Injection Hydride Generation Atomic Absorption Research Articles

A robust method for the determination of lead in water samples using flow injection hydride generation atomic absorption spectrometry

Flow injection hydride generation atomic absorption spectrometry (FI-HGAAS) is a sensitive technique for the quantification of trace amounts of lead. However, plumbane generation is not straightforward and usually HG methods for lead are not robust enough for routine analysis. The optimum pH range for Pb HG is very narrow, so strict control of the acidity of the reaction medium is required for reliable results and in some cases even acid concentrations used for sample preservation can interfere. Moreover, some elements, like Cu, can interfere in the HG reaction suppressing the Pb signal. In this paper we report the development and validation of a method for the determination of Pb in water samples that is robust towards acidity and Cu levels usually found in water samples.All hydride generation parameters were optimized, but special emphasis was put on robustness. The use of borate as a buffer significantly improved the robustness of the method towards acidity, compared to the typical non-buffered HG. Furthermore, the interference of Cu, Sb and Sn in the HG reaction was overcome using thiocyanate as a masking agent. Other elements do not interfere at levels typically found in water samples. The limit of quantification achieved (0.9 μg L−1) is below the current guideline value for Pb in drinking water (10 μg L−1). The linearity of the method was verified between the LOQ and up to 15 μg L−1. An analytical frequency of 25 samples per hour with 3 measurement replicates each was achieved. The method was applied to the analysis of 50 water samples. The concentrations found ranged from <LOD (0.3 μg L−1) and up to 88.8 μg L−1.The proposed method is robust, cost-effective, easily automated and does not require unconventional or expensive equipment. It can be applied for routine analysis of different types of water samples.

Selenium speciation in soils using flow injection hydride generation atomic absorption spectrometry with on-line removal of organic matter interferences

A method based on flow injection hydride generation atomic absorption spectrometry (FI-HGAAS) with an on-line pre-reduction of Se(VI) to Se(IV) was developed and optimized to determine phosphate-extractable Se (0.1 M phosphate buffer KH2PO4/K2HPO4 at pH 7). The extracted fraction involves water-soluble Se (i.e. the most mobile Se fraction) and exchangeable Se (i.e. sorbed onto soil component surface). Kinetic discrimination mechanisms allowed the complete removal of interferences caused by organic matter due to the formation of humic substances (HS)–Se(IV) complexes observed when batch pre-reduction processes were used. Se(IV) and Se(VI) recoveries ranged 95–105% at a fortification level of 150 μg kg−1. The pre-reduction was efficiently carried out in 20 s in a 6 M HCl medium at 100 °C. Results from phosphate-extractable fractions were comparable to those obtained by ICP-MS. Se bound to organic matter was released digesting the remaining material from the phosphate buffer extraction with 0.1 M K2S2O8. Detection and quantification limits were 15 μg kg−1 Se and 50 μg kg−1 Se, respectively, in each fraction. The methodology was applied to 10 agricultural soils from Argentina with total Se concentration levels between 130 μg kg−1 and 419 μg kg−1.

Arbuscular mycorrhizal fungi reduce arsenic uptake and improve plant growth in Lens culinaris.

Arsenic (As) is a carcinogenic and hazardous substance that poses a serious risk to human health due to its transport into the food chain. The present research is focused on the As transport in different lentil genotypes and the role of Arbuscular Mycorrhizal Fungi (AMF) in mitigation of As phyto-toxicity. Arsenic transport from soil to root, shoot and grains in different lentil genotypes was analyzed by flow injection hydride generation atomic absorption spectrophotometry. AMF were applied for the reduction of As uptake as well as the improvement of plant growth in lentil genotypes. Arsenic phyto-toxicity was dose-dependent as evidenced by relatively higher shoot length, fresh and dry weight of root and shoot in 5 and 15 mgkg-1 As-treated lentil plants than that in 100 mgkg-1 As-treated lentil. Arsenic accumulation occurred in roots and shoots of all BARI-released lentil genotypes. Arsenic accumulation in grains was found higher in BARI Mashur 1 than other lentil genotypes. AMF treatment significantly increased growth and biomass accumulation in lentil compared to that in non-AMF plants. Furthermore, AMF effectively reduced the As concentrations in roots and shoots of lentil plants grown at 8 and 45 mgkg-1 As-contaminated soils. This study revealed remarkable divergence in As accumulation among different BARI-released lentil genotypes; however, AMF could reduce As uptake and mitigate As-induced phyto-toxicity in lentil. Taken together, our results suggest a great potential of AMF in mitigating As transfer in root and shoot mass and reallocation to grains, which would expand lentil cultivation in As-affected areas throughout the world.

