion ◽  
Projectile Energy ◽  
X Rays ◽  
Ion Energy ◽  
Electron Bremsstrahlung ◽  
Wide Range ◽  
Charge Dependence ◽  
Rutherford Scattering ◽  
Atom Collision

Continuous X rays produced by light-ion·atom collisions, which mainly form continuous backgrounds and determine the detection limit of PIXE, have been experimentally and theoretically studied, and it is shown that the experimental results over the wide range of projectile-ion energy from 0.5 MeV to 40 MeV can be well explained by three kinds of radiative process: atomic bremsstrahlung (AB), secondary-electron bremsstrahlung (SEB), and quasifree electron bremsstrahlung (QFEB). Results on the X-ray spectra, the projectile-energy dependence and the projectile-charge dependence, and on the angular distribution of these bremsstrahlungs will be summarized and the importance of AB in heavy-ion atom collision is presented. Discussions are also given on the other origins of continuous backgrounds such as the Compton scattering background, cosmic rays, the Rutherford scattering background, piling up of signals and response functions of detector, charge up effect of the target and natural backgrounds. On the basis of analyses of continuous backgrounds, the detection limit of PIXE is estimated.

scholarly journals RISIKO KESEHATAN PAJANAN BENZENA, TOLUENA DAN XYLENA PETUGAS PINTU TOL

2016 ◽  
Vol 11 (2) ◽  
pp. 188 ◽  
Author(s):  
Bambang Wispriyono ◽  
Eko Handoyo
Keyword(s):  
Detection Limit ◽  
Health Risks ◽  
Risk Groups ◽  
Health Impacts ◽  
Method Detection Limit ◽  
Cross Sectional ◽  
Risk Management System ◽  
Environmental Health Risk ◽  
Benzene Concentration ◽  
Benzene Toluene

<p>Efek negatif dari polusi udara terhadap kesehatan manusia banyak diteliti termasuk polusi akibat sistem transportasi. Emisi kendaraan bermotor menghasilkan Benzena, Toluena dan Xylena (BTX) yang merupakan bahan kimia yang bersifat karsinogenik dan petugas pintu tol merupakan kelompok berisiko terpajan BTX. Penelitian bertujuan mengetahui risiko kesehatan akibat pajanan BTX pada petugas pintu tol. Desain penelitian adalah <em>cross-sectional</em> dengan pendekatan Analisis Risiko Kesehatan Lingkungan (ARKL) dan  faktor-faktor antropometri. Hasil penelitian menunjukkan pada pintu tol rata-rata konsentrasi (mean<span style="text-decoration: underline;">+</span>SD) benzena sebesar 0,00167<span style="text-decoration: underline;">+</span>0,000056 mg/m<sup>3</sup>, toluena sebesar 0,00124<span style="text-decoration: underline;">+</span>0.000049 mg/m<sup>3</sup> dan xylena sebesar 0,00147<span style="text-decoration: underline;">+</span>0,000063 mg/m<sup>3</sup> sedangkan pada kantor administrasi konsentrasi tidak terdeteksi oleh alat (<em>Method Detection Limit</em>). Rata-rata risiko non karsinogenik (RQ) BTX pada petugas pintu tol lebih tinggi secara signifikan dibandingkan dengan rata-rata RQ BTX petugas administrasi. Risiko kesehatan non karsinogenik dan karsinogenik belum menunjukkan adanya risiko kesehatan yang signifikan. Upaya pencegahan berupa pengelolaan manajemen risiko untuk pengendalian risiko bahan berbahaya di lingkungan perlu ditingkatkan.</p><p> </p><p><strong>Kata Kunci:</strong> Pintu Tol, Benzena, Toulena, Xylena</p><p> </p><p>The researches of BTX (Benzene, Toluene and Xylene) related to the health impacts have been done and published in any publications. One of the risk groups is toll gate’s workers who have been exposed every day with BTX. The design of this study is cross-sectional with Environmental Health Risk Analysis to determine the magnitude of health risks of BTX on the toll gate. The results showed at the toll workers’s respondents have  benzene concentration 0.00167+0.000056 mg/m<sup>3</sup>, toluene 0.00124+0.000049 mg/m<sup>3</sup> and xylene 0.00147+0,000063 mg/m<sup>3</sup> respectively, while in the administrative office’s respondents, BTX was undetectable (Minimum Detection Limit). The average RQ of toll gate respondents was significantly higher than administrative office’s respondents. In conclusion, the risk of all workers have the RQ ≤ 1. Non carcinogenic and carcinogenic health risks to all toll gate’s workers recently have not shown any risk yet. Nevertheless, risk management system should be developed and improved.</p><p> </p><p><strong>Keywords</strong>: Toll Gate, Benzene, Toulene, Xylene</p>

