Open Access Original Research Article

Speciation of Manganese in Natural Waters Using Differential Pulse Stripping Voltammetry in Correlation with Physico-chemical Parameters

Indira Šestan, Amra Odobašić, Almir Šestan, Amra Bratovčić, Melisa Ahmetović

International Research Journal of Pure and Applied Chemistry, Page 1-7
DOI: 10.9734/irjpac/2021/v22i630411

To understand the bio-geochemical distribution, activities and environmental consequences of heavy metals, it is very important to know their physico-chemical form and the conditions under which the transformation from one form to another occurs. The bioavailability of heavy metals directly depends on the physico-chemical conditions of the environment, the concentration of anions and cations in water, the content of heavy metals as well as the ionic strength. Depending on the physico-chemical properties of water, metals are found in water as free ions or as complex compounds. Their change in the form in which metals occur is significantly influenced by pH, temperature, alkalinity, water hardness, organic matter, and biological activity. The total concentration of metal in water is only an indicator of pollution, and it is necessary to determine the form of the metal. Differential Pulse Anode Stripping Voltammery with mercury electrode was used for determination of chemical speciation. Manganese belongs to the group of essential heavy metals if its concentration does not exceed the maximum allowed value.

The aim of this work is to determine the available forms of manganese in the water of Modrac Lake in relation to the analyzed physico-chemical parameters. In addition to industrial applications, Modrac Lake is also used as an alternative source of drinking water, and it is a strategic resource for water supply of the region of north-eastern Bosnia.

Open Access Original Research Article

Green Atomic Absorption Spectroscopic Methods for the Determination of Rabeprazole Sodium and Fluvastatin Sodium in Pure and Pharmaceutical Dosage Forms

Miranda F. Kamal, Samir Morshedy, Dina A. Saad, Marwa S. Moneeb

International Research Journal of Pure and Applied Chemistry, Page 8-14
DOI: 10.9734/irjpac/2021/v22i630412

Aims: Novel green analytical methods have been proposed for the assay of Rabeprazole sodium and Fluvastatin sodium in their pure and formulated dosage forms.

Study Design: The methods determine each drug through the estimation of its sodium content, using Flame Atomic Absorption Spectroscopy at wavelength 589 nm. 

Place and Duration of Study: Central laboratory at Faculty of Pharmacy, Damanhour University. Time duration January-March, 2020.

Methodology: Methods are developed and optimized for maximum sensitivity, selectivity and degree of greenness. Linearity is achieved in the range of 8.29- 66.33 ppm of Rabeprazole sodium (equivalent to 0.5- 4 ppm Na) and 14.13- 141.32 ppm of Fluvastatin sodium (equivalent to 0.75 -7.5 ppm Na). The proposed assays are fully validated regarding ICH guidelines. 

Results: Atomic spectroscopic assays are compared to reported spectrophotometric ones for each drug separately using Student t-test and F-variance ratio. 

Conclusion: Satisfactory values indicate good agreement and the insignificant difference between both methods. The obtained percentages of recovery (99-101%) indicate no interference from excipients in formulation matrices.

Open Access Original Research Article

Removal of Arsenic from Simulated Groundwater using Calcined Shale as the Adsorbent

N’Da Akoua Alice Koua-Koffi, Lassina Sandotin Coulibaly, Drissa Sangare, Lacina Coulibaly

International Research Journal of Pure and Applied Chemistry, Page 31-39
DOI: 10.9734/irjpac/2021/v22i630414

Well water intended for human consumption in the Akouédo area (Ivory Coast) contained arsenic at a concentration average above 0.01 mg/L, WHO guideline value. The shale was used as an adsorbent for the removal of arsenic from these waters. This shale was collected in Lomo Nord in Ivory Coast, washed then dried at a temperature of 60°C and finally calcined in an oven at several temperatures: 200°C, 300°C, 400°C, 500°C, 600°C and 700°C. X-ray diffraction, Fourier transform infrared spectroscopy (FTIR) and thermal analysis (TGA-DSC) were used to characterize the fraction of uncalcined and calcined shale powder. Batch mode tests were performed with water containing arsenic in order to study the influence of contact time, initial concentration and pH on the adsorption of arsenic on calcined shale. The results showed that shale calcined at 300°C could remove 99.41% of arsenic in water. The treated water meets the World Health Organization (WHO) standard for drinking water. Regarding the kinetic data, 0.034 mg/g of arsenic was adsorbed on the calcined shale within 7 hours. At pH 8, the maximum reduction rate was estimated up to 96%. The pseudo-second order model is the most appropriate of all the models applied to describe the kinetic data. This study shows that slate shale calcined at 300°C could be used as a low cost adsorbent to remove arsenic from Akouédo well water for consumption.

