Abdul Niaz

The correlation of arsenic levels in drinking water with the biological samples of skin disorders.

Arsenic (As) poisoning has become a worldwide public health concern. The skin is quite sensitive to As and skin lesions are the most common and earliest nonmalignant effects associated to chronic As exposure. In 2005-2007, a survey was carried out on surface and groundwater arsenic contamination and relationships between As exposure via the drinking water and related adverse health effects (melanosis and keratosis) on villagers resides on the banks of Manchar lake, southern part of Sindh, Pakistan. We screened the population from arsenic-affected villages, 61 to 73% population were identified patients suffering from chronic arsenic toxicity. The effects of As toxicity via drinking water were estimated by biological samples (scalp hair and blood) of adults (males and females), have or have not skin problem (n=187). The referent samples of both genders were also collected from the areas having low level of As (<10 microg/L) in drinking water (n=121). Arsenic concentration in drinking water and biological samples were analyzed using electrothermal atomic absorption spectrometry. The range of arsenic concentrations in lake surface water was 35.2-158 microg/L, which is 3-15 folds higher than World Health Organization [WHO, 2004. Guidelines for drinking-water quality third ed., WHO Geneva Switzerland.]. It was observed that As concentration in the scalp hair and blood samples were above the range of permissible values 0.034-0.319 microg As/g for hair and <0.5-4.2 microg/L for blood. The linear regressions showed good correlations between arsenic concentrations in water versus hair and blood samples of exposed skin diseased subjects (R2=0.852 and 0.718) as compared to non-diseased subjects (R2=0.573 and 0.351), respectively.

Ultra-trace level determination of hydroquinone in waste photographic solutions by UV-vis spectrophotometry.

A simpler UV-vis spectrophotometric method was investigated for hydroquinone (HQ) determination using KMnO(4) as oxidizing agent for conversion of HQ to p-benzoquinone (BQ) as well as signal enhancer. Various parameters such as analytical wavelength, stability time, temperature, pH, solvent effect and interference of chemicals were checked and parameters optimized by using 1mugml(-1) standard solution of HQ. Beers Law was applicable in the range of 0.07-2mugml(-1) and 0.005-0.05mugml(-1) at 245.5nm and at 262nm for aqueous standard solutions of HQ with linear regression coefficient value of 0.9978 and 0.9843 and detection limit of 0.021mugml(-1) and 0.0016mugml(-1) HQ, respectively. Standard deviation of 1.7% and 2.4% was true for 1mugml(-1) and 0.03mugml(-1) HQ solution (n=11) run at respective wavelengths. The method was successfully applied to dilute waste photographic developer samples for free HQ determination.

Simultaneous assessment of zinc, cadmium, lead and copper in poultry feeds by differential pulse anodic stripping voltammetry.

In the present work four metals (Zn, Cd, Pb and Cu) were determined simultaneously in 28 commercial broiler poultry feeds by differential pulse anodic stripping voltammetry (DPASV) using hanging mercury drop electrode (HMDE). The digestion of poultry feeds was carried out with concentrated nitric acid and hydrogen peroxide (2:1) with the help of microwave heating. Acetate buffer of pH 5 was used as a supporting electrolyte. The limit of detection for Zn, Cd, Pb and Cu was 0.69, 0.35, 0.68 and 0.24 microg/kg, respectively. The amount of Zn, Cd, Pb and Cu in the analyzed poultry feeds was ranged between 54.3-482.2, 3.8-33.6, 23.2-32.6 and 12.3-65.8 mg/kg, respectively. In most of analyzed poultry feed samples, the amount of Cd and Pb was found to be greater than the maximum tolerable level (MTL) which could be harmful for the poultry.

