An improved metal extraction procedure for the determination of trace metals in sea water by atomic absorption spectrometry with electrothermal atomization
Abstract
A rapid carbamate extraction method with pyrrolidinedithiocarbamate and diethyldithiocarbamate is described for the simultaneous determination of Cd, Co, Cu, Fe, Ni, Pb and Zn in sea water by atomic absorption spectrometry with a graphite atomizer. The metal—carbamate complexes are extracted from 500 ml of sea water into Freon TF and back-extracted into 10 ml of 0.3 M nitric acid. The method has considerable advantages over previously recommended extraction procedures. The metals are transferred to a solution in which their concentrations do not change with time, and which can be easily stored for transportation. The sensitivity is high enough for analysis of open ocean waters.
References (6)
- G.E. Batley et al.
Mar. Chem.
(1976) - K. Kremling et al.
Anal. Chim. Acta
(1974) - E.A. Boyle et al.
Anal. Chim. Acta
(1977)
Cited by (325)
Long-term variation of dissolved metals and metalloid in the waters of an Atlantic mesotidal estuary (Sado Estuary, Portugal)
2023, Marine Pollution BulletinEstuaries have long been preferred sites of human settlement due to the benefits regarding proximity to fresh water and the ocean. As such, these environments have been subject to increasing anthropogenic pressures, resulting in issues of pollution and contamination. However, since the second half of the 20th century an environmental concern has reflected in the development of legislation, monitoring programmes and measures to diminish and control those impacts. The study presented herein integrates metals and metalloid concentrations from surface water samples obtained in a long-term monitoring programme (1986–2020) conducted in the Sado Estuary. The results obtained show a decrease and stabilisation of the concentrations of elements (between 81 % for Pb and 11 % for As in the average concentrations, between 83 % for Pb and 11 % for Cd in the median concentrations, and an increase of 1 % in the As median values). Nevertheless, high concentrations were still observed in the stations closest to the industrial area and the main freshwater to confluence with the estuary. Despite the efforts in improving the environmental quality of the Sado Estuary, possible effects in native species such as cuttlefishes and oysters are still a possibility, particularly in the stations where higher concentrations were registered, as well as close to nurseries as a result of trace metal transport through currents and tides.
Bubble-propelled micro/nanomotors: a robust platform for the detection of environmental pollutants and biosensing
2023, Materials AdvancesThe sensitive and rapid detection of a variety of hazardous environmental pollutants and bio-analytes such as microorganisms and biomolecules is of great importance for environmental and health care monitoring. Thus, significant progress has been made in the development of numerous sensor platforms for the quick and reliable sensitive detection of these analytes. However, most of the sensor platforms require complex technology, skillful personnel, prolonged operation, and laborious protocols, which limit their use worldwide, especially in low- and middle-income countries. Over the past few decades, the emergence and progress of nanotechnology have revolutionized the field of sensing. Particularly, the birth of self-propelled micro/nanomotors has become an area of interest in the current era owing to their versatility, ranging from environmental monitoring to biosensing. These are synthetic tiny multifunctional intelligent systems, capable of converting external energy such as light, magnetic field, ultrasound, electric field, and chemical fuel to kinetic energy and accomplishing tedious jobs. Among the external driving sources, chemically driven micromotors based on the bubble propulsion mechanism hold considerable promise in sensing on account of their greater propulsion rate, enhanced fluid mixing, and mass transfer. Employing this advantage, many leading research groups have focused on the fabrication of differently shaped bubble-propelled micromotors for the sensitive and selective detection of targets by functionalizing the motors with specific recognition units. In this review, we highlight the current progress in bubble-propelled micro/nanomotors for the detection of various environmental pollutants and bioanalytes such as microorganisms, cells, and biomolecules, and discuss their sensing mechanism. Finally, the challenges and limitations of these micromotors are presented together with their future direction.
Synthesis and characterization of reduced graphene oxide-Fe<inf>3</inf>O<inf>4</inf>@polydopamine and application for adsorption of lead ions: Isotherm and kinetic studies
2020, Materials Chemistry and PhysicsThe functionalization of graphene causes many of its features to be altered, which can be used to better adsorption metal ions in aqueous solution. In this work, catecholamine, with a stable polymeric structure and as a safe material, was coated on graphene oxide by the self-polymerization and creates strong and toughness composite that exhibits high resistance to destruction due to stirring or sonication. Graphene oxide (GO) was reduced in the polymerization process and many functional groups including amine and hydroxyl groups are formed on the composite structure, which causes more interaction with Pb2+ ions. The surface area of the magnetic GO was increased after covering with polydopamine. The sorbent was characterized by Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, Vibrating-sample magnetometer and Energy-dispersive X-ray spectroscopy. To achieve the highest adsorption efficiency, various parameters including pH, sorbent amount, breakthrough volume, adsorption time, desorption time and volume and concentration of eluent solution were optimized. The sorbent capacity was achieved as about 35.2 mg g−1. The isotherm data fitted well with the Langmuir isotherm model. The experimental results proved that rGO/Fe3O4@PDA had higher stability than GO@Fe3O4 and can be reused many times after washing with eluent.
