Determination Of Arsenic Research Articles

Nano-Coral Gold (NCG) Electrode for Electrochemical Determination of Arsenic (III) in Industrial Wastewater by Square Wave Anodic Stripping Voltammetry (SWASV)

The motivation of this work is to develop a simple method for the on-site detection of total arsenic at the ppb level. For this purpose, novel nano-coral gold (NCG) was fabricated using NH4Br to lead the growth of Au along a definite direction on a gold substrate. Square wave anodic stripping voltammetry (SWASV) was used for the determination of arsenic in industrial water with a NCG working electrode. Due to the high specific surface area and nano-structure of the nano-coral gold, high sensitivity was achieved with a limit of detection (LOD) of 0.4 ppb. 3.2 ppb arsenic was determined in industrial water. The detectable arsenic concentration is far below the regulatory limit of 10 ppb by the World Health Organization (WHO). Across the As (III) linear range from 2.5 to 100 ppb, the sensor response is stable, reproducible, and linear with concentration.

Magnetically induced catalytic electrooxidation of As(III) on GC modified Fe@Cu-BTC MOF nanoparticles: Application for determination of As(III)

Here, an ultrasensitive multilateral electrochemical determination of arsenic (III) was performed using Fe3O4@Cu-BTC nanoparticles grafted on a glassy carbon electrode coupled with a magnet. The Fe3O4@Cu-BTC surface-modified glassy carbon electrode shows excellent catalytic activity toward electrooxidation of As(III). Magnetic attachment of Fe3O4@Cu-BTC on the surface of the glassy carbon electrode improved stability, electrical connection, and reduced the charge transfer resistance dramatically. Multilateral functionality of the proposed sensing procedure was checked out using impedance spectroscopy, cyclic voltammetry, differential pulse voltammetry, and amperometry. Under the optimal conditions, the constructed sensing platform showed a wide linear range from 1 to 80 ppb with the detection limit of 0.11 ppb (S/N ratio of 3) for As(III) detection. The designed surface-modified glassy carbon electrode exhibits a highly sensitive and selective sensing platform for the detection of As(III). The applicability of the designed electrochemical sensor for real samples showed the high ability of the proposed electrochemical platform for real water samples.

Determination of arsenic, cadmium, mercury, lead and nickel as elemental impurities in atorvastatin calcium by inductively coupled mass spectrometer.

Atorvastatin calcium is employed as front-line treatment for cardiovascular diseases. According to the international conference on harmonization (ICH) guideline ICH Q3D, elemental impurities can come into drug products from various sources. These elemental impurities do not have any therapeutic benefit to the end-user. On the contrary, it harms the normal physiological system. Class 1 elements like arsenic, cadmium, mercury, and lead are inorganic impurities that can cause toxic effects on the human body. Nickel was used as a catalyst during the synthesis process of atorvastatin calcium. It comes under the Class-2A, can cause toxicity to humans, and must be quantified. A simple, fast, reliable inductively coupled plasma mass spectrometric method for the estimation of elemental impurities like arsenic, cadmium, mercury, lead, and nickel in atorvastatin calcium by open sample digestion technique was developed and validated in accordance with ICH Q3D and USP < 232 > and USP <233 > general chapter. Internal standards like indium, terbium, thallium, bismuth and yttrium were used to correct the non-spectral interferences that were generated during analysis. Gold was added to all solutions as it preserves mercury by amalgamation. The system performance was evaluated every time my performing system suitability parameters. The limits for all the elements were fixed in accordance with ICH Q3D. The limit of detection and the limit of quantification for all the five elements were estimated. Method specificity was proven by checking for interferences due to the sample matrix and other elements. Linearity of each element in standards was established from 25% to 200% of sample concentration, and correlation coefficients were found to be not less than 0.999. The accuracy of the method was demonstrated at three spiking levels at 50%, 100%, and 150% of the J-value for all the elements. The recoveries for all elements at each level were within the range of 90-120%. Method precision was proved at 100% J-value. The relative standard deviation of all elements was less than 5%. It concludes that this newly developed and validated reliable inductively coupled plasma mass spectrometric method for estimating of elemental impurities like arsenic, cadmium, mercury, lead, and nickel in atorvastatin calcium was within the permitted limit and suitable for routine use.

