Influence of the physical properties and handling of silica gel modified carbon paste electrodes on the phase transfer of solved Cu(II) ions

EDTA, a powerful chelating agent, is used extensively in soil sciences to determine the bioavailability of trace metals and their possible decontamination from polluted soils. Because of its non-selective nature, the co-dissolution of major elements also occurs, in addition to the extraction of trace metal ions.In this work, the reactivity of trace and major elements (Pb, Cu, Cd, Al, Fe, Ca and Mg) with different concentrations of EDTA was studied in eight soil samples (Burgundy, France). The limit between lack and excess of EDTA with respect to total metal extracted, determined after 24 h of reaction for different types of soil varied from 0.002 to 0.05 M, respectively.For calcareous samples the amount of Pb, Cu and Cd extracted by EDTA was reduced to 50% of that extracted in non-calcareous soils.From the kinetic point of view, the extraction behavior of major elements seemed to depend heavily on excess or lack of EDTA and the soil Ca content. For a lack of EDTA, different competitive behaviors were revealed for the major elements (Al, Ca, Fe and Mg) towards the reagent, depending on the soil matrix.According to these experimental results, the mass balance between the reagent and cations in any EDTA-soil media is strongly controlled by major metal extraction. When choosing the reagent concentration needed to extract the trace metals efficiently, all the extractable metal present in the concerned sample must be taken into account.     

Optimisation of solvent desorption conditions for chemical warfare agent and simulant compounds from Porapak Q using experimental design. Part 2: Extraction of sulphur mustard from steel and glass Porapak tubes

The ion-pair solid-phase extraction (SPE) of 4-alkylphenols followed by derivatization with pentafluoropyridine is demonstrated. Under alkaline conditions, the 4-alkylphenols could be efficiently adsorbed on a C18 SPE cartridge conditioned with an ion-pair reagent, tetra-n-hexylammonium bromide. The ion pairs, ammonium phenolates, formed on the C18 solid phase, were eluted with a solvent containing the derivatizing reagent, pentafluoropyridine, and completely derivatized during the elution. After optimization of the adsorption and derivatization, we established a method for the determination of the 4-alkylphenols in water samples. The method showed good linearity between 20 and 1000 ng (200-10,000 ng for nonylphenol). By processing 20-ml samples, the method detection limits (MDL) were in the range of 5.2-8.9 ng/l for the 4-alkylphenols (76 ng/l for nonylphenol). To evaluate its applicability to a real aqueous matrix, several river water samples were analyzed.     

粉末压片-X射线荧光光谱法测定富硅土壤和沉积物样品中的5种重金属元素

X射线荧光光谱法测定土壤和沉积物中的重金属具有简便、快速、准确等优点,但现有的环境行业标准方法不适用于SiO2含量大于80%的土壤和沉积物。为提高X射线荧光光谱法测定土壤和沉积物中的重金属在环境监测领域中的适用性,建立基于粉末压片-X射线荧光光谱法测定富硅土壤和沉积物中重金属的分析方法。通过选取富硅的土壤和沉积物标准物质提高校准曲线的测量范围以及优化各元素的测量条件,探讨基体效应和谱线重叠干扰、研究压片制样的最佳压力等途径,测定富硅土壤和沉积物中的Pb、Cr、Cu、Ni、Zn。结果表明在已优化的测定条件下,通过延长校准曲线的测量上限,保证待测元素含量在校准曲线范围内,同时采用经验系数法和康普顿散射内标法校正基体效应,可进一步提高方法的准确度和精密度。方法比对结果显示该方法的测定结果与原子吸收光谱法的测定结果无显著性差异。选用2种不同的富硅标准物质进一步验证方法的精密度和准确度,Pb、Cr、Cu、Ni、Zn的测定结果与标准物质认定值的对数误差为0.002~0.08,相对标准偏差为1.0%~4.6%。该方法的精密度和正确度满足土壤和水系沉积物环境监测分析的技术要求,具有良好的应用前景。     

Determination of Hg,As, Pb,and Cd in Orchard Soils by Sequential Injection Vapor Generation Atomic Fluorescence Spectrometry

