Titrimetric Method Research Articles

Evaluation of Antibacterial Activity of Lactic Acid Bacteria Isolated from Kunun Zaki against Selected Bread Rope Spoilage Bacteria

In line with increasing demand by consumers for safe and minimally processed food products, biopreservation has been advocated over the traditional use of chemical additives in combating food spoilage. This study evaluated the antibacterial activity of four lactic acid bacteria (LAB) (Lactobacillus fermentum, Lactococcus lactis, Lactobacillus brevis and Lactobacillus plantarum) isolated from kunun-zaki against the bread rope spoilage bacteria, Bacillus subtilis and Bacillus cereus. Antibacterial activity was determined using the dual agar overlay method with subsequent measurement of zones of inhibition. Titrimetric methods were used to determine the abilities of the isolated LAB to produce antimicrobials including lactic acid, hydrogen peroxide and diacetyl. Lactobacillus fermentum brought about the highest inhibition zone (20 mm) against Bacillus cereus. The smallest zone of inhibition (6 mm) was recorded for L. plantarum against B. cereus. Whereas L. plantarum produced the highest amount of lactic acid (0.540 g/L), L. brevis produced the lowest lactic acid amount of 0.348 g/L. L. fermentum produced the highest amount of hydrogen peroxide (0.020 g/L) whereas L.brevis recorded the lowest hydrogen peroxide production of 0.010 g/L. L. lactis and L. fermentum had the highest and lowest values of 0.649 g/L and 0.219 g/L respectively for diacetyl production. Differences in the antibacterial activities and antimicrobials production by the LAB were statistically significant (P < .05). The findings show that the LAB isolates possessed antibacterial activity against the selected spoilage bacteria and as such could be exploited as potential biocontrol agents against the selected bread rope spoilage bacteria.

Molecular Characterization of Lactic Acid Producing Bacteria Isolated from Tiger nut (Cyperus esculentus L) tuber and Soybean (Glycine max L) seeds

Lactic acid-producing bacteria (LAB) are a diverse group of bacteria which play a crucial role in fermentation processes. They produce lactic acid a primary product of fermentation, by exploiting food substances like carbohydrates proteins and lipids, leading to the production of secondary metabolites such as alcohols, aldehydes, acids, esters and Sulphur. The aim of this study was to characterize lactic acid bacterial isolated from tiger nut tubers (Cyperus esculentus L) and soybean seeds (Glycine max L), using 16S rRNA gene. Lactic acid production was determined by titrimetric method from 0 to 48h. Four of the ten isolates, identified as: Lactobacillus plantarum strain AMA2A, L. fermentum strain AMA5, L. buchneri strain AMA11 and L. plantarum strain AMA14 produced percentage lactic acid of 1.27, 0.93, 0.86 and 0.92 respectively after 48h. This study has demonstrated that the lactic acid producing bacteria namely: Lactobacillus plantarum AMA2A, Lactobacillus fermentum AMA5, Lactobacillus buchneri AMA11 and Lactobacillus plantarum AMA14 could be isolated from tiger nut and soybean since these substrates contain sufficient ingredients or nutrients which serve as enabling environments for their proliferation

PS-P14-9: SALT CONTENT IN COMMONLY CONSUMED PROCESSED PACKAGED FOODS AND THEIR CONFORMITY WITH LABEL INFORMATION IN BANGLADESH

