Direct Determination of the Environmental Contaminant Acid 2,4-diclorofenoxiacetic in Natural Waters by Solid Surface Fluorescence.

Rare earth element (REE) patterns in natural water and geological samples provide information on previous changes in environmental conditions, such as redox changes and material cycles; however, quantitative analysis of REEs in these samples is complicated by the relatively low contents of REEs in such samples as well as mass interference from 135Ba16O and 137Ba16O in inductively coupled plasma mass spectrometry (ICP-MS) analyses. In this study, onsite solid-phase extraction and preconcentration methods for REEs using an iminobisacetic acid–ethylenediaminetriacetic acid chelate resin (Nobias Chelate PA1, Hitachi High-Tech Fielding) were adopted for the analyses. Standard reference materials (SPS-SW1 artificial surface water) and natural ground water and spring water samples were used to evaluate the methods. Using the chelate resin, background levels of REEs were found to be less than 0.3 ng L−1 and recovery rates (REEs, 1 ng L−1) were 97.9–106.7% for the artificial surface water. Ba contents were lower than the detection limit after extraction. Additionally, duplicate analyses were performed to check the reproducibility of the onsite extraction. The REE patterns in the natural water samples were in good agreement with those obtained using a previous method (the interference calibration method without solid-phase extraction). Therefore, onsite solid-phase extraction using the chelate resin was demonstrated to be a rapid and simple preparation technique for REE analyses.

A novel poly(safranine)-modified electrode has been constructed for the determination of 4-nitrophenol (4-NP) in natural water sample. The electrochemical behavior of poly(safranine) film electrode and its electrocatalytic activity toward 4NP were studied in detail by cyclic voltammetry (CV) and adsorptive linear stripping voltammetry (LSV). All experimental parameters were optimized and LSV was proposed for its determination. In optimal working conditions, the reduction current of 4-NP at this poly(safranine)-modified electrode exhibited a good linear relationship with 4-NP concentration in the range of 8.0 × 10 ‒8 to 4.0 × 10 ‒5 mol L ‒1 . The detection limit was 3.0 × 10 ‒8 mol L ‒1 . The high sensitivity and selectivity of the sensor were demonstrated by its practical application for the determination of trace amounts of 4-NP in natural water and fruit samples.

Precise determination of Sc in natural waters by neutron activation analysis coupled with preconcentration of Sc

A comprehensive investigation into the impact of spectral baseline on temperature prediction in natural marine water samples by Raman spectroscopy is presented. The origin of baseline signals is investigated using principal component analysis and phytoplankton cultures in laboratory experiments. Results indicate that fluorescence from photosynthetic pigments and dissolved organic matter may overlap with the Raman peak for 532 nm excitation and compromise the accuracy of temperature predictions. Two methods of spectral baseline correction in natural waters are evaluated: a traditional tilted baseline correction and a new correction by temperature marker values, with accuracies as high as ± 0.2°C being achieved in both cases.

An anion exchange pretreatment method for the determination of low-level uranium in the environmental water samples

The applicability of ozone as a digesting agent in the trace analysis of arsenic in natural water samples has been investigated. Differential pulse polarographic (DPP) and spectrophotometric (SP) methods were applied for the determination of arsenic in ozone and, as reference, in persulphate treated samples. Additionally, inductively coupled plasma mass spectrometry (ICP-MS) was used for the total arsenic determinations. No significant differences were found between the results of the measurements using different techniques in the investigated natural ground water samples. Similar detection limits of 5 µg/L, lower quantification limits of approximately 10 µg/L and linearity limit up to 300 µg/L were estimated for the both DPP and SP measurements. Thus, ozone treatment may, in many cases, be successfully used for the pretreatment of samples prior to both DPP and SP determination of arsenic in natural water samples.

Direct determination of rare earth elements in natural water samples by inductively coupled plasma tandem quadrupole mass spectrometry with oxygen as the reaction gas for separating spectral interferences

A column solid-phase extraction procedure for separation and preconcentration of bismuth in natural water samples using sodium diethyldithiocarbamate (NaDTTC) or piperidene dithiocarbamate (pipDTC)-coated Amberlite XAD-7 resin prior to their determination by inductively coupled plasma atomic emission spectrometry (ICP-AES) is reported. The results showed that solution pH and flow rate would affect the sorption of bismuth. The sorbed bismuth was eluted with 4 M/L of HNO3. The extractor system has good sorption capacity values of 9.82 mg/g of Bi on NaDTTC-coated resin and 9.56 mg/g of Bi on pipDTC-coated resin. The preconcentration factor was 150 and 170 for pipDTC-coated resin and NaDTTC-coated resin, respectively. The detection limits are 0.9 and 1.2 µg/L for resin-coated with NaDTTC and pipDTC, respectively. The results showed that resin coated with NaDTTC performs slightly better in the recovery of bismuth than resin coated with pipDTC. The accuracy of the proposed method was investigated by determining the bismuth in spiked water samples. The relative standard deviations of the determination of bismuth were below 5%. The proposed procedure was applied for the determination of bismuth in natural water and seawater samples.