An analytical procedure was developed for determination of Hg, As, Pb, and Cd in soil samples using sequential injection vapor generation atomic fluorescence spectrometry (SI-VG-AFS) with sample preparation by microwave digestion system. The effects of analytical conditions on the fluorescence intensity were investigated and optimized. Under the optimized condition, the detection limits of the method were 5, 68, 40, and 3 ng L^?1 for Hg, As, Pb, and Cd, respectively. The accuracy of method was verified by the determination of the certified reference soil, and the recoveries for Hg, As, Pb, and Cd were in the range of 98.7–106.1%. The proposed method has been successfully applied to determine the heavy metals in navel orange orchard soils in Ganzhou, and the environmental quality of the orchard soils was assessed based on the content of the heavy metals. According to the second criterion of environmental quality standard for soils, Pb content in all soil samples collected from the orchards of 18 districts were within safe limits, but a few orchards were slightly contaminated with Hg, As, and Cd. Comparison of heavy metal mean concentrations with the safe limits of environmental quality standard for soils, the quality of Ganzhou navel orange orchard soils were in line with the request of the green food production base.     

Extraction procedures for the determination of heavy metals in contaminated soil and sediment

Extraction tests are commonly used to study the mobility of metals in soils and sediments by mimicking different environmental conditions or dramatic changes on them. The results obtained by determining the extractable elements are dependent on the extraction procedure applied. The paper summarises state of the art extraction procedures used for heavy metal determination in contaminated soil and sediments. Two types of extraction are considered: single and sequential. Special attention is paid to the Standard, Measurement and Testing projects from the European Commission which focused on the harmonisation of the extraction procedures and on preparing soil and sediment certified reference materials for extractable heavy metal contents.     

Extractable chromium determination in soils by AAS

The lixiviation of trace metals from soils using selective extractants gives valuable information, especially for agricultural purposes. The two reagents validated by a group of European researchers coordinated by the Measurements and Testing Program (MAT) of the Commission of the European Community, in single extraction procedures, are EDTA 0.05 moll^–1 and CH₃COOH 0.43 moll^–1.This paper reports the effect of these extractants upon chromium determination in extracts by AAS. Matrix effects were studied in extracts of two soils of different origin: a terra rossa soil from a Mediterranean area and a sewage amended soil.For the FAAS technique, the matrix effects were studied for air-acetylene and nitrous oxide-acetylene flames and using Cr(VI) and Cr(III) as standard solutions. The interfering effects observed are circumvented by the use of 1% 8-hydroxyquinoline as suppressor agent.For the ETAAS technique, charring and atomization curves were obtained for extracts in each reagent and after setting up the graphite furnace program, matrix effects were studied. Different matrix modifiers (Mg(NO₃)₂, Pd and Triton X-100) were also tested.Once the analytical method had been established, single extraction procedures were applied in the two soils, determining the percentage of extractable chromium in relation to the total content.     

Simultaneous determination of pharmaceuticals, endocrine disrupting compounds and hormone in soils by gas chromatography-mass spectrometry

Analytical methods have been developed for simultaneous determination of six different pharmaceuticals and personal care products (PPCPs) (clofibric acid, ibuprofen, naproxen, ketoprofen, diclofenac, and triclosan), three endocrine disrupting compounds (EDCs) (4-tert-octylphenol, 4-n-nonylphenol, and bisphenol A (BPA)) and one estrogenic compound (estrone) in soil matrix. The soils were extracted by different solvents with the help of an ultrasonic treatment at 42 kHz, followed by a solid phase extraction (SPE) as a cleanup procedure. The purified extracts were derivatized with N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide (MTBSTFA) and then analyzed by GC-MSD (SIM mode). The method was evaluated by testing the following variables: initial spiking levels, extraction solvents, solvent volumes, and soil types (sandy and clay soils). For 5 g of soil, four successive extraction steps with the mixture of acetone-ethyl acetate provided satisfactory recoveries. In the sandy soil, the recoveries of all the compounds were from 63.8 to 110.7% for the spiking level of 100 ng/g dry soil, and from 52.2 to 108.2% for 5 ng/g dry soil, respectively. Result was similar for the clay soil. The precision across all recoveries was high, suggesting that this method has a good reproducibility. The method was successfully employed to soil samples collected from a golf course irrigated with reclaimed wastewater in southern California, and resulted in the detection of clofibric acid, ibuprofen, naproxen, triclosan, bisphenol A, and estrone at ng per gram dry weight concentration levels. The method is robust and simple, and provides straightforward analyses of these current-emerging trace organic pollutants in solid matrices.     

