Development, validation, and application of a method for quantification of methylmercury in biological marine materials using gas chromatography atomic emission detection

A gas chromatographic method was developed for the quantification of alkylmercury species using microwave-induced plasma atomic emission detection (GC-AED). The column conditioning and analyte derivatization required for previous methods were found to be unnecessary for stable, accurate, and sensitive element-specific detection using GC-AED. Chromatographic and detection parameters such as stationary phase type, stationary phase film thickness, GC column dimensions, helium mobile phase column head pressure, detector makeup gas flow rate, and detector reagent gas type and flow rate were found to significantly affect analyte response. The detection limit for the optimized GC-AED conditions was 0.8 pg (0.1 pg/s) of methylmercury chloride (as mercury). A solid-liquid extraction procedure with preparative gel permeation chromatography cleanup and GC-AED analysis was used to quantify methylmercury in a variety of complex matrix marine materials. The methylmercury quantification method was validated with four marine certified reference materials (CRMs). The method was then applied to 13 standard reference materials, CRMs, and control materials for which no certified reference values for methylmercury have been determined. Four National Institute of Standards and Technology Standard Reference Materials and one control material, which were analyzed using the GC-AED method, were also analyzed by two other laboratories using independent methods to further validate the method.     

Ultrasonic extraction followed by sonolysis-ozonolysis as a sample pretreatment method for determination of reactive arsenic toward sodium tetrahydroborate by flow injection-hydride generation AAS

A new sample pretreatment method based on ultrasonic extraction in HCI medium and subsequent oxidation of the extracts by sonozone (i.e., sonolysis-ozonolysis) has been developed for determination of reactive arsenic toward sodium tetrahydroborate [mainly As(III) + As(V)] by flow injection-hydride generation atomic absorption spectrometry. This method avoids the use of intensive treatments with concentrated and corrosive acids, high pressures, and temperatures that are inherent with traditional wet or dry ashing procedures and entails reduced waste production and reagent consumption. A sonozone process at room temperature was optimized to break the bond of As to proteins and macromolecular constituents which was an essential requirement for effective reduction by L-cysteine prior to arsine generation. Spiking experiments showed that As(III), As(V), MMA, and DMA were fully recovered from several matrixes on applying the above treatment. On the other hand, a nonreducible As species such as arsenobetaine that is predominant in some biological samples remained unchanged. Application of the method to sediment, soil, fly ash, and plant CRMs demonstrated that, in general, a good agreement existed between certified and found As contents, thereby indicating the absence of nonreducible As forms. Low As recoveries were observed for fish CRMs, as a result of the nondegradability of arsenobetaine by sonozone. The detection limit of As in the samples investigated was in the range 0.19-2.8 microg g(-1).     

Determination of polybrominated diphenyl ethers in environmental standard reference materials

The total concentrations (sigmaPBDE) of 15 polybrominated diphenyl ethers, BDEs 17, 28, 47, 49, 66, 71, 85, 99, 100, 138, 153, 154, 183, 190, and 209, and a predominant polybrominated biphenyl (PBB) congener, 2,2',4,4',5,5'-polybrominated biphenyl (PBB-153) were determined in six natural matrix Standard Reference Materials (SRM) provided by the National Institute of Standards and Technology (NIST). The sigmaPBDE concentrations (+/- one standard deviation