Silver In Water Samples Research Articles

Fast Procedure for Removing Silver Species in Waters Using a Simple Magnetic Nanomaterial

The increase in the production and use of disinfectants containing silver atoms (in both its ionic and nanomeric forms) in their formulation, due to the global pandemic situation caused by COVID-19, has increased the presence of silver species in wastewater. Moreover, silver atoms are now considered as emerging pollutants in water. In this work, we propose a novel method for the instantaneous and simultaneous removal of ionic and nanomeric silver in water samples, using a previously unpublished methodology consisting of the in situ formation of magnetic nanoparticles in the aqueous samples to be treated. While the nanoparticle precursors react to form them, the silver atoms present in the sample are adsorbed onto them due to a strong electrostatic interaction. As the final nanoparticles are magnetic, they can be easily removed from the aqueous medium using a magnet, leaving the samples free of silver species. The innovative feature of the method is that the adsorbent is synthesized in situ, within the sample to be treated, making the approach a low-cost, easy-to-perform solution. Temperature, contact time, dose of Fe3O4, and concentration of nanomeric and ionic silver were investigated. The results showed that at 50 °C, 100% of both silver species were removed from the water samples simultaneously. The surface of Fe3O4 was characterized before and after the application of the removal process using energy-dispersive X-ray spectroscopy and Field Emission scanning electron microscopy. Adsorption kinetics and equilibrium isotherms studied reveal a Langmuir-type physicochemical process. The procedure has been applied to different water samples (river and drinking water) with excellent results, making the method a new standard for the removal of ionic and nanomeric silver. In addition, the nanoparticles formed could be recycled and reused for other analytical and decontamination purposes.

Application of magnetic nanocomposite modified with a thiourea based ligand for the preconcentration and trace detection of silver(I) ions by electrothermal atomic absorption spectrometry

In this study, a novel and simple modified magnetic nanocomposite was investigated for the analysis of trace amount of silver(I). For this purpose, the magnetically activated carbon/γ-Fe2O3 (AC/γ-Fe2O3) nanocomposite was successfully synthesized and modified with a symmetrical thiourea derivative, 4,4′-bis-(3-phenylthiourea)diphenyl methane (BPDM). The different experimental factors affecting the preconcentration and detection of the analyte ions were studied in detail. The effects of foreign ions on the extraction of Ag(I) ions were also investigated. Under the optimum conditions, a sensitive response to Ag(I) within a wide concentration range (0.01–28μgL−1) was achieved. The limit of detection (LOD, 3Sb/m) was 2.3ngL−1. The maximum adsorption capacity of the novel magnetic adsorbent for Ag(I) was found to be 32.6mgg−1. An enrichment factor (EF) of 125 was obtained by the ratio of the highest sample volume for analyte (125mL) and the lowest final eluent volume (1mL). The developed method was successfully applied to monitoring silver in water samples and the certified reference material. The procedure exhibited some advantages, such as simplicity, rapidity, high sensitivity, and low cost. In addition, the mechanism of silver extraction by modified nanocomposite was proposed.

Determination of trace amount of silver in water samples by flame atomic absorption after preconcentration by ZnO nano sorbent

ABSTRACTA simple and fast method based on solid phase extraction (SPE) applying zinc oxide (ZnO) nanoparticles and atomic absorption spectrometry (AAS) was developed for the trace amount determination of silver (Ag) in aqueous samples. The method linearity was in the range of 14 to 700 ng mL−1. The extraction efficiency of Ag was greater than 98% and limit of detection (LOD) was 4.2 ng mL−1. The preconcentration factor was 200 and the relative standard deviation (RSD%) of the method was 3.7% (n = 6).