Simultaneous selective detection of organophosphate and phthalate esters using gas chromatography with positive ion chemical ionization tandem mass spectrometry and its application to indoor air and dust

A selective and sensitive method for the simultaneous determination of 14 organophosphate and six phthalate esters using gas chromatography (GC) and mass spectrometry (MS) is presented. Both of these compound classes are frequently found in the indoor environment due to their use as bulk additives in numerous polymers, consumer products and building materials. GC/MS utilizing positive ion chemical ionisation (PICI) in selected reaction monitoring (SRM) mode with isobutane as the reagent gas was found to be the best of the tested methods; it proved superior to electron ionisation (EI) in selected ion monitoring (SIM) mode and to PICI using methane as the reagent gas. The method was applied to indoor air samples collected by active air sampling using solid‐phase extraction (SPE) cartridges. Organophosphates and phthalates were simultaneously determined with method detection limits (MDLs) in the range of 0.1–47 ng m^?3. For most compounds the MDLs were ≤0.2 ng m^?3, but due to the presence of some of these ubiquitous indoor air pollutants in the blanks, significantly higher MDLs were observed for a few compounds. Finally, the method was also applied in the screening of a much more complex sample matrix, indoor dust. Copyright © 2010 John Wiley & Sons, Ltd.     

Simultaneous extraction and determination of fluoroquinolones,tetracyclines and sulfonamides antibiotics in soils using optimised solid phase extraction chromatography-tandem mass spectrometry

An analytical method was developed for the simultaneous extraction and determination of 18 fluoroquinolones (FQs), tetracyclines (TCs) and sulfonamides (SAs) antibiotics from soils using solid phase extraction and liquid chromatography-tandem mass spectrometry. The soils were extracted by different solvents with the help of mechanical shaking and ultrasonic treatment at 59?kHz, followed by a strong anion exchange (SAX) cartridge to clean up soil samples and a hydrophilic lipophilic balance (HLB) cartridge as enrichment. The method was evaluated by testing the following variables: extraction solvents, the type of SPE cartridges, solvent volumes, initial spiking levels and soil types (silty clay loam and clay loam soils). The soil extraction method was validated using these two types of soils, representing two typical agricultural soils in northern China. For 2?g soil, the extraction steps with the mixture of potassium phosphate buffer and acetonitrile (ACN) (1/1, v/v, pH 3.2) provided satisfactory recoveries. In the clay loam soil, the recoveries of all the compounds were from 56% to 89% at the spiking level of 50?µg?kg^?1 soil, and from 69% to 97% at the spiking level of 200?µg?kg^?1 soil, respectively. Recoveries in silty clay loam soil were similar to that in clay loam. The method was successfully employed using soil samples collected from a farmland and afforestion area irrigated with sewage in northern China. The result indicates that trace antibiotics in sewage may accumulate in soil irrigated by river water containing sewage.     

A novel approach for the determination of detection limits for metal analysis of environmental water samples

Despite the widespread use of the USEPA method (U.S. Environmental Protection Agency, 40 CFR 136 Appendix B) for the determination of method detection limit (MDL), criticisms have been raised that the method does not account for measurement bias and outliers that subsequently lead to a common misunderstanding of the requirement for the determination of MDL. This paper demonstrates that it is difficult to follow the USEPA method for verifying the MDL for analysis involving multiple metals and proposes a precision and bias criterion for determining the MDL. A multiple-point fitted profile, based on the correlation between relative standard deviation (RSD) and concentration, is used to derive a robust MDL value. Representative examples of As, Ca, Cr, and Cu are used to illustrate this procedure. A procedure for identifying outliers is also discussed.     