The concentration levels of mercury (Hg) species in natural water samples are usually low. Consequently, accurate analysis with low detection limits is still a major problem. In this work, a method was applied for the simultaneous direct determination of dissolved mercury species in water samples by on-line hydride generation (HG), cryogenic trapping (CT), gas chromatography (GC) and detection by atomic fluorescence spectrometry (AFS). The suitability of the method for real samples with different organic matter and chloride contents was evaluated by recovery experiments in synthetic and natural spiked water samples. The HG method was compared with other current available methods for mercury analysis with respect to the different fraction of mercury analysed, i.e. 'reactive', 'reducible' or total. HG derivatization and SnCl2 reduction (with and without previous oxidation with BrCl) were applied to synthetic and natural (spiked and non-spiked) water samples. The influence of chloride and dissolved organic matter concentrations was studied. The results suggest that the HG procedure is suitable for the simultaneous determination of Hg2+ and MeHg+ in surface water samples. Inorganic mercury analysed by HG (i.e. reducible) is close to the total inorganic mercury.

In order to research the origin of taste of so-called "delicious natural water", chemical components of tap and natural water samples were measured and compared to each other. The values of pH, carbonate ion, KMnO4-consumed values and ion levels in the samples were determined by the officially established methods for drinking water. Twenty-one kinds of tap water samples were collected from the domestic water supply of Hyogo, Osaka and Nara prefectures. On the other hand, 10 kinds of natural water samples were collected from Hyogo, Osaka and Nara prefectures, while the other 11 samples purchased at markets were originated from several parts of Japan. The tap water samples gave significantly higher values on the KMnO4-consumed values and the concentrations of chloride and sulfate ions and iron (Fe2++Fe3+) than the respective data in the natural water samples. In contrast, the concentrations of carbonate ion in the natural water samples were significantly higher than those in the tap water samples.

Novel electrochemical immunosensors for sensitive detection of 17-β estradiol (E2) and ethinylestradiol (EE2) are described on the basis of the use of magnetic beads (MBs) as solid support and screen-printed electrodes as sensing platforms. Four synthetic estrogen derivatives containing either a carboxylic group or an amine group at the C-3 position were synthesized and covalently bound to MBs functionalized with amine or carboxyl groups, respectively. The assay was based on competition between the free and immobilized estrogen for the binding sites of the primary antibody, with subsequent revelation using alkaline phosphatase-labeled secondary antibody. Preliminary colorimetric tests were performed in order to validate the applicability of the synthetic estrogens to immuno-recognition and to optimize different experimental parameters. In a second step, electrochemical detection was carried out by square wave voltammetry (SWV). Under the optimized working conditions, the electrochemical immunosensors showed a highly sensitive response to E2 and EE2, with respective detection limits of 1 and 10 ng/L. Cross-reactivity evaluated against other hormones demonstrated an excellent selectivity. The developed devices were successfully applied to analysis of spiked and natural water samples. These new immunosensors offer the advantages of being highly sensitive, easy, and rapid to prepare, with a short assay time.

An efficient method for preconcentration of trace amounts of Mn (II) and Ni (II) ions by using a minicolumn (10 mm × 30 mm i.d.) filled with a diimine derivative Schiff base on silica‐gel has been reported. The retained analytes on the column were recovered with 5 mL of mixture of nitric acid 5 mol L−1 and methanol (1 : 1) and were determined by a flame atomic absorption spectrometer. Different factors including pH of sample solution, sample volume, amount of sorbent, eluent volume, and interference of other ions have been studied and the optimized conditions developed were utilized for the trace determination of Mn (II) and Ni (II) in natural water samples. The recoveries for the analytes under the optimum working conditions were higher than 98%. The relative standard deviations of the determinations (10 replicate analyses) at 25 μg L−1 of Mn (II) and Ni (II) were 2.5% and 2.3%, respectively. The limit of the detection (3s, n = 10) for analytes were found to be 0.20 μg L−1 for Mn (II) and 0.15 μg L−1 for Ni (II). The proposed method was applied to the analysis of natural water samples with satisfactory results.

This work describes the application of gold electrodes constructed from recordable compact discs for the analytical determination of the herbicide paraquat in natural water samples using square wave voltammetry. The detection limit for pure water (laboratory samples) was 21 µg L−1, lower than the EPA limit for drinking water (100 µg L−1). The experimental quantification limit was determined as 73 µg L−1. In polluted creek water samples the detection limit rose to 76.4 µg L−1 and is shown to be dependent on BOD and COD values. Recovery measurements in tea and natural water samples were approximately 95%, which indicates that the methodology can be employed to analyze paraquat in such matrices. The authors acknowledge the financial support of FAPESP and CNPq.

Arsenic (III,V) removal from aqueous solution by ultrafine α-Fe 2O 3 nanoparticles synthesized from solvent thermal method

Sequential determination of nickel and cadmium in tobacco, molasses and refill solutions for e-cigarettes samples by molecular fluorescence