Is There Any Role of Arsenic Toxicity in HPV Related Oral Squamous Cell Carcinoma?

Arsenic is a potent human carcinogen affecting the rate of cancer deaths worldwide. In India, West Bengal is the worst affected state by arsenic. To our best knowledge, this is the first study relating arsenic toxicity with oral carcinoma, along with HPV infection, the latter being well established in western countries. To find out a possible correlation between arsenic toxicity and oral carcinoma in the population of West Bengal, in or without any association with human papilloma virus infection. Ethical clearance of this study was obtained from the institutional committee. One hundred and four malignant and 103 premalignant cases were selected for this study along with 200 healthy age and sex-matched individuals selected as control (100 each for malignant and premalignant) (2013-2017). On proper consent, their buccal swab and hair samples were assessed for the presence of HPV DNA by DNA extraction, followed by PCR and arsenic estimation by flow injection hydride generation atomic absorption spectrometry respectively. A very highly significant correlation has been observed between arsenic toxicity, HPV infection and the occurrence of oral carcinoma (p value=2.18e-06; p value=0.00100 respectively). A correlation has also been observed between these two factors simultaneously, contributing to this malignancy (phi coefficient = 0.2194839). A statistically significant correlation observed between this metal toxicity and viral infection in the occurrence of oral carcinoma in this population indicates a possible symbiotic role between these two factors in this malignancy.

Implications of extrapolative factors and their role in the development of breast cancer in females susceptible to Autoimmune Thyroid Disorders (AITDs)

Background: Apart from different cancer types in females, breast cancer falls among frequent cancers all over the world. The data from the current studies shows that females with advanced stages of breast cancer also prone to Autoimmune Thyroid Disorders (AITDs). Methodology: Hundred breast cancer patients (Stage-III) with palpable thyroid nodule in the age group of 30-75 y were eligible for inclusion in the study. Hundred age and sex-matched clinically apparently healthy individuals were included as controls. FT3, FT4, TSH, TPOAb, TgAb, TSHr Ab, prolactin and estradiol were estimated by using ELISA kit method. Serum Protein-Bound Iodine (PBI) and selenium were estimated by using a flow injection hydride generation Atomic Absorption Spectrometric (AAS) method. Results: The mean age and weight for diseased group were 58.36 ± 11.78 y and 74.96 ± 12.66 kg. The decreased levels (3.73 ± 0.189 pmol/L) of T3 were observed in newly diagnosed breast cancer patients as compared to controls (4.72 ± 0.24 pmol/L). Higher levels of T4 (17.86 ± 4.98 pmol/L) were recorded in patients as compared to controls (10.11 ± 1.64 pmol/L). The serum TSH levels in the breast cancer patients were raised (3.54 ± 0.26 mIU/L) in contrary to control group (1.9 ± 0.134 mIU/L). Significantly higher levels of Thyroglobulin Antibodies (TgAb), Thyro-Peroxidase Antibodies (TPOAb) and Thyrotropin Stimulating Hormone receptor Antibodies (TSHrAb) were recorded in breast cancer patients (62.07 ± 6.94 pmol/L, 24.1 ± 6.81 and 3.1 ± 0.43 IU/L pmol/L) as compared to controls respectively. The levels of iodine and selenium in patients were reduced (32.03 ± 4.76 ng/ml and 51.03 ± 2.13 mlU/L) as compared to the controls. Highly significant higher serum levels of prolactin (35.09 ± 4.76) were observed in diseases group as compared to controls (7.14 ± 1.57 pg/ml). Serum estrogen levels in patients were 10.47 ± 1.67 pg/ml, while in healthy individuals they were 6.55 ± 0.88 pg/ml, which shows statistically highly significant profile between the two groups. Conclusion: The present study show an association in between breast cancer and thyroid disorders, as thyroid hormone profile regulates breast cancer initiation. Therefore, these biomarkers can be used in prognosis i.e., in management and progression of breast cancer.

