Tritium in surface waters, tap water and in precipitation in Poland during the 1994–1999 period

Concentrations of tritium in environmental waters (precipitation, rivers, lakes, tap water) have been determined using electrolytic enrichment and liquid scintillation counting. In waters of big rivers (the Vistula and the Odra rivers), lakes and tap water the annual average concentrations were similar to each other being from 1.4 to 1.9 Bq·dm^-3. These concentrations were similar to those in the precipitation in which they ranged from 1.7 to 2.2 Bq·dm^-3. The lowest tritium concentrations were found in waters of the Seashore Region rivers (average for 1994–1999 was 1.1 Bq·dm^-3). The tritium concentrations in surface waters and in precipitation are still higher than that of natural level. The data obtained show that tritium concentration in the water of rivers might depend on the size of drainage area. The observed seasonal variations of tritium concentration in the precipitation collected in Warsaw and at the Mount Sniezka indicate the stratospheric source of tritium. It was found that about 30% of tritium deposited with precipitation is removed to the Baltic Sea with river waters.     

Gold and silver determination in Waters by SPHERON® Thiol 1000 preconcentration and ETAAS

A reliable procedure for the electrothermal atomic absorption spectrometry (ETAAS) determination of gold and silver in waters at trace level is described. The method is based on prior separation and preconcentration of the metals using a chelating sorbent SPHERON® Thiol 1000 after acidification of water samples (pH < 3) with nitric acid. Optimization of analytical variables during enrichment and ETAAS determination of the metals are discussed. The accuracy of the method is verified by analysis of certified reference materials. The limits of determinations based on 10 σ definition were 0.005 ng cm^?3 for Au and 0.02 ng cm^?3 for Ag. Precision of studied elements determination expressed by relative standard deviation varied in the range from 2.9 % to 16.4 %.     

A procedure for the determination of very low activity levels of tritium in water samples

We describe the procedure developed for the electrolytic concentration of³H in water, together with systematically applied checks to guarantee the reproducibility of the process and to minimize the variability between water samples concentrated simultaneously in the different electrolytic cells. Starting from initial volume of 250 ml water, we obtained enrichment parameters normally greater than 70%, with a dispersion always less than 5%. Measuring the concentrated and the unelectrolyzed samples under the same conditions, we found that the lowest detectable activities had been improved from around 1.5 to 0.3 Bq/l. This allowed us to quantify the³H activity levels of 100% of the rainwater samples collected in Cáceres from 1994 to 1996. The resulting average value for this period was (0.79±0.38) Bq/l.     

Supported Liquid Membrane Enrichment Studies of Natural Water Samples Applied to Liquid Chromatographic Determination of Triazine Herbicides

Abstract

A method for sample work-up and enrichment using Supported Liquid Membrane (SLM) and liquid chromatographic determination of triazine herbicides in natural waters was investigated. A porous PTFE membrane was impregnated with a water immiscible organic solvent, forming a barrier between two aqueous phases. With a flowing donor and a stagnant acceptor solution, an enrichment of the triazines was obtained. The various factors that influence the extraction efficiency and selectivity of the extraction procedure were experimentally studied. The obtained results were in good agreement with the developed theoretical model. The pH of the acceptor solution was found to be the critical limiting factor in obtaining higher extraction efficiencies and led to an extraction efficiency decrease with an increase in enrichment time. By increasing both the trapping capacity of the acceptor solution and the donor flow rate, the method detection limit of the triazines ranged from 0.03 to 0.16 μgL^?1 in natural waters with 20 minutes extraction time.     

On-line solid phase extraction-liquid chromatography–mass spectrometry for trace determination of nerve agent degradation products in water samples

Three primary nerve agent degradation products (ethyl-, isopropyl- and pinacolyl methylphosphonic acid) have been determined in water samples using on-line solid phase extraction-liquid chromatography and mass spectrometry (SPE-LC–MS) with electrospray ionisation. Porous graphitic carbon was employed for analyte enrichment followed by hydrophilic interaction chromatography. Diethylphosphate was applied as internal standard for quantitative determination of the alkyl methylphosphonic acids (AMPAs). By treating the samples with strong cation-exhange columns on Ba, Ag and H form, the major inorganic anions in water were removed by precipitation prior to the SPE-LC–MS determination. The AMPAs could be determined in tap water with limits of detection of 0.01–0.07 μg L⁻¹ with the [M−H]⁻ ions extracted at an accuracy of ±5 mDa. The within and between assay precisions at analyte concentrations of 5 μg L⁻¹ were 2–3%, and 5–9% relative standard deviation, respectively. The developed method was employed for determination of the AMPAs in three natural waters and a simulated waste water sample, spiked at 5 μg L⁻¹. Recoveries of ethyl-, isopropyl- and pinacolyl methylphosphonic acid were 80–91%, 92–103% and 99–106%, respectively, proving the applicability of the technique for natural waters of various origins.     

