A fast and reliable method for quantitative determination of total mercury in vegetables

A cloud-point extraction (CPE) process using the nonionic surfactant, polyethylene glycol tert octylphenyl ether (Triton X-114) was employed for determination of Hg(II) ions in aqueous solutions. The method is based on the ion-pairing reaction of Hg(II) with Pyronin B (PyrB⁺) in the presence of excess iodide at pH 6.0 and extraction of the complex formed. The chemical variables affecting CPE efficiency were studied, and the analytical characteristics of the method were obtained. The calibration curves were linear in the range of 1–40 μg L^?1 with the detection limits of 0.35 and 0.30 μg L^?1 at 556 and 521 nm. Selectivity was also tested. The coefficients of variation of the method are 2.4% and 5.2% for five replicate measurements of mercury at levels of 10 and 25 μg L^?1, respectively. The results obtained for two certified reference samples were in a good agreement with the certified values. The method was applied to the determination of total mercury in vegetable samples.     

Ultrasound-assisted emulsification/microextraction based on solidification of trace amounts of thallium prior to graphite furnace atomic absorption spectrometry determination

In the present work, determination of ultratrace amounts of thallium in water samples was performed by ultrasound-assisted emulsification microextraction based on solidification of a floating organic drop as sample preparation method prior to furnace atomic absorption spectrometry. 1-(2-Pyridylazo)-2-naphthol was used as chelating agent. The factors influencing the complex formation and extraction, such as pH of the aqueous solution, the type and the volume of extraction solvent, the volume of chelating agent solution, and the extraction time were investigated. Under optimized conditions, the enrichment factor was 200. The calibration graph was linear from 0.2 to 10.0 μg L^?1 with a correlation coefficient of 0.9966, the detection limit was 0.03 μg L^?1 and reproducibility was ±3.3% (C = 5.0 μg L^?1, n = 8). The method was successfully applied for the determination of thallium in water samples.     

Ultrastructural responses and oxidative stress induced by cypermethrin in the liver of Labeo rohita

The present study was conducted to establish the relationship between selected oxidative stress parameters and ultrastructural responses in liver tissue of Labeo rohita fingerlings exposed to cypermethrin. Fish were exposed to lethal (4.0 μg L^?1) and sublethal (0.4 μg L^?1) concentrations of cypermethrin for a period of 24, 48, 72 and 96 h for acute studies and 1, 5, 10 and 15 days for subacute studies, respectively. Results showed increased catalase (CAT) and protease activity, hydrogen peroxide (H₂O₂), malondialdehyde (MDA), protein carbonyls and free amino acid (FAA) levels at both concentrations. This suggests participation of free-radical-induced oxidative cell injury in mediating the hepatotoxicity of cypermethrin. In corroboration of this, ultrastructural lesions witnessed a reduction in the number of cell organelles, swollen, vacuolated and condensed mitochondria, dilated rough endoplasmic reticulum, and reduced numbers of smooth enodplasmic reticulum, peroxisomes and lysosomes at the lethal (4.0 μg L^?1) concentration. At the sublethal (0.4 μg L^?1) concentration, cytoplasmic vacuolation, condensed, vacuolated and swollen mitochondria, dilated rough endoplasmic reticulum and an absence of hepatocyte microvilli were prominent. Ultrastructural changes were exhibited as subcellular responses due to the imbalance in cellular oxidative status by means of oxidative damage.     

Cloud point extraction of trace cyanide from environmental waters for indirect flame atomic absorption spectrometric determination

A method has been developed for indirect determination of cyanide in environmental waters based on cloud point extraction (CPE), preconcentration and determination by flame atomic absorption spectrometry (FAAS). The method was based on reduction of Cu(II) to Cu(I) in the presence of cyanide and complexation of the produced Cu(I)(CN)₂^? with gallocyanin (GC⁺) as an ion-pairing reagent at pH 4.0, followed by its extraction into polyethyleneglycol mono-p-nonylphenylether (Ponpe 7.5). Selectivity was improved with the use of suitable masking agents. Various factors influencing separation and preconcentration of cyanide have been investigated, and conditions were optimized, allowing determination of cyanide in the range of up to 1.2 mg L^?1 with a detection limit of 0.00045 mg L^?1. The method has been applied to the determination of cyanide in environmental waters, the results being in agreement with those obtained by a reference method.     