Quantitative Determination of Antimony, Bismuth, and Tellurium in Geological Samples by Inductively Coupled Plasma Mass Spectrometry and Flow Injection Hydride Generation Atomic Absorption Technique

Quantitative Determination of Antimony, Bismuth, and Tellurium in Geological Samples by Inductively Coupled Plasma Mass Spectrometry and Flow Injection Hydride Generation Atomic Absorption Technique

Groundwater arsenic contamination from parts of the Ghaghara Basin, India: influence of fluvial geomorphology and Quaternary morphostratigraphy

A groundwater arsenic (As) distribution in Faizabad, Gonda, and Basti districts of Uttar Pradesh is shown in the entrenched channels and floodplains of the Ghaghara River. Tubewell water samples were analysed for As through flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) system. About 38, 61, and 42 % of tubewells in Faizabad, Gonda, and Basti districts, respectively, have As >10 µg/l (WHO guideline). Moreover, 15, 45, and 26 % of tubewells in Faizabad, Gonda, and Basti districts, respectively, have As above 50 µg/l. About 86, 69, and 35 % of tubewells in Faizabad, Gonda, and Basti districts, respectively, are from shallow depth (21–45 m), and it is worth noticing that 47 % As-contaminated (As >10 µg/l) tubewells in these three districts are located within the depth of 10–35 m in Holocene Newer Alluvium aquifers. The high content of As (7.11 mg/kg) is measured in suspended river sediments of the Ghaghara River. Most of the As-contaminated villages in the Ghaghara Basin are located close to abandoned or present meander channels and floodplains of the Ghaghara River. In contrast, tubewells in Faizabad, Ayodhya, and Nawabganj towns are As-safe because of their positions on the Pleistocene Older Alluvium upland surfaces. Quaternary geomorphology plays an important role in groundwater arsenic contamination in the Ghaghara Basin. The sources of groundwater arsenic are geogenic and perennial mountainous rivers in the Ghaghara Basin supplied high sediment loads. The arsenic in groundwater of Ghaghara Basin is getting released from associated sediments which were likely deposited from the Himalayas. The process of release of groundwater arsenic is reductive dissolution of iron hydroxides.

Accuracy of a method based on atomic absorption spectrometry to determine inorganic arsenic in food: Outcome of the collaborative trial IMEP-41

A collaborative trial was conducted to determine the performance characteristics of an analytical method for the quantification of inorganic arsenic (iAs) in food.The method is based on (i) solubilisation of the protein matrix with concentrated hydrochloric acid to denature proteins and allow the release of all arsenic species into solution, and (ii) subsequent extraction of the inorganic arsenic present in the acid medium using chloroform followed by back-extraction to acidic medium. The final detection and quantification is done by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS).The seven test items used in this exercise were reference materials covering a broad range of matrices: mussels, cabbage, seaweed (hijiki), fish protein, rice, wheat, mushrooms, with concentrations ranging from 0.074 to 7.55mgkg−1.The relative standard deviation for repeatability (RSDr) ranged from 4.1 to 10.3%, while the relative standard deviation for reproducibility (RSDR) ranged from 6.1 to 22.8%.

A comparative study of two nanosubstrates for the on-line solid phase extraction of antimony by FI-HG-AAS

Nanoporous carbon (NPC) prepared from metal organic frameworks (MOFs) was studied to serve as a sorbent for preconcentrating Sb(III) at trace levels. The performance of NPC regarding sensitivity, enrichment factor, analytical throughput and recovery was compared with that of multiwalled carbon nanotubes functionalised with l-proline (pro-MWCNTs). In this study, Sb(III) was preconcentrated using both substrates using an on-line flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) system. A low molecular weight polyethylene was added to the sorbent material to fill the preconcentration columns to avoid nanoparticle aggregation. A comprehensive study of the type and concentration of the reaction media and the eluent was carried out to select the best substrate not only in terms of adsorption capacity but also considering potential interferent control. The study evidenced that for Sb(III) retention, phtalate buffers (1.0mM at pH=6) resulted the best alternative. Under optimal conditions, both substrates exhibited high adsorption capacities: 343mgSbg−1 NPC and 559mgSbg−1 pro-MWCNTs. The preconcentration factors reached were: 258 and 420 for NPC and pro-MWCNTs, respectively. The high adsorption capacity of both substrate allowed reaching detection limits (3σ) of 1.47 and 0.52ngL−1 for NPC and pro-MWCNTs, respectively when using a sorbent column containing only 1.0mg of sorbent. Precision, expressed as relative standard deviation (RSD) turned to be ~2% at the 0.1μgL−1 level (n=10) for both substrates. Trueness test for the entire analytical procedure was performed by means of the Standard Reference Material (SRM) NIST 1643e (Trace elements in water) and results were in good agreement with the certified values. The system was evaluated for quantitative determination of Sb(III) in different kind of waters. The method is simple and relatively cheap in comparison with other methodologies.