NH4NO3 extractable trace element contents of soil samples prepared for proficiency testing--a stability study.

In view of its intended use as a sample for proficiency testing or as a reference material the stability of the extractable trace element contents of a soil from an irrigation field was tested using the extraction with 1 mol/L ammonium nitrate solution according to DIN 19730. Therefore, changes of the extractability of sterilized and non sterilized soil samples stored at different temperatures were evaluated over a period of 18 months. Sets of bottles were kept at -20 degrees C, +4 degrees C, about +20 degrees C and +40 degrees C, respectively. The NH4NO3 extractable contents of Cd, Cr, Cu, Ni, Pb and Zn were determined immediately after bottling and then after 3, 6, 12 and 18 months with ICP-AES or ETAAS. Appropriate storage conditions are of utmost importance to prevent deterioration of soil samples prepared for the determination of NH4NO3 extractable trace element contents. Temperatures above +20 degrees C must be avoided. The observed changes in the extractability of the metals (especially for Cr and Cu) most likely could be related to thermal degradation of the organic matter of the soil. There is no need to sterilize dry soil samples, because microbiological activity in soils with a low moisture content appears to be negligible with regard to trace element mobilization.     

Determination of hexabromocyclododecane diastereoisomers in air and soil by liquid chromatography-electrospray tandem mass spectrometry

Hexabromocyclododecanes (HBCDs), used as additive brominated flame retardants, are of high concern due to their widespread use and increasing levels in various environmental systems. High-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-MS/MS) was developed for the determination of HBCD diastereoisomers. A detailed study was carried out to optimize the composition of the mobile phase involving methanol/acetonitrile/water, and the values of MS/MS parameters. It was found that the mobile phase could simultaneously affect the chromatographic separation and sensitivity. The instrumental limits of detection (LODs) on column in this study were 0.5, 0.3 and 0.3 pg for alpha-HBCD, beta-HBCD and gamma-HBCD, respectively. The effects of extracted matrix components on HBCD determination were investigated by spiking air and soil sample extracts with three 13C-labelled individual stereoisomers. The results indicated that the responses of the HBCD analysis in air and soils were not significantly affected by matrix effects. The method reported here was further applied to the air and soil samples. Three HBCD diastereoisomers were detected in all the air and soil samples, with levels ranging from 1.2 to 1.8 pg/m3 and 1.7 to 5.6 ng/g dry weight, respectively.     

Factors affecting arsenic speciation in environmental samples: sample drying and storage

Arsenic is a ubiquitous element. Its toxicity, mobility, and bioaccumulation depend usually on its chemical form, and therefore, arsenic speciation is indispensable for the assessment of environmental risk and human hazard. Little is known about the effect of sample preparation procedures, such as drying and storage, on the resulting arsenic speciation. In this study, we investigated the influence of different drying methods and storage conditions on the arsenic speciation in mineral soils, organic soils, and plants. Drying soils and plants using different methods may change the concentrations of the total methanol–water (20%,?v/v) extractable arsenic, the proportion of organic arsenic and the ratio of arsenite-to-arsenate. Loss of methanol–water extractable arsenic compounds (up to 63%) was observed particularly in the samples rich in water. Following drying, the speciation of organic arsenic changed less than that of inorganic arsenic. Drying showed little influence on the total arsenic determination. None of the storage methods tested could preserve the arsenic speciation in organic soils and plants, although arsenic speciation after one-month storage varied less in freeze-dried samples than wet samples. Storage of the samples at low temperatures (2 or??20°C) had the largest impact on the samples rich in organic matters, leading to less arsenic being extractable by methanol–water. Both drying and storage of the soil and plant samples changed apparently the arsenic speciation. Therefore, we recommend conducting the arsenic speciation possibly with fresh and wet samples, so that the results of arsenic speciation may be more approaching the original states.     