A simple ligandless microextraction method based on ionic liquid for the determination of trace cadmium in water and biological samples

A simple and efficient ionic liquid-based ligandless microextraction method has been developed for preconcentration of cadmium ions (Cd²⁺) as a step prior to its determination by flame atomic absorption spectrometry (FAAS) with a micro-sample introduction system. In this approach, the ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate [C₄mim][PF₆] and ethanol were used as extractant and dispersive solvents to preconcentrate the Cd²⁺ in different waters, acid digested scalp hair, and nail samples. Some analytical parameters influencing the extraction efficiency of Cd²⁺ and its subsequent determination, including pH, IL volume, dispersant solvent volume, sample volume, temperature, incubation time, and matrix effect, were optimized. Under optimal conditions, the limit of detection (LOD), limit of quantification (LOQ), and enhancement factor (EF) were 0.4 μg L^?1, 1.3 μg L^?1, and 50, respectively. The relative standard deviation (RSD) of 100 μgL^?1 Cd²⁺ was 4.3% (n = 6). The validity of the proposed method was checked by determining Cd²⁺ in certified reference material (TM-25.3 fortified water) and standard addition; the results showed sufficient recovery (>98%) of Cd²⁺ within the certified value. The method was applied for preconcentration and determination of cadmium in waters and biological samples.     

Evaluation of the toxicity of tetrabromobisphenol A and some of its oxidation products using a micro-scale algal growth inhibition test

A micro-scale algal growth inhibition (μ-AGI) test using a common micro-plate based fluorometric detection was used to demonstrate the effects of humic substances (HSs) on the toxicity of tetrabromobisphenol A (TBBPA) and its oxidative decomposition products 2,5-dibromo-1,4-benzoquinone (2,5-DBBQ), 2,5-dibromohydroquinone (2,5-DBHQ), 2,6-dibromobenzoquinone (2,6-DBBQ), and 2,6-dibromophenol (2,6-DBP) to Pseudokirchneriella subcapitata. The EC₅₀ values were: EC_50(TBBPA) = 7 mg L^?1, EC_50(2,5-DBHQ) = 7 mg L^?1, EC_50(2,5-DBBQ) = 19 mg L^?1, EC_50(2,6-DBP) = 49 mg L^?1, and EC_50(2,6-DBBQ) = 13 mg L^?1. The toxicity of the chemicals was slightly lower in the presence of HA. The toxicity of TBBPA decomposed by a biomimetic catalytic system consisting of iron (III) 5,10,15,20-tetrakis (p-sulfonatophenyl) porphyrin (Fe(III)-TPPS) and KHSO₅ was also evaluated using P. subcapitata and Chlamydomonas reinhardtii.     

Mercury pollution in the Sonbhadra district of Uttar Pradesh,India, and its health impacts

The Sonbhadra district in the Singrauli area of Uttar Pradesh, India, has many coal mines and thermal power plants and is a critically polluted area. Many residents of this area reported adverse health conditions which may be linked to metal pollution, especially of mercury investigated here.

In May 2012, samples of water (23), soil (7), blood, hair, and nails from persons showing adverse health conditions selected at random were collected and analyzed for total mercury by atomic absorption spectrometry.

Twenty percent drinking water samples contained mercury from 3 to 26 μg L^?1 (3–26 times the permissible limit). Soil samples had 0.5–10.1 mg kg^?1 Hg.

The average concentrations of mercury in human blood, hair, and nails were found to be 34 μg L^?1, 7.4 mg kg^?1, and 0.8 mg kg^?1, respectively. Mercury concentrations in the blood of these persons were 45 and 28 μg L^?1 on average in the case of men and women. This is much higher than the safe level of 5.8 μg L^?1 set by the United States Environmental Protection Agency (USEPA).

It was concluded that all residents of Sonbhadra sampled could be suffering from mercury toxicity as the area is polluted by Hg released from the coal-fired thermal power plants.     

