Lead In Natural Waters Research Articles

Low-blank method for the offline batch analysis of the low concentration of dissolved lead in natural waters and its application to natural waters, including the tropical Northwest Pacific Ocean

In this study, Presep® PolyChelate resin was utilized for the offline batch extraction process and then combined with the isotope dilution method for the analysis of low concentrations of dissolved lead (Pb) in freshwater and seawater. The application of Presep® PolyChelate resin further lowered the procedural blank by reducing the amount of resin beads and buffer solution that were added with an 8-fold preconcentration. The adsorption and elution times were shortened to 2 d and 30 min, respectively, and > 85% recovery was achieved. The total procedural blank and detection limit were 0.2 ± 0.1 pmol/kg and 0.2 pmol/kg, respectively. The accuracy of this method was also verified using GEOTRACES intercalibration SAFe seawaters, with concentrations of 48.0 ± 0.5 pmol/kg (n = 3) and 27.0 ± 0.7 pmol/kg (n = 3) observed for SAFE S and D2, respectively. Full-depth profiles of dissolved Pb concentrations collected during the 2016 tropical Northwest Pacific Ocean cruise were analyzed. The dissolved Pb concentration increased from 30 pmol/kg at the surface to 50 pmol/kg at the subsurface and it then decreased to 8–9 pmol/kg in the bottom waters.

An offline column extraction with Presep® PolyChelate resin and AG1‐X8 resin for the determination of the isotope compositions of low‐concentration lead in natural waters by the multi‐collector inductively coupled plasma mass spectrometry

AbstractA new high‐precision offline method for the determination of seawater lead (Pb) isotope ratios was developed, which simplifies and optimizes previously published protocols for the isotopic analysis of trace elements. The procedure involves initial separation of Pb from 250 to 500 mL of seawater by Presep® PolyChelate cation exchange resin and purification by AG1‐X8 anion exchange resin, and subsequently analyzed by Neptune multi‐collector ICP‐MS. For the extraction of Pb in seawater, the Presep® PolyChelate resin was characterized by a wide pH range and a faster adsorption rate, greatly reducing the volume of buffer solution required and significantly shortening the time required for the whole process. The total procedural Pb blank of this method is < 0.05% of the sample extract and the typical Pb recovery is ~ 100%. The method was evaluated by processing GEOTRACES intercalibration samples surface water (GSI, 206Pb/207Pb = 1.1744, 208Pb/206Pb = 2.0844) and GEOTRACES GP15 sample (14140#, 206Pb/207Pb = 1.1685, 208Pb/206Pb = 2.0960). Finally, this method was applied to riverine samples from the Changjiang and seawater samples from the East China Sea, and the in situ extraction was also applied in the Indian Ocean.

Waste toner-derived micro-materials as low-cost magnetic solid-phase extraction adsorbent for the analysis of trace Pb in environmental and biological samples.

Lead (Pb) is a toxic heavy metal and is commonly used in industrial applications. Thus, Pb poisoning is a concerning public health issue worldwide. The amounts of lead in natural water, urine, and blood can serve as significant indicators for monitoring the exposure of Pb poisoning. Waste toner has the characteristics of both "waste" and "resource," as it is a "resource in the wrong place." Here, a low-cost carboxylate-functionalized magnetic adsorbent was first synthesized from waste toner by a simple thermal treatment and served as a novel adsorbent with a flexible multidentate O-donor for pre-concentration of trace Pb. The characterization, adsorption behavior, and various factors of adsorption and desorption were adequately optimized, and prior to graphite furnace atomic absorption spectrometry (GFAAS) detection, a new magnetic solid-phase extraction method was proposed for the analysis of Pb in real environmental water and biological samples. The developed method exhibited a low detection limit (0.003μgL-1), high enrichment factor (88.6-fold), good linearity (0.01-0.3μgL-1), satisfactory precision with relative standard deviations of 7.9% (n = 7, CPb = 0.02μgL-1), fast adsorption kinetics (5min), and strong ability to overcome matrix interference. Validation was also performed by analyzing a certified standard reference material, and the method was successfully applied to real tap water, lake water, human urine, and human blood serum with satisfactory recoveries of 92.6-109%.