Objective: Consumption of processed foods is surging in low and middle-income countries and gradually replacing home-cooked meals. Unfortunately, the salt content is usually high in these processed foods which eventually causes hypertension, heart diseases and stroke. As the reduction of overall salt intake serves as a preventive measure for Non-communicable Diseases, so, the present study was undertaken to estimate the content of salt in commonly consumed processed foods in Bangladesh and to assess their conformity with label declaration. Along with salt, total sugar, total fat, saturated fat, trans fat, protein, fiber and energy were also assessed. Design and Methods: It was a cross-sectional population-based study. A total of 11 most consumed processed packaged foods were identified from the 8 administrative divisions of Bangladesh through a household survey (n = 480) and a market survey (n = 24) done in 2019. Samples from all the 8 divisions were collected following a list of commonly consumed foods and brands. The foods included for analysis were chips, chanachur, fried peas, pulse, noodles, biscuits, lozenge/lollipop, milk chocolate, chutney, and ice cream. A brand-wise composite sample of each processed food item was prepared by pooling at least 12 samples in the Institute of Nutrition and Food Science. Samples were analyzed by ‘Association of Official Analytical Chemists’ and titrimetric method (IS-1743) method at an accredited lab. The healthiness of the products was evaluated in terms of the Health Star Rating scheme of Australia and the UK traffic light labelling system. Label information was compared with corresponding analytical values and per cent variation was calculated. Results: Most of the analyzed foods contained excessive amounts of salt, sugar and saturated fat. Alarmingly, for salt, where WHO labels ‘> 1.5 g/100g’ as ‘High/Excessive’ the products range from 4 g to 0.14 g per 100 g. Among them, 8 out of 11 food items were red marked. None of the brands qualifies for health claims in the star rating scheme and the UK traffic light system due to high content of salt and other critical nutrients. Most of the products misreported the nutrient content on labels. Conclusions: For the sake of public health, modification is highly needed in the processing of commonly consumed processed foods to make them healthy and less salt-containing. Study findings strongly advocate the necessity for strict regulations for appropriate user-friendly nutritional labelling. These measures will help in attaining Sustainable Development Goal 3-the health targets.

Development of a fabricated first-flush rainwater harvested technology to meet up the freshwater scarcity in a South Asian megacity, Dhaka, Bangladesh

The scarcity of freshwater in most of the megacities in the world is an important concern. In this regard, scientifically harvested rainwater could provide an effective measure to this crisis. In this attempt, we developed a cost-effective sensor-based automated first-flush rainwater harvesting system (RHS) to improve the freshwater scarcity and economic development of megacities like Dhaka, Bangladesh. To investigate the performance of the developed system, a suit of representative rainwater samples was systematically collected, preserved, and assessed between the months of July–December 2021 for water quality parameters such as physicochemical (pH, EC, TDS, DO, hardness, and alkalinity), anions (F−, Cl−, NO2−, NO3−, Br−, and SO42−), elemental (Ca, Mg, Cr, As, Cd, Hg, Pb, Be, Ni, Se, and Fe), and microbial contamination analysis. A Multiparameter digital meter and a titrimetric method were employed for measuring the physicochemical properties whereas elemental concentration was detected using an inductively coupled plasma-mass spectrometer and atomic absorption spectrometer. The changes in microbial contamination in the preserved rainwater were investigated from time to time during the whole experimental period. The findings showed that the mean pH (6.90) and concentrations (mg/L) of other concerning parameters such as TDS (15.5), DO (7.26), hardness (14.9), Cl− (3.59), NO3− (4.84), SO42− (4.62), Fe (<0.2), Cr (0.086 μg/L), As (0.224 μg/L), Cd (0.260 μg/L), Hg (0.270 μg/L), and Pb (5.530 μg/L) in the harvested rainwater samples were below the WHO drinking water guidelines and literature data implying that the harvested rainwater derived from the developed RHS is completely safe for drinking and other uses even in respect to the microbial contamination (total bacterial counts: 0–15 CFU/mL, and total and fecal coliform less than 1.8 MPN/100 mL) for long storage. Hence, this technology has a huge opportunity to mitigate safe freshwater scarcity and groundwater depletion issues, especially in megacities such as Dhaka, Bangladesh.