Development and Validation of Procedures for Determination of Elemental Toxicants in Herbal Substances and Herbal Medicinal Products

When the approach to quality control of herbal substances (HSs) and herbal medicinal products (HMPs) changed from determination of the total content of heavy metals by calorimetry to selective determination by spectrometric techniques, many manufacturers of such products failed to meet the new requirements in their registration dossiers. Test procedures submitted by manufacturers often need to be clarified, and validation protocols often lack data.The aim of the study was to provide recommendations to HS and HMP manufacturers on the choice of test methods, materials, reagents, methods of organic matrix mineralisation, and main validation parameters, as well as recommendations on validation of the procedure for elemental toxicants determination, and preparation of the “Heavy metals and arsenic” part of the regulatory submission.Materials and methods: the study included analysis and systematisation of scientific literature, requirements of the Russian and foreign pharmacopoeias, guidelines, manuals on instrumental methods of analysis, and first-hand experience in elemental analysis of various types of HSs and HMPs.Results: the authors formulated recommendations on the choice of sample mineralisation conditions for quantification of elemental impurities in biological products, and substantiated requirements for the reagents, materials, and equipment. The paper compares different methods of elemental analysis. It was demonstrated that the main mistakes made by manufacturers stem from disregard to the organic matrix effect on the measurement results and lack of agreement between the impurity concentration being determined and the range of the calibration curve used. The paper gives acceptance criteria for validation parameters of test procedures for heavy metals and arsenic determination in HSs and HMPs.Conclusions: it is not correct to use reference standards containing heavy metals as inorganic salts not bound to organic compounds, for HS and HMP analysis. The criteria given in the European Pharmacopoeia and the United State Pharmacopoeia can be used for a number of validation parameters, when they are not included in the Russian Pharmacopoeia.

Determination of Total Arsenic, Soluble Arsenic, Total Mercury and Soluble Mercury for a Realgar and Cinnabar-containing Traditional Chinese Medicine Compound Niuhuang Xiaoyan Capsule by Semi-bionic Extraction- ICP-MS

Background:: Compound Niuhuang Xiaoyan capsule is a realgar and cinnabar-containing traditional Chinese medicine, the contents of total arsenic and total mercury are found over regulation defined limits. However, only a small amount of arsenic in realgar and mercury in cinnabar are dissolved in the gastric juice, so the determination of soluble arsenic and soluble mercury is more significant than that of total arsenic and total mercury in Compound Niuhuang Xiaoyan capsule. Objective: : To study the contents of total arsenic, total mercury, soluble arsenic and soluble mercury in Compound Niuhuang Xiaoyan capsule. Method:: Microwave digestion and semi-bionic extraction were used to pretreat the samples of Compound Niuhuang Xiaoyan capsule, and the inductively coupled plasma mass spectrometry method was established to determine the contents of total arsenic, total mercury, soluble arsenic and soluble mercury in Compound Niuhuang Xiaoyan capsule. The accuracy of the established method was further evaluated by using a certified standard reference material prepared from dried citrus leaves (GBW10020(GSB-11)). Results: : The spiked recoveries were within 95-105 %. The R.S.D% of repeatability (N=6) and precision (N = 6) were below 5.0 %. The correlation coefficients of linear (R) for arsenic and mercury were both above 0.998. The limits of quantification (LOQ) were below 0.1 μg/L. The contents of As and Hg were defined in the dried citrus leaves and very near to the standard values provided by the manufacturer. The established method was applied to the analysis of three batches of Compound Niuhuang Xiaoyan capsule produced by three different manufacturers successfully. Insufficient realgar or cinnabar was formulated in some Compound Niuhuang Xiaoyan capsule samples. Conclusion: : The analysis showed that the contents of soluble arsenic and soluble mercury in artificial gastric juice were significantly less than that of total arsenic and total mercury in Compound Niuhuang Xiaoyan capsule. The results provided a reference for further study on the toxicology and pharmacokinetics of Compound Niuhuang Xiaoyan capsule.