Novel ion imprinted polymer electrochemical sensor for the selective detection of lead(II)

The application of a novel Pb2+ selective sensor based on the ionic imprinted polymer in determining trace levels of lead in natural water and in fruit juice was investigated using differential pulse voltammetry (DPV). The new and selective magnetic ion-imprinted polymer (Fe3O4@SiO2@IIP) was synthesized using 2-(2-aminophenyl)-1H-benzimidazole and 4-vinyl pyridine as a ligand and functional monomer, respectively. The new polymer was utilized for modifying a GCE to generate a new electrochemical sensor. Box–Behnken design (BBD) was utilized for optimizing the parameters influencing the peak current. Extremely suitable voltammetric performance was demonstrated for the electrochemical detection of lead with a low detection limit (0.05 ng mL−1), over a wide linear concentration range (0.1–80 ng mL−1). This modified electrode as a novel sensor was utilized for determining Pb(II) ions in natural water and in fruit juice with very reasonable outcomes.

3D-printed flow system for determination of lead in natural waters

The development of 3D printing in recent years opens up a vast array of possibilities in the field of flow analysis. In the present study, a new 3D-printed flow system has been developed for the selective spectrophotometric determination of lead in natural waters. This system was composed of three 3D-printed units (sample treatment, mixing coil and detection) that might have been assembled without any tubing to form a complete flow system. Lead was determined in a two-step procedure. A preconcentration of lead was first carried out on TrisKem Pb Resin located in a 3D-printed column reservoir closed by a tapped screw. This resin showed a high extraction selectivity for lead over many tested potential interfering metals. In a second step, lead was eluted by ammonium oxalate in presence of 4-(2-pyridylazo)-resorcinol (PAR), and spectrophotometrically detected at 520nm. The optimized flow system has exhibited a linear response from 3 to 120µgL−1. Detection limit, coefficient of variation and sampling rate were evaluated at 2.7µgL−1, 5.4% (n=6) and 4 sampleh−1, respectively. This flow system stands out by its fully 3D design, portability and simplicity for low cost analysis of lead in natural waters.

Determinations of trace lead in various natural samples by a novel active microband-electrode probe

A novel active microband-electrode probe is introduced for determinations of trace lead in various natural samples. It integrates a micro electrode array (MEA) on a silicon substrate and a compact homemade potentiostat. On-chip microband gold electrodes, microband platinum electrodes and silver electrode compose a tri-electrode system. Homemade potentiostat performs cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV) measurements, not requiring external commercial potentiostat analyzer. Performances of the as-fabricated sensor are validated in CVs and DPSVs. The sensor shows lower noise than traditional setups. Linearity is outstandingly established from 0.2μgL−1 to 150μgL−1, and detection limit reaches as low as 0.06μgL−1. Other analytical properties as accuracy, precision and selectivity are also well obtained. This sensor is extensively adopted to detect trace lead in natural water, soil and fish. Results meet certified method (graphite-furnace atomic absorption spectrometer, GF-AAS) well, and validate promising applicability of the proposed method in many environmental areas.

Sample preparation in crucible atomizers for determining cadmium and lead in natural water by atomic absorption

In the determination of trace elements in samples of natural water in crucible electrothermal atomizers, it is promising to carry out two consecutive stages of sample preparation, i.e., the dynamic preconcentration of dissolved forms of elements on a solid sorbent with the simultaneous separation of suspended matter and subsequent thermal decomposition of the concentrate with fractional evaporation-condensation of an analyte. This approach allows us to reduce the risks of introducing impurities and losses of elements. The first stage of sample preparation can be executed under field conditions out of the laboratory.

Application of Nitrilotriacetic Acid Modified Gold Electrode for Determination of Lead in Natural Waters with Differential Pulse Adsorptive Cathodic Stripping Voltammetry

Application of Nitrilotriacetic Acid Modified Gold Electrode for Determination of Lead in Natural Waters with Differential Pulse Adsorptive Cathodic Stripping Voltammetry

Multiwalled carbon nanotube impregnated with tartrazine: Solid phase extractant for Cd(II) and Pb(II)

A solid phase extraction procedure has been presented by using multiwalled carbon nanotube impregnated with tartrazine for cadmium (Cd(II)) and lead (Pb(II)) ions. The influences of pH, flow rate, eluent and sample volume were investigated. No interference effects were observed from the alkaline, alkaline earth and some transition metals. The detection limits (LOD) were 0.8 and 6.6μgL−1 for Cd(II) and Pb(II), respectively. The preconcentration factor was 40. The validation of the procedure was controlled by the analysis of certified references materials. The procedure was applied to the determination of cadmium and lead in natural water and food samples.