Photosynthetic and growth responses of Japanese sasabamo (Potamogeton wrightii Morong) under different photoperiods and nutrient conditions

Controlled laboratory experiments were conducted to examine how photosynthesis and growth occur in Potamogeton wrightii Morong under different photoperiods and nutrient conditions. The experiment was based on a 3×2 factorial design with three photoperiods (16, 12 and 8 h) of 200 μE · m^?2·s^?1 irradiance and two nutrient conditions, high (90 μmol N · L^?1·d^?1 and 9 μmol P · L^?1·d^?1) and low (30 μmol N L^?1·d^?1 and 3 μmol P · L^?1·d^?1). After 14, 28, 56 and 70 days of growth, plants were harvested to determine net photosynthesis rate and various growth parameters. Above- and below-ground biomass were investigated on days 56 and 70 only. Plants under low nutrient conditions had greater leaf area, more chlorophyll a, a higher rate of net photosynthesis and accumulated more above- and below-ground biomass than plants in the high nutrient condition. Plants with an 8 h photoperiod in the low nutrient condition had a significantly higher rate of net photosynthesis, whereas 8 h photoperiod plants in the high nutrient condition had a lower rate of net photosynthesis and their photosynthetic capacity collapsed on day 70. We conclude that P. wrightii has the photosynthetic plasticity to overcome the effects of a shorter photoperiod under a tolerable nutrient state.     

Concentrations of uranium in drinking water and cumulative,age-dependent radiation doses in four districts of Uttar Pradesh,India

The present work deals with the determination of uranium concentrations in drinking and ground water samples by laser fluorimetry and calculation of cumulative, age-dependent radiation doses to humans. The concentrations were found to be between 0.20 ± 0.03 and 64.0 ± 3.6 μg L^?1, with an average of 11.1 ± 1.5 μg L^?1, well within the drinking water limit of regulatory bodies. The concentrations of uranium increase with depth of water samples collection. The estimated annual ingestion dose due to the intake of uranium through drinking water for all age groups varied between 0.2 and 137 μSv a^?1, with an average of 17.3 μSv a^?1. The mean annual ingestion dose is 5% of the global average ingestion dose, for infants, marginally higher than for other age group. Most effective dose values were less than 20 μSv a^?1.     

Seasonal variations in physicochemical characteristics and cyanobacterial diversity of a lake in Northern India

Physicochemical analyses and cyanobacterial diversity of Ramgarh Lake water were performed at five sampling sites during winter, summer, and monsoon seasons. Higher load of solids, carbon, and nutrients were persistent throughout the analysis that indicates the conversion of lake from oligotrophic to eutrophic nature. High nutrients load enhanced cyanobacterial biomass, while low nutrients load produced relatively less biomass. The physicochemical parameters of water samples revealed minimum 2.9 mg L^?1 dissolved oxygen (DO) at site-1 during summer, while maximum (5.6 mg L^?1) at site-4 in monsoon season. Maximum biochemical oxygen demand (BOD) (40 mg L^?1) and chemical oxygen demand (COD) (126 mg L^?1) were recorded at site-1 during summer, whereas minimum BOD (18 mg L^?1) and COD (52 mg L^?1) were evident at site-3 in monsoon season. Minimum concentration of nitrate (0.72 mg L^?1) was recorded at site-3 in summer, whereas maximum 2.7 mg L^?1 was present at site-5 in winter season. The phosphate concentration was maximum (0.52 mg L^?1) at site-5 in summer, and minimum (0.18 mg L^?1) was observed at site-4 in monsoon season. Cyanobacterial diversity was higher during all the seasons, and dominated by the species of Microcystis at all the five sampling sites.     