Проектное обучение и кейс-технологии: подготовка специалиста-агроинженера на курсе химии

The requirements for the level of theoretical and practical knowledge and skills of agricultural specialists are increasing every year. Chemical subjects form the basis of natural science education of future agricultural specialists. To improve the effectiveness of the educational process, the practice of teaching introduces many different teaching methods. The authors analyzed didactic opportunities of project-based learning and case technology n the context of methodological psychological and pedagogical concepts, in particular, the structure of activity and the logic of personality development. It is established that these methods used in the teaching of chemistry activate all the components of the structure of learning activity: cognitive, value-oriented, communicative, transformative, physical, and aesthetic. The article outlines the ways of using project-based learning and case technologies in the study of chemical subjects by agricultural engineering students. Given as an example is a case study on determining the quality of drinking water by titrimetric and potentiometric analysis methods and selection of a household filter for drinking water purification. The authors dwell on the methodology of performing tasks and define the criteria for evaluating the learning outcomes. Project-based learning and case technologies should meet a number of requirements, have a system of evaluation criteria, certain goals and practice-oriented task, which will enable and motivate students to solve practical problems in their future professional activities.

Chemical and microbiological properties of Lake Aygır in Turkey and usage of drinking, fisheries, and irrigation.

Since water is one of the essentials for life, the presence and quality of water in the habitat is extremely important. Therefore, water quality change and management of Lake Aygır was investigated in this study. For this, water samples collected from the lake and the irrigation pool between May 2015 and May 2016 were analyzed monthly. Spectrophotometric, titrimetric and microbiological methods were used to determine the water quality. According to some water quality regulations, HCO3, NH4, Cu, Mo, Br, fecal coliform and total suspended solid (TSS) values were found above the limit values. The other 29 parameters comply with Turkish national and international legislations. Lake Aygır was negatively affected by the surrounding settlements and agricultural activities. It is thought that the water resource should be monitored periodically and remedial studies should be done to prevent parameters exceeding the limits. However, Lake Aygır was generally suitable for drinking, use, fishing and irrigation.

Effect of &lt;i&gt;Bacillus thuringiensis&lt;/i&gt; strains on growth and metabolic processes in &lt;i&gt;Pisum sativum&lt;/i&gt; L. sprouts

Although the entomopathogenic bacteria Bacillus thuringiensis Berliner are well-known bio-agents for regulating the population of leaf-eating pests of agricultural and ornamental crops, other agricultural properties of this microorganism are promising. In this work, the growth-stimulating effect of entomopathogenic strains of B. thuringiensis on Deviz pea plants was studied. The entomopathogenic strains B. thuringiensis 685, 926 and 109-C obtained from the Crimean Collection of Microorganisms of the Crimean Agricultural Research Institute, registered online (http://www.ckp-rf.ru) with number 507484, were used as research material. The morphometric parameters of pea sprouts were evaluated following standard methods. Biochemical parameters of pea sprouts were determined for 10-day-old sprouts. The amylase activity of pea sprouts was determined by photocalorimetry; total acidity was measured by titration using 0.1 n NaOH solution; total water-soluble phenolic compounds were determined by Leventhal titrimetric method. It was found that liquid spore culture of strains B. thuringiensis 685, 926 and 109-C had a stimulating effect on the length of root and stem and the weight of 10-day-old sprouts of Deviz pea variety. Treatment with a spore suspension of all tested strains B. thuringiensis led to an increase in the content of organic acids in the sprouts by an average of 12.4% compared with that of the control. Maximum stimulating effect on amylolytic activity and synthesis of phenolic compounds in Deviz pea sprouts was achieved by treating with a spore suspension of the strain B. thuringiensis 926. The amylase activity increased on average by 41.5% when compared to that of the control, while the total content of phenolic compounds in this experiment was 2.3 times higher than that of the control. Therefore, in light of the entomopathogenic properties and the obtained data on the growth-stimulating activity of the strains of B. thuringiensis, it can be concluded that these bacteria have additional potential for their use in agriculture as a bio-agent for plant protection having a complex action.