Trace Analysis of Vanadium in Environment as its Ternary Complex with N-p Methoxyphenyl-2-Furylacrylohydroxamic Acid and 3-(o-Carboxyphenyl)-1-Phenyltriazine-N-Oxide

Abstract

A method is presented for the highly sensitive, selective, and rapid determination of vanadium (V) at sub-microgram levels in rocks, animal tissues, plant tissues and natural waters. The method is based on the selective extraction of vanadium (V) from strongly acidic (3-8 M hydrochloric acid) medium with solution of N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) in chloroform. The reddish-violet extract (molar absorbance 8.6x10³ 1 mole^?1 cm^?1 at λ max 545 nm) is then equilibrated with 3-(o-carboxyphenyl)-1-phenyltriazine-N-oxide (CPPTNO) at pH = 1.5. The resulting ternary complex has enhanced colour (molar absorbance 1.4 × 10⁴ 1 mole^?1 cm^?1 at Λ max 450 nm). The ternary system obeys Beer's Law at 450 nm over the range 0-18 μ g/ml of vanadium. The extraction system achieves 20-fold enrichment of vanadium and enables the determination of the metal down to parts per billion (ng 1^?1) levels. The method tolerates the presence of a large number of anions and cations which are normally present with vanadium in rocks, plant tissues, animal tissues and natural waters. The applicability of the method was tested by the analysis of vanadium in these matrices. MFHA was selected from nine hydroxamic acids as it provided maximum sensitivity and selectivity.     

A simplified mass isotopomer approach to estimate gluconeogenesis rate in vivo using deuterium oxide

We compare a new simplified ²H enrichment mass isotopomer analysis (MIA) against the laborious hexamethylentetramine (HMT) method to quantify the contribution of gluconeogenesis (GNG) to total glucose production (GP) in calves. Both methods are based on the ²H labeling of glucose after in vivo administration of deuterium oxide. The ²H enrichments of plasma glucose at different C‐H positions were measured as aldonitrile pentaacetate (AAc) and methyloxime‐trimethylsilyl (MoxTMS) derivatives or HMT by gas chromatography/mass spectrometry (GC/MS). Two pre‐ruminating fasted Holstein calves (51 kg body mass, BM, age 7 days) received two oral bolus doses of ²H₂O (10 g/kg BM, 70 atom% ²H) at 7:00 h and 11:00 h after overnight food withdrawal. Blood samples for fractional GNG determination were collected at ?24 and between 6 and 9 h after the first ²H₂O dose. The ratio of ²H enrichments C5/C2 represents the contribution of GNG to GP. The ²H enrichment at C2 was calculated based on the ion fragments at m/z 328 (C1‐C6) ‐ m/z 187 (C3‐C6) of glucose AAc. The ²H enrichment at C5 was approximated either by averaging the ²H enrichment at C5‐C6 using the ion fragment of glucose MoxTMS at m/z 205 or by conversion of the C5 of glucose into HMT. The fractional GNG calculated by the C5‐C6 average ²H enrichment method (41.4 ± 6.9%) compared to the HMT method (34.3 ± 11.4%) was not different (mean ± SD, n = 6 replicates). In conclusion, GNG can be estimated with less laborious sample preparation by means of our new C5‐C6 average ²H enrichment method using AAc and MoxTMS glucose derivatives. Copyright © 2010 John Wiley & Sons, Ltd.     