Open Access Original Research Article

Determination of the Mechanism of Nucleophilic Reaction of Fenitrothion Using Substituted Phenoxide Nucleophiles in Aqueous Media

E. G. Amadi, C. I. Egwuatu, C. U. Okoro, F. O. Obumselu, M. U. Onuoha

International Research Journal of Pure and Applied Chemistry, Page 40-46
DOI: 10.9734/irjpac/2021/v22i630415

The mechanism of the nucleophilic displacement reaction at the phosphorus centre of organophosphates was determined. Phenoxide nucleophiles were reacted with fenitrothion (O,O-dimethyl O-(3-methyl-4-nitrophenyl) phosphorothioate) in water at 25oC and pseudo-first order rate constant measurements taken. Second-order rate constant (kNuc) was determined for the different concentrations of nucleophiles while the second-order rate constant (klg) for the investigation of 2,4-dichlorophenoxide ion with and series of aryl phosphorothioate esters was also determined. Linear free energy relationship was further determined using the Brϕnsted-type plot. The plots are linear over a range of pKaNuc of 7.15-11.10 that straddles the pKa of the leaving 3-methyl-4-nitrophenoxide ion (pKa = 7.20) with statistically acceptable linear correlations (R2 = 0.987) and (R2 = 0.980). The linearity in the traditional Brϕnsted-type plots shows the sensitivity of the nucleophilic displacement to the basicity of the nucleophiles and hence is consistent with a single transition-state mechanism whose barrier to decomposition is low hence concerted. Analysis of the values of βNuc, βLg and βeq (0.734) with the effective charge distribution in the transition state shows that it has no positive character. The Leffler index presents bond formation being slightly ahead of bond rupture.

Open Access Review Article

The Role of Pulmonary Surfactant in COVID-19 Understanding

Zaineb O. Ettarhouni, Aysha B. Mezoughi

International Research Journal of Pure and Applied Chemistry, Page 15-30
DOI: 10.9734/irjpac/2021/v22i630413

Background: In Covid-19 the virus infects the respiratory tract in human. When lung tissue becomes diseased, the walls and lining of the alveoli and capillaries are damaged. At this point lung compliance and ventilation decrease. Pulmonary surfactant that is produced and dispersed into alveolar space, has a significant role in understanding how heavily covid-19 interferes and infects lung cells. The importance of pulmonary surfactant in alveoli is to lower surface tension at air/liquid interface in the lung. This is achieved by reducing the work of breathing and preventing alveolar collapse. The main constituent of pulmonary surfactant is dipalmitoylphosphatidylcholine (DPPC) (C40H80NO8P). It is a phospholipid containing two non polar palmitic acid C16 chains as hydrophobic tails linked to a polar head group of a phosphatidylcholine (also known as lecithin).

Rationale of the Review and Objective Method: When DPPC molecules are in contact with a polar solvent, micelles which grow further into bilayers are formed considering their cylindrical structures. This trait makes the whole structure of pulmonary surfactant as amphipathic and surface active molecules. The head group of phosphatidylcholine in the pulmonary surfactant is attracted by polar liquid molecules causing a reduction of the liquid surface tension.

Conclusion: This review complements the quoted information analysing them theoretically and integrates recent advances in pulmonary surfactant research with the global pandemic.

Open Access Review Article

Concentration effect of Sodium Chloride Salt on Benzoic Acid Solubility and Dissociation into Water at 298 K Temperature

Shiv Prakash Mishra

International Research Journal of Pure and Applied Chemistry, Page 47-52
DOI: 10.9734/irjpac/2021/v22i630416

In article, we have been reported the study of a concentration effect of sodium chloride (NaCl) salt on benzoic acid solubility and its dissociation in water at 298 K temperature. At this temperature the benzoic acid solubility into water and their dissociation value for six samples in range of 0.00, 0.05, 0.10, 0.30, 0.40 and 0.50 M. Each of these different ionic strength or concentration of sodium chloride is analyzed by titrimetrically against of 0.05 M sodium hydroxide (NaOH) basic solution. The pH of each solution is measured well by using of calibrated pH-meter. Observation reveals that the value of pH of benzoic acid into water at applying temperature is may inversely related with concentration of NaCl. Graphically, the value of ionic strength (I) of that benzoic acid is plotted versus with dissociation constant (Kc) of acid into water at specific 298 K temperature. The value of benzoic acid dissociation constant for given each six concentration of NaCl is found to be -4.169, -4.045, -3.993, -3.885, -3.848 and -3.788, respectively.