Sediment Standard Reference Material Research Articles

Organic matter biomarker and 13C NMR characteristics of soil and sediment standard reference materials from China.

Soil and sediment organic matter (OM) in terrestrial environments represent two critical organic carbon pools on Earth and are likely subject to distinct degrees of oxidation and modification. However, few studies have identified critical molecular-level characteristics that differentiate soil and sediment OM from various climate zones. Using biomarkers and solid-state 13C nuclear magnetic resonance (NMR) spectroscopy analyses, we studied the OM characteristics of 11 soil and 7 sediment standard reference materials (SRMs) originating from various geographical locations in China. Results showed significantly higher concentrations of lignin phenols in sediment OM than in soil OM, which may result from protection by higher contents of CaO and less microbial degradation in sediments. Nevertheless, the relative abundances of solvent-extractable lipids (alkanes, alkanols, and alkanoic acids) and ester-bound cutin and suberin biomarkers did not differ significantly between soil and sediment SRMs. The concentrations of lignin biomarkers decreased with increasing weathering degree of the soil, while cutin biomarkers increased with mean annual temperature and precipitation. This phenomenon was not observed in sediment SRMs. This study reveals the distinct OM characteristics between Chinese soil and sediment SRMs and provides fundamental data for future studies to link OM characteristics and functions.

Speciation of chromium in river sediments by graphite furnace-atomic absorption spectrometry after microwave-assisted extraction

ABSTRACT Rivers could be polluted by receiving wastes from municipal and industrial sources as well as runoff from agricultural land. This could leave river sediments contaminated with potentially toxic elements (PTEs) including chromium (Cr). The aim of this study was to assess and quantify total Cr and hexavalent Cr (Cr(VI)) in sediment samples, obtained from Mokolo and Blood Rivers in the Limpopo Province, South Africa. Sediment samples were collected from ten sampling points from each river. Microwave-assisted acid digestion and microwave-assisted extraction methods were employed to obtain a simple, rapid and safe method for the determination of total Cr and Cr(VI) in sediments, respectively. The accuracy of the method was confirmed by employing a sediment standard reference material (SRM 8704). Total Cr and Cr(VI) in sediment samples were quantified using flame-atomic absorption spectrometry (F-AAS) and graphite furnace-atomic absorption spectrometry (GF-AAS), respectively. The total Cr concentrations in sediments of Blood and Mokolo Rivers ranged from 129 to 253 μg/g and 25.7 to 193 μg/g, respectively. The Cr(VI) in sediments was extracted by employing 0.1 M Na2CO3 as a leaching reagent. The extraction procedure was followed by atomic spectrometric measurements and provided satisfactory results with percentage recoveries of 94.9% to 105%. The leached Cr(VI) was quantified by GF-AAS after filtration of the sample solutions through a hydrophilic Millipore PVDF 0.45 µm filter. The levels of Cr(VI) in sediment samples of Blood and Mokolo Rivers were in the range of 0.410 to 1.32 μg/g and 0.180 to 1.04 μg/g, respectively. Low limit of detection (LOD) and limit of quantification (LOQ) values were achieved using the leaching method described in this study.

Errors in alkylated polycyclic aromatic hydrocarbon and sulfur heterocycle concentrations caused by currently employed standardized methods

Alkylated polycyclic aromatic hydrocarbon (PAH) and polycyclic aromatic sulfur heterocycle (PASH) standardized methods often rely on gas chromatography/mass spectrometry operated in the selected ion monitoring mode (GC/MS-SIM). The objective of this study is to develop a method that produces accurate data while minimizing sample preparation and achieving low levels of detection. Most standardized methods are based on acquiring a given homologue's molecular ion (1-ion). Some methods include a second, confirming ion (2-ion) in the hopes of excluding non-target ion signals from the total homologue peak area. Although all methods use homologue-specific retention windows, these windows differ greatly among the methods. In this paper we evaluate, for the first time, errors in quantitation caused by using different windows as well as common ion effects when target and/or matrix compounds coelute. Two NIST-certified Standard Reference Materials (SRMs), crude oil SRM 1582 and marine sediment SRM 1941b, were analyzed by five standardized methods and by the new method we developed, which relies on spectral deconvolution of three to five ions per PAH/PASH and as many fragmentation patterns as needed to correctly identify the C1 to C4 homologues (MFPPH). All of the standardized methods overestimated the concentrations of the majority of alkylated homologues whereas MFPPH obtained values much closer to NIST-certified concentrations. Rather than straight-line integration of all peaks in the retention window or recognizing peak patterns, the MFPPH data analysis software integrates only those peaks that meet the compound identity criteria.

