scholarly journals Quantification of Hypochlorite in Water Using the Nutritional Food Additive Pyridoxamine

Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3616
Author(s):  
Kamilla M. S. Kaarsholm ◽  
Argyro Kokkoli ◽  
Eleni Keliri ◽  
Paul D. Mines ◽  
Maria G. Antoniou ◽  
...  
Keyword(s):  
Absorption Maximum ◽  
Potable Water ◽  
Colorimetric Method ◽  
Fluorescence Emission ◽  
Industrial Applications ◽  
Food Additive ◽  
Free Chlorine ◽  
Negative Slope ◽  
Residual Chlorine ◽  
Limit Of Quantification

Chlorine is a widely used disinfectant and oxidant used for an array of municipal and industrial applications, including potable water, swimming pools, and cleaning of membranes. The most popular method to verify the concentration of free chlorine is the colorimetric method based on DPD (N, N-diethyl-p-phenylenediamine), which is fast and reasonably cheap, but DPD and its product are potentially toxic. Therefore, a novel, environmentally friendly colorimetric method for the quantification of residual chlorine based on the food additive pyridoxamine (4-(aminomethyl)-5-(hydroxymethyl)-2-methylpyridin-3-ol) was investigated. Pyridoxamine is a B6 vitamin with an absorption maximum at 324 nm and fluorescence emission at 396 nm. Pyridoxamine reacts rapidly and selectively with free chlorine, resulting in a linear decrease both in absorbance and in emission, giving therefore calibration curves with a negative slope. The pyridoxamine method was successfully applied for the quantification of free chlorine from 0.2 to 250 mg/L. Using 1 cm cuvettes, the limit of quantification was 0.12 mg Cl2/L. The pyridoxamine and the DPD methods were applied to actual environmental samples, and the deviation between results was between 4% and 9%. While pyridoxamine does not react with chloramine, quantification of monochloramine was possible when iodide was added, but the reaction is unfavourably slow.

scholarly journals First Derivative UV Spectra of Surface Water as a Monitor of Chlorination in Drinking Water Treatment

2001 ◽  
Vol 1 ◽  
pp. 39-43 ◽  
Author(s):  
V. Zitko
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Surface Water ◽  
Distribution System ◽  
Drinking Water Treatment ◽  
Uv Spectra ◽  
Free Chlorine ◽  
Residual Chlorine ◽  
First Derivative ◽  
Derivative Spectra

Many countries require the presence of free chlorine at about 0.1 mg/l in their drinking water supplies. For various reasons, such as cast-iron pipes or long residence times in the distribution system, free chlorine may decrease below detection limits. In such cases it is important to know whether or not the water was chlorinated or if nonchlorinated water entered the system by accident. Changes in UV spectra of natural organic matter in lakewater were used to assess qualitatively the degree of chlorination in the treatment to produce drinking water. The changes were more obvious in the first derivative spectra. In lakewater, the derivative spectra have a maximum at about 280 nm. This maximum shifts to longer wavelengths by up to 10 nm, decreases, and eventually disappears with an increasing dose of chlorine. The water treatment system was monitored by this technique for over 1 year and changes in the UV spectra of water samples were compared with experimental samples treated with known amounts of chlorine. The changes of the UV spectra with the concentration of added chlorine are presented. On several occasions, water, which received very little or no chlorination, may have entered the drinking water system. The results show that first derivative spectra are potentially a tool to determine, in the absence of residual chlorine, whether or not surface water was chlorinated during the treatment to produce potable water.

scholarly journals A sensitive, accurate, and high-throughput gluco-oligosaccharide oxidase based HRP colorimetric method for lytic polysaccharide monooxygenase activity assay

2021 ◽  
Author(s):  
Gang Liu
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Direct Method ◽  
Total Concentration ◽  
Colorimetric Method ◽  
Industrial Applications ◽  
Assay Method ◽  
Activity Assay ◽  
Lytic Polysaccharide Monooxygenase ◽  
Monooxygenase Activity

