Fahmida Khan

Potentiometric determination of free acidity in presence of hydrolysable ions and a sequential determination of hydrazine.

A simple potentiometric method for the determination of free acidity in presence of hydrolysable ions and sequential determination of hydrazine is developed and described. Both free acid and hydrazine are estimated from the same aliquot. In this method, free acid is titrated with standard sodium carbonate solution after the metal ions in solutions are masked with EDTA. Once the end point for the free acid is determined at pH 3.0, an aliquot of formaldehyde is added to liberate the acid equivalent to hydrazine which is then titrated with the same standard sodium carbonate solution using an automatic titration system. The described method is simple, accurate and reproducible. This method is especially applicable to all ranges of nitric acid and heavy metal ion concentration relevant to Purex process used for nuclear fuel reprocessing. The overall recovery of nitric acid is 98.9% with 1.2% relative standard deviation. Hydrazine content has also been determined in the same aliquot with a recovery of nitric acid is 99% with 2% relative standard deviation. The major advantage of the method is that generation of corrosive analytical wastes containing oxalate or sulphate is avoided. Valuable metals like uranium and plutonium can easily be recovered from analytical waste before final disposal.

Green approach to corrosion inhibition of mild steel in hydrochloric acid medium using extract of spirogyra algae

ABSTRACT In the present investigation, a fresh water green algae spirogyra is used as an inexpensive and efficient mild steel corrosion inhibitor. The study is carried out in 0.5 M HCl solution using weight loss measurements, scanning electron microscopy–energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transforms infrared (FT-IR) techniques. The maximum inhibition efficiency was found to be 93.03% at 2 g L−1. The adsorption of extract of spirogyra on mild steel surface obeys the Langmuir adsorption isotherm. Corrosion inhibition mechanisms were inferred from the temperature dependence of the inhibition efficiency as well as from calculation of thermodynamic and kinetic parameters which direct the process. FT-IR analysis of green algae spirogyra revealed the presence of hydroxyl, amino, and carbonyl groups, which are responsible for the adsorption on the mild steel surface. SEM analysis supported the inhibitive action of the spirogyra extract against the mild steel corrosion in acid solution. GRAPHICAL ABSTRACT

On-site determination of tin in geological and water samples using novel organic reagent with iodide

A new, simple and sensitive method for spectrophotometric determination of tin (IV) with iodide and amide is described. The Sn(IV)-I(-) complex is extracted with chloroform solution of amide (N-phenylacetamide, N-alkylacetamide, alkyl=butyl, phenyl, hexyl and octyl group) in the strong sulphuric acid solution. Among five amides studied, N-octylacetamide (OAA) has been selected as it yielded best sensitivity. The apparent (at twofold preconcentration) molar absorptivity with respect to tin is (2.40)x10(5)Lmol(-1)cm(-1) at lambda(max), 410nm. The detection limit of the method is 4microgL(-1) Sn. The method is free from interferences of common ions that are normally associated with Sn. The method is highly sensitive and found to be applicable for the rapid determination of tin in water samples at micro-gram levels.

Spectrophotometric determination of trace amounts of phosphate in water and soil

A simple spectrophotometric method has been developed for the determination of phosphate dissolved in soil and water. The method is based on the formation of phosphomolybdate with added ammonium molybdate followed by reduction with hydrazine in acidic medium. Orthophosphate and molybdate ions condense in acidic solution to give molybdophosphoric (phosphomolybdic) acid, which upon selective reduction (perhaps with hydrazinium sulphate) produces a blue colour, due to molybdenum blue of uncertain composition. The intensity of blue colour is proportional to the amount of phosphate. If the acidity at the time of reduction is 0.5 M in sulphuric acid and hydrazinium sulphate is the reductant, the resulting blue complex exhibits maximum absorption at 830 nm. The system obeys Lambert-Beers law at 830 nm in the concentration range of 0.5-5 μg/mL of phosphate with a relative standard deviation (RSD) of 0.1% and correlation coefficient of 0.99. Molar absorptivity was determined to be 2.9 × 10⁴ L mol⁻¹ cm⁻¹ at 830 nm. The method is also applicable for the determination of phosphate in nuclear reprocessing plants, medical science, clinical science, agriculture, metallurgy and environmental science.

Sequential determination of free acidity and hydrazine in presence of hydrolysable ions

Abstract A simple method for the sequential determination of free acidity and hydrazine in presence of hydrolysable ions is developed and described. In this method, free acid is titrated with standard sodium carbonate solution after the metal ions in solutions are masked with EDTA. Once the end point for the free acid is determined at pH 3.0, an aliquot of formaldehyde is added to liberate the acid equivalent to hydrazine which is then titrated with the same standard sodium carbonate solution using an automatic titration system. The described method is simple, accurate and reproducible. This method is especially applicable to all ranges of nitric acid and heavy metal ion concentration relevant to Purex process used for nuclear fuel reprocessing. The overall recovery of nitric acid is 98.9% with 3% relative standard deviation. The major advantage of the method is that it uses sodium carbonate a primary standard as titrant and generation of corrosive analytical wastes containing oxalate or sulphate is avoided. Valuable metals like uranium and plutonium can easily be recovered from analytical waste before final disposal.