Formation of resistance in the Chironomus plumosus to four pesticides over 45 generations

A study was conducted on the Chironomus plumosus larvae to determine initiation of resistance to four pesticides – chlorfenvinphos, chlorpyrifos, chlorpyrifos-methyl, and malathion. First generational LC₅₀ values were well within the threshold value for chironomids based upon the literature. Subsequent LC₅₀ values were observed to increase, indicating a lessening of the toxicity of the pesticides to the chironomid. In the case of chlorfenvinphos, the 96 h LC₅₀ for generations 1–23 was 6 µg L^?1, in generations 3–7 was 8.57 µg L^?1 and 11.14 µg L^?1 for generations 8–9. Generations 10–12 had an LC₅₀ value of 22.58 µg L^?1 and generation 13 had an LC₅₀ value of 35.08 µg L^?1. Generation 14 had an LC₅₀ value of 47.58 µg L^?1. Generations 15–19 and 20–24 had 96 h LC₅₀ values of 60.68 µg L^?1, 72.58 µg L^?1, 85.08 µg L^?1, 97.58 µg L^?1 and 110.08 µg L^?1, respectively. Generations 25, 26 to 30, 31 to 38 and 39 to 45 had 96 h LC₅₀ values of 160.42 µg L^?1, 210.7 µg L^?1, 262.24 µg L^?1 and 274.36 µg L^?1, respectively. The variation between LC₅₀ values was found to be statistically significant. This was observed for most pesticides tested. Larval size and life cycle duration was observed to change from generation to generation with the body size decreasing markedly from 1 to 0.3 cm with life cycle increasing from 7 to 39 days.     

Biosolids application affects the competitive sorption and lability of cadmium,copper, nickel,lead, and zinc in fluvial and calcareous soils

The objective of this research was to investigate the effects of biosolids on the competitive sorption and lability of the sorbed Cd, Cu, Ni, Pb, and Zn in fluvial and calcareous soils. Competitive sorption isotherms were developed, and the lability of these metals was estimated by DTPA extraction following their sorption. Sorption of all metals was higher in the fluvial than in the calcareous soil. Sorption of Cu and Pb was stronger than that of Cd, Ni, and Zn in all soils. Biosolids application (2.5%) reduced the sorption of all metals especially Cu and Pb (28–43%) in both soils (especially the calcareous soil) at the lower added metal concentrations (50 and 100 mg L^?1). However, it increased the sorption of all metals especially Pb and Cu in both soils (especially the calcareous soil; 15.5-fold for Cu) at the higher added concentrations (250 and 300 mg L^?1). Nickel showed the highest lability followed by Cd, Zn, and Pb in both soils. Biosolids increased the lability of the sorbed Ni in the fluvial soils at all added concentrations and the lability of Cd, Pb, and Zn at 50 mg L^?1, but decreased the lability of Cd, Pb, and Zn at 250 and 300 mg L^?1 in both soils. We conclude that at low loading rate (e.g., 50 mg L^?1) biosolids treatment might increase the lability and environmental risk of Cd, Cu, Pb, and Zn. However, at high loading rate (e.g., 300 mg L^?1) biosolids may be used as an immobilizing agent for Cd, Cu, Pb, Zn and mobilizing agent for Ni.     

The evolution of pollution profile and health risk assessment for three groups SVOCs pollutants along with Beijiang River,China

Three important groups of semi-volatile organic compounds (SVOCs), polycyclic aromatic hydrocarbons (PAHs), organic chlorinated pesticides (OCPs) and phthalate esters (PAEs), were produced by various human activities and entered the water body. In this study, the pollution profiles of three species including 16 PAHs, 20 OCPs and 15 PAEs in water along the Beijiang River, China were investigated. The concentrations of Σ₁₆PAHs in the dissolved and particulate phases were obtained as 69–1.5 × 10² ng L^?1 and 2.3 × 10³–8.6 × 10⁴ ng g^?1, respectively. The levels of Σ₂₀OCPs were 23–66 ng L^?1 (dissolved phase) and 19–1.7 × 10³ ng g^?1 (particulate phase). Nevertheless, higher levels of PAEs were found both in the dissolved and particulate phases due to abuse use of plastic products. Furthermore, non-cancer and cancer risks caused by these SVOCs through the ingestion absorption and dermal absorption were also assessed. There was no non-cancer risk existed through two kinds of exposure of them at current levels, whereas certain cancer risk existed through dermal absorption of PAHs in the particulate phase in some sampling sites. The results will show scientific insights into the evaluation of the status of combined pollution in river basins, and the determination of strategies for incident control and pollutant remediation.     