Total arsenic in selected food samples from Argentina: Estimation of their contribution to inorganic arsenic dietary intake

An optimized flow injection hydride generation atomic absorption spectroscopy (FI-HGAAS) method was used to determine total arsenic in selected food samples (beef, chicken, fish, milk, cheese, egg, rice, rice-based products, wheat flour, corn flour, oats, breakfast cereals, legumes and potatoes) and to estimate their contributions to inorganic arsenic dietary intake. The limit of detection (LOD) and limit of quantification (LOQ) values obtained were 6μgkg−1 and 18μgkg−1, respectively. The mean recovery range obtained for all food at a fortification level of 200μgkg−1 was 85–110%. Accuracy was evaluated using dogfish liver certified reference material (DOLT-3 NRC) for trace metals. The highest total arsenic concentrations (in μgkg−1) were found in fish (152–439), rice (87–316) and rice-based products (52–201). The contribution to inorganic arsenic (i-As) intake was calculated from the mean i-As content of each food (calculated by applying conversion factors to total arsenic data) and the mean consumption per day. The primary contributors to inorganic arsenic intake were wheat flour, including its proportion in wheat flour-based products (breads, pasta and cookies), followed by rice; both foods account for close to 53% and 17% of the intake, respectively. The i-As dietary intake, estimated as 10.7μgday−1, was significantly lower than that from drinking water in vast regions of Argentina.

Arsenic groundwater contamination and its health effects in Patna district (capital of Bihar) in the middle Ganga plain, India

We investigated the extent and severity of groundwater arsenic (As) contamination in five blocks in Patna district, Bihar, India along with As in biological samples and its health effects such as dermatological, neurological and obstetric outcome in some villages. We collected 1365 hand tube-well water samples and analyzed for As by the flow injection hydride generation atomic absorption spectrometer (FI-HG-AAS). We found 61% and 44% of the tube-wells had As above 10 and 50 μg/l, respectively, with maximum concentration of 1466 μg/l. Our medical team examined 712 villagers and registered 69 (9.7%) with arsenical skin lesions. Arsenical skin lesions were also observed in 9 children of 312 screened. We analyzed 176 biological samples (hair, nail and urine). Out of these, 69 people had arsenical skin lesions and rest without skin lesions. We found 100% of the biological samples had As above the normal levels (concentrations of As in hair, nail and urine of unexposed individuals usually ranges from 20 to 200 μg/kg, 20–500 μg/kg and <100 μg/l, respectively), indicating many people are sub-clinically affected. Arsenical neuropathy was observed in 40.5% of 37 arsenicosis patients with 73.3% prevalence for predominant sensory neuropathy and 26.7% for sensor-motor. Among patients, different clinical and electrophysiological neurological features and abnormal quantitative sensory perception thresholds were also noted. The study also found that As exposed women with severe skin lesions had adversely affected their pregnancies. People including children in the affected areas are in danger. To combat As situation in affected areas, villagers urgently need (a) provision of As-safe water for drinking and cooking, (b) awareness about the danger of As toxicity, and (c) nutritious food.

On-line solid phase extraction of bismuth by FI–HG–AAS using l-proline immobilised on carbon nanotubes combined with factorial design

This study explores further the analytical capabilities of functionalised multiwalled carbon nanotubes with l-proline (pro-MWCNTs) for the reliable preconcentration and determination of Bi(III) in waters using an on-line flow injection hydride generation atomic absorption spectrometry (FI–HG–AAS) system. To avoid carbon nanoparticles aggregation, the preconcentration was carried out on a microcolumn filled with functionalised pro-MWCNTs and a low molecular weight polyethylene. The optimisation was performed by employing a full factorial design. The factors related to the optimisation process were the concentration of eluent and pH of the sample. The best performance was achieved packing the substrate in a microcolumn of 2.3mm (i.d)×25mm (pro-MWCNTs net length: 10mm), the pH was 7.0 and the concentration of the eluent (HCl) was 10% (v/v). Under optimal conditions, the adsorption capacity of the substrate was found to be 0.1mgg−1 reaching a preconcentration factor (PF) of 160. A detection limit (3σ) of 0.7ngL−1 was achieved, when using only 3.0mg of substrate. Interferences affecting Bi(III) signal were carefully studied. Precision, expressed as relative standard deviation (RSD) turned to be 1.5% at the 0.1μgL−1 level (n=10). Accuracy test for the entire analytical procedure was performed by means of the Standard Reference Material (SRM) NIST 1643e (trace elements in water) and results were in good agreement with the certified values. The system was evaluated for quantitative determination of Bi(III) in different categories of waters.