Comparative Study of Heavy Metals in Soil and Selected Medicinal Plants

Essential and nonessential heavy metals like iron (Fe), nickel (Ni), manganese (Mn), zinc (Zn), copper (Cu), cadmium (Cd), chromium (Cr), and lead (Pb) were analyzed in four selected medicinal plants such as Capparis spinosa, Peganum harmala, Rhazya stricta, and Tamarix articulata by flame atomic absorption spectrophotometer (FAAS). These medicinal plants are extensively used as traditional medicine for treatment of various ailments by local physicians in the area from where these plants were collected. The concentration level of heavy metals in the selected plants was found in the decreasing order as Fe > Zn > Mn > Cu > Ni > Cr > Cd > Pb. The results revealed that the selected medicinal plants accumulate these elements at different concentrations. Monitoring such medicinal plants for heavy metals concentration is of great importance for physicians, health planners, health care professionals, and policymakers in protecting the public from the adverse effects of these heavy metals.

Direct synthesis and stabilization of Bi-sized cysteine-derived gold nanoparticles: Reduction catalyst for methylene blue

Bi-sized and separable gold nanoparticles (AuNps) with smaller sizes were synthesized by treatment of cysteine with tetrachloroauric acid solution. These nanoparticles were made stable with further reduction in size after adding very small volume of NaOH solution before controlled heating. In NaOH treated solution the AuNps stopped precipitation as compared to untreated solution. Various methods such as UV-Vis spectroscopy, Transmission Electron Microscopy (TEM), X-ray Diffractometry (XRD), FTIR and Raman spectroscopy were used for characterization of surface properties and interaction between AuNps and cysteine. The results showed good correlation with literature regarding the interaction but interesting differences in size distribution as evident from high resolution TEM micrograph. Zeta potential studies revealed that these particles are negatively charged. Surprisingly, the Raman of the cysteine-derived AuNps without NaOH showed tremendous enhancement as compared to pure cysteine and cysteine-derived AuNps treated with NaOH. The NaOH treated Cyst-AuNps sol proved as excellent homogeneous catalyst for reduction of methylene blue (MB).

Biologically synthesized silver nanoparticle-based colorimetric sensor for the selective detection of Zn2+

A simple, selective and cost effective colorimetric sensor has been investigated for the detection of Zn2+ using biologically synthesized silver nanoparticles (AgNPs). The AgNPs were prepared from the leaf extract of Amomum subulatum via two different procedures i.e., at room temperature and by a heat treatment procedure. The AgNPs prepared through the heat treatment procedure exhibited efficient results. The as synthesized AgNPs were studied by simple UV-vis spectroscopy which showed an intense absorption band at 425 nm which was further confirmed by FT-IR and SEM analysis. The synthesized AgNPs exhibited a good colorimetric sensing property towards Zn2+ by changing the color of the solution from yellowish-brown to colorless accompanying a decrease in absorption intensity. The proposed detection mechanism of the sensor has been discussed. The sensor showed an excellent linear response towards Zn2+ in the concentration range from 1 × 10−5 to 8 × 10−5 M with a correlation coefficient (R2) of 0.996. The detection limit of the method was found to be 3.5 × 10−6 M. There was no interference effect observed for Zn2+ detection in the presence of other heavy metal ions. The proposed sensor was successfully applied for the detection of Zn2+ in drinking water samples.

A new simple sensitive differential pulse polarographic method for the determination of acrylamide in aqueous solution.

A new simple sensitive differential pulse polarographic (DPP) method was investigated for the determination of acrylamide (AA) directly in a neutral aqueous solution. The AA showed a well-defined and well-resolved peak in pure aqueous LiCl at -1.84V in the potential range from -1.6V to -1.97V at nitrogen pressure of 0.5kgcm(-2). Among the various electrolytes studied, the AA showed good DPP response in the presence of LiCl and tetra methyl ammonium iodide, while it showed poor response in the presence of tetra butyl ammonium hydroxide and tetra butyl ammonium bromide due to their strong adsorption on the surface of electrode which hindered its reduction. The effect of LiCl concentration, the cyclic voltammetric response and the drop time study showed that AA exhibited an irreversible adsorptive electrochemical behavior. The good electrochemical response in pure aqueous medium suggested that hydrogen bonding might be involved which may favor the electrode reaction. Under optimized conditions, the peak current was linear in the entire concentration range from 0.2 mgL(-1) to 20 mgL(-1) with the correlation coefficient of R(2)=0.9998. The method showed good reproducible results with R.S.D. of 0.3% (n=16). The detection limit (LOD) was 27 microgL(-1). The influence of various interfering agents was also studied. The method was applied successfully for the quantification of AA in water samples without any interference effect from alkali metals.

