Sumaira Khan

Biosorption studies on powder of stem of Acacia nilotica: Removal of arsenic from surface water

In present study a biomass derived from the stem of Acacia nilotica has been investigated to remove As ions from surface water samples of different origins (lake, canal and river). The effects of various parameters viz. pH, biosorbent dosage, contact time and temperature on the biosorption processes were systematically studied. Experimental data were modeled by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. It was observed that As biosorption best fitted to the Langmuir and Freundlich isotherms. The mean sorption energy (E) calculated from D-R model, indicated physico-chemical biosorption. Study of thermodynamic parameters revealed the endothermic, spontaneous and feasible nature of biosorption process. The pseudo-second-order rate equation described better the kinetics of As biosorption with good correlation coefficients than pseudo-first-order equation. The biomass of A. nilotica was found to be effective for the removal of As with 95% sorption efficiency at a concentration of <200 microg/L of As solution, and thus uptake capacity is 50.8 mg As/g of biomass. The A. nilotica biomass could be used as a low-cost biosorbent for As ion removal.

Optimization of cloud point extraction and solid phase extraction methods for speciation of arsenic in natural water using multivariate technique.

The simple and rapid pre-concentration techniques viz. cloud point extraction (CPE) and solid phase extraction (SPE) were applied for the determination of As(3+) and total inorganic arsenic (iAs) in surface and ground water samples. The As(3+) was formed complex with ammonium pyrrolidinedithiocarbamate (APDC) and extracted by surfactant-rich phases in the non-ionic surfactant Triton X-114, after centrifugation the surfactant-rich phase was diluted with 0.1 mol L(-1) HNO(3) in methanol. While total iAs in water samples was adsorbed on titanium dioxide (TiO(2)); after centrifugation, the solid phase was prepared to be slurry for determination. The extracted As species were determined by electrothermal atomic absorption spectrometry. The multivariate strategy was applied to estimate the optimum values of experimental factors for the recovery of As(3+) and total iAs by CPE and SPE. The standard addition method was used to validate the optimized methods. The obtained result showed sufficient recoveries for As(3+) and iAs (>98.0%). The concentration factor in both cases was found to be 40.

Arsenic fractionation in sediments of different origins using BCR sequential and single extraction methods.

The arsenic (As) contaminated sediment serves as a long-term source of arsenic because its mobility and transport in the environment are strongly influenced to associated solid phase. A single extraction method based on the reagents employed in the BCR three steps sequential extraction scheme (BCR-SES) for partitioning of arsenic (As) in sediment samples has been developed. The single-step extraction enabled a reduction of extraction times, yielding extractable contents in accordance with those obtained by application of the BCR-SES, which can be regarded as a standard method and validated by using certified reference material BCR 701. The extractable As content associated with different phases in sediment samples were analysed by electrothermal atomic absorption spectrophotometer. The extraction efficiency of As by single-step extraction was slightly higher than BCR-SES, ranged (100-104%), while difference was not significant at 95% confidence limit with <10% precision. The sediment samples from different origins varied in their physico-chemical properties and total As content. The relative mobility of As obtained from different origins was found in increasing order as: acid soluble fraction<oxidizable fraction<reducible fraction. The acid soluble fraction of As was higher in lake sediment samples as compared to those of canal and river sediments, indicating the contamination of lake ecosystem.

Rapid ionic liquid-based ultrasound assisted dual magnetic microextraction to preconcentrate and separate cadmium-4-(2-thiazolylazo)-resorcinol complex from environmental and biological samples.