Abstract Background The AA9 (auxiliary activities) family of lytic polysaccharide monooxygenases (AA9 LPMOs) are ubiquitous and diverse group of enzymes amongst the fungal kingdom. They catalyze the oxidative cleavage of glycosidic bonds in lignocellulose and exhibit great potential for secondary biorefinery applications. Screening of AA9 LPMOs for desirable properties is crucial for biorefinery industrial applications. However, robust, high-throughput and direct method for AA9 LPMO activity assay, which is prerequisite for screening of LPMOs with excellent properties, is still lacking. Here, we have described a gluco-oligosaccharide oxidase (GOOX) based horseradish peroxidase (HRP) colorimetric method for AA9 LPMO activity assay. Results We cloned and expressed a GOOX gene from Sarocladium strictum in Trichoderma reesei, purified the recombinant SsGOOX, validated its properties, and set up a SsGOOX based HRP colorimetric method for cellobiose concentration assay. Then we expressed two AA9 LPMOs from Thielavia terrestris, TtAA9F and TtAA9G in T. reesei, purified the recombinant proteins, and analyzed their product profiles and regioselectivity towards phosphoric acid swollen cellulose (PASC). TtAA9F was characterized as a C1 type (class 1) LPMO, while TtAA9G was characterized as a C4 type (class 2) LPMO. Finally, the SsGOOX based HRP colorimetric method was used to quantify the total concentration of reducing lytic products from LPMO reaction, and consequently, the activities of both C1 and C4 types of LPMOs were analyzed. These LPMOs could be effectively analyzed with limits of detection (LoDs) lower than 30 nmol/L, and standard curves between A515 and LPMO concentrations with determination coefficients greater than 0.994 were obtained. Conclusions A novel, sensitive and accurate assay method that directly targets the main activity of both C1 and C4 type of AA9 LPMOs was established. This method is easy to use and could be performed on a microtiter plate ready for high-throughput screening of AA9 LPMOs with high properties.

scholarly journals The effect of free chlorine on Burkholderia pseudomallei in potable water

2003 ◽  
Vol 37 (18) ◽  
pp. 4425-4432 ◽  
Author(s):  
Kay Howard ◽  
Timothy J.J Inglis
Keyword(s):  
Burkholderia Pseudomallei ◽  
Potable Water ◽  
Free Chlorine

scholarly journals Electrochemical Detection of Free-Chlorine in Water Samples Facilitated by In-Situ pH Control Using Interdigitated Microelectrodes

2020 ◽  
Author(s):  
Alan O'Riordan ◽  
Benjamin O'sullivan ◽  
Pierre Lovera ◽  
Ian Seymour ◽  
James Rohan
Keyword(s):  
Water Samples ◽  
Hypochlorous Acid ◽  
Control Method ◽  
Tap Water ◽  
Distribution Networks ◽  
Ph Control ◽  
Free Chlorine ◽  
Residual Chlorine ◽  
Solution Ph

Residual free-chlorine concentration in water supplies is a key metric studied to ensure disinfection. High residual chlorine concentrations lead to unpleasant odours and tastes, while low concentrations may lead to inadequate disinfection. The concentration is most commonly monitored using colorimetric techniques which require additional reagents. Electrochemical analysis offers the possibility for in-line analysis without the need for additional reagents. Electrochemical-based detection of chlorine is influenced by the solution pH, which defines the particular chlorine ionic species present in solution. As such, controlling the pH is essential to enable electrochemical based detection of residual chlorine in water. To this end, we explore the application of solid state interdigitated electrodes to tailor the in-situ pH of a solution while simultaneously detecting free-chlorine. Finite element simulations and subsequent electrochemical characterization, using gold interdigitated microelectrode arrays, were employed to explore the feasibility of an in-situ pH control approach. In practice, the approach converted residual chlorine from an initial mixture of two species (hypochlorous acid and hypochlorite ion), to one species (hypochlorous acid). Chlorine detection was shown in water samples using this exploratory method, resulting in a two-fold increase in signal response, compared to measurements without pH control. Finally, tap water samples were measured using the in-situ pH control method and the results showed excellent correlation (within experimental error) with a commercial instrument, demonstrating the efficacy of the developed technique. This work establishes the possibility of deploying an electrochemical based reagent-free, in-line chlorine sensor required for water distribution networks.

scholarly journals Self-colorimetric determination of bio-ethanol using permanganate in fermentation samples

2021 ◽  
Author(s):  
Mohamed Abdelazim
Keyword(s):  
Optical Density ◽  
Limit Of Detection ◽  
Fermentation Broth ◽  
Potassium Dichromate ◽  
Colorimetric Method ◽  
Density Difference ◽  
Neutral Medium ◽  
Colorimetric Determination ◽  
Limit Of Quantification