Simpler and highly sensitive enzyme-free sensing of urea via NiO nanostructures modified electrode

In this study, NiO nanostructures were synthesized via a hydrothermal process using ascorbic acid as doping agent in the presence of ammonia. As prepared nanostructures were characterized using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Brunauer–Emmett–Teller (BET) specific surface area analysis, and thermogravimetric analysis (TGA). These analyses showed that these nanostructures are in the form of cotton-like porous material and crystalline in nature. Furthermore, the average size of these NiO crystallites was estimated to be 3.8 nm. These nanostructures were investigated for their potential to be a highly sensitive and selective enzyme-free sensor for detection of urea after immobilizing on a glassy carbon electrode (GCE) using 0.1% Nafion as binder. The response of this as developed amperometric sensor was linear in the range of 100–1100 μM urea with a R2 value of 0.990 and limit of detection (LOD) of 10 μM. The sensor responded negligibly to various interfering species including glucose, uric acid, and ascorbic acid. This sensor was applied successfully for determining urea in real water samples such as mineral water, tap water, and river water with acceptable recovery.

The Effects of Phosphate Adsorption on the Surface Characteristics of Mn Oxides

Mn-oxide was characterized using X-ray diffractometry, scanning electron, transmission electron microscopy, and thermogravemetric and differential thermal analysis. The surface charge density and zero point if charge (pHzpc) of the solid surface were determined by potentiometic titration. Mn-oxide was subjected to different phosphate concentrations in the pH range 3 to 7 at 303 K to investigate the effect of phosphate complexation on the surface properties of solid. The surface compositions before and after phosphate sorption were studied with X-ray photoelectron spectroscopy. The O/OH groups at the surface of Mn-oxide differed with acidity and below pH 6, a drastic change was observed in the O1 s peaks in X-ray photoelectron spectrum, due to the dissolution of Mn-oxide. The surface charges arise as a result of H/OH bond breaking and phosphate anions complexation with solid surface. These charges are compensated by counter ions (K+ and NO3-) of the background electrolyte at solid-liquid interface. The phosphate sorption increased with increased phosphate concentration but decreased with pH increasing of the aqueous solution, a process which is the characteristics of metal oxides surfaces. Thus, it was concluded from the present investigation that phosphate anion sorption on Mn oxide have greatly affected the overall surface characteristics of the solid.

Fast voltammetric assay of water soluble phthalates in bottled and coolers water

Detection of phthalic acid and phthalates esters is of growing interest due to their significant use and potential toxicity. A fast, simple and highly sensitive Square Wave Voltammetric (SWV) method developed for determination of total water soluble phthalates using a glassy carbon electrode (GCE) is demonstrated using di-n-butyl phthalate (95%) (DBP) as a test example. The study showed that 100 μmol L−1 aqueous solution of DBP gives the best response with 0.05 mol L−1 tetrabutylammonium bromide (TBAB), at stirring rate of 1400 rpm, deposition time, 20 s and pH 4.0 ± 0.1. The optimum frequency and scan rate was 100 Hz and 0.9 V s−1 respectively. Voltammetric response was linear over 3 ranges, 70–110 μmol L−1, 20–60 μmol L−1 and 2–10 μmol L−1 with regression coefficient of 0.9873, 0.9978 and 0.9935 respectively and limit of detection (LOD), 0.47 μmol L−1 for total water soluble phthalates in aqueous medium. The method was successfully applied to the determination of total phthalates in water samples taken from sources of water stored in PVC coolers and plastic bottles.