Selective Quantification of Trace Silver in Water Samples by Solidified Floating Organic Drop Micro-extraction Coupled with Electrothermal Atomic Absorption Spectrometry

Selective Quantification of Trace Silver in Water Samples by Solidified Floating Organic Drop Micro-extraction Coupled with Electrothermal Atomic Absorption Spectrometry

Supramolecular solvent-based extraction coupled with vortex-mixing for determination of palladium and silver in water samples by flame atomic absorption spectrometry

A simple and practical extraction method of supramolecular solvents (SUPRAS) was developed for separation and enrichment of trace amounts of palladium (Pd) and silver (Ag) in water samples prior to flame atomic absorption spectrometry (FAAS) analysis. The SUPRAS selected was made up of an aqueous solution containing tetrahydrofuran and nonanoic acid. Pd and Ag reacted with diethyldithiocarbamate to form hydrophobic chelates, which were extracted into the vesicles of SUPRAS. Different parameters such as the concentration of chelating agent, sample pH, supramolecular solvent and the effect of foreign ions were studied. Under the optimal conditions, the linear ranges of Pd and Ag were from 10 to 1,000 μg/L. The relative recoveries of Pd and Ag in tap and river water samples at the spiking level of 10 ug/mL ranged from 90.8 to 116%. The relative standard deviations were 3.6-4.0% (n = 9), the limits of detection were 2.8 and 1.9 μg/L and the enrichment factors were 36 and 18 for Pd and Ag, respectively. The quantification limits were 3.2 and 2.4 μg/L. The method was successfully applied to the determination of Pd and Ag in water samples.

Ligand-less in situ surfactant-based solid phase extraction for preconcentration of silver from natural water samples prior to its determination by atomic absorption spectroscopy

A simple and rapid ligand-less in situ surfactant-based solid phase extraction method for preconcentration of silver from water samples is developed. In this method, a cationic surfactant containing a proper alkyl group (n-dodecyltrimethylammonium bromide) is dissolved in the aqueous sample and then a proper ion-pairing agent (ClO4 −) is added. Due to the interaction between surfactant and ion-pairing agent, solid particles are formed and used for adsorption of silver carbonate. After centrifugation, the sediment is dissolved in 2.0 mL 1 M HNO3 in ethanol and then aspirated directly into the flame atomic absorption spectrometer. Variables affecting the extraction efficiencies such as pH, concentrations of surfactant and CO3 2−, ion pair concentration, and extraction time, are optimized. Under such conditions, the calibration curve is linear from 3 to 700 μg L−1. Detection limit is 1.1 μg L−1 with an enrichment factor of 37. The relative standard deviation for eight replicate measurements of 100 μg L−1 is 2.1%. The method has been applied for the determination of silver in water samples.

Ionic Liquid-Based Dispersive Liquid-Liquid Microextraction Combined with Flame Atomic Absorption Spectrometry for Determination of Silver in Water Samples

-1 . The relative standard deviation for five replicate determinations of 200 µg L -1 Ag was 2.9 %. The calibration graph was linear in the range of 15-300 µg L -1 with a cor relation coefficient of 0.9961. The a pplicability of the proposed method was e valuated by determination of trace amounts of silver in water samples.

Selective Quantification of Trace Silver in Water Samples by Displacement Solidified Floating Organic Drop Microextraction Coupled With Electrothermal Atomic Absorption Spectrometry

ABSTRACT In this work, a novel displacement solidified floating organic drop microextraction (D-SFODME) technique was developed and coupled with electrothermal atomic absorption spectrometry (ETAAS) for the determination of trace silver in water samples without need of any masking agents. The method involved the formation of copper diethyldithiocarbamate (Cu–DDTC), extracted from the resultant Cu–DDTC with SFODME procedure using 1-undecanol. Then, the solidified floating organic drop was transferred into a sample solution containing silver ion, and another SFODME procedure was carried out. Trace Ag+ was selectively preconcentrated using 1-undecanol through a displacement reaction between Ag+ and the preconcentrated Cu-DDTC and the floating organic drop was diluted by ethanol for ETAAS detection. Interferences from coexisting heavy metal ions with lower stability of their DDTC complexes relative to Cu-DDTC were minimized. Under the optimal conditions, the limit of detection was 4.7 ng L−1 (3σ) for silver with a sample volume of 5.0 mL, and an enrichment factor of 250 was achieved. The relative standard deviation under optimum conditions is 3.6% (n = 7). The proposed method was successfully applied to determine trace silver in some environmental samples with satisfactory results.