Abstract Without the aid of chromatographic techniques, quantification of bio-ethanol in fermentation-broth distillate becomes inconvenient. Potassium permanganate is preferable over potassium dichromate because of the latter well-known toxic properties, it is common used in ethyl alcohol determination either by visible determination of Cr(III) green optical density, a consumed Cr(VI) determination in strong acid medium by measuring band absorbance decrease at 267 nm or the unreacted Cr(VI) determination iodometrically after alcohol oxidation. Nevertheless, these titre methods arise difficulties experience analysts from multiple solutions preparation, standardization that should be carried out every day and to successful end point detection in the presence of Cr(III) green color which leads to a significant ethanol quantification error. Noteworthy permanganate-iodometry drawbacks as same as titre dichromate difficult practical procedures and multiple reagents employed. In this laboratory a self colorimetric method was developed in neutral medium as alcohol-specific oxidizing agent precludes both of its undesirable high oxidizing properties and difficult titrimetric methodologies for bio-ethanol quantification. It is based on unreacted permanganate optical density difference between a non ethanol-containing sample as a blank and ethanol-containing sample is directly proportional to the consumed permanganate amount in ethanol red-ox reaction and consequently directly proportional to ethanol content. This optical density difference versus ethanol concentration 1–6% v/v obeys Beer-Lampert law provides limit of detection, limit of quantification and correlation coefficient equal 0.17%, 0.56% and 0.999 respectively.

scholarly journals Validation of a Simple and Robust Liebermann–Burchard Colorimetric Method for the Assay of Cholesterol in Selected Milk Products in Ghana

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Joseph K. Adu ◽  
Cedric D. K. Amengor ◽  
Naomi Kabiri ◽  
Emmanuel Orman ◽  
Stella Abla Gameli Patamia ◽  
...  
Keyword(s):  
Cardiovascular Diseases ◽  
Steroid Hormones ◽  
Dairy Products ◽  
Limit Of Detection ◽  
Colorimetric Method ◽  
Good Alternative ◽  
Human Consumption ◽  
Future Health ◽  
Limit Of Quantification ◽  
Milk Products

Cholesterol plays a key role in the synthesis of bile acids and steroid hormones in the human body. However, excessively high levels are usually implicated in cardiovascular diseases. For this reason, it is essential to monitor exposure to high levels of it in products meant for human consumption, and this calls for the need to develop analytical methods to detect them. The use of Liebermann–Burchard reaction in this study has been explored to develop a simple, reliable, and robust quantitative colorimetric method to assay cholesterol, and hence provide a good alternative to chromatographic methods. The developed method was validated and used to determine the contents of cholesterol in selected dairy products on the Kumasi Metropolis market. The method demonstrated a good linearity (R2=0.996) over concentration range of 0.01–0.08 mg/ml. It was also shown to be precise and robust. The limit of detection (LOD) and limit of quantification (LOQ) were determined to be 0.00430 mg/ml and 0.01304 mg/ml, respectively. Ten selected brands of canned milk (B1–B5) and fresh yoghurt products (A1–A5) were then assayed using the developed method. The results showed that three products from each category had cholesterol contents above the allowable content of 5 mg/100 g in dairy products. The study thus has proposed a simple colorimetric method that can be adopted by dairy products manufacturing facilities to rapidly determine cholesterol contents during manufacturing in order to monitor the safe consumption of their products, and eliminate or minimize possible future health hazards.

scholarly journals ULTRAVIOLET-SPECTROPHOTOMETRIC METHOD DEVELOPMENT AND VALIDATION FOR THE DETERMINATION OF NORFLOXACIN PRESENT IN TASTE MASKED DRUG RESIN COMPLEX

2018 ◽  
Vol 11 (4) ◽  
pp. 244
Author(s):  
Ayya Rajendra Prasad ◽  
Jayanthi Vijaya Ratna
Keyword(s):  
Spectrophotometric Method ◽  
Absorption Maximum ◽  
Method Development ◽  
Limit Of Detection ◽  
Statistical Parameters ◽  
Limit Of Quantification ◽  
Relative Standard ◽  
Validation Parameters ◽  
Development And Validation