Изучение антиоксидантной активности травы люцерны серповидной (Medicago falcata L.)

Objective: study of the antiradical and antioxidant activity of water, water-alcohol and alcohol extracts obtained from alfalfa sickle grass. Materials and methods. As an object of research of the antiradical and antioxidant activities of water, water-alcohol and alcohol extracts of alfalfa sickle, the grass of alfalfa sickle in the flowering stage, which was harvested in the Russian Federation in the Kursk region, was considered. The antioxidant activity was evaluated using a titrimetric method based on the result of the interaction of substances of a reducing nature that are present in extracts from alfalfa sickle grass and potassium permanganate used as a titrant. Antiradical activity was studied by spectrophotometric method based on the ability of extracts to inactivate DPPH (2,2-diphenyl-1-picrylhydrazyl). The content of phenolic compounds (direct spectrophotometry) in terms of chlorogenic acid and flavonoids (differential spectrophotometry) in terms of rutin was determined. Statistical analysis was used to process the data obtained as a result of experiments. Results. Processing of the results of data obtained during experiments to determine the level of antioxidant and antiradical activity for various concentrations of aqueous, water-alcohol and alcohol extractants from alfalfa sickle grass confirmed the presence of such effects for all types of extracts studied. Under experimental conditions with the use of 30% ethanol as an extractant, the maximum atioxidant activity was observed at the level of 58.55%. The use of 96% ethanol as an extractant showed similarly the maximum antioxidant activity, at the level of 56.63%, which is slightly less, but significantly exceeds other indicators. The content of flavonoids was fixed at the maximum level (0.51%) when using 30% ethanol. Under the same conditions, phenolic compounds were recorded with an index of 0.88%. The results obtained visualize a direct correlation between the level of antioxidant activity of the studied object of the herb Medicago falcata L. and the level of phenolic compounds in it. As for the use of 96% ethanol as an extractant, then in this extraction the content of hydroxycinnamic acids and flavonoids was less (0.14% and 0.04% respectively). Conclusion. The resulting data from a series of experiments on alfalfa sickle grass collected during the flowering phase confirm the prospects of medicinal plant raw materials Medicago falcata L. as a raw material having antioxidant activity, which makes it possible to consider it as a basis for continuing pharmacological research.

The Oxidation Behavior of Potato Starch and Benzyl Alcohol via Peroxide in the Catalysis of Metal Complexes

AbstractTwo new Schiff bases ligands (HL1 and HL2) and their Co2+, Mn2+, Fe3+, Ru3+, Cr3+, and VO2+ complexes were synthesized and characterized by FT‐IR, 1H‐NMR, and Mass spect. and analytical methods. A single‐crystal X‐ray diffraction study determined the molecular structure of HL1. The catalytic effects of metal complexes on benzyl alcohol and potato starch (PS) oxidation were compared in an H2+O2 medium. The percent conversion of benzyl alcohol to benzaldehyde and benzoic acid was determined by Gas Chromatography. [Co(L1)2], [Mn(L1)2], [Co(L2)2], and [Mn(L2)2] showed the highest catalytic effect with a value between 97–98% in the conversion of benzyl alcohol to benzaldehyde and benzoic acid. Maximum % benzoic acid formation was observed in [Mn(L1)2] (39%) and [VO(L1)2] (58%). To determine the effect of the catalyst properties of the complexes on the oxidation of PS, carbonyl and carboxyl groups formed in potato starch were determined by the titrimetric method, and PS oxidation degrees were calculated as DS (DSCHO and DSCOOH). In potato starch oxidation, the [VO(L1)2] had the highest catalytic effect with DSSum = 0.96, while the [Mn(L1)2] had a relatively lower DSSum = 0.86 value. On the other hand, the [Cr(L2)2ClH2O] showed a catalytic impact with DSSum = 0.63.