Accurate Determination of Sulphur Content in Sediments by Double Focusing Inductively Coupled Plasma Mass Spectrometry Combined with Microwave Digestion and Studies on Related Matrix Effect

Abstract A robust method for measuring sulphur content in sediments was established using double focusing inductively coupled plasma mass spectrometry at medium resolution combined with microwave digestion technique. The capability of Standard curve method (SCM) and Standard addition method (SAM) using Rh as internal standard was compared in correction of the matrix effect. The results showed that the matrix effect was not suppressed by SCM, but was effectively eliminated by SAM with drawback of low sample throughout. Therefore, the Standard addition calibration method (SACM) was creatively proposed in this study, which could simply and easily correct the matrix effect as the matrix content of sample and standard solution was matched within ±50%. The detection limit and liner range of this method were proved to be 0.5 mg kg −1 and 3.0–1000 μg L −1 , respectively, with spiked recovery of 95.8%-99.2%. Four sediment standard reference materials GBW07306, GBW07309, GBW07313 and SRM1646a were measured repetitively with the obtained sulphur contents of (853 ± 14) μg g −1 (2σ, n = 12), (181 ± 7) μg g −1 (2σ, n = 9), (3131 ± 52) μg g −1 (2σ, n = 12) and (3543 ± 70) μg g −1 (2σ, n = 9), respectively. The relative error of the four reference materials was +8.8%, +13.3%, +1.0% and +0.7%, respectively, with precision (RSD) less than 2%. This method was applied to measure the sulphur content in the sediment cores collected in the Yangtze Estuary and Hangzhou Bay. This proposed method was demonstrated as an accurate and rapid way of determining sulphur content in great batch of sediment samples, and has a broad application range including soil samples.

Novel Extractant Impregnated Resin for Thorium Preconcentration from Different Environmental Samples: Column and Batch Study

A developed method based upon impregnation of Isonitroso-4-methyl-2-pentanone (HIMP) as extractant on Amberlite XAD-4 for Th4+ enrichment and spectrophotometric determination in a variety of samples were reported. This Extractant Impregnated Resin (EIR) sorbent is characterized by Fourier Transforms-Infrared Spectrometer (FT-IR), Field Emission-Scanning Electron Microscope (FE-SEM), and Brunauer-Emmett-Teller (BET) analysis. The EIR packed in column was studied for various parameters to optimize sorption desorption condition for Th4+. Sorption of Th4+ from aqueous solution onto EIR was studied and equilibrium isotherms, kinetics were determined. These investigations facilitate its determination in different real samples. The developed method was validated by analyzing lake sediment standard reference material (IAEA-SL-1).

Distribution of polycyclic aromatic hydrocarbons in sediments of Akaki River, Lake Awassa, and Lake Ziway, Ethiopia.

The quantification of 14 polycyclic aromatic hydrocarbons (PAHs) was carried out in sediment samples collected from Akaki River, Lake Awassa, and Lake Ziway, Ethiopia. The concentration of PAHs in the samples was determined using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode, after microwave-assisted extraction (MAE), using acetone/n-hexane (1:1, v/v) mixture. The accuracy of the method was determined by extracting and analyzing New York/New Jersey waterway sediment standard reference material (SRM 1944). The measured concentrations of PAHs in SRM 1944 agreed well with the certified values. In samples from Akaki River, Lake Awassa, and Lake Ziway, the total content of PAHs determined ranged from 0 to 3070ng/g (average 534ng/g), 24.9 to 413ng/g (average 169ng/g), and 15.0 to 305ng/g (average 175ng/g), respectively. Source ratios indicated that the PAHs were mainly from petrogenic origin. Sediments from all sampling sites indicated negligible levels of toxicity with no risk of adverse biological effects.