Effect of dye auxiliaries on chemical oxygen demand and colour competitive removal from textile effluents using Posidonia oceanica

The use of an abundant and widely distributed seagrass species, Posidonia oceanica, as a biosorbent for the direct dye Yellow 44 was successfully shown. The studies were performed on the single dyestuff dissolved in water and in a dyebath containing agents commonly used in the textile industry, i.e. a surfactant (Lavotan TBU), a sequestring agent (Meropan DPE), a softening agent (Eurosoft CI10) and a salt (NaCl). The colour reduction results showed that P. oceanica was found to be more efficient for removal of Yellow 44 from an aqueous solution (162 mg g^?1) than from a dyebath solution (135 mg g^?1), according to the Langmuir isotherm model. For the single dyestuff sorption, Fourier transform infrared and X-ray photoelectron spectroscopy studies highlighted chemical sorption between the dye alcohol function and the sorbent acid function. The chemical oxygen demand removal percentages were found to be 54.9 and 76.6% for Yellow 44 dissolved in aqueous solution and in dyebath solution, respectively. This confirmed the both sorption of the chemical auxiliaries and the dye on P. oceanica.     

Green chemistry approach to analysis of formic acid and acetic acid in aquatic environment by headspace water-based liquid-phase microextraction and high-performance liquid chromatography

A simple and totally organic-free (green) method, viz. headspace water-based liquid-phase microextraction combined with high-performance liquid chromatography-ultraviolet detection has been successfully developed for analysis of formic acid and acetic acid in environmental water samples. A microdrop of an aqueous solution of sodium hydroxide was suspended from the tip of a microsyringe needle over the headspace of the stirred sample solution containing the analytes at pH 1.0 for a given time. The microdrop was then retracted into the microsyringe, diluted with HPLC mobile phase, and injected to HPLC. Optimum efficiency has been achieved for: 3.0 µL NaOH microdrop (0.1 mol L^?1) exposed for 15 min over the headspace of an aqueous sample of 6.5 mL at 55 °C, containing 15% w/v of Na₂SO₄, adjusted to pH = 1.0 and stirred at 750 rpm. Under these conditions, enrichment factors of 162 and 187, limits of detection of 0.3 and 0.1 µg L^?1 (S/N = 3) with dynamic linear ranges of 1–500 and 0.5–500 µg L^?1 were obtained for formic acid and acetic acid, respectively. A reasonable repeatability (5.8% ≤ RSD ≤ 8.8%, n = 6) and satisfactory linearity (r² ≥ 0.997) illustrated the performance of the method.     

Solar-induced generation of singlet oxygen and hydroxyl radical in sewage wastewaters

Singlet oxygen (¹O₂) and hydroxyl radical (·OH) play an important role in the degradation of pollutants in surface waters. However, the mechanism underlying the photochemical generation of ¹O₂ and ·OH in wastewaters is poorly known. Here we studied the photo-induced generation of ¹O₂ and ·OH in different sewage treatment plant units. The correlation between the generation of ¹O₂ and ·OH and the water constituents was discussed. Our results show that in sewage units the ¹O₂ formation rate ranges from 2.19 × 10^?8 to 6.74 × 10^?8 mol L^?1 s^?1, and the ·OH formation rate ranges from 1.7 × 10^?11 to 3.06 × 10^?10 mol L^?1 s^?1. The average ¹O₂ formation rates in the various sewage units are similar to those in wetland and estuarine waters containing rich dissolved organic matter and 2–4 times higher than those in lake and seawater samples. The average ·OH formation rates of the sewage units are 5–50 times higher than for other water samples reported. The ·OH generation rate increased with the iron content with a correlation coefficient of 0.85, which indicates that the photo-Fenton reaction plays a dominant role in ·OH generation in sewage wastewater.     

Determination of cobalt by air-assisted liquid–liquid microextraction

Abstract

A rapid and selective technique for extraction, preconcentration and determination of trace amounts of cobalt in water and pharmaceutical samples by air-assisted liquid–liquid microextraction combined with flame atomic absorption spectrometry is proposed. 1-Nitroso-2-naphthol is used as a complexing agent and 1-octanol as an extraction solvent. Parameters relevant for analytical effectivity, i.e. pH of sample solution, concentration of complexing agent, volume of extraction solvent, and number of extraction cycles are optimized using a Box–Behnken design. At optimum conditions, a dynamic linear range of 5–600?µg L^?1 is obtained, with a limit of detection of 1.2?µg L^?1. The method is used for determination of Co(II) in environmental water and pharmaceutical samples.     