Low-cost electrochemical detection of arsenic in the groundwater of Guanajuato state, central Mexico using an open-source potentiostat.

Arsenic is a carcinogenic groundwater contaminant that is toxic even at the parts-per-billion (ppb) level and its on-site determination remains challenging. Colorimetric test strips, though cheap and widely used, often fail to give reliable quantitative data. On the other hand, electrochemical detection is sensitive and accurate but considerably more expensive at the onset. Here, we present a study on arsenic detection in groundwater using a low-cost, open-source potentiostat based on Arduino technology. We tested different types of gold electrodes (screen-printed and microwire) with anodic stripping voltammetry (ASV), achieving low detection limits (0.7 μg L-1). In a study of arsenic contaminated groundwaters in Mexico, the microwire technique provides greater accuracy than test strips (reducing the median error from -50% to +2.9%) and greater precision (reducing uncertainties from ±25% to ±4.9%). Most importantly, the rate of false negatives versus the World Health Organisation’s 10 μg L-1 limit was reduced from 50% to 0% (N = 13 samples). Arsenic determination using open-source potentiostats may offer a low-cost option for research groups and NGOs wishing to perform arsenic analysis in-house, yielding superior quantitative data than the more widely used colorimetric test strips.

Simple and reliable determination of total arsenic and its species in seafood by ICP-MS and HPLC-ICP-MS

Quantitative, rapid, selective and sensitive methods for the determination of total arsenic (tAs) and six arsenic compounds (arsenite (As(III)), arsenate (As(V)), arsenobetaine (AsB), arsenocholine (AsC), monomethylarsonic acid (MMA), dimethylarsonic acid (DMA)) in seafood were developed. The measurement of the tAs concentration was performed using quadrupole inductively-coupled plasma mass spectrometry (ICP-MS). Microwave-assisted extraction was used for the isolation of arsenic species. The separation and quantification of analysed compounds were performed by ion-exchange chromatography coupled with ICP-MS in one chromatographic run using ammonium carbonate-based buffers, which has little effect on ICP-MS sensitivity compared to commonly used phosphate buffers. The results of validation and proficiency tests confirmed the reliability, robustness, and applicability of the developed procedures to various types of matrices. The proposed methods are relatively simple, time- and cost-efficient, therefore could be used to routinely analyse tAs content and arsenic species in different types of seafood at trace and ultra-trace levels.

An application of miniaturized electrochemical sensing for determination of arsenic in herbal medicines.

This study aimed to create a miniaturized electrochemical platform for detecting As(III) contamination in herbal medicines. To reduce the operational steps of modification and determination, only a single drop of mixed standard Au(III) and sample solution is proposed to perform the electrochemical measurements using a screen-printed graphene electrode (SPGE). Square wave anodic stripping voltammetry was employed to integrate the simultaneous modification and determination processes. To perform the measurement, As(III) and Au(III) migrate to the SPGE surface while the reduction potential is held at -0.5 V, forming an Au-As intermetallic alloy. Then, As is stripped off for the electrochemical determination of As(III). The total assay time is less than 3 min. Under suitable conditions, the electrochemical sensing system can detect As(III) at concentrations ranging from 0.1 to 3.0 ppm, with a limit of quantification and limit of detection of 0.1 and 0.03 ppm, respectively. The applicability and accuracy of the proposed sensor were verified by determining As(III) in herbal medicinal samples, and they were found to be in line with the standard method (ICP-OES). The benefits of simple operation, rapid detection, portability, and low cost (<1 USD) make this a more powerful tool for routine monitoring and on-site analysis applications.