Development and Validation of Analytical Method for Estimation of Calcium in Herbomineral Formulation by Atomic Absorption Spectrophotometry

Calcium determination is normally done by conventional titrimetric methods (complexometric titration). In this study, a simple, precise, accurate, rapid and sensitive method has been developed for calcium (Ca) determination in Maxcal-C Tablet (herbo-mineral formulation) and its raw materials by Atomic Absorption Spectrophotometer (AAS). For complete digestion of the sample, closed vessel wet digestion technique was used with 69% HNO3 and 30% H2O2 (7:1) as digestive solvents. Analysis was performed on AAS (AA-6300) at λmax 422.7 nm. Calcium nitrate Ca(NO3)2 was used as a standard for Calcium and the linearity of the standard was excellent over a concentration range of 0.5 to 20 μgmL-1. The regression coefficient (r2) was 0.999. For intraday and interday precision % RSD was obtained between 0.48%-1.95% and 3.48%-5.01%, respectively which complied with the standard range for AAS. Recovery was achieved at 93.24%, 99.73%, 101.75% for 3 levels of spikes (80%, 100%, 120%) respectively, which complied with the standard range 75- 125% for AAS. However, the AAS method produced accurate and reproducible results and also overcame the colour and other ions interference, which are common problems with the titrimetric method. The results of both techniques (the AAS method and the titrimetric method) were compared, which showed good estimation by AAS.

Определение содержания йода, йодидов и йодатов в пищевых продуктах

Currently iodine deficiency diseases are one of the most important medical and social problems. In this regard, the purpose of the study is to determine the content of iodine, iodides, iodates in iodized salt, drinking and mineral water, seaweed, to determine the stability of the iodine content in salt. For the qualitative determination of iodides and iodates ions in salts and molecular iodine in seaweed, an iodine starch reaction has been carried out. The presence of iodide ions in iodized water has been determined by reaction with silver nitrate and chlorine water, the iodine released has been extracted with chloroform. Quantitative determination of iodine in salt has been carried out by the titrimetric method, in water – by colorimetric method, in seaweed – by gravimetric method with subsequent titration. The study has found that iodized salt contains iodine in the form of potassium iodate, in an amount of 18.65 μg / g of elemental iodine, kelp contains molecular iodine in the amount of 8.12 μg / g of elemental iodine, and iodized water contains potassium iodide in the amount of 0.327 μg / ml of elemental iodine. The study has proved that over time, the amount of iodine in the salt iodized with potassium iodate decreases after a month by 5.6 times. In order to comply with the daily rate of iodine intake, it is necessary to include in your diet about 9.7 g of iodized salt, which exceeds the daily norm of its consumption in 5 g. In this regard, it is recommended to use iodized salt (not more than 5 g) or iodized water (0.7 L of water) or kelp (18.47 g) as a prevention of iodine deficiency.

CONTENT OF BIOLOGICALLY ACTIVE SUBSTANCES IN THE ABOVEGROUND PART OF SOME STONECROPS (SEDOIDEAE)

The results of a comparative study of the content of biologically active substances in 8 species of the Sedoideae subfamily Aizopsis aizoon (L.) Grulich, A. hybrida (L.) Grulich, A. kurilensis (Vorosch.) S. Gontch., Hylotelephium ewersii (Ledeb.) H. Ohba, Sedum album L., S. hispanicum L., S. rupestre L., S. spurium M. Bieb. are presented: The aboveground shoots collected during the mass flowering phase were analyzed. The dry matter content was determined by drying of raw materials at 100‒105 °C. The amount of phenolic compounds, pectin substances, and total sugars was determined spectrophotometrically using SF-56 (Russia) and Agilent 8453 UV-Vis (USA) devices; the concentration of ascorbic acid was determined by titrimetric method. It was established the content of dry substances (up to 18.94%), flavonols (up to 4.45%), catechins (up to 3.72%), tannins (up to 20.2%), pectins (up to 13.36%), and sugars (up to 39.54%) per mass of absolutely dry raw materials, and ascorbic acid – up to 123.7 mg% per raw mass. A. kurilensis has the greatest capacity to accumulate bioactive substances. The data point to the prospects of stonecrops as a potential source for the production of food and feed additives.