Determination of Trace Silver in Water Samples by Online Column Preconcentration Flame Atomic Absorption Spectrometry Using Termite Digestion Product

A new method for Ag determination in water samples using solid phase extraction (SPE) coupled to a flow injection system and flame atomic absorption spectrometry was developed. The sorbent used for Ag preconcentration and extraction was the termite digestion product. Flow and chemical variables of the system were optimized through a multivariate procedure. The factors selected were adsorbent mass, buffer type and concentration, sample pH, and sample flow rate. The detection limit and precision were 3.4 μg L−1 and 3.8% (n = 6, 15 μg L−1), respectively. The enrichment factor and the linear working range were, respectively, 21 and 10–50 μg L−1. Results for recovery tests using different water samples were between 96 and 107%. The proposed methodology was applied with success for the determination of Ag in water used to wash clothes impregnated with silver nanoparticles, supplied by a factory located in Santa Catarina, Brazil.

Carbon Nanotubes-Loaded Silica Gel for Preconcentration of Trace Silver with Detection by Flame Atomic Absorption Spectrometry

Abstract Carbon nanotubes (CNTs) were loaded onto the surface of silica gel (SG) beads, and the CNTs/SG composite was used as a novel adsorbent for the preconcentration of trace silver in a flow system by adsorbing nascent Ag2O in solution. This treatment of the material significantly improved the mechanical strength and capability of preconcentration of CNTs. With NaOH as precipitating reagent, the nascent Ag2O in the solution was readily retained on the surface of the CNTs/SG composite and recovered afterward by elution with nitric acid (10%, V/V). The eluate was finally introduced into a flame atomic absorption spectrometer for quantification. By loading 5.4 mL of sample solution, a liner range of 1–120 μg L−1, an enrichment factor of 34.5, a detection limit of 0.35 μg L−1 and a precision of 0.5% RSD at 40 μg L−1 level (n = 7) were obtained, along with a sampling frequency of 47 h−1. The enrichment factor, the detection limit and the precision of this procedure are obviously superior to those achieved by using wither pure CNTs or pure silica gel as adsorbents. The procedure was applied for the determination of silver in water samples, and satisfactory spiking recoveries were obtained in the range of 96%–108%.

Determination of colloidal and dissolved silver in water samples using colorimetric solid-phase extraction

The increase in bacterial resistance to antibiotics has led to resurgence in the use of silver as a biocidal agent in applications ranging from washing machine additives to the drinking water treatment system on the International Space Station (ISS). However, growing concerns about the possible toxicity of colloidal silver to bacteria, aquatic organisms and humans have led to recently issued regulations by the US EPA and FDA regarding the usage of silver. As part of an ongoing project, we have developed a rapid, simple method for determining total silver, both ionic (silver(I)) and colloidal, in 0.1–1 mg/L aqueous samples, which spans the ISS potable water target of 0.3–0.5 mg/L (total silver) and meets the US EPA limit of 0.1 mg/L in drinking water. The method is based on colorimetric solid-phase extraction (C-SPE) and involves the extraction of silver(I) from water samples by passage through a solid-phase membrane impregnated with the colorimetric reagent DMABR (5-[4-(dimethylamino)benzylidene]rhodanine). Silver(I) exhaustively reacts with impregnated DMABR to form a colored compound, which is quantified using a handheld diffuse reflectance spectrophotometer. Total silver is determined by first passing the sample through a cartridge containing Oxone, which exhaustively oxidizes colloidal silver to dissolved silver(I). The method, which takes less than 2 min to complete and requires only ∼1 mL of sample, has been validated through a series of tests, including a comparison with the ICP-MS analysis of a water sample from ISS that contained both silver(I) and colloidal silver. Potential earth-bound applications are also briefly discussed.