The effect of a complex fortified preparation on the quality indicators of broiler chicken meat

The article presents the results of the conducted studies on the effect of the complex fortified preparation "Nitamin" on the quality indicators of meat of broiler chickens of the Cobb-500 cross. The preparation was administered with drinking water at a dose of 1 ml per 1 liter of drinking water, according to the scheme from 2 day to 5 day of keeping and from 15 to 18 day, poultry slaughter was carried out on 42 day of keeping. The composition of the preparation includes vitamins A; D3; E; trace elements organic iodine and selenium. The research material was the muscle tissue of broiler chickens of the studied groups, according to generally accepted methods, the content of amino acid composition and trace elements of selenium and iron was determined according to GOST R 55569-2013 Feed, compound feed, compound feed raw materials. Determination of proteinogenic amino acids by capillary electrophoresis, GOST 31707-2012 (EN 14627:2005) Trace element food products. Determination of total arsenic and selenium by atomic absorption spectrometry with generation of hydrides with preliminary mineralization of the sample under pressure and GOST 30178-96 Raw materials and food products. Atomic absorption method for the determination of toxic elements. According to the results obtained, the meat of broiler chickens treated with Nitamin was superior in amino acid composition to the meat of broiler chickens of the control group (essential amino acids by 14.38%, nonessential amino acids by 10.9%). When studying the content of trace elements in the muscle tissue of broiler chickens treated with Nitamin, an increase in the iron content of 10 mg/kg was noted, no iron was found in the muscle tissue of broiler chickens of the control group.

Gold nanoparticles/over-oxidized poly-eriochrome black T film modified electrode for determination of arsenic.

A glassy carbon electrode, modified with gold nanoparticles/over-oxidized poly-eriochrome black T film, was fabricated for sensitive determination of As(III) by stripping voltammetry in an acidic medium. The electrode surface properties were characterized by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). The electrode demonstrated a good response towards As(III), with a detection of 0.077 μM and good linearity in the range of 0.1 to 10 μM (R2 = 0.9977). For the determination of As(III), the fabricated electrode was placed in different mineral water samples, acidified with 0.75 M HCl solution, spiked with various concentrations of As(III). Spiked recoveries for mineral water samples were obtained in the range of 100.3%-105.0%. The relative standard deviations were lower than 4.0%.

Ultratrace determination of arsenic by hydride generation atomic absorption spectrometry with preconcentration on gold nanoparticles

A fast and simple preconcentration step was developed for ultratrace arsenic determination after hydride generation.

A flexible and disposable electrochemical sensor for the evaluation of arsenic levels: A new and efficient method for the batch fabrication of chemically modified electrodes

In this study, a novel flexible and disposable electrochemical sensor was fabricated through the straightforward laser-induced synthesis of catalytic Au nanoparticles (AuNPs)@LIG composite for the square wave stripping voltammetry (SWASV) determination of arsenic in soil. In this process, polyimide and a metal precursor (PI-MP) were transformed to three-dimensional porous LIG and AuNPs through the graphitization, photoreduction and thermal reduction of laser ablation. To our knowledge, this is the first time that laser-induced PI-MP was employed to fabricate chemically modified electrodes on a large scale for arsenic determination. X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectrometer (EDX), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and N2 adsorption isotherm were used to characterize the morphological and physical properties of the materials, which demonstrated the successful synthesis of AuNPs@LIG nanocomposite. Additionally, the mechanism of AuNPs@LIG synthesis by laser induction was also investigated, and the deposition potential and the deposition time for the SWASV determination of arsenic were also optimized. The electrochemical sensor fabricated using the proposed method shows satisfactory sensitivity, stability and reliability and exhibits a good linear relationship over concentrations ranging from 0 to 40 μg/L, with a low determination limit of 0.18 μg/L. Furthermore, the obtained AuNPs@LIG surface exhibited good conductivity with a charge transfer resistance (Rct) of 73.85 Ω and a large real surface area of 807.28 mm2. Finally, several real soil samples were analyzed using the prepared sensor with a satisfactory result, which verified the feasibility of this sensor. The results show that the method for chemically modified electrode fabrication proposed in this paper has good commercial potential for the batch manufacturing of electrochemical sensors.