Groundwater arsenic contamination in Bangladesh—21 Years of research

Department of Public Health Engineering (DPHE), Bangladesh first identified their groundwater arsenic contamination in 1993. But before the international arsenic conference in Dhaka in February 1998, the problem was not widely accepted. Even in the international arsenic conference in West-Bengal, India in February, 1995, representatives of international agencies in Bangladesh and Bangladesh government attended the conference but they denied the groundwater arsenic contamination in Bangladesh. School of Environmental Studies (SOES), Jadavpur University, Kolkata, India first identified arsenic patient in Bangladesh in 1992 and informed WHO, UNICEF of Bangladesh and Govt. of Bangladesh from April 1994 to August 1995. British Geological Survey (BGS) dug hand tube-wells in Bangladesh in 1980s and early 1990s but they did not test the water for arsenic. Again BGS came back to Bangladesh in 1992 to assess the quality of the water of the tube-wells they installed but they still did not test for arsenic when groundwater arsenic contamination and its health effects in West Bengal in Bengal delta was already published in WHO Bulletin in 1988. From December 1996, SOES in collaboration with Dhaka Community Hospital (DCH), Bangladesh started analyzing hand tube-wells for arsenic from all 64 districts in four geomorphologic regions of Bangladesh. So far over 54,000 tube-well water samples had been analyzed by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS). From SOES water analysis data at present we could assess status of arsenic groundwater contamination in four geo-morphological regions of Bangladesh and location of possible arsenic safe groundwater. SOES and DCH also made some preliminary work with their medical team to identify patients suffering from arsenic related diseases. SOES further analyzed few thousands biological samples (hair, nail, urine and skin scales) and foodstuffs for arsenic to know arsenic body burden and people sub-clinically affected. SOES and DCH made a few follow-up studies in some districts to know their overall situations after 9 to 18 years of their first exposure. The overall conclusion from these follow-up studies is (a) villagers are now more aware about the danger of drinking arsenic contaminated water (b) villagers are currently drinking less arsenic contaminated water (c) many villagers in affected village died of cancer (d) arsenic contaminated water is in use for agricultural irrigation and arsenic exposure from food chain could be future danger. Since at present more information is coming about health effects from low arsenic exposure, Bangladesh Government should immediately focus on their huge surface water management and reduce their permissible limit of arsenic in drinking water.

Status of groundwater arsenic pollution of Mirzapur district in Holocene aquifers from parts of the Middle Ganga Plain, India

A groundwater arsenic (As) distribution in Mirzapur district of Uttar Pradesh is shown in the entrenched channels and floodplains of the Ganga River. A total of 45 tubewell water samples were analysed for As through flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) system. Iron in tubewell water was analysed by 1,10-phenanthroline method by the use of UV spectrophotometer. About 37.7 % of tubewells in this district have As >10 µg/l (WHO guideline) and 15.5 % of tubewells have As above 50 µg/l. About 84.4 % of tubewells have higher concentrations of iron (Fe) beyond its permissible limit 1 mg/l (BIS guideline). The iron (Fe) content in tubewell water samples varies from 0.1 to 7.6 mg/l. About 75.5 % of tubewells in Mirzapur district are from shallow depth (20–40 m), and it is worth noticing that 37.7 % of As-contaminated (As >10 µg/l) tubewells are located within the depth of 25–40 m in the Holocene Newer Alluvium aquifers. Most of the As-contaminated villages in Mirzapur district are located close to abandoned or present meander channels and floodplains of the Ganga River. In contrast, tubewells in Mirzapur and Chunar towns have low concentrations of As in groundwater (As 50 m) in the Pleistocene Older Alluvium aquifers would be better option for As-safe groundwater. The potential sources of As are mainly from the Himalayas and the Himalayas rivers have high content of As in suspended river sediments.