 Objective: The objective of this study was developed and validated a novel, specific, precise, and simple ultraviolet (UV)-spectrophotometric method for the estimation of norfloxacin present in taste masked drug-resin complex.Methods: UV-spectrophotometric determination was performed with ELICO SL 1500 UV-visible spectrophotometer using 0.1 N HCl as a medium. The spectrum of the standard solution was run from 200 to 400 nm range for the determination of absorption maximum (λ max). λ max of norfloxacin was found at 278 nm. The absorbance of standard solutions of 1, 2, 3, 4, and 5 μg/ml of drug solution was measured at an absorption maximum at 278 nm against the blank. Then, a graph was plotted by taking concentration on X-axis and absorbance on Y-axis which gave a straight line. Validation parameters such as linearity and range, selectivity and specificity, limit of detection (LOD) and limit of quantification (LOQ), accuracy, precision, and robustness were evaluated as per the International Conference on Harmonization (ICH) guidelines.Results: Linearity for the UV-spectrophotometric method was noted over a concentration range of 1–5 μg/ml with a correlation coefficient of 0.9995. The LOD and LOQ for norfloxacin were found at 0.39 μg/ml and 1.19 μg/ml, respectively. Accuracy was in between 99.00% and 99.17%. % relative standard deviation for repeatability, intraday precision, and interday precision was found to be 0.600, in between 0.291 and 0.410, and in between 0.682 and 1.439, respectively. The proposed UV spectrophotometric method is found to be robust.Conclusion: The proposed UV-spectrophotometric method was validated according to the ICH guidelines, and results and statistical parameters demonstrated that the developed method is sensitive, precise, reliable, and simple for the estimation of norfloxacin present in taste masked drug-resin complex.

Electrochemical Detection of Free-Chlorine in Water Samples Facilitated by In-Situ pH Control Using Interdigitated Microelectrodes

2020 ◽  
Author(s):  
Alan O'Riordan ◽  
Benjamin O'sullivan ◽  
Pierre Lovera ◽  
Ian Seymour ◽  
James Rohan
Keyword(s):  
Water Samples ◽  
Hypochlorous Acid ◽  
Control Method ◽  
Tap Water ◽  
Distribution Networks ◽  
Ph Control ◽  
Free Chlorine ◽  
Residual Chlorine ◽  
Solution Ph

Residual free-chlorine concentration in water supplies is a key metric studied to ensure disinfection. High residual chlorine concentrations lead to unpleasant odours and tastes, while low concentrations may lead to inadequate disinfection. The concentration is most commonly monitored using colorimetric techniques which require additional reagents. Electrochemical analysis offers the possibility for in-line analysis without the need for additional reagents. Electrochemical-based detection of chlorine is influenced by the solution pH, which defines the particular chlorine ionic species present in solution. As such, controlling the pH is essential to enable electrochemical based detection of residual chlorine in water. To this end, we explore the application of solid state interdigitated electrodes to tailor the in-situ pH of a solution while simultaneously detecting free-chlorine. Finite element simulations and subsequent electrochemical characterization, using gold interdigitated microelectrode arrays, were employed to explore the feasibility of an in-situ pH control approach. In practice, the approach converted residual chlorine from an initial mixture of two species (hypochlorous acid and hypochlorite ion), to one species (hypochlorous acid). Chlorine detection was shown in water samples using this exploratory method, resulting in a two-fold increase in signal response, compared to measurements without pH control. Finally, tap water samples were measured using the in-situ pH control method and the results showed excellent correlation (within experimental error) with a commercial instrument, demonstrating the efficacy of the developed technique. This work establishes the possibility of deploying an electrochemical based reagent-free, in-line chlorine sensor required for water distribution networks.

scholarly journals Drinking water microbiological survey of the Northwestern State of Sinaloa, Mexico

2007 ◽  
Vol 6 (1) ◽  
pp. 125-129 ◽  
Author(s):  
Cristobal Chaidez ◽  
Marcela Soto ◽  
Celida Martinez ◽  
Bruce Keswick
Keyword(s):  
Escherichia Coli ◽  
Aeromonas Hydrophila ◽  
Potable Water ◽  
Additional Treatment ◽  
Capital City ◽  
Plate Count ◽  
Residual Chlorine ◽  
Opportunistic Pathogens ◽  
Total Coliforms ◽  
Physico Chemical

A potable water survey, in two important municipalities of the state of Sinaloa, Mexico was conducted. Culiacan, capital city of Sinaloa and its neighboring municipality, Navolato were selected to enumerate Aeromonas hydrophila, Escherichia coli, fecal and total coliforms, Pseudomonas aeruginosa, and Heterotrophic plate count bacteria from 100 households' taps. Manganese; residual chlorine; pH; temperature and turbidity were also examined. Overall, Aeromonas hydrophila was not detected in any of the samples, 3% contained Escherichia coli, 28% had fecal and 46 total coliforms, P. aeruginosa was present in 15% of the samples. HPC bacteria were found in all of the samples but 43% had numbers greater than 500 CFU per ml. The average numbers obtained for the physico-chemical parameters were 0.15 mg/L; 0.32 mg/L; 6.5; 28.7°C and 2.92 NTU for manganese, residual chlorine, pH, temperature and turbidity, respectively. The findings of the current study demonstrate that potable water from both municipalities can harbor substantial numbers of indicator and opportunistic pathogens suggesting that additional treatment in the household may be needed.

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