A rapid and innovative microextraction technique named as, ionic liquid-based ultrasound-assisted dual magnetic microextraction (IL-UA-DMME) was developed for the preconcentration and extraction of trace cadmium from environmental and biological samples, prior to analyzed by flame atomic absorption spectrometry (FAAS). The proposed method has many obvious advantages, including evading the use of organic solvents and achieved high extraction yields by the combination of dispersive liquid-liquid microextraction (DLLME) and magnetic mediated-solid phase extraction (MM-SPE). In this approach ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6] play an important role to extract the cadmium-4-(2-thiazolylazo)-resorcinol (Cd-TAR) complex from acid digested sample solutions and ultrasonic irradiation was applied to assist emulsification. After then, dispersed small amount of Fe3O4 magnetic nanoparticles (MNPs) in sample solutions to salvaged the IL and complete phase separation was attained. Some analytical parameters that influencing the efficiency of proposed (IL-UA-DMME) method, such as pH, volume of IL, ligand concentration, ultra-sonication time, amount of Fe3O4 MNPs, sample volume and matrix effect were optimized. Limit of detection (LOD) and enrichment factor (EF) of the method under optimal experimental conditions were found to be 0.40μgL(-1) and 100, respectively. The relative standard deviation (RSD) of 50μgL(-1) Cd was 4.29%. The validity and accuracy of proposed method, was assessed to analyzed certified reference materials of fortified lake water TMDA-54.4, SPS-WW2 waste water, spinach leaves 1570a and also checked by standard addition method. The obtained values showed good agreement with the certified values and sufficiently high recovery were found in the range of 98.1-101% for Cd. The proposed method was facile, rapid and successfully applied for the determination of Cd in environmental and different biological samples.

Environmental exposure of lead and iron deficit anemia in children age ranged 1–5 years: A cross sectional study

Iron (Fe) deficiency is the most common nutritional problem among children and lead (Pb) toxicity is the most common environmental health threat to children all over the world. The objective of this study was to determine blood lead (BPb) levels and prevalence of Fe deficient anemia among 1 to 5year old children attending day care clinic in pediatric ward of civil hospital Karachi, Pakistan. A total of 340 children of both genders participating in this study, were screened for anemia. Among them 215 were anemic and 125 non-anemic. The anemic group was further divided in two groups on the basis of % hemoglobin (Hb), mild (Hb <10g/dL) and severe anemic group (Hb <8g/dL), while non-anemic as referent children (Hb >10g/dL). The blood samples were analysed for Pb and Fe, along with hematological parameters. The result indicated that anemic children had a higher mean values of Pb in blood than referent children with Hb >10g/dL. The Pb levels <100μg/L were detected in 40% referent children while 60% of them had >10μg/dL. The BPb concentration in severe anemic children (53%) was found in the range of 100-200μg/L, whereas 47% had >200μg/L. The significant negative correlations of BPb level with % Hb (r=-0.514 and r=-0.685) and Fe contents (r=-0.522, r=-0.762, p<0.001) were observed in mild and severe anemic children respectively. While positive correlation was observed between BPb and age of both group and genders (r=0.69, p<0.01). The BPb levels were significantly associated with biochemical indices in the blood which have the potential to be used as biomarkers of Pb intoxication and Fe deficient anemia.

Evaluating the accumulation of arsenic in maize (Zea mays L.) plants from its growing media by cloud point extraction

A cloud point extraction has been developed for the determination of As in maize (Zea mays L.) and adjoining agriculture soil. The different parts of maize (grains, shoots and roots) and soil were subjected to microwave assisted digestion in a mixture of nitric acid and hydrogen peroxide (2:1 ratio). The trace amounts of As was pre-concentrated by cloud point extraction, as prior step to its determination by electrothermal atomic absorption spectrometry. The main factors affecting cloud point extraction efficiency, such as pH of sample solution, concentration of ammonium pyrrolidine dithiocarbamate and Triton X-114, equilibration temperature and time period for shaking were investigated in detail. For validation of proposed method a certified reference material of whole meal flour BCR 189 was used. No significant difference p>0.05 was observed between the experimental results and the certified values of CRM (paired t-test). The translocation of total As in different parts of maize were found in the order of, Root>Shoot>Grain.

Evaluation of arsenic levels in grain crops samples, irrigated by tube well and canal water

The aim of this study was to evaluate the uptake of arsenic (As) by grain crops (wheat, maize and sorghum) grown on agricultural soil irrigated with tube well water (SIT) as test samples and for comparative purposes, same grain crop samples grown on agricultural soil irrigated with fresh canal water (SIC) were marked as control samples, collected simultaneously from three sub-districts of Khairpur, Pakistan. Moreover, this paper demonstrated the total and EDTA (0.05 M) extractable As in both understudied soils that correlate with the respective total As in the edible parts of the studied grain crops. A significantly high accumulation of As was found in grains grown on SIT as compared to those grown on SIC. This study highlights the increased danger of growing food crops in the agricultural land continuously irrigated by As contaminated ground water.

Separation and preconcentration of trace amounts of aluminum ions in surface water samples using different analytical techniques.