Interference of Humic Substances in the Spectrophotometric Determination of Bromate by Phenothiazines in Natural Waters

Abstract

The spectrophotometric method of bromate (BrO₃ ^?) determination by phenothiazines was applied to natural water samples and the interferences due to the presence of inorganic and humic substances were investigated. Common ions present in natural waters did not interfere and only the less abundant NO₂ ^? and Fe²⁺ exhibited strong interferences. Interferences of the two latter ions, if they existed, could be controlled and the method proved to be accurate and with a low detection limit. However, it was found that the presence of soluble humic substances resulted in positive interference, rendering the method unsuitable for bromate determination in natural waters and restricted its use in pure bromate solutions. This interference can be attributed to the electron acceptor groups invariably existing in the humic molecules. Since humic substances can remain in the water even after its ozonation, they will also contribute to a positive interference in bromate determination in potable waters.     

Single-drop microextraction for the determination of manganese in seafood and water samples

We describe a method for single drop microextraction of manganese from fish, mollusk, and from natural waters using the reagent 1-(2-pyridylazo)-2-naphthol as the complexing agent and chloroform as the fluid extractor. After extraction, the analyte was directly submitted to graphite furnace electrothermal atomic absorption spectrometry. Once optimized, the method has a detection limit of 30 ng L^?1, a limit of quantification of 100 ng L^?1, and an enrichment factor of 16. Its accuracy was verified by applying the procedure to the following certified reference materials: apple leaves, spinach leaves, bovine liver, and mussel tissue. The procedure was also successfully applied to the determination of manganese in seafood and natural waters.

Evaluation of a new electrolytic cold vapor generation system for mercury determination by AFS

In this study we firstly report a new electrolytic cold vapor generation system for mercury determination on Pt/Ti cathode in the presence of organic acid catholyte. Comparing with the traditional inorganic acid, formic acid increased the signal intensity of Hg vapor from electrolytic generation on Pt cathode and reduced the impact of cathode erosion on the stability of signal intensity. Moreover, formic acid has better interference tolerance. The introduction location for carrier gas is probably the most important factor that influences the signal intensity of Hg from electrolytic vapor generation. The effects of the electrolytic conditions and interference ions on the ECVG have been studied. Under the optimized conditions, the detection limit (3σ) of Hg (II) in aqueous solutions is 1.4 ng L⁻¹; a relative standard deviation of 2.3% for 1 μg L⁻¹ Hg was obtained. The accuracy of this method was verified by the determination of mercury in the certified reference materials. This system has been applied satisfactorily to the determination of Hg in Traditional Chinese Medicines samples.     

Determination of methyl mercury in water samples with electromagnetic induction thermal desorption/pyrolysis coupled to atomic fluorescence spectrometry

A novel non-chromatographic method for the pre-concentration and determination of trace methyl mercury in water samples has been proposed. This method included two main steps: (1) The methyl mercury in sample solution was adsorbed on PDMS of the Fe/SiO₂/PDMS bed enrichment column; (2) the analyte was thermally desorbed from the enrichment column and pyrolysed to Hg⁰ in an iron particle bed pyrolysis column by using electromagnetic induction heating technique, and then detected by an on-line coupled atomic fluorescence detector. Several factors affecting the enrichment column preparation and concentration procedure have been investigated and optimised. Under optimal condition, the detection limit (3σ) was 0.2 ng L^–1, along with relative standard deviations of 2.4% (10 ng L^–1, N = 11) for the repeatability study. The enrichment factor obtained was 108. The two standard reference materials (GBW08675, GBW10029) were analysed to validate the present method. This method was successfully applied to the determination of ng L^–1 methyl mercury in water samples.     

Differential electrolytic potentiometric titration method for the determination of ciprofloxacin in drug formulations

A simple and rapid differential electrolytic potentiometric titration method for the determination of ciprofloxacin was developed. The work is based on the fast complexation reaction between iron(III) and ciprofloxacin in a ratio of 1:3, respectively, in sulfuric acid media of 0.09 mol dm⁻³. Among the electrodes tested silver amalgam electrodes were found to be a suitable indicating system. By applying a current density of 0.5 μA cm⁻² to these electrodes and using iron(III) solution of 0.097 mol dm⁻³ as a titrant, normal titration curves were obtained. The method was successfully applied for the determination of ciprofloxacin in drug formulations as low as 4.0 ppm.     