Co-extraction and simultaneous determination of multi-class hydrophobic organic contaminants in marine sediments and biota using GC-EI-MS/MS and LC-ESI-MS/MS

A multi-residue analytical method was developed involving co-extraction and simultaneous determination of 89 hydrophobic organic contaminants (HOCs) in marine sediments and biota using gas chromatography-electron ionization-triple quadrupole mass spectrometry (GC-EI-MS/MS) and liquid chromatography-electrospray ionization-triple quadrupole mass spectrometry (LC-ESI-MS/MS). Target analytes include polychlorinated biphenyls (PCBs), pesticides, chlorobenzenes, brominated and chlorinated flame retardants, nitro-aromatic and polycyclic musks, triclosan and methyl triclosan. Spike-recovery experiments showed relative recoveries of analytes were generally between 70% and 130%. Analyses of a sediment standard reference material (SRM 1944) demonstrated recoveries between 80% and 120% for certified concentrations of individual PCBs and pesticides. Method detection limits of individual compounds ranged from 0.1 to 57.1pg/g dw for sediments and 0.1 to 22.8pg/g ww for biota. A field survey of sediments and biota from Singapore's marine environment demonstrated the occurrence of polycyclic and nitro-aromatic musks (galaxolide, tonalide, musk ketone, etc.), halogenated flame retardants (syn- and anti-dechlorane plus (DP), α, β and γ-hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBPA), etc.), as well as triclosan and methyl triclosan. Galaxolide exhibited relatively high concentrations, with highest levels in polychaete worms (161.7±72.5ng/g ww) and clams (546.8±220.3ng/g ww) from mangroves. Triclosan and methyl triclosan levels were highly correlated in sediments (r2=0.9752), while syn- and anti-DP were strongly correlated in biota (r2=0.9279). anti-DP/syn-DP stereoisomer ratios were typically >1 and ranged between 0.94 and 29.2 in sediments and biota samples. γ-HBCD exhibited the highest concentrations among HBCD isomers in sediments. Conversely, α-HBCD was the dominant HBCD isomer in biota.

Speciation analysis of 129I, 137Cs, 232Th, 238U, 239Pu and 240Pu in environmental soil and sediment

The environmental mobility and bioavailability of radionuclides are related to their physicochemical forms, namely species. We here present a speciation analysis of important radionuclides including 129I (also 127I), 137Cs, 232Th, 238U and plutonium isotopes (239Pu and 240Pu) in soil (IAEA-375) and sediment (NIST-4354) standard reference materials and two fresh sediment samples from Øvre Heimdalsvatnet Lake, Norway. A modified sequential extraction protocol was used for the speciation analysis of these samples to obtain fractionation information of target radionuclides. Analytical results reveal that the partitioning behaviour, and thus the potential mobility and bioavailability, are exclusively featured for the individual radionuclide. Iodine is relatively mobile and readily binds to organic matter, while plutonium is mainly bound to both organic matter and nitric acid leachable fractions. Thorium is predominated in nitric acid leachable fraction and caesium is primarily observed in nitric acid and aqua regia leachable fractions and residue. Our analytical results reveal that around 50% of uranium might still remain in the residue which could not be extracted with aggressive acid, namely, aqua regia.

Application of ion molecule reaction to eliminate WO interference on mercury determination in soil and sediment samples by ICP-MS

Mercury is subject to severe tungsten oxide (WO) interference in the direct ICP-MS analysis for soil or sediment samples. In this study, a method based on ion molecule reaction (IMR) was used to eliminate the WO spectral interference in a dynamic reaction cell (DRC). Interfered ion (202WO+) was drastically oxidized to higher oxide ions (218WO2+ or 234WO3+) by O2 as the reaction gas in the DRC, while the analyte ion (202Hg+) cannot react with O2. Under the optimized O2 flow rate (1.9 mL min−1) and DRC rejection parameter q (Rpq, 0.80), the background signal was reduced by up to 1000-fold at m/z 202 and the limit of quantitation (LOQ, 10σ) for 202Hg was 1 ng g−1. The proposed method was applied to direct determination of Hg in a series of soil and sediment standard reference materials (SRMs) and the satisfactory results indicate that it has great potential for the determination of trace or ultra-trace level mercury in various environmental or geological samples.