Flow injection on-line solid phase extraction for ultra-trace lead determination with hydride generation electrothermal atomic absorption spectrometry

The efficiencies of two types of chelating resins were evaluated and optimized for the extraction and determination of lead by flow injection graphite furnace and hydride generation atomic absorption spectrometry (FI-HG-ETAAS) in environmental water samples. The optimum analytical conditions were examined and the analytical features of each method were revealed and compared in terms of sensitivity, selectivity and accuracy. Lead determination by FI-HG-ETAAS using [1,5-bis(2-pyridyl)-3-sulphophenyl methylene] thiocarbonohydrazide immobilised on aminopropyl-controlled pore glass (PSTH-cpg, 55 nm) provides a detection limit of 3.0 ng l−1 lead with a relative standard deviation (R.S.D.) of 2.5% at the 50 ng l−1 level (n = 10) compared to silica gel funtionalized with methylthiosalicylate (TS-gel) which provides a detection limit of 82 ng l−1. Under the optimal experimental conditions, with the use of PSTH-cpg and a tungsten–rhodium coated graphite furnace, an enhancement factor of 20 was obtained with a sample consumption of 6.4 ml, while an enhancement factor of 3.5 was obtained with the use of TS-gel. Both methods have been applied to the determination of low levels of lead in environmental water samples. The results obtained show good agreement with certified or expected values.

Especiação química de arsênio inorgânico no estuário da Laguna dos Patos (RS, Brasil)

This study optimized and validated a method to perform chemical speciation of inorganic arsenic in water samples collected under the Monitoring Program of the Port of Rio Grande-RS in July and October 2010 from the Laguna dos Patos Estuary (RS, Brazil). The flow injection hydride generation atomic absorption spectrometry technique was employed, allowing quantification of As3+ and As5+ present in estuarine water samples. Data interpretation for results generated using the improved method for analyzing water samples collected from Laguna dos Patos Estuary was done by main components analysis.

Total and inorganic arsenic concentrations in different species of economically important algae harvested from coastal zones of Chile

Chile is one of the major producers of phytocolloids extracted from seaweed. Multicellular algae are considered to be primary accumulators of arsenic. We analyzed 14 species of algae belonging to the groups Rhodophyceae (10), Phaeophyceae (3) and Chlorophyceae (1) from different coastal zones of Chile in 2003–2004. Dry ashing mineralization (for total As) and acid digestion (for inorganic As) together with quantification by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) were employed. In general, total arsenic concentrations varied between 3.0 and 68mgkg−1, whereas inorganic arsenic concentrations ranged between 0.15 and 1.06mgkg−1. The algal species Durvillaea antarctica and Porphyra columbina, used for direct human consumption, did not have inorganic arsenic levels that represent a health risk to consumers. Among species used for phytocolloids production, such as Macrocystis piryfera, Gracilaria chilensis and Gigartina skottsbergii, observed levels of inorganic arsenic were greater than 1mgkg−1, the limit value established by the regulations of some countries. Among the 14 species of algae tested, inorganic arsenic levels were between 0.8% and 13% of the total arsenic concentrations; that is, arsenic present in these algae was found primarily as organic arsenic.

Application of geostatistics with Indicator Kriging for analyzing spatial variability of groundwater arsenic concentrations in Southwest Bangladesh

This article seeks to explore the spatial variability of groundwater arsenic (As) concentrations in Southwestern Bangladesh. Facts about spatial pattern of As are important to understand the complex processes of As concentrations and its spatial predictions in the unsampled areas of the study site. The relevant As data for this study were collected from Southwest Bangladesh and were analyzed with Flow Injection Hydride Generation Atomic Absorption Spectrometry (FI-HG-AAS). A geostatistical analysis with Indicator Kriging (IK) was employed to investigate the regionalized variation of As concentration. The IK prediction map shows a highly uneven spatial pattern of arsenic concentrations. The safe zones are mainly concentrated in the north, central and south part of the study area in a scattered manner, while the contamination zones are found to be concentrated in the west and northeast parts of the study area. The southwest part of the study area is contaminated with a highly irregular pattern. A Generalized Linear Model (GLM) was also used to investigate the relationship between As concentrations and aquifer depths. A negligible negative correlation between aquifer depth and arsenic concentrations was found in the study area. The fitted value with 95 % confidence interval shows a decreasing tendency of arsenic concentrations with the increase of aquifer depth. The adjusted mean smoothed lowess curve with a bandwidth of 0.8 shows an increasing trend of arsenic concentration up to a depth of 75 m, with some erratic fluctuations and regional variations at the depth between 30 m and 60 m. The borehole lithology was considered to analyze and map the pattern of As variability with aquifer depths. The study has performed an investigation of spatial pattern and variation of As concentrations.

