Mohammad Balal Arain

Evaluation of status of toxic metals in biological samples of diabetes mellitus patients

There is accumulating evidence that the metabolism of several trace elements is altered in diabetes mellitus and that these nutrients might have specific roles in the pathogenesis and progress of this disease. The aim of present study was to compare the level of toxic elements, lead (Pb), cadmium (Cd), and arsenic (As) in biological samples (whole blood, urine, and scalp hair) of patients having diabetes mellitus type-2 age ranged (31-60) (n=238), with those of age matched non-diabetics (ND) as control subjects (n=196), of both genders. The concentrations of elements were measured by means of an atomic absorption spectrophotometer after microwave-assisted acid digestion. The validity and accuracy was checked by conventional wet acid digestion method and using certified reference materials. The overall recoveries of all elements were found in the range of 98.1-99.4% of certified values. The results of this study showed that the mean values of Pb, Cd and, As were significantly higher in scalp hair samples of smoker and non-smoker diabetic patients as compared to control subjects (p<0.001). The concentration of understudy toxic metals was also high in blood and urine samples of DM patient but difference was more significant in smoker DM patients. These results are consistent with those obtained in other studies, confirming that toxic metals may play a role in the development of diabetes mellitus.

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.

Evaluation of toxic metals in biological samples (scalp hair, blood and urine) of steel mill workers by electrothermal atomic absorption spectrometry.

The determination of toxic metals in the biological samples of human beings is an important clinical screening procedure. This study aimed to assess the possible influence of environmental exposure on production workers (PW) and quality control workers (QCW) of a steel mill, all male subjects aged 25-55 years. In this investigation, the concentrations of Pb, Cd, Ni and Cr were determined in biological samples (blood, urine and scalp hair samples) from these steel mill workers in relation to controlled unexposed healthy subjects of the same age group. After pre-treatment with nitric acid-hydrogen peroxide, the samples were digested via a microwave oven, and for comparison purposes, the same samples were digested by the conventional wet acid digestion method. The samples digested were subjected to graphite furnace atomic absorption spectrometry (GFAAS). To assess the reliability of these methods, critical factors, such as detection limit(s), calibration range(s), accuracy and precision, were studied. Quality control for these procedures was established with certified sample of human hair, urine and whole blood. The results indicate that the level of lead, cadmium and nickel in scalp hair, blood and urine samples were significantly higher in both groups of exposed workers (QW and PW) than those of the controls. The possible connection of these elements with the etiology of disease is discussed. The results also show the need for immediate improvements in workplace ventilation and industrial hygiene practices. Toxicology and Industrial Health 2006; 22: 381-393.

Speciation of heavy metals in untreated domestic wastewater sludge by time saving BCR sequential extraction method

In this work the modified three-stage sequential extraction procedure developed within the Standards, Measurement and Testing Programme (formally the Community Bureau of Reference BCR) of the European Commission, was applied for the fractionation of Cd, Cr, Cu, Ni, Pb and Zn in the untreated domestic wastewater sludge (DWS) collected from the Hyderabad city of Pakistan. The aim of our study was to evaluate the impact of different time intervals for shaking, and sample mass of sewage sludge on optimal recovery of all metals under study. Analyses of the extracts were performed by flame atomic absorption spectrometry (FAAS) and electrothermal atomic absorption spectrometry (ETAAS). The precision and accuracy of the proposed procedure was evaluated by using a certified reference material of soil amended with sewage sludge BCR 483. The maximum recoveries for Cd and Zn were observed for all three steps of BCR protocol at 26 hours (h) total shaking period, while Cr, Cu, Ni and Pb were achieved at 32 hours instead of previously reported 51 hours, with (p < 0.05). The maximum level of all heavy metals was achieved in samples mass 0.2–0.4 g, where as the extractant-sample mass ratio was kept according to the optimized BCR method. The results of the sequential extraction study of untreated DWS indicates that more easily mobilized forms (acid exchangeable) were found to be 31.0, 3.1, 2.5, 7.6, 2.6 and 8.4% of total contents of Cd, Cr, Cu, Ni, Pb and Zn, respectively. The oxidizable fraction is dominant for all the heavy metals, except Cd. The lixiviation tests (DIN 38414-S4) were used to evaluate the leaching of heavy metals from sewage sludge used for agricultural purposes.

Hazardous impact of toxic metals on tobacco leaves grown in contaminated soil by ultrasonic assisted pseudo-digestion: multivariate study.