Direct determination of trace cadmium in environmental samples by dynamic reaction cell inductively coupled plasma mass spectrometry

Cadmium is subject to significant Zr and Mo based oxide/hydroxide interferences in ICP-MS analysis of environmental samples. In this work, a dynamic reaction cell (DRC) technology was used to eliminate these metal oxide/hydroxide interferences. The potentially interfering ions 94Zr 16OH +, 94Mo 16OH + and 95Mo 16O + on 111Cd + were oxidized to higher oxides 94ZrO 2H +/ 94ZrO 3H +, 94MoO 2H +/ 94MoO 3H +, and 95 MoO 2 + / 95 MoO 3 + by O 2 as the reaction gas in DRC. Under the optimized O 2 flow rate (2.0 mL min −1) and DRC rejection parameter q (Rpq, 0.75), the background signal was reduced by up to 100-fold at m/z 111 and the limit of quantitation (LOQ, 10σ) of 0.1 ng g −1 was obtained. The proposed method was applied to direct analysis of trace Cd in a series of soil and sediment standard reference materials and the satisfactory results showed that it has great potential for the direct determination of trace or ultra-trace levels of cadmium in environmental samples.

Determination of polybrominated diphenyl ethers in environmental standard reference materials

Standard reference materials (SRMs) are valuable tools in developing and validating analytical methods to improve quality assurance standards. The National Institute of Standards and Technology (NIST) has a long history of providing environmental SRMs with certified concentrations of organic and inorganic contaminants. Here we report on new certified and reference concentrations for 27 polybrominated diphenyl ether (PBDE) congeners in seven different SRMs: cod-liver oil, whale blubber, fish tissue (two materials), mussel tissue and sediment (two materials). PBDEs were measured in these SRMs, with the lowest concentrations measured in mussel tissue (SRM 1974b) and the highest in sediment collected from the New York/New Jersey Waterway (SRM 1944). Comparing the relative PBDE congener concentrations within the samples, we found the biota SRMs contained primarily tetrabrominated and pentabrominated diphenyl ethers, whereas the sediment SRMs contained primarily decabromodiphenyl ether (BDE 209). The cod-liver oil (SRM 1588b) and whale blubber (SRM 1945) materials were also found to contain measurable concentrations of two methoxylated PBDEs (MeO-BDEs). Certified and reference concentrations are reported for 12 PBDE congeners measured in the biota SRMs and reference values are available for two MeO-BDEs. Results from a sediment interlaboratory comparison PBDE exercise are available for the two sediment SRMs (1941b and 1944).

Preconcentration of Pb(II), Cr(III), Cu(II), Ni(II) and Cd(II) ions in environmental samples by membrane filtration prior to their flame atomic absorption spectrometric determinations

A method for separation–preconcentration of Pb(II), Cr(III), Cu(II), Ni(II) and Cd(II) ions by membrane filtration has been described. The method based on the collection of analyte metal ions on a cellulose nitrate membrane filter and determination of analytes by flame atomic absorption spectrometry (FAAS). The method was optimized for several parameters including of pH, matrix effects and sample volume. The recoveries of analytes were generally in the range of 93–100%. The detection limits by 3 sigma for analyte ions were 0.02 μg L −1 for Pb(II), 0.3 μg L −1 for Cr(III), 3.1 μg L −1 for Cu(II), 7.8 μg L −1 for Ni(II) and 0.9 μg L −1 for Cd(II). The proposed method was applied to the determination of lead, chromium, copper, nickel and cadmium in tap waters and RM 8704 Buffalo River Sediment standard reference material with satisfactory results. The relative standard deviations of the determinations were below 10%.

Determination of Metal Components in Marine Sediments Using Energy‐Dispersive X‐Ray Fluorescence (ED‐XRF) Spectrometry

A rapid energy-dispersive X-ray fluorescence (ED-XRF) spectrometric method for the analysis of metal components of marine sediments has been presented. Calibrations were made using synthetic matrix. The agreement of the results for sediment standard reference materials with reference values is satisfactory. Major advantages of the non-destructive ED-XRF technique over conventional chemical digestion methods include the applicability to analyzing the major oxide components, as well as to trace metals, and the avoidance of hazardous chemicals. The method has been applied to the routine analysis of Hong Kong marine sediment.