Coacervative extraction of trace lead from natural waters prior to its determination by electrothermal atomic absorption spectrometry

In this work, a relatively simple and sensitive method for separation/preconcentration of trace lead from natural waters prior to its determination by electrothermal atomic absorption spectrometry has been proposed. The method is based on the extraction of Pb–dithizone chelate with coacervates made up of lauric acid in the presence of potassium ions and methanol. Several important factors affecting extraction efficiency such as pH, concentration of lauric acid and dithizone, ionic strength, incubation and centrifugation time were investigated and optimized. After separation of aqueous bulk solution from surfactant-rich phase, the final extract was redissolved by using 500μl of methanol acidified with 0.2moll−1 HNO3. Under the optimized conditions (using initial sample volume of 10ml), enrichment factor of 17.0, detection limit of 0.12μgl−1, quantification limit of 0.38μgl−1, relative standard deviation of 4.2% (for 2μgl−1 of Pb; n=26), linearity of the calibration graph in the range of 0.5–4.0μgl−1 (with correlation coefficient better than 0.995) were achieved. The method was validated by the analysis of certified reference material (TMDA-61). Extraction recoveries for the CRM, spiked model solutions and spiked natural water samples were in the range of 91–96%. Finally, the method was applied to the separation/preconcentration and determination of trace lead in natural waters.

Voltammetric sensing of lead and cadmium using poly(4-azulen-1-yl-2,6-bis(2-thienyl)pyridine) complexing films

Complexing polymer-coated electrodes have been synthesized by oxidative electropolymerization of 4-azulen-1-yl-2,6-bis(2-thienyl)pyridine (monomer L). The novel chelating chemically modified electrodes were used for the electrochemical detection of Pb(II) and Cd(II) ions by means of the chemical preconcentration–anodic stripping technique. The electrode material showed a particular selectivity towards lead ions, even in the presence of a large excess of other metal cations. Detection limits of 0.7nM and 10nM were obtained for lead(II) and cadmium(II) ions, respectively. The modified electrodes have been used for the determination of lead in natural water and tap-water.

Determination of lead in water by combining precolumn adsorption and fluorimetric detection in a microfluidic device

A microfluidic device equipped for in situ fluorescence detection and combined with an off-line microcolumn adsorption is proposed for the determination of lead in natural water. The precolumn adsorption is based on a microcapillary filled with aminopropyl silica. An efficient Pb2+ adsorption on aminopropyl silica was proved by Langmuir isotherm adsorption experiments. The maximum adsorption capacity was found to be 5.7 × 10−4 mol g−1. By using this solid phase extraction procedure (SPE), a 100-fold specific lead concentration was obtained. The concentrated solution was then run into a microfluidic device equipped for fluorescence detection and the complete procedure allows lead determination with a detection limit of 2 μg L−1. Furthermore, it was found that these measurements are not disrupted by the addition of a large excess of other interfering cations.

Simple micro-column with multi-walled carbon nanotubes for on-line preconcentration and determination of lead in natural water by hydride generation atomic fluorescence spectrometry

A flow injection on-line preconcentration system was developed for the determination of lead by hydride generation atomic fluorescence spectrometry (HG-AFS). It is based on a simple micro-column filled with multiwalled carbon nanotubes (MWCNTs). The preconcentration of lead on the MWCNTs was carried out based on the adsorptive retention of analyte via on-line introducing the sample into the micro-column system. A 0.3 mol L−1 HNO3 was introduced to elute the retained analyte and merged with KBH4 solution for HG-AFS detection. Under the optimal experimental conditions, an enhancement factor of 26 was obtained with a sample consumption of 14.4 mL. The limit of detection was 2.8 ng L−1 and the precision (RSD) of 11 replicate measurements of 0.2 μg L−1 Pb was 4.4%. The method was validated by analyzing three certified reference materials, and was successfully applied to the determination of trace lead in natural water samples.

Saturated Solution of PbSO4 as Standard Stock Solution and Its Applications in Analytical Spectroscopy: Screening Analysis of Lead in Natural Water and Usnea longissima

A saturated PbSO4 aqueous solution, which was prepared by dissolving commercially available solid PbSO4 in doubly distilled water, was employed as a standard stock solution of lead for the visual colorimetric determination of lead in water and atomic fluorescence spectrometric determination of lead in whole Usnea longissima (i.e., Methuselah's beard lichen). The concentration of lead in this saturated solution is theoretically calculated to 27.8 mg/L by using the solubility product constant of PbSO4 at 25°C. The standard solution series is by further dilution of the saturated solution. A validation experiment proved the feasibility of using the saturated solution as the standard stock solution of lead. The experimental conditions, mainly the temperature, that affect the equilibrium of precipitation–dissolution in the saturated solution were investigated. The saturated PbSO4 solution was proved to be accurate enough for the purpose of screening analysis of lead in these samples.