Determination of As(III) and total inorganic As in water samples using an on-line solid phase extraction and flow injection hydride generation atomic absorption spectrometry

A simple and robust on-line sequential injection system based on solid phase extraction (SPE) coupled to a flow injection hydride generation atomic absorption spectrometer (FI-HGAAS) with a heated quartz tube atomizer (QTA) was developed and optimized for the determination of As(III) in groundwater without any kind of sample pretreatment. The method was based on the selective retention of inorganic As(V) that was carried out by passing the filtered original sample through a cartridge containing a chloride-form strong anion exchanger. Thus the most toxic form, inorganic As(III), was determined fast and directly by AsH 3 generation using 3.5 mol L −1 HCl as carrier solution and 0.35% (m/v) NaBH 4 in 0.025% NaOH as the reductant. Since the uptake of As(V) should be interfered by several anions of natural occurrence in waters, the effect of Cl −, SO 4 2−, NO 3 −, HPO 4 2−, HCO 3 − on retention was evaluated and discussed. The total soluble inorganic arsenic concentration was determined on aliquots of filtered samples acidified with concentrated HCl and pre-reduced with 5% KI–5% C 6H 8O 6 solution. The concentration of As(V) was calculated by difference between the total soluble inorganic arsenic and As(III) concentrations. Detection limits (LODs) of 0.5 μg L −1 and 0.6 μg L −1 for As(III) and inorganic total As, respectively, were obtained for a 500 μL sample volume. The obtained limits of detection allowed testing the water quality according to the national and international regulations. The analytical recovery for water samples spiked with As(III) ranged between 98% and 106%. The sampling throughput for As(III) determination was 60 samples h −1. The device for groundwater sampling was especially designed for the authors. Metallic components were avoided and the contact between the sample and the atmospheric oxygen was carried to a minimum. On-field arsenic species separation was performed through the employ of a serial connection of membrane filters and anion-exchange cartridges. Advantages derived from this approach were evaluated. HPLC–ICPMS was employed to study the consistency of the analytical results.

Status of groundwater arsenic contamination in Bangladesh: A 14-year study report

Since 1996, 52,202 water samples from hand tubewells were analyzed for arsenic (As) by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) from all 64 districts of Bangladesh; 27.2% and 42.1% of the tubewells had As above 50 and 10 μg/l, respectively; 7.5% contained As above 300 μg/l, the concentration predicting overt arsenical skin lesions. The groundwater of 50 districts contained As above the Bangladesh standard for As in drinking water (50 μg/l), and 59 districts had As above the WHO guideline value (10 μg/l). Water analyses from the four principal geomorphological regions of Bangladesh showed that hand tubewells of the Tableland and Hill tract regions are primarily free from As contamination, while the Flood plain and Deltaic region, including the Coastal region, are highly As-contaminated. Arsenic concentration was usually observed to decrease with increasing tubewell depth; however, 16% of tubewells deeper than 100 m, which is often considered to be a safe depth, contained As above 50 μg/l. In tubewells deeper than 350 m, As >50 μg/l has not been found. The estimated number of tubewells in 50 As-affected districts was 4.3 million. Based on the analysis of 52,202 hand tubewell water samples during the last 14 years, we estimate that around 36 million and 22 million people could be drinking As-contaminated water above 10 and 50 μg/l, respectively. However for roughly the last 5 years due to mitigation efforts by the government, non-governmental organizations and international aid agencies, many individuals living in these contaminated areas have been drinking As-safe water. From 50 contaminated districts with tubewell As concentrations >50 μg/l, 52% of sampled hand tubewells contained As <10 μg/l, and these tubewells could be utilized immediately as a source of safe water in these affected regions provided regular monitoring for temporal variation in As concentration. Even in the As-affected Flood plain, sampled tubewells from 22 thanas in 4 districts were almost entirely As-safe. In Bangladesh and West Bengal, India the crisis is not having too little water to satisfy our needs, it is the challenge of managing available water resources. The development of community-specific safe water sources coupled with local participation and education are required to slow the current effects of widespread As poisoning and to prevent this disaster from continuing to plague individuals in the future.