Two new marine sediment standard reference materials (SRMs) for the determination of organic contaminants

Two new marine sediment standard reference materials (SRMs), SRM 1941b Organics in Marine Sediment and SRM 1944 New York/New Jersey Waterway Sediment, have been recently issued by the National Institute of Standards and Technology (NIST) for the determination of organic contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCB) congeners, and chlorinated pesticides. Both sediment SRMs were analyzed using multiple analytical methods including gas chromatography/mass spectrometry (GC/MS) on columns with different selectivity, reversed-phase liquid chromatography with fluorescence detection (for PAHs only), and GC with electron capture detection (for PCBs and pesticides only). SRM 1941b has certified concentrations for 24 PAHs, 29 PCB congeners, and 7 pesticides, and SRM 1944 has certified concentrations for 24 PAHs, 29 PCB congeners, and 4 pesticides. Reference concentrations are also provided for an additional 58 (SRM 1941b) and 39 (SRM 1944) PAHs, PCB congeners, and pesticides. SRM 1944, which was collected from multiple sites within New York/New Jersey coastal waterways, has contaminant concentrations that are generally a factor of 10-20 greater than SRM 1941b, which was collected in the Baltimore (Maryland) harbor. These two SRMs represent the most extensively characterized marine sediment certified reference materials available for the determination of organic contaminants.

New NIST sediment SRM for inorganic analysis.

NIST maintains a portfolio of more than 1300 standard reference materials (SRM), more than a third of these relating to measurements in the biological and environmental fields. As part of the continuous renewal and replacement efforts, a set of new marine sediments has been recently developed covering organic and inorganic determinations. This paper describes the steps taken in sample preparation, homogeneity assay, and analytical characterization and certification with specific emphasis on SRM 2702 inorganics in marine sediment. Neutron activation analysis showed the SRM to be highly homogeneous, opening the possibility for use with solid sampling techniques. The certificate provides certified mass fraction values for 25 elements, reference values for eight elements, and information values for 11 elements, covering most of the priority pollutants with small uncertainties of only several percent relative. The values were obtained by combining results from different laboratories and techniques using a Bayesian statistical model. An intercomparison carried out in field laboratories with the material before certification illustrates a high commutability of this SRM.

The uses of 1-(2-pyridylazo) 2-naphtol (PAN) impregnated Ambersorb 563 resin on the solid phase extraction of traces heavy metal ions and their determinations by atomic absorption spectrometry

1-(2-pyridylazo) 2-naphtol (PAN) impregnated Ambersorb 563 resin was used as solid phase extractor of copper, nickel, cadmium, lead, chromium and cobalt ions in aqueous solutions prior to their atomic absorption spectrometric determinations. The parameters including pH, sample volume, matrix effects were also investigated. The relative standard deviation (R.S.D.) of the combined method of sample treatment, preconcentration and determination with atomic absorption spectrometry is generally lower than 10%. The limit of detection was between 0.21 and 1.4 μg l −1. The results were used for preconcentration of analyte ions from natural water samples. The method was also applied to a stream sediment standard reference material (GBW7309) for the determination of Cu, Ni, Cd, Pb, Cr and Co.

Flame Atomic Absorption Spectrometric Determination of Cu(II), Co(II), Cd(II), Fe(III) and Mn(II) in Ammonium Salts and Industrial Fertilizers after PrEconcentration/Separation on Diaion HP-20

A sensitive and simple separation-enrichment technique for the determination of trace amounts of Cu(II), Co(II), Cd(II), Fe(III) and Mn(II) was described. Metal ions were complexed with 1-nitroso-2-naphthol at pH 9. Following solid-phase extraction on Diaion HP-20 resin, metals were determined by flame atomic absorption spectrometry. The effect of the matrix ions were investigated. The recoveries of metal ions were greater than 95%. The detection limits of the analyte ions ( k = 3, N = 21) were varying 0.18 µg/l for Cd(II) to 0.44 µg/l for Fe(III). The method was applied to a stream sediment standard reference material (GBW7309), some ammonium salts and industrial fertilizer samples for the determination of copper, cobalt, cadmium, iron and manganese. The relative standard deviations (RSD) of the determinations for analyte ions at µg/g levels varied from 1 to 10%.