Influence of the soil matrices on the analytical performance of headspace solid-phase microextraction for organotin analysis by gas chromatography-pulsed flame photometric detection

Organotin compounds (OTCs) have been identified in a variety of environmental media (air, surface water, groundwater, soil and sediments). In the past, much attention was assigned to the study of the OTCs content in biological samples, water and sediments. Little information about OTCs in soil is available. In this work, a procedure for butyl and phenyltin determination in soils by headspace-solid-phase microextraction (HS-SPME) gas chromatography-pulsed flame photometric detection (GC-PFPD) was investigated. For SPME analysis, a polydimethylsiloxane (PDMS) coating was applied. Peat soil rich in organic matter and with a high cation-exchange capacity (CEC), and clay soil low in organic matter and with a low CEC were analysed. The influence of these different soil matrices on HS-SPME analysis was evaluated by spiking of samples. In general, the recoveries for the two spiked soils exceeded 80%. The repeatability of the method was better than 10%. The limits of detection (LODs) and limits of quantification (LOQs) were in the ng S ng(-1) range. The technique may be reliably applied for the determination of butyltins and monophenyltin in soils, while it shows some limitations for the analysis of di- and triphenyltin (TPhT).     

Limitations in the analytical use of invertase inhibition for the screening of trace mercury content in environmental samples.

The possibility of screening the mercury(II) content in real environmental samples based on inhibition of the activity of dissolved invertase has been examined. The extent of inhibition was measured with an amperometric glucose biosensor with glucose oxidase immobilized on a membrane. Data concerning the stability and reproducibility of measurements are provided. The effects of heavy metals on the inhibition of invertase, together with that of common anions such as chloride, nitrate and sulfate are reported. The determination of mercury using this procedure has been carried out in samples of natural and waste water samples of various origins already analyzed by ICP-AES, by spiking ppb levels of mercury(II). Differences in the inhibiting effect of the samples and in the recoveries were found and are discussed.     

The utilization of modified BCR three-step sequential extraction procedure for the fractionation of Cd, Cr, Cu, Ni, Pb and Zn in soil reference materials of different origins

A modified three-step sequential extraction procedure for the fractionation of heavy metals, proposed by the Commission of the European Communities Bureau of Reference (BCR) has been applied to the Slovak reference materials of soils (soil orthic luvisols, soil rendzina and soil eutric cambisol), which represent pedologically different types of soils in Slovakia. Analyses were carried out by flame or electrothermal atomic absorption spectrometry (FAAS or ETAAS). The fractions extracted were: exchangeable (extraction step 1), reducible-iron/manganese oxides (extraction step 2), oxidizable-organic matter and sulfides (extraction step 3). The sum of the element contents in the three fractions plus aqua-regia extractable content of the residue was compared to the aqua-regia extractable content of the elements in the origin soils. The accuracy obtained by comparing the determined contents of the elements with certified values, using BCR CRM 701, certified for the extractable contents (mass fractions) of Cd, Cr, Cu, Ni, Pb and Zn in sediment following a modified BCR-three step sequential extraction procedure, was found to be satisfactory.     

Optical molecular fluorescence determination of ultra-trace beryllium in occupational and environmental samples using highly alkaline conditions

Exposures to beryllium (Be), even at extremely low levels, can cause severe health effects in a percentage of those exposed; consequently, occupational exposure limits (OELs) promulgated for this element are the lowest established for any element. This work describes the advantages of using highly alkaline dye solutions for determination of Be in occupational hygiene and environmental samples by means of an optical molecular fluorescence technique after sample extraction in 1–3% (w?w^?1) aqueous ammonium bifluoride (NH₄HF₂). Improved attributes include the ability to further enhance the detection limits of Be in extraction solutions of high acidity with minimal dilution, which is particularly beneficial when NH₄HF₂ solutions of higher concentration are used for extraction of Be from soil samples. Significant improvements in Be method detection limits (MDLs) are obtained at levels manyfold below those reported previously for this methodology. Notably, MDLs for Be of <0.01 ng L^?1 /0.1 ng per sample have been attained, which are superior to MDLs routinely reported for this element by means of the most widely used ultra-trace elemental measurement technique, inductively coupled plasma mass spectrometry (ICP-MS). Very low MDLs for Be are essential in consideration of reductions in OELs for this element in workplace air by health organisations and regulatory agencies in the USA and internationally. Applications of enhanced Be measurements to air filter samples, surface wipe samples, soils and newly designed occupational air sampler inserts are illustrated.     