Determination of arsenic, cadmium, selenium, zinc and other trace elements in Bangladeshi fish and arsenic speciation study of Hilsa fish flesh and eggs: Implications for dietary intake

Exposure to As from drinking water and its impact on the health of the Bangladeshi population has received much attention. However, very little information is available regarding As exposure through consumption of fish, which is the main source of animal protein for the majority of Bangladeshis. In this study, concentrations of As, Cd, Pb, Mn Se and Zn in different types of fish, consumed by Bangladeshis, were determined using Inductively Coupled Plasma Mass Spectrometry. Daily intakes of the toxic elements As, Cd and Pb through fish consumption were estimated to be 31.8, 0.4 and 4.8 μg/day, respectively. Hilsa (Tenualosa ilisha) contained the highest concentrations of total As (mean ± SD was 2.55 ± 1.3 mg/kg; n = 15) among the fish analysed. However, toxic inorganic As species were not detected. The dominant As species in Hilsa fish were: dimethylarsenic acid, arsenobetaine and arsenosugars, at 69, 11 and 20% of total As, respectively. The high concentration of Cd detected in Hilsa eggs (average 278 ± 518 μg/kg; range 7.4–1725 μg/kg; n = 10) is of concern since this may have harmful effects on the development of embryos and lead to a decline in the Hilsa population or the quality of the fish. It can also be harmful to those who consume Hilsa eggs on a regular basis. Selenium was found to be highest in Shoal (Micropterus cataractae) fish and a type of small fish, and lowest in Mrigal (Cirrhinus cirrhosis). Small fish species contained Mn and Zn at 7.1- and 4.3-fold higher concentrations, respectively, compared to big fish species. Keski (Corica soborna), a small fish species, contained by far the highest concentrations of Mn (52 mg/kg) and Zn (140 mg/kg), although the concentration of As (1.4 mg/kg) in this fish was lower than that of several other fish species. Small fish species are often consumed whole, including the bones, and therefore the essential trace elements present are potentially bioavailable for cellular metabolism. Our study shows that the Bangladeshi population can easily meet their daily requirement of Se and Zn from consumption of fish such as Shoal fish (Se and Zn), Hilsa fish (Se and Zn) and Keski fish (Se and Zn). Consumption of small fish (such as Keski) and big fish (such as Hilsa) from Bangladesh can provide valuable sources of essential trace elements as part of a balanced diet and thus negate the need for supplements and biofortification of certain foods. Ours is a small study and a detailed total dietary intake and human biomonitoring studies, that includes coverage of different socio-economic groups, are needed in Bangladesh before giving people supplements or biofortified foods.

Ultrasensitive determination and non-chromatographic speciation of inorganic arsenic in foods and water by photochemical vapor generation-ICPMS using CdS/MIL-100(Fe) as adsorbent and photocatalyst

The determination of inorganic arsenic species in real samples can be particularly challenging due to their trace levels and the interferences arising from sample matrix. Normally, the speciation analysis necessitates chromatographic separation. Herein, we report a novel method for the ultrasensitive detection and non-chromatographic speciation of inorganic arsenic by inductively coupled plasma mass spectrometry (ICP-MS), utilizing CdS/MIL-100(Fe) composites as an adsorbent and photocatalyst. The synthesized CdS/MIL-100(Fe) could completely adsorb As(V) and As(III) within 5 and 105 min, respectively. Following filtration and re-suspension in formic acid, the adsorbed As(III)/As(V) were reduced to arsine (AsH3) under UV irradiation and swept to ICP-MS for detection. The limits of detection were found to be 1.7 ng L−1 (without preconcentration) and 0.11 ng L−1 (after 20-fold preconcentration). The method was successfully applied to the determination of trace inorganic arsenic in various food and water samples.

Validation of an analytical method for the determination of inorganic, organic, and total arsenic in fish sauce based on hydride generation atomic absorption spectrometry

An atomic absorption spectrometric (AAS) method was performed to determine the total, inorganic, and organic arsenic in fish sauce. The total organic arsenic was calculated from the total and inorganic arsenic values quantified using the hydride generation AAS (HG-AAS). Under optimal experimental conditions at the absorbance wavelength of 193.7 nm, the concentration of inorganic arsenic in fish sauce ranged from 0.05 to 1.2 mg/L, with a limit of detection (LOD) of 0.015 mg/L. The detectable total arsenic concentrations varied widely, ranging from 0.03 to 2.5 mg/L with the LOD of as low as 0.01 mg/L. The practical applicability of the method was demonstrated with the recovery in the range from 97 to 102% for inorganic arsenic, and 97 to 101% for organic arsenic. The method was applied to the analysis of commercial products from Nha Trang, Phan Thiet, and Phu Quoc City, Vietnam. The total organic arsenic in fish sauce samples determined by HG-AAS was compared with the results of liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP/MS). The f-test and t-test showed null hypothesis for acceptable variance and mean at a confidence level of 95%. The results showed that the HG-AAS method had high efficiency, accuracy, and sensitivity in quantifying inorganic and total organic arsenic in fish sauce using simple instrumentation.