Thermodynamic models for determination of solid–liquid equilibrium of para-tert-butylbenzoic acid in binary and ternary solvent system

Accurate solubility data is essential to make critical decisions from the earliest stage of drug discovery, through the entire process development, formulation, and up to process design. The present research work aims to evaluate the solid–liquid equilibrium data of para-tert-butylbenzoic acid (PTBBA) in binary systems such as acetonitrile + water, isopropyl alcohol + water, and isopropyl alcohol + acetonitrile at 288.15 to 328.15 K and a ternary solvent mixture of isopropyl alcohol + acetonitrile + water system in the temperature range of 298.15 to 323.15 K with varying mass fraction of the binary mixture (isopropyl alcohol + acetonitrile) for a constant mass fraction of water (0.1 and 0.3) using gravimetric and titrimetric methods. It is observed that the solubility of PTBBA increases with an increase in temperature for all the selected solvent systems. Moreover, the solubility of PTBBA in the binary and ternary system is affected by an increase in the mass fraction of water at a given temperature, which acts as an antisolvent. The measured data is correlated with various thermodynamic models such as Van’t Hoff equation, Modified Apelblat equation, Buchowski equation, and Wilson models. It is observed that there is a good agreement between measured and calculated values with an average relative deviation of 0.95 for isopropyl alcohol + acetonitrile system in the case of the modified Apelblat equation.

Determination of Heavy Metals and Ascorbic Acids in Some Soft Drinks Sold Within Bauchi Metropolis, Nigeria

Soft drinks are consumed in Nigeria due to their easy availability, distinct taste and ability to quench thirst. However, the high demand can reduce production quality due to possible heavy metal contamination, leading to human poisoning and death. This study evaluated some components of 100 soft drinks in Nigeria and investigated the presence of heavy metal contaminants and ascorbic acid concentrations. The presence of Arsenic, Cadmium, Lead, Manganese, Nickel and Chromium in soft drinks was determined using an atomic absorption spectrophotometer; the Ascorbic acid was determined using the titrimetric method. The analysis of the soft drink revealed that Arsenic was present in all the samples in a concentration ranging from 0.017 to 0.33 mg/l; Cadmium - 0.027 to 0.160 mg/l; Lead - 0.046 to 0.109 mg/l; Manganese - 0.036 to 0.116 mg/l; Nickel - 0.002 to 0.110 mg/l; Chromium - 0.057 to 0.122 mg/l. The attention of ascorbic acid ranged between 4.03 to 7.2 mg/100 ml. Compared to WHO standards, the levels of the heavy metal contaminants were above the tolerated limits for good quality drinking water in most samples. Moreover, the ascorbic acid values in this analysis were lower than those the manufacturers reported. Therefore, the National Health Surveillance agency should monitor ascorbic acid. These results suggest that soft drinks in Nigeria may be contaminated with heavy metals, which constitute a significant public health problem. Quality control is recommended during production, especially during sterilization and purification steps.

Titrimetric methods for determining cationic surfactants

Aim. To generalize and systematize information on titrimetric methods for determining quaternary ammonium compounds (QACs).Results and discussion. The review summarizes and systematizes information on the properties of surfactants, provides their classification, shows the main ways of use in the national economy, and their role in pharmacy and medicine. Currently known titrimetric methods for determining cationic surfactants (СS), in particular quaternary ammonium compounds, which are widely used in medicine and pharmacy, are described and summarized.Conclusions. As a result of the study, the main directions of developing methods for determining QACs by titrimetry methods have been summarized; the disadvantages and advantages of each of the methods described have been shown. In the future, it can be the basis for developing new and more effective methods of analysis.