Spatial distribution of copper in relation to recreational boating in a California shallow-water basin

The overall effect of the number of boats on the copper (Cu) levels in the water column and sediment, along with their spatial variability within Shelter Island Yacht Basin (SIYB), San Diego Bay, California was examined. We identified a horizontal gradient of increasing dissolved Cu and Cu in sediment from outside to the head of SIYB which was coincident with the increasing number of boats. Spatial models of Cu distribution in water and sediment indicated the presence of ‘hotspots’ of Cu concentration. From outside to the head of SIYB, dissolved Cu ranged from 1.3 μ g L^?1 to 14.6 μ g L^?1 in surface water, and 2.0 μ g L^?1 to 10.2 μ g L^?1 in bottom water. Cu in sediment exceeded the Effect Range Low of 34 mg kg^?1 (i.e. where adverse effects to fauna may occur), with a peak concentration of 442 mg kg^?1 at the head of the basin. Free Cu⁺⁺ in surface water was several orders of magnitude higher than in sediment porewater. High-resolution data of Cu species together with probability maps presented in this paper will allow managers to easily visualise and localise areas of impaired quality and to prioritise which areas should be targeted to improve Cu-related conditions.     

Population health risk via dietary exposure to trace elements (Cu,Zn, Pb,Cd, Hg,and As) in Qiqihar,Northeastern China

The estimated daily intakes (EDIs) of six trace elements (Cu, Zn, Pb, Cd, Hg, and As) in vegetables (leafy vegetable, i.e., bok choy, fruit vegetables, i.e., cucumber and tomato, and other categories, i.e., mushroom, kidney bean, and potato), cereals (rice and wheat flour), and meats (pork, mutton, and beef) most commonly consumed by adult inhabitants of Qiqihar, Northeastern China, were determined to assess the health status of local people. The average EDIs of Cu, Zn, Pb, Cd, Hg, and As were with 20.77 μg (kg bw)^?1 day^?1 of Cu, 288 μg (kg bw)^?1 day^?1 of Zn, 2.01 μg (kg bw)^?1 day^?1 of Pb, 0.41 μg (kg bw)^?1 day^?1 of Cd, 0.01 μg (kg bw)^?1 day^?1 of Hg, and 0.52 μg (kg bw)^?1 day^?1 of As, respectively, which are below the daily allowance recommended by FAO/WHO. However, the maximum EDIs of Pb and Cd were 4.56 μg (kg bw)^?1 day^?1 and 1.68 μg (kg bw)^?1 day^?1, respectively, which are above the recommended levels [i.e., 3.58 μg (kg bw)^?1 day^?1 for Pb and 1.0 μg (kg bw)^?1 day^?1 for Cd] by FAO/WHO. This finding indicates that the potential health risk induced by daily ingestion of Pb and Cd for the local residents should receive a significant concern. Similarly, we detected elevated Pb and Cd concentrations, i.e., with average of 13.58 and 0.60 mg kg^?1 dw, respectively, in the adult scalp hairs. Consumption of rice, potato, bok choy, and wheat flour contributed to 75 and 82% of Pb and Cd daily intake from foodstuffs. Nevertheless, human scalp hair is inappropriate biological material for determination of the nutritional status of trace elements in this region.     

Spectrophotometric and HPLC method for quantification of Loratadine on swabs for cleaning validation

Cleaning validation is a major challenge in multi-product pharmaceutical industries. UV spectrophotometric and HPLC methods have been developed and validated for determination of residual amount of Loratadine. Both methods were validated for linearity, range, accuracy, precision, and robustness. The limit of quantification was 1 mg L^?1 by UV spectrophotometric method and 0.5 mg L^?1 by HPLC method. A spike recovery study was done on a stainless steel (316 grade) plate and specific residual cleaning level (SRCL) was down to 6 μg 25.8 cm^?2. Recovery was found to be more than 70%. Both methods were simple, highly sensitive, precise, and accurate, and have potential of being useful for routine quality control.