Microwave-assisted extraction of monomethyl arsonic acid from soil and sediment standard reference materials

Arsenic-containing species were extracted from soil and sediment SRM by a mixture (1 + 1) of acetone and hydrochloric acid (10% v/v) in a sealed vessel in a microwave oven during heating to 160 °C at pressures up to 1150 kPa (160 psi). Following separation by anion-exchange HPLC those species which gave a volatile derivative on reaction with borohydride in acid were detected by plasma-source mass spectrometry. The procedure was used to determine the monomethyl arsonate species in SRM 2704 Buffalo River sediment (0.30 ppm), SRM 1944 New York–New Jersey waterway sediment (0.23 ppm) and in SRM 2710 highly elevated Montana soil (1.03 ppm). The method was developed by investigating the recovery of dimethylarsinate added to Buffalo River sediment as a function of various experimental parameters, including the composition of the solvent. For 1 + 1 mixtures of acetone and 5% HCl, methanol and 5% HCl, and isopropanol and 5% HCl, recoveries ranged from 91% to 112%. Similar recoveries were obtained for ultrasound-assisted extractions with the same solvents. The chromatographic eluent was not directly introduced into the mass spectrometer as, compared to the post-column hydride generation procedure, the sensitivity was too low for reliable quantitative measurements, although the chromatographic resolution was better. Problems with signal pulsations were overcome by incorporating pulse dampers into the reagent delivery lines.

An alternative statistical approach for interlaboratory comparison data evaluation

Interlaboratory comparisons are an essential component of method validation, laboratory proficiency and equivalency evaluation, and standard reference material certification. The reliability of the results from interlaboratory comparison largely depends upon analyzing the data with appropriate statistical methods. Intercomparison data are often found to be non-normally distributed as a result of sample heterogeneity, uneven laboratory variance, and methodology bias. The statistical methods that require data normality are inappropriate for analyzing such skewed data. Instead of using data transformation or non-parametric methods, an alternative method which sets aside the assumption of data normality is utilized in the certification of new National Institute of Standards and Technology (NIST) Ocean Sediment Standard Reference Material (SRM-4357). It first determines the best-fit distribution for the data, then calculates appropriate distributional mean and tolerance limits, and finally estimates the uncertainties for the derived statistics by bootstrap analysis. The method was applied to evaluate the data from the SRM intercomparison, and revealed homogeneity for natural radionuclides and inhomogeneity for anthropogenic radionuclides in the SRM. It was found that the data of natural radionuclides in the SRM are normally distributed. In contrast, the data of anthropogenic radionuclides, such as 90Sr, 137Cs, 238Pu, and (239+240)Pu, are best fitted by Weibull distributions. The difference on data distributions for the two types of radionuclides is believed to be related to "hot" particles in the SRM. By determining the best-fit data distribution and applying bootstrap analysis, more reliable and realistic massic activity (Bq·kg-1) for anthropogenic radionuclides were certified in comparison to those obtained using data transformation and nonparametric methods. Although the developed method is computationally intensive, it provides a straightforward, rigorous procedure for computing the statistics that would otherwise be difficult to obtain when the data distribution form is complicated. With the help of advanced personal computers and use of the DataPlot software from NIST, this method becomes very practical and has enhanced interlaboratory comparison data studies and certification of the NIST standard reference materials.

Focused microwave-assisted extraction of polycyclic aromatic hydrocarbons and alkanes from sediments and source rocks

Focused microwave-assisted extraction (FMW) of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes from sediments and rocks was compared to conventional extraction methods such as Soxhlet extraction. With the FMW technique, extraction time is reduced to 10 min and the solvent volume is small (∼30 ml). The extraction procedure and analysis was validated on a certified marine sediment standard reference material, then applied to four source rocks of different origins, compositions and analyte concentrations. Recoveries of individual compounds were calculated for both FMW and Soxhlet methods and the results suggested that there was no analyte selectivity. The moisture content of the sample matrix had a positive effect on the extraction recovery of some PAHs with a maximum increase of 30%, whereas n-alkane extraction seems less affected by this factor. The conventional biomarker parameters determined after FMW extraction were the same as those found after Soxhlet extraction. A study of matrix effects on the extraction recovery showed that the recovery of analytes was near 100% if the matrix was ground and above 74%, if the matrix was used without prior grinding