Control of milk acidity by photoluminescence

SummaryFor a quality assessment of milk and dairy products, the optical methods are used. In this paper, the use possibility is investigated of the optical method of photoluminescence for the milk acidity value finding out. The spectral measurements were carried out on a diffraction spectrofluorimeter in the range of 200–500 nm. The milk acidity measurement accuracy was controlled by the titrimetric method. It is established that as far as milk sours, the excitation spectra in the range of 200–500 nm decrease; but there are qualitative changes in the range of 350–500 nm. With acidity growth, the photoluminescence flux decreases if it is excited by the radiation value λe = 262 nm, grows at λe = 385 nm and decreases at λe = 442 nm. It is advisable to control the milk acidity in terms of the photoluminescence fluxes ratio Φ385/Φ442. The linear approximation of the function Φ385/Φ442(K) is statistically reliable (the determination factor R2 = 0.99).

Microplastic quantification of nylon and polyethylene terephthalate by chromic acid wet oxidation and ultraviolet spectrometry

Microplastics are ubiquitous and their quantification in an environmental sample is important. This study modified the Walkley–Black titration method to measure the organic content of a synthetic sample containing polyethylene terephthalate (PET) or/and Nylon66 (NY) dissolved in a concentrated sulfuric acid solution, which was further converted to mass by incorporating the factors of carbon mass ratios by their molecular structures. The PET mass in concentrated sulfuric acid was also measured using UV/VIS spectrophotometer. The experimental results from the chromic acid wet oxidation showed that almost-complete oxidation of PET and NY by dichromate was achieved at the elevated temperature of 135 ∼ 140 °C, and the organic carbon resulting from existing PET and NY can be determined accurately. This study is a pioneer investigation using wet oxidation for PET and NY quantification. A step-by-step protocol was proposed to delineate the operating procedure of the modified chromic acid wet oxidation. By incorporating the UV/VIS spectrometry with chromic acid wet oxidation, the PET and NY content in a synthetic sample can be quantified. • Chromic acid wet oxidation was applied to quantifying PET and NY accurately. • UV/VIS spectrophotometer was found capable of measuring PET. • A heating system was introduced to improve the accuracy of wet oxidation analysis. • PET and NY can be measured by combining titrimetric and optical methods.

Experience of using the evaluations of the repeatability and reproducibility in compa­ ring test methods according to ISO 5725-6 "Accuracy (trueness and preci­ sion) of methods and measurement results. Part 6. Using precision values in practice"

The trueness and precision indicators of two methods — complexometric titration and atomic absorption spectrometry (AAS) — were evaluated to select a method that would provide a higher accuracy of copper determination in a brass coating. In the titrimetric method of copper determination, the brass coating was dissolved in a mixture of ammonia and hydrogen peroxide and titrated with a solution of Trilon В in the presence of xylenol orange indicator, whereas for the atomic absorption method the coating was dissolved in nitric acid and the test solution was measured on an atomic absorption spectrometer. Two laboratories took part in the experiment. The results of measurements and the calculated precision indicators (repeat­ability and reproducibility) for both methods are presented. The intra-laboratory (intermediate precision) and general precision of the methods was compared using the Fisher test, whereas the overall average cop­ per content was compared with the certified value of a standard brass sample in accordance with ISO 5725-6 "Accuracy (trueness and precision) of methods and measurement results. Part 6. Using precision values in practice. " It is shown that the atomic absorption method is the most accurate among two consid­ered methods for determining the mass content of copper in a brass coating, as it has acceptable indicators of precision and trueness.