Unchecked Climate Change and Mass Migration

2018 ◽  
pp. 43-59
Author(s):  
Fonna Forman ◽  
Veerabhadran Ramanathan
Keyword(s):  
Climate Change ◽  
Heat Waves ◽  
Probabilistic Approach ◽  
Climate Feedbacks ◽  
Central Values ◽  
Mass Migration ◽  
Wide Range ◽  
Low Probability ◽  
Ethical Response ◽  
Causal Complexity

With unchecked emissions of pollutants, global warming is projected to increase to 1.50C within 15 years; to 20C within 35 years and 40C by 2100. These projections are central values with a small (<5%) probability that warming by 2100 can exceed 60C with potentially catastrophic impacts on every human being, living and yet unborn. Climate is already changing in perceptible ways through floods, droughts, wildfires, heat waves and sea level rise, displacing communities and catalyzing migration. Climate migration describes the voluntary and forced movement of people within and across habitats due to changes in climate. While estimates vary from 25 million to as many as one billion climate change migrants by 2050, achieving reliable quantitative estimates of future climate migration faces forbidding obstacles due to: 1) a wide range of projected warming due to uncertainties in climate feedbacks; 2) the lack of a settled definition for climate migration; and 3) the causal complexity of migration due to variability in non-environmental factors such as bioregion, culture, economics, politics and individual factors. But waiting for reliable estimates this creates unacceptable ethical risks. Therefore, we advocate a probabilistic approach to climate migration that accounts for both central and low probability warming projections as the only ethical response to the unfolding crisis. We conclude that in the absence of drastic mitigation actions, climate change-induced mass migration can become a major threat during the latter half of this century.

Graphite Furnace Atomic Absorption Method for the Determination of Lead in Sugars and Syrups

1994 ◽  
Vol 77 (5) ◽  
pp. 1288-1292 ◽  
Author(s):  
Nancy J Miller-Ihli
Keyword(s):  
Detection Limit ◽  
Atomic Absorption ◽  
Graphite Furnace ◽  
Absorption Spectrometry ◽  
Magnesium Nitrate ◽  
Method Detection Limit ◽  
High Fructose ◽  
Graphite Furnace Atomic Absorption ◽  
Characteristic Mass

Abstract A method was developed for the determination of lead in sugars and syrups. Samples are wet-ashed with a nitric acid–hydrogen peroxide procedure and analyzed by graphite furnace atomic absorption spectrometry. The method involves the use of magnesium nitrate as a matrix modifier, air ashing, platform atomization, and quantitation by peak area measurements with direct calibration against aqueous standards. The instrumental detection limit (based on 3.29σ) was 10 pg, or 0.5 μg/L for a 20 μL injection, corresponding to a method detection limit of 3.3 ng/g sugar. The characteristic mass was approximately 12 pg. This method was validated by analyzing sucrose and high-fructose corn syrup samples spiked with known quantities of lead. The average recovery was 101 ± 6%.

scholarly journals Enhancement of the Peroxidase-Like Activity of Iodine-Capped Gold Nanoparticles for the Colorimetric Detection of Biothiols

Biosensors ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 113 ◽  
Author(s):  
Chia-Chen Chang ◽  
Tsz-Lian Hsu ◽  
Chie-Pein Chen ◽  
Chen-Yu Chen
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Detection Limit ◽  
Enzymatic Activity ◽  
Catalytic Properties ◽  
Colorimetric Assay ◽  
Colorimetric Detection ◽  
Synergetic Effect ◽  
Vis Spectroscopy ◽  
Wide Range

A colorimetric assay was developed for the detection of biothiols, based on the peroxidase-like activity of iodine-capped gold nanoparticles (AuNPs). These AuNPs show a synergetic effect in the form of peroxidase-mimicking activity at the interface of AuNPs, while free AuNPs and iodine alone have weak catalytic properties. Thus, iodine-capped AuNPs possess good intrinsic enzymatic activity and trigger the oxidation of 3,3’,5,5’-tetramethylbenzidine (TMB), leading to a change in color from colorless to yellow. When added to solution, biothiols, such as cysteine, strongly bind to the interface of AuNPs via gold-thiol bonds, inhibiting the catalytic activity of AuNPs, resulting in a decrease in oxidized TMB. Using this strategy, cysteine could be linearly determined, at a wide range of concentrations (0.5 to 20 μM), with a detection limit of 0.5 μM using UV-Vis spectroscopy. This method was applied for the detection of cysteine in diluted human urine.

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