Multisyringe flow injection system for solid-phase extraction coupled to liquid chromatography using monolithic column for screening of phenolic pollutants

In this work a fast, automatic solid-phase extraction procedure hyphenated to HPLC-UV is proposed for screening of priority phenolic pollutants in waters at ng mL⁻¹ levels. A flow through column, containing polystyrene-divinylbenzene sorbent, was incorporated to a multisyringe flow injection system (MSFIA), where the sample loading and analyte elution were carried out after computer control. The MSFIA system also directed the eluent to fill the injection loop of the chromatograph, coupling the sample preparation to its determination. High enrichment factors were attained for phenol and ten of its derivatives (mean value 176 for 50 mL of sample), with LOD values lower than 1 ng mL⁻¹ for the maximum volume of sample used (100 mL). For all analytes, mean recoveries between 89 and 103% were obtained for different water matrices. Certified reference material and a contaminated soil (RTC-CRM 112) were also tested successfully. The determination frequency was 4-10 h⁻¹, providing an automatic, fast and reliable tool for water quality and environmental monitoring.     

Study on Determination of Trace Nickel in Water Samples after Separation/enrichment using Microcrystalline Phenolphthalein Loaded with Chelate

The paper presents a novel method for the separation/enrichment of trace Ni²⁺ using microcrystalline phenolphthalein loaded with chelate prior to the determination by spectrophotometry. The effects of different parameters, such as the dosages of phenolphthalein and sodium diethyldithiocarbamate (DDTC), various salts and acidity on the enrichment yield of Ni²⁺ have been investigated to select the experimental conditions. The possible enrichment mechanism of Ni²⁺ was discussed. The results showed that under the optimum conditions, Ni²⁺ could be quantificationally adsorbed on the surface of microcrystalline phenolphthalein in the form of the chelate precipitate of Ni(DDTC)₂, while K⁺, Na⁺, Ca²⁺, Mg²⁺, Zn²⁺, Fe²⁺, Al²⁺, Pb²⁺ and Cd²⁺ could not be adsorbed at all. Therefore, Ni²⁺ was completely separated from the above metal ions in the solution. A new method for the separation/enrichment and determination of trace nickel using microcrystalline phenolphthalein loaded with chelate was established. The proposed method has been successfully applied to the determination of Ni²⁺ in various water samples, and the results agreed well with those obtained by FAAS method.     

Electrochemical hydride generation atomic absorption spectrometry for determination of cadmium

An electrolytic hydride generation system for determination of another hydride forming element, cadmium, by catholyte variation electrochemical hydride generation (EcHG) atomic absorption spectrometry is described. A laboratory-made electrolytic cell with lead-tin alloy as cathode material is designed as electrolytic generator of molecular hydride. The influences of several parameters on the analytical signal have been evaluated using a Plackett-Burman experimental design. The significant parameters such as cathode surface area, electrolytic current, carrier gas flow rate and catholyte concentration have been optimized using univariate method. The analytical figures of merit of procedure developed were determined. The calibration curve was linear up to 20 ng ml⁻¹of cadmium. The concentration detection limit (3σ, n = 8) of 0.2 ng ml⁻¹ and repeatability (relative standard deviation, n = 7) of 3.1% were achieved at 10.0 ng ml⁻¹. It was shown that interferences from major constituents at high concentrations were significant. The accuracy of method was verified using a real sample (spiked tap water) by standard addition calibration technique. Recovery of 104% was achieved for Cd in the spiked tap water sample.     

Rubidium Determination In Mineral and Thermal Waters By Atomic-Absorption Spectrometry

Abstract

A new procedure for rubidium determination in mineral and thermal waters using flame atomic-absorption spectrometry is described. to supress ionisation interference potassium solution was added. Rubidium can be determined in presence of Ca, Mg, Sr, Li, Cs, Fe, Al, CO² ₃, F^? and S^2? at higher levels that levels of these elements in waters. the precision and accuracy of the method were also investigated. In 163 mineral and thermal waters analysed, the rubidium concentration range is between 0.08 to 0.84 μg mL^?1.     

Mercury determination and speciation analysis in surface waters

A sorbent L-cysteine grafted silica gel has been evaluated for separation and enrichment of dissolved inorganic i-Hg(II) and methylmercury CH₃Hg(I) from surface waters at sub-μg L⁻¹ concentrations. Chemical parameters for mercury species enrichment and separation have been optimized. Analytical schemes for the determination of Hg species, using selective column solid phase extraction (SPE) with continuous flow chemical vapor generation atomic absorption spectrometry (CF-CVG-AAS) or inductively coupled plasma-mass spectrometry (ICP-MS) were developed. Possibilities for on-site SPE enrichment were demonstrated as well. The limits of quantification were 1.5 and 5 ng L⁻¹ for dissolved i-Hg(II) and CH₃Hg(I) by CF-CVG-AAS and 1 and 2.5 ng L⁻¹ by ICP-MS with relative standard deviations between 7–12% and 7–14%, respectively. The chemically modified SPE sorbent has demonstrated high regeneration ability, chemical and mechanical stability, acceptable capacity and good enrichment factors. Results for total dissolved mercury were in reasonable agreement with those from independent analyses by direct ICP-MS determinations for river waters and for estuarine water certified reference material.      