Dispersive Liquid–Liquid Microextraction of Silver Prior to Determination by Microsample Introduction-Flame Atomic Absorption Spectrometry

A new simple and sensitive method has been proposed for rapid determination of trace levels of silver in environmental water samples, using dispersive liquid–liquid microextraction (DLLME) prior to its microsample introduction-flame atomic absorption spectrometry. Under the optimum conditions, the linear range was 0.1–7 µg L−1 and limit of detection was 0.018 µg L−1. The relative standard deviation for 0.50 and 5.00 µg L−1 of silver in water sample was 4.0 and 1.7%, respectively. The relative recoveries of silver from tap, well, river, and seawater samples at spiking levels of 1.00 and 5.00 µg L−1 were in the range of 86.4–98.6%.

Off-line determination of trace silver in water samples and standard reference materials by cloud point extraction–atomic absorption spectrometry

An off-line method for the determination of tr ace silver in water samples and certified reference materials by cl oud point extraction (CPE) followed by flame atomic absorption spectrometry (FAAS) has been worked out. Preconcentration of CPE was based on complex formation of silver with dithizone in the presence of non-ionic micelles of octylphenoxy polyethoxy ethanol (Triton X-114) at pH 4.0. Optimization was performed on the variables influencing complexation and phase separation. The detection limit of silver in certified samples was 1.42 ng mL -1 , the quantification limit was 4.72 ng mL -1 , and precision expressed as relative standard deviation was 2.2% (n = 3, for silver concentration of 50 ng mL -1 ). The method was applied for the

Ultra-trace determination of silver in water samples by electrothermal atomic absorption spectrometry after preconcentration with a ligand-less cloud point extraction methodology

A very simple and ligand-less cloud point extraction (CPE) methodology for the preconcentration of ultra-trace amounts of silver as a prior step to its determination by electrothermal atomic absorption spectrometry (ETAAS) has been developed. The method is based on the extraction of silver at pH 9 by using non-ionic surfactant polyethyleneglycolmono- p-nonylphenylether (PONPE 7.5) without adding any chelating agent. Several important variables that affect the CPE efficiency and ETAAS signal were investigated and optimized. The preconcentration of 15 ml sample solution allowed us to achieve an enhancement factor of 60. The calibration graph using the preconcentration system was linear in the range of 5–100 ng l −1 with a correlation coefficient of 0.9991. The lower limit of detection (3 s) obtained in the optimal conditions was 1.2 ng l −1. The relative standard deviation (R.S.D.) for eight replicate determinations at 30 ng l −1 Ag level was 4.2%. The proposed method was successfully applied to the ultra-trace determination of silver in water samples.

Highly selective cloud point extraction and preconcentration of trace amounts of silver in water samples using synthesized Schiff’s base followed by flame atomic absorption spectrometric determination

A simple and useful method employing cloud point extraction is proposed for the preconcentration and separation of silver in water samples. The silver cation reacts with bis(2-mercaptoanil) acetylacetone (BMAA) at pH 6. The resulting compound is subsequently entrapped in the Triton X-114 micelles. After optimization of the complexation and extraction conditions, a preconcentration factor of 50 was obtained (volume of initial sample was 10 mL). As an analytical example, trace amounts of Ag were determined, after preconcentration, in a complex aqueous matrix such as seawater using flame atomic absorption spectrometry. The calibration curve was linear in the range 2–200 ng/mL and the limit of detection was 0.43 ng/mL. The relative standard deviation was lower than 2.4%.

Selective cloud point extraction and preconcentration of trace amounts of silver as a dithizone complex prior to flame atomic absorption spectrometric determination

Dithizone (diphenylthiocarbazone) was used as a complexing agent in cloud point extraction for the first time and applied for selective preconcentration of trace amounts of silver. The analyte in the initial aqueous solution was acidified with sulfuric acid (pH<1) and Triton X-114 was added as a surfactant. After phase separation, based on the cloud point separation of the mixture, the surfactant rich phase was diluted with tetrahydrofuran (THF) and the analyte determined in the enriched solution by flame atomic absorption spectrometry. After optimization of the complexation and extraction conditions, a preconcentration factor of 43 was obtained for only 10 ml of sample. The analytical curve was linear in the range of 3–200 ng ml −1 and the limit of detection was 0.56 ng ml −1. The proposed method was applied to the determination of silver in water samples.