Critical evaluation of a seaFAST system for the analysis of trace metals in marine samples
2019, TalantaA seawater preconcentration system (seaFAST) with offline sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) detection was critically evaluated for ultra-low trace elemental analysis of Southern Ocean samples over a four-year period (2015–2018). The commercially available system employs two Nobias PA1 resin columns for buffer cleaning and sample preconcentration, allowing salt matrix removal with simultaneous extraction of a range of trace elements. With a primary focus on method simplicity and practicality, a range of experimental parameters relevant to oceanographic analysis were considered, including reduction of blank levels (over weeks and years), instrument conditioning, extraction efficiencies over different pH ranges (5.8–6.4), and preconcentration factors (~10–70 times). Conditions were optimised for the analysis of ten important trace elements (Cd, Co, Cu, Fe, Ga, Mn, Ni, Pb, Ti and Zn) in open ocean seawater samples, and included initial pre-cleaning and conditioning of the seaFAST unit for one week before each separate analytical sequence; a controlled narrow buffer pH of 6.20 ± 0.02 used for extraction; and a sample preconcentration factor of 10 for (relatively) concentrated rainwater or sea ice, 40 for typical seawater samples, and up to 67 times for seawater samples collected in the remote open ocean such as the Southern Ocean.
Method accuracy (both short – days to weeks - and long term – months to years) were evaluated through extensive analysis of a range of oceanographic standard reference samples including SAFe D1 (n = 20), D2 (n = 3), S (n = 15), GEOTRACES GD (n = 6), GSC (n = 42) and GSP (n = 42), as well as NASS-6 (n = 6). Measured values for oceanographic samples were found to agree with consensus values to within ± 6% for Cd, Cu, Fe, Ni, Pb and Zn. Offsets were noted for Co (labile fraction only; no UV oxidation), Mn (difference also noted in other recent studies) and Ti (limited reference values). No consensus values currently exist for Ga. Iron and Mn in Southern Ocean samples were also independently verified via flow injection analysis methods (R2 = 0.95, n = 244 (Fe) and 0.92, n = 85 (Mn), paired t-test, p ≪0.05). Precisions over four years were evaluated through analysis of community seawater samples as well as a range of bulk in-house seawaters (3 sources, each n~100) and acid blanks (n = 250), and were typically found to be within 5–8%, depending on analyte and concentration.
Values presented here represent one of the largest independent data sets for these reference samples, as well as the most documented comprehensive suite of GSP and GSC values currently available (consensus values have not yet been released). Samples covering a range of salinities (0–60) were investigated to demonstrate method versatility, with excellent recoveries noted using the seaFAST Nobias PA1 column (>98% for most elements, with 70–80% for Ga and Ti). By way of example, data is presented showing the application of the method to samples collected on the Kerguelen plateau in the Indian sector of the Southern Ocean (HEOBI voyage, January-February 2016) and in land-fast ice and brine collected near Davis station, Antarctica, in austral summer 2015 (with a salinity range from 0 to 73 g kg−1). Finally, a range of recommendations for successful implementation of a seaFAST system are provided, along with considerations for future investigation.
An innovative application of graphitic carbon nitride (g-C <inf>3</inf> N <inf>4</inf> ) nano-sheets as silver ion carrier in a solid state potentiometric sensor
2019, Materials Chemistry and PhysicsExistence of silver ion in wide range of applications have led to a considerable increase of its concentration in environment. As a consequence and due to probable environmental and health issues, development of a highly sensitive and reliable method for the determination of Ag ion in environmental samples such as water is essential. An ion-selective potentiometric sensor was developed by introducing graphitic carbon nitride (g-C3N4) as a novel ion career to detect the trace level of silver ion in water samples. The graphitic carbon nitride (g-C3N4) nanosheets were synthesized and then characterized by scanning electron microscopy, Uv–vis spectroscopy, fluorescence spectroscopy, XRD and FT-IR. The material was synthesized and then used for the modification of a carbon paste electrode. The electrode containing 14.3% n-eicosane, 80.7% graphite powder and 5.0% g- C3N4, presented the stable potential response to Ag+ ion with the Nernstian slope of 54.2 mVdecade−1 at 25 °C. The proposed sensor exhibited reliable response over a wide linear concentration range of 1.0 × 10−6–1.0 × 10−1 mol L−1 with a detection limit of 9.0 × 10−7. The sensor provided no memory effect, prompt response time and long-term stability. The implemented electrode was resistant against interfering foreign ions such as Hg2+, Cd2+, Cu2+, Pb2+ and Cr3+.
The present work describes a simple method for the preparation of gold nanoparticles (AuNPs) in aqueous media under ambient conditions and their use in colorimetric detection of Cr (III) and Fe (II) ions. The AuNPs were prepared using methylene blue (MB) as the capping agent and sodium borohydride as the reducing agent in the aqueous medium. The prepared MB-AuNPs were thoroughly characterized using UV–vis spectroscopy, TEM, and FT-IR techniques. The MB-AuNPs were employed as colorimetric for Cr (III) and Fe (II) ions at pH range of 3–8, at room temperature in aqueous solution. In the present of Cr (III) and Fe (II) ions, the MB-AuNPs induces aggregation of the nanoparticles. Upon aggregation, the surface plasmon absorption band red-shifts so that the nanoparticle solution appears a blue color. The MB-AuNPs were found to be highly sensitive to Cr (III) and Fe (II) ions with the detection limit 23.66 and 11.21 nM respectively under optimized conditions in the aqueous medium.