Tobacco leaves (Nicotiana tabacum L.), agricultural soil and pollute irrigated lake water samples were collected during 2005--2006 and analyzed for Cd and Ni by electrothermal atomic absorption spectrometry (ETAAS). A simple and efficient procedure was investigated for the complete decomposition of tobacco leaves using ultrasonic assisted acid pseudo-digestion method (UPDM). A Plackett-Burman experimental design was used as a multivariate strategy for the evaluation of seven factors/variables at once, while central composite were used to found optimum values of significant variables. The accuracy of the proposed methods was assessed by analyzing certified reference (CRM); Virginia tobacco leaves (CTA-VTL-2). The results being compared with those obtained by conventional wet acid digestion method. The result obtained by optimized method showed good agreement with the certified values and sufficiently high recovery 97.8 and 98.7% for Cd and Ni, respectively. Under optimal conditions, the detection limits (3sigma) were evaluated to be 0.019 microg g(-1) for Cd and 0.37 microg g(-1) for Ni. The proposed method was successfully applied to the determination of Cd and Ni in raw, processed tobacco and different branded cigarettes samples.

Assessment of toxic metals in raw and processed milk samples using electrothermal atomic absorption spectrophotometer.

Milk and dairy products have been recognized all over the world for their beneficial influence on human health. The levels of toxic metals (TMs) are an important component of safety and quality of milk. A simple and efficient microwave assisted extraction (MAE) method has been developed for the determination of TMs (Al, Cd, Ni and Pb), in raw and processed milk samples. A Plackett-Burman experimental design and 2(3)+star central composite design, were applied in order to determine the optimum conditions for MAE. Concentrations of TMs were measured by electrothermal atomic absorption spectrometry. The accuracy of the optimized procedure was evaluated by standard addition method and conventional wet acid digestion method (CDM), for comparative purpose. No significant differences were observed (P>0.05), when comparing the values obtained by the proposed MAE method and CDM (paired t-test). The average relative standard deviation of the MAE method varied between 4.3% and 7.6% based on analyte (n=6). The proposed method was successfully applied for the determination of understudy TMs in milk samples. The results of raw and processed milk indicated that environmental conditions and manufacturing processes play a key role in the distribution of toxic metals in raw and processed milk.

Evaluation of an ultrasonic acid digestion procedure for total heavy metals determination in environmental and biological samples.

In this study, a sample preparation method based on ultrasonic assisted acid digestion (UAD) has been evaluated for total heavy metals (Cd, Cr, Ni and Pb) determination in different environmental (soil, sediment and sewage sludge), and biological (fish muscles, vegetables and grains) samples, using electrothermal atomic absorption spectrometry (ETAAS). The investigated parameters influencing UAD such as presonication time, sonication time, temperature of ultrasonic bath, and different acid mixtures were fully optimized, whereas power was maintained constant at 100% of nominal power of ultrasonic bath. Six different sets of above parameters were applied on six certified reference materials (CRMs) having different matrices. The accuracy of the method was also tested by comparing the results with those obtained from conventional hot plate assisted acid digestion method on same CRMs. Analytical results for HMs by both methods showed no significant difference at 95% confidence limit (p<0.05). Recoveries of HMs ranging from 96.2% to 102% and 96.3% to 98.6% were obtained from biological and environmental samples, respectively. The average relative standard deviation of UAD method varied between 3.5% and 8.2%, depending on the analyte.

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.

Determination of toxic elements in infant formulae by using electrothermal atomic absorption spectrometer.

In present work concentrations of toxic elements (TEs), aluminum (Al), cadmium (Cd), and lead (Pb) in seventeen imported samples of infant milk-based (IMF) and infant soy-based formulae (ISF), were measured, to evaluate whether the intakes of understudy TEs accomplished within recommended permissible levels. The TEs were analyzed by electrothermal atomic absorption spectrometer, prior to microwave induced acid digestion. The validity of methodology was tested by simultaneously analyzing certified reference material and standard addition method. It was observed that ISF contains higher concentration of understudy toxic analytes as compared to IMF. The all three TEs, Al, Cd and Pb were detected in different branded infant formulae, in the range of (1070-2170), (10.5-34.4), and (28.7-119) microg/kg, respectively. The estimated intakes of TEs as microg/kg/week for infants (>1year) through milk formulae are well below the recommended tolerable levels of these elements.