Water quality, microcystin-LR, and Cylindrospermopsin contamination status of spring and dug well water in CKDu high, low, and non-prevalent areas of Sri Lanka

Cyanotoxins, Microcystin LR (MC-LR) and Cylindrospermopsin (CYN) are hepato and nephro toxins and considered as one of the hypotheses for Chronic Kidney Disease of Unknown Etiology (CKDu) in Sri Lanka. Recent studies have revealed that significant number of dug wells in the North Central and Uva provinces where CKDu is prevalent are contaminated with cyanotoxins MC-LR and CYN. In the present study, cyanotoxin; MC-LR, CYN, and potential toxin-producing cyanobacteria were studied in 330 dug wells and 9 spring water samples collected from CKDu high prevalent areas in several Divisional Secretariats (DS) and Grama Niladhari (GN) divisions of Anuradhapura (Padaviya DS, Medawachchiya DS, Kebithigollewa DS), Polonnaruwa (Medirigiriya DS), Badulla (Girandurukotte GN) and Ampara (Dehiaththakandiya DS) districts, low prevalent areas in Anuradhapura district (Galnewa DS, Rajanganaya DS), non-prevalent areas in Angunakolapelessa DS of the Hambanthota district. General water quality parameters: temperature, pH, conductivity, Dissolved Oxygen (DO), Nitrate (N-NO3-), Nitrite (N-NO2-), Ammonia (N-NH3), Total Phosphorus (TP), and Total Hardness (TH) were determined using standard spectrophotometric and titrimetric methods. BACON test kits were used following manufactures instructions to quantify the CYN, and MC-LR concentrations by using the ELISA plate reader. Cyanobacteria density and species composition were determined under light microscopy following the standard algae and cyanobacteria keys. With the exception of Electrical Conductivity, all of the water quality parameters tested remained within the SLSI drinking water quality standard range. Microcystis spp. cell densities ranged from 14±3 to 1590±256 cells mL-1, where MC-LR concentration ranging from 0.04±0.01 to 3.89±0.02 µg L-1. At different CYN concentrations (0.04±0.01 to 3.59±0.05 µg L-1), Cylindrospermopsis spp. cell densities varied from 15 ±4 to 615±112 cells mL-1. Well water collected from Hambanthota district and spring water was collected Kebithigollewa DS, in Anuradhapura did not record cyanotoxins and cyanobacteria. The factor analysis classified well waters into three clusters of high, low, and non-prevalence areas with presence and absence of cyanobacteria and cyanotoxins. In contrast, springs were classified to a separate cluster. High concentrations of MC-LR and CYN were found in wells where CKDu high prevalent 85% of Padaviya DS and 80% of Medirigiriya DS, respectively. High Nitrate-N (3.01±0.56 mg L-1) and Nitrite-N (0.69±0.09 mg L-1) concentrations were recorded in well water collected from high CKDu prevalence areas. Thus, the results of the present study showed a relationship between cyanobacteria, cyanotoxins and CKDu records in the study area. Accordingly, further comprehensive studies are needed to be carried out to confirm the relationship between cyanotoxins and CKDu in Sri Lanka as cyanotoxin were listed in the WHO report as one of the possible reasons for CKDu.

Determination of Metoclopramide Hydrochloride in Pharmaceutical Formulations using N-Oxidation Caroate.

To develop two (titrimetric and spectrophotometric) simple, rapid, sensitive and cost-effective methods for the determination of metoclopramide (MCP) in pharmaceutical dosage forms. The titrimetric method (A) was based on the N-oxidation reaction involving the use of potassium hydrogen peroxymonosulfate and subsequent iodometric back titration of a known residual reagent. The spectrophotometric method (B) was based on derivatization of MCP with potassium hydrogen peroxymonosulfate in the presence of iodide to produce a chromogen (triiodide) with a wavelength of maximum absorption at 350 nm. Method "A" was applicable over the concentration range of 0.25-3.5 mg to end volume 10 mL. In method "B", Beer's law was obeyed over the concentration range of 0.3-3.5 μg/mL with molar absorptivity of 24600 L/mol cm. The limits of quantification were calculated to be 0.25 mg/10 mL (A) and 0.2 μg/mL (B), respectively. The proposed methods were suitable for determination of MCP as a pure substance in tablets and injection.