Determination of Arsenic in Soil by Ultrasonic Assisted Slurry Sampling Hydride Generation (HG) in-Situ Dielectric Barrier Discharge Trap (DBD)-Optical Emission Spectrometry (OES)

An ultrasonic assisted slurry sampling procedure was coupled with hydride generation in-situ dielectric barrier discharge trap optical emission spectrometry (HG-in situ DBD trap-OES) to provide the simple and fast determination of arsenic in soil. The soil was treated HNO3 and HF in an ultrasonic bath for 25 min, subsequently diluted with 6% HCl (v/v) and 40 g L−1 thiourea, and placed into the ultrasonic bath again for 10 min to obtain a stable and homogeneous slurry that was introduced to HG-in-situ DBD trap-OES for As determination. Under the optimal conditions, the calibration coefficient exceeded 0.995 from 2 μg L−1 to 200 μg L−1. A method detection limit of 0.18 mg kg−1 was achieved for As in soil (250 times dilution) with a 3.4% relative standard deviation. The developed method was validated by the determination of As in three soil certified reference materials including GBW07430 (As, 18 ± 2 mg kg−1), GBW07447 (As, 10.7 ± 0.5 mg kg−1), and GBW07449 (As, 8.7 ± 0.6 mg kg−1), as well as two real soil samples. The results agreed well with the certified values and the measurements by inductively coupled plasma – mass spectrometry. With advantages of simple pretreatment procedures, small size/weight, low power consumption, and low manufacturing cost, the developed method has the potential to be widely applied in soil analysis.

Novel Dielectric Barrier Discharge Trap for Arsenic Introduced by Electrothermal Vaporization: Possible Mechanism and Its Application.

In this work, a novel integrated dielectric barrier discharge (IDBD) reactor coupled to an electrothermal vaporizer (ETV) was established for arsenic determination. It is for the first time gas-phase enrichment (GPE) was fulfilled based on the hyphenation of ETV and DBD. The mechanisms of evolution of arsenic atomic and molecular species during vaporization, transportation, trapping, and release processes were investigated via X-ray photoelectron spectroscopy (XPS) and other approaches. Tentative mechanisms were deduced as follows: the newly designed DBD atomizer (DBDA) tube upstream to the air inlet fulfills the atomization of arsenic nanoparticles in vaporized aerosol, leading to free arsenic atoms that are indispensable for forming arsenic oxides; the DBD trap (DBDT) tube traps arsenic oxides under an O2-domininating atmosphere and then releases arsenic atoms under H2-dominating atmospheres. In essence, this process is a physical-chemical process rather than an electrostatic particle deposition. Such a trap and release sequence separates matrix interference and enhances analytical sensitivity. Under the optimized conditions, the method detection limit (LOD) was 0.04 mg/kg and the relative standard deviations (RSDs) were within 6% for As standard solution and real seafood samples, indicating adequate analytical sensitivity and precision. The mean spiked recoveries for laver, kelp, and Undaria pinnatifida samples were 95-110%, and the results of the certified reference materials (CRMs) were consistent with certified values. This ETV-DBD preconcentration scheme is easy and green and has low cost for As analysis in seafood samples. DBD was proved a novel ETV transportation enhancement and preconcentration technique for arsenic, revealing its potential in rapid arsenic analysis based on direct solid sampling ETV instrumentation.