Radiochemical analysis of radionuclides difficult to measure for waste characterization in decommissioning of nuclear facilities

Some radiochemical analytical methods for the determination of important beta-radionuclides for decommissioning are presented. An analytical method is briefly described, which is used for the determination of ³H and ¹⁴C in steel and aluminum by combustion using commercial oxidizer. A leaching method was developed for the determination of ³H in the contaminated silica gel. A simple distillation method is presented for the determination of ¹⁴C in heavy water and wastewater sample. A method developed for the simultaneous determination of ³H, ¹⁴C, ³⁶Cl, ⁵⁵Fe, ⁶³Ni, ⁴¹Ca and ¹²⁹I in concrete, graphite, aluminium, lead, and steel is presented. The developed methods have been successfully used to analyse various materials for characterization of the waste during the decommissioning of Danish nuclear reactors.     

Determination of the enrichment of isotopically labelled molecules by mass spectrometry

A general method for the determination of the enrichment of isotopically labelled molecules by mass spectrometry (MS) is described. In contrast to other published procedures, the method described here takes into account and corrects for measurement errors such as the contribution at M ? 1 due to loss of hydrogen or lack of spectral resolution and provides an uncertainty value for the determined enrichment. The general procedure requires the following steps: (1) evaluation of linearity in the mass spectrometer by injecting the natural abundance compound at different concentration levels, (2) determination of the purity of the mass cluster using the natural abundance analogue, (3) calculation of the theoretical isotope composition of the labelled compound using different tentative isotope enrichments, (4) calculation of ‘convoluted’ isotope distributions for the labelled compound taking into account the purity of the mass cluster determined with the natural abundance analogue and (5) comparison of the isotope distributions measured for the labelled compound with those calculated for different isotope enrichments using linear regression. The method was applied to a series of commercially available ¹³C‐ and ²H‐labelled compounds and to a suite of singly ¹³C‐labelled β₂‐agonist prepared in‐house both by gas chromatography (GC)–MS, GC–tandem MS (MS/MS) and liquid chromatography–MS/MS with satisfactory results. It was observed that the main uncertainty source for the isotope enrichment was the uncertainty in the purity of the measured cluster as determined with the natural abundance compound. Copyright © 2014 John Wiley & Sons, Ltd.     

Study on Separation/Enrichment and Determination of Mercury(II) using Microcrystalline Thymolphthalein Loaded with Ternary Association Complex

The paper presents a novel method for the separation/enrichment of Hg²⁺ using microcrystalline thymolphthalein loaded with ternary association complex prior to the determination by spectrophotometry. The effects of different parameters, such as the dosages of KI and dodecyl trimethyl ammonium bromide (DTAB) and thymolphthalein, various salts and acidity etc. on the enrichment yield of Hg²⁺ have been investigated to select the experimental conditions. The results showed that in the presence of 1.0 g NaCl, when the dosage of 0.1 M KI solution was 1.50 mL and 5.0 × 10⁻³ M dodecyl trimethyl ammonium bromide (DTAB) solution was 1.50 mL respectively, the water‐insoluble ternary association complex of (DTAB)₂(HgI₄) which produced by Hg²⁺ and I⁻, DTAB cation (DTAB⁺) was quantificationally absorbed on the surface of microcrystalline thymolphthalein Therefore, Hg²⁺ was separated completely from Zn²⁺, Mn²⁺, Ni²⁺, Co²⁺, Fe³⁺, Al³⁺, Pb²⁺, Bi³⁺ and Cr³⁺ etc. by contolling acidity. The possible enrichment mechanism of Hg²⁺ was deduced. The proposed method has been successfully applied to the determination of Hg²⁺ in the sample of industrial waster water, and the results agreed well with the dithizone method. The recoveries were 94.5%∼106.5%, and the RSD was 2.0%∼2.8%.