Efficacy of thermal treatment and copper-silver ionization for controlling Legionella pneumophila in high-volume hot water plumbing systems in hospitals

Background: Thermal treatment and copper-silver ionization are often used for controlling Legionella pneumophila in high-volume hospital plumbing systems, although the comparative efficacies of these measures in high-volume systems are unknown. Methods: Thermal treatment of a hot water circuit was accomplished by flushing hot water (>60° C) through distal fixtures for 10 minutes. Copper-silver ionization was conducted in three circuits by installing units into return lines immediately upstream from hot water tanks. Recovery rates of L. pneumophila were monitored by culturing swab samples from faucets. Concentrations of copper and silver in water samples were determined by atomic absorption spectrophotometry. Results: Four heat-flush treatments failed to provide long-term control of L. pneumophila. In contrast, ionization treatment reduced the rate of recovery of L. pneumophila from 108 faucets from 72% to 2% within 1 month and maintained effective control for at least 22 months. Only three samples (1.9%) of hot water from faucets exceeded Environmental Protection Agency standards for silver, and none exceeded the standards for copper. Of 24 samples obtained from hot water tanks, 42% and 50% exceeded the silver and copper standards, respectively. Conclusions: Copper-silver ionization effectively controls L. pneumophila in high-volume plumbing systems and is superior to thermal treatment; however, high concentrations of copper and silver can accumulate at the bottom of hot water tanks.

Direct determination of silver at parts-per-billion level in waters by derivative atomic absorption spectrometry using the atom trapping technique

A method has been developed for the direct determination of trace silver using derivative atom trapping flame atomic absorption spectrometry with modified water-cooled stainless steel trapping equipment. The conditions that influence the sensitivity of the method were studied. For a 1 min collection, the characteristic concentration (giving a derivative absorbance of 0.0044) and detection limit (3σ) were 0.18 ng ml −1 and 0.29 ng ml −1, respectively, 383 and 66-fold better than those of the conventional flame atomic absorption spectrometry. The detection limit and characteristic concentrations of the proposed method for a 3 min collection time were 2 and 3 orders of magnitude higher than those of conventional flame atomic absorption spectrometry. The present method was applied to the determination of silver in water samples with a recovery range of 91–109% and a relative standard deviation of 5.0–5.8%.

Synthesis and properties of C 24 cyclic hydrocarbons

In this study, a novel and simple modified magnetic nanocomposite was investigated for the analysis of trace amount of silver(I). For this purpose, the magnetically activated carbon/γ-Fe2O3 (AC/γ-Fe2O3) nanocomposite was successfully synthesized and modified with a symmetrical thiourea derivative, 4,4′-bis-(3-phenylthiourea)diphenyl methane (BPDM). The different experimental factors affecting the preconcentration and detection of the analyte ions were studied in detail. The effects of foreign ions on the extraction of Ag(I) ions were also investigated. Under the optimum conditions, a sensitive response to Ag(I) within a wide concentration range (0.01–28 μg L−1) was achieved. The limit of detection (LOD, 3 Sb/m) was 2.3 ng L−1. The maximum adsorption capacity of the novel magnetic adsorbent for Ag(I) was found to be 32.6 mg g−1. An enrichment factor (EF) of 125 was obtained by the ratio of the highest sample volume for analyte (125 mL) and the lowest final eluent volume (1 mL). The developed method was successfully applied to monitoring silver in water samples and the certified reference material. The procedure exhibited some advantages, such as simplicity, rapidity, high sensitivity, and low cost. In addition, the mechanism of silver extraction by modified nanocomposite was proposed.