Sorption-photometric and test determination of lead in environmental materials

The main analytical characteristics of the reaction of hexaoxacycloazochrom with lead were determined. A method for the sorption preconcentration of lead on the Thiopan 14 sorbent was proposed. Procedures were developed for the photometric determination of lead in natural waters, air, and soil at the level of the maximum permissible concentration. A new melange gel technique for preparing silicic acid xerogels modified with hexaoxacycloazochrom was developed for the test determination of lead in environmental samples at the level of the maximum permissible concentration.

Response of the ascorbate-peroxidase of Selenastrum capricornutum to copper and lead in stormwaters.

The green alga Selenastrum capricornutum expresses a unique ascorbate peroxidase, that responds to copper and lead. Attempts were made to test if this peroxidase could be used to monitor the levels of copper and lead in natural waters. When S. capricornutum was exposed to a stormwater sample, the specific activity of the peroxidase in the cell extract was commensurate with the combined copper and lead contents in the sample. The peroxidase responses were also correlated with the 96 hr biomass toxicity assay of S. capricornutum. However, unlike the biomass toxicity assay, the peroxidase activity was not affected by the anions in the samples. The use of this peroxidase can be used as a marker for testing heavy metal toxicity in the water.

Use of ultramicroelectrodes for determining lead in natural waters by stripping voltammetry

Anin situ obtained graphite-fiber-based thin-film mercury microelectrode was used for determining lead(II) in natural water by stripping voltammetry without removing oxygen and using no supporting electrolyte. Under the optimum voltammetric conditions (Eel = -1.2 V,tel = 5 min,cHg(II) = 1 x 10-7 M, ΔE = 40 mV, v= 105 mV/s), the calibration graph was linear in the range of actual lead(II) concentrations in natural waters. At a lead(II) concentration of 0.002 mg/L, the RSD was 11%.

On-line coupling of electrochemical preconcentration in tungsten coil electrothermal atomic absorption spectrometry for determination of lead in natural waters

A flow injection system was coupled to a tungsten coil electrothermal atomizer (150 W) for on-line separation and preconcentration of lead based on its electrochemical reduction on the atomizer surface. The electrochemical cell is built up inside the furnace by using a Pt flow-through anode and the atomizer itself as the flow-through cathode. The manifold and the tungsten coil power supply were controlled by a computer running a program written in Visual Basic, which was utilized in synchronism with the original software of the atomic absorption spectrometer. The flow-through anode (50 mm long, 0.7 mm i.d.) was inserted in tip of the autosampler arm by replacing the last section of the PTFE sample delivering tube. The tungsten coil atomizer and the counter electrode were easily connected to a d.c. power supply. An enrichment factor of 25 was obtained for lead after a 120-s electrodeposition for a sample flowing at 1.0 ml min−1. The method detection limit was 0.2 μg l−1 Pb and the R.S.D.<5% (n=10 for 5 μg l−1 Pb). Up to 2% m/v NaCl or KCl and 5% m/v CaCl2 or MgCl2 did not interfere on the separation and atomization of 5 μg l−1 Pb.

Speciation, Preconcentration and Determination of Lead in Natural Water Using Chelating Resin and Direct GFAAS

A method has been developed for determination of trace metals in natural waters at the sub ppb level using sorption under static conditions on fine chelating resin beads. The metal can be quickly eluted from loaded beads with acid for GFAAS analysis, or the beads can be slurried in acid solution for direct GFAAS measurement. The method was applied to natural fresh water samples and lead was detected at levels down to 0.1 μg/L. The method distinguishes between lead in stable complexes and free lead ion. It permits preconcentration of trace metals from water in the field, thus avoiding the need to transport bulky water samples to the laboratory, and prevents the possibility of species inter-converting during storage and transportation. The sample-loaded beads can be stored before analysis with no apparent change in results.

Microcolumn Ion-Exchange Method for Kinetic Speciation of Copper and Lead in Natural Waters

A scheme for metal speciation based on an ion-exchange column procedure has been developed. The dissociation kinetics of metal complexes were studied using a Amberlite XAD-8 microcolumn technique, covering a time scale of measurement between 0.02 and 3 s. Application of this procedure to copper and lead complexes permits their characterization in four lability categories: labile, quasi-labile, slowly labile, and inert. This procedure has been applied to species of copper and lead in natural waters (e.g., Jarama River).