DNA binding study of Co (III) complexes of hydroxamic acid and 1, 10-phenanthroline complex

Feng-Liao-Chang-Wei-Kang (FLCWK), a traditional Chinese patent medicine, consists primarily of Polygonum hydropiper and Daphniphyllum calycinum roots. As a complex containing several kinds of flavonoids, FLCWK has the potential to impact the drug metabolism enzyme P450 3A4 (CYP3A4) and nuclear receptors. The purpose of this research was to probe the effects of FLCWK on CYP3A1, the homolog of CYP3A4 in rats, and to confirm whether FLCWK interferes with PXR and CAR-mediated transactivation of CYP3A4. The effects of FLCWK on Cyp3a1 mRNA, catalytic activity levels, and protein expression in Sprague-Dawley (SD) rat liver tissues were examined using real-time PCR, western blotting, and high-performance liquid chromatography (HPLC) assays, respectively. The efficacy of PXR and CAR on CYP3A4 transcriptional activity were detected using luciferase reporter assays and further research of the impact of FLCWK on CYP3A4 gene expression mediated by the PXR pathway was examined by transient transfection of PXR siRNA. FLCWK significantly increased Cyp3a1 mRNA, CYP3A1 activity, and protein expression levels in SD rats. FLCWK highly induced CYP3A4 luciferase activity mediated by PXR in PXRCYP3A4 co-transfected cells. A siRNA-mediated drop-off in PXR expression greatly cut the effect of FLCWK on CYP3A4 mRNA expression in HepG2 cells. These findings show that FLCWK up-regulates CYP3A4 levels via the PXR pathway. This effect should be considered being applied in clinical use as FLCWK has the potential to interact with other drugs.T human body contains about 10 microbes per each human cell if you do not consider red blood cells which are lacking DNA. This means microbes significantly impact the chemistry in and on our body. Despite the role of microbial chemistry on human health, we know very little about its chemistry, let alone quantitatively. One of the analytical methods that are sensitive enough to measure microbial chemistry can be mass spectroscopy (MS). Here we introduce PALMS platform that is capable of analyzing full sample profile using high accuracy Orbitrap instrument and quantify set of targeted metabolites using triple quadrupole in a single LC run. Several hundred of fecal swabs samples from the American Gut project were tested and then people were swabbed at several hundred locations for the creation of 3D quantitative maps. The system setup comprises of triple quadrupole (qqq) and Orbitrap mass spectrometers connected in parallel to a single UHPLC system. Liquid connection was split into equal ratio and directed into two MS which are equipped with identical HESI ion sources; tubing length maintained equal in order to avoid any retention time (RT) differences between two MS. The data acquisition was triggered by UHPLC system by mean of contact closure signal that is sent to both MS simultaneously. Data captured by Q Exactive recorder in untargeted profiling mode with high resolution while quantitative data on defined targets were acquired by TSQ. We first evaluated our system by screening of several hundreds of fecal swabs extracts received from American Gut project. For targeted quantification we used mix of 200 standards containing microbial primary and secondary metabolites. We evaluated a distribution of the standards in fecal samples by constructing a calibration curve with triple quadrupole data. Our results showed that even in such high background as fecal matter we can quantify metabolites with relatively low error rate. By feeding mass list to triple quadrupole we managed to achieve pictogram sensitivity at the same time acquiring a full molecular profile using Orbitrap. By analyzing untargeted data we were able to putatively identify thousands of molecules using molecular networking while quantification was performed for selected microbial metabolites. Because in molecular networking structurally similar molecules clustered together we were able to relatively quantify analogs of the standards by extrapolating their concentrations. We then used the platform for screening the microbial metabolites reside on human body. We constructed 3D chemical composition maps of human skin surface. Highly accurate, untargeted data allowed for identification of some key microbial metabolites that are distributed on the skin in the specific locations such as armpit and groin area. We then relatively quantified the metabolites as some of our standards clustered with molecules of interest, which concentration was accurately measured by triple quadrupole. Determining the quantitative information for key microbial metabolites grant us the possibility to calculate the amount of the microbial cells that are primary producers and potentially assess the impact of them on our health.

Corrosion Inhibition of Mild Steel by Using Sulpha Drugs in Phosphoric Acid Medium: A Combined Experimental and Theoretical Approach

The corrosion inhibition effect of Sulfacetamide and sotalol on the mild steel has been investigated in 1M H3PO4 acid medium. The inhibiting effect was investigating using weight loss measurement and quantum chemical method. The obtained results revealed that both inhibitors inhibited the mild steel corrosion in the phosphoric acid solution. The inhibitors showed more than 90% inhibition efficiency at optimum concentration. Sulfacetamide shows inhibition efficiency of 94.22 whereas sotalol shows efficiency of 91.40 at optimum concentration. Results obtained exposed that inhibition occurs through adsorption of the drugs on mild steel surface without modifying the mechanism of corrosion process obeying the Langmuir adsorption isotherm. Density functional theory (DFT) has been used to determine the relationship between molecular configuration and their inhibition efficiencies. The order of inhibition performance obtained from experimental results is successfully verified by DFT. Scanning electron microscopy (SEM) studies of the mild steel surfaces established the presence of a protective adsorbed film. Original Research Article Verma and Khan; ACSJ, 14(3): 1-8, 2016; Article no.ACSJ.26282 2