Impact of industrial activities on total chromium in alluvial Egyptian soils as determined by neutron activation analysis

Twenty-one surface (0-30 cm) soil samples were collected from different locations in Egypt representing non-, moderately and highly polluted soils. The aim of this study was to evaluate the total Cr content in alluvial soils of Nile Delta in Egypt using neutron activation analysis (NAA). The prominent gamma-ray line at 320 keV was efficiently used for ⁵¹Cr determination. The results indicated that the Cr concentration in non-polluted soil samples ranged between 17.57 to 25.0 ppm. Chromium concentration in moderately polluted soils ranged between 34.65 to 41.45 ppm. The highest Cr levels, ranged from 71.97 to 87.03 ppm, were observed in soil samples collected from, either highly polluted agricultural soils due to prolonged irrigation with industrial wastewater or surface soil samples from industrial sites. Neutron activation techniques has shown to provide a good method for analysis of wide variety of samples of various fields of interest. It is applicable to multi-element analysis for both solid and liquid samples. NAA technique could be used successfully for the determination of heavy metals due to its high sensitivity. This revised version was published online in August 2006 with corrections to the Cover Date.     

Simultaneous determination of fluoroquinolone, sulfonamide, and trimethoprim antibiotics in wastewater using tandem solid phase extraction and liquid chromatography-electrospray mass spectrometry

A robust and sensitive method for the detection of fluoroquinolones, sulfonamides and trimethoprim has been developed. Wastewater samples were acidified and extracted through an anion-exchange cartridge in tandem with a hydrophilic-lipophilic balance (HLB) cartridge, a procedure that reduced interferences from wastewater organic matter. The extracted antibiotics were analyzed using liquid chromatography electrospray mass spectrometry and selected ion monitoring. Quantification of antibiotics was assessed both by internal standard and standard addition methods. Average recoveries for a range of wastewater matrices were 37 to 129% for a 1 microg/L spiking concentration. The method detection limits (MDLs) of antibiotics in deionized water, final and secondary effluent ranged from 2 to 7 ng/L, from 20 to 50 ng/L, and from 30 to 90 ng/L, respectively. Assessment of matrix interference shows that signal suppression and MDL increases with higher amounts of organic matter in the sample. Analyses of samples from two municipal wastewater treatment plants indicate that ciprofloxacin, ofloxacin, sulfamethoxazole and trimethoprim are present in the secondary effluents at median concentrations of 100-160, 205-305, 395-575, and 40-705 ng/L, respectively.     

Single and Sequential Extraction in Sediments and Soils

Abstract

The determination of extractable trace metal contents in soils and sediments is currently performed in many laboratories to assess the bioavailable metal fraction (and related potential phyto-toxic effects) and the importance and possibility of mobilization of trace metals from polluted soil, sludge and sediment upon landfill application. Single and sequential extraction schemes are used for the assessment of the different “forms” of trace metals (e.g. “mobile/bioavailable”, “carbonate-bound” etc.). The lack of uniformity in the different extraction procedures used throughout the world does not allow the results to be compared or the procedures to be validated which has led to many criticisms in the past few years. Moreover, the lack of suitable reference materials for this type of operationally defined determinations did not enable the quality of the measurements to be controlled. Owing to the need for establishing common schemes for single and sequential extractions as well as for the improvement of the quality of extractable trace metal determinations in soil and sediments, the Community Bureau of Reference (BCR) has organised a project which results along with the state of the art of extractable trace metal determinations, use and applicability of extraction schemes and analytical limitations were decided to be thoroughly discussed in a workshop. This paper presents its main conclusions.