Noble-metal-free Fe3O4/Co3S4 nanosheets with oxygen vacancies as an efficient electrocatalyst for highly sensitive electrochemical detection of As(III)

The electrochemical method for highly sensitive determination of arsenic(III) in real water samples with noble-metal-free nanomaterials is still a difficult but significant task. Here, an electrochemical sensor driven by noble-metal-free layered porous Fe3O4/Co3S4 nanosheets was successfully employed for As(III) analysis, which was prepared via a facile two-step method involves a hydrothermal treatment and a subsequent sulfurization process. As expected, the electrochemical detection of As(III) in 0.1 M HAc-NaAc (pH 6.0) by square wave anodic stripping voltammetry (SWASV) with a considerable sensitivity of 4.359 μA/μg·L−1 was obtained, which is better than the commonly used noble metals modified electrodes. Experimental and characterization results elucidate the enhancement of As(III) electrochemical performance could be attributed to its nano-porous structure, the presence of oxygen vacancies and strong synergetic coupling effects between Fe3O4 and Co3S4 species. Besides, the Fe3O4/Co3S4 modified screen printed carbon electrode (Fe3O4/Co3S4-SPCE) shows remarkable stability and repeatability, valuable anti-interference ability and could be used for detection in real water samples. Consequently, the results confirm that as-prepared porous Fe3O4/Co3S4 nanosheets is identified as a promising modifier to detect As(III) in real sample analysis.

Bioconcentration and bioaccumulation of toxic metals in Scirpus californicus from natural wetlands in the Central Andes of Peru

Bioconcentration and bioaccumulation levels of lead, zinc, iron and arsenic in Scirpus californicus of the Paca and Tragadero Lagoons, Jauja, Peru, were evaluated. Water, sediment and Scirpus californicus samples were collected from each lagoon, which were transported to the laboratory for the analytical determination of lead, iron, zinc and arsenic, which was performed by atomic absorption spectrophotometry based on the methodology recommended by FAO. The results obtained reveal the current status of the quality of the aquatic environment of natural wetlands in the central region of Peru in terms of heavy metals and arsenic, which provide an important source of water for the populations of large cities in the central region of Peru. The presence of heavy metals and arsenic with great impact on the quality of these water bodies may be due to the pressure exerted by anthropogenic activities such as mining, agriculture, industrial and domestic wastewater. The sediments of Paca and Tragadero Lagoons showed high concentrations of Fe, exceeding international standards. Aquatic vegetation represented by Scirpus californicus in both lagoons bio accumulated mainly Zn, without exceeding international standards.

Determination of Chromium(VI), Chromium(III), Arsenic(V), Aluminum(III), Iron(II), and Manganese(II) by Colorimetry and Surface-Enhanced Raman Scattering (SERS) Using Ferulic Acid Functionalized Silver Nanoparticles

Plasmonic nanoparticles having localized surface plasmon resonance in the visible and infrared region are potential candidates for the fabrication of simple, rapid, selective and specific metal ion detection systems based on colorimetry and surface-enhanced Raman spectroscopy. The study describes simple approaches for selective colorimetric and surface-enhanced Raman scattering determination of aluminum(III), chromium (VI), chromiun(III), manganese (II), iron(II) and arsenic (V) ions in aqueous medium using ferulic acid functionalized silver nanoparticles (F-AgNPs) synthesized by chemical reduction and microwave assisted method. The analysis of photographs reveals that ferulic acid functionalized silver nanoparticles synthesized by chemical reduction (C-F-AgNPs) sensitively detect Al(III) ions in aqueous media while nanoparticles synthesized by microwave reduction method can be used to determine As(V), Mn(II) and Fe(II) ions. In addition, C-F-AgNPs also enhance the Raman spectral profile of the water samples spiked by Cr(III) ions giving a peculiar vibration spectral feature that assists in the detection of Cr(III) ion in aqueous medium. Moreover, ferulic acid functionalized silver nanoparticles synthesized by the microwave assisted method (M-F-AgNPs) increase the intensity of Raman bands in the spectral profile of the water samples spiked with Cr(VI) and Mn(II) ions. The specific and selective interactions of F-AgNPs with the Cr(VI), Cr(III), Mn(II), Fe(II), Al(III) and As(V) leading to the aggregation of the dispersed silver nanoparticles enable their determination in aqueous media . The results of the present study shows the potential of F-AgNPs based sensor probes toward conceptualizing and fabricating simple, rapid and cost effective detection tools onsite determination of metal ions in aqueous media.