A separation/preconcentration of aluminum (III) (Al(3+)) has been developed to overcome the problem of high matrix species, which may interfere with the determination of trace quantity of Al(3+) in natural water samples. The separation of Al(3+) in water samples was carried out from interfering cations by complexing them with 2-methyle 8-hyroxyquinoline (quinaldine) on activated silica. Whereas the separated trace amounts of Al(3+) was preconcentrated by cloud point extraction (CPE), as prior step to its determination by spectrofluorimetry (SPF) and flame atomic absorption spectrometry (FAAS). The Al(3+) react with 8-hydroxyquinoline (oxine) and then entrapped in non-ionic surfactant Triton X-114. The main factors affecting CPE efficiency, such as pH of sample solution, concentration of oxine and Triton X-114, equilibration temperature and time period for shaking were investigated in detail. The validity of separation/preconcentration of Al(3+) was checked by certified reference material of water (SRM-1643e). After optimization of the complexation and extraction conditions, a preconcentration factor of 20 was obtained for Al(3+) in 10 mL of natural water samples. The relative standard deviation for 6 replicates containing 100 microg L(-1) of Al(3+) was 5.41 and 4.53% for SPF and FAAS, respectively. The proposed method has been applied for determination of trace amount of Al(3+) in natural water samples with satisfactory results.

Multivariate optimization of cloud point extraction procedure for zinc determination in aqueous extracts of medicinal plants by flame atomic absorption spectrometry.

Cloud point extraction method has been developed for preconcentration of trace quantities of zinc (Zn) in aqueous extract of medicinal plants and blood samples of liver cancer patients using flame atomic absorption spectrometry. The Zn in aqueous extracts of medicinal plants (MPs) was complexed with 2-methyl-8-hydroxyquinoline (quinaldine) and 1-(2-pyridylazo)-2-naphthol (PAN) separately and entrapped in a non-ionic surfactant Triton X-114. After centrifugation, the surfactant-rich phase was diluted with 0.25mL acidic ethyl alcohol. The multivariate strategy was applied to estimate the optimum values of experimental variables (pH, time temperature, ligands and surfactant concentrations). Interactions between analytical factors and their optimal levels were investigated by two level factorial designs. Students t-test on the results of factorial design with 16 runs for Zn extraction, demonstrated that the factors, ligands concentrations, pH and temperature were statistically significant. The accuracy was assessed by analysis of certified reference materials, namely, BCR 101 (spruce needles), Clincheck control-lyophilized human whole blood. Enhancement factor of 30 and 26 were achieved for the preconcentration of Zn by 2-methyl-8-hydroxyquinoline (L1) and 1-(2-pyridylazo)-2-naphthol (L2), respectively. The relative standard deviation for six replicate determinations of Zn at 10μg/L level using 2-methyl-8-hydroxyquinoline (L1) and 1-(2-pyridylazo)-2-naphthol (L2) were <4% and >5%, respectively.

Evaluation of cadmium and zinc in biological samples of tobacco and alcohol user male mouth cancer patients.

There is compelling evidence in support of positive associations between zinc (Zn) deficiency and high accumulation of cadmium (Cd) in biological samples of different cancerous patients. The incidence of mouth cancer has been increased among people who possess habit of drinking alcohol, tobacco smoking and chewing with gradients in Pakistan. In the present study, Cd and Zn contents of blood and scalp hair samples of 92 male mouth cancer patients and 78 referents of same age group (range 35—65 years), socio-economic status, localities and dietary habits. Among referent male subjects, 56 consumed tobacco (smoking/chewing), 22 had none of smoking and chewing tobacco habits, while none of them admitted for alcohol drinking. The scalp hair and whole blood samples were oxidized by 65% nitric acid and 30% hydrogen peroxide (2:1) ratio in microwave oven. The Zn in digests was determined by flame atomic absorption while Cd was determined by electrothermal atomic absorption spectrometry. The average Cd concentration was higher, while level of Zn was lower in the blood and scalp hair samples of mouth cancer patients as compared to referent subjects (p < .001). The male referents consuming tobacco (chewing and smoking) have high level of Cd in both their biological samples as compared to those not smoking or chewing tobacco (p < .012). The Cd/Zn ratio in both biological samples was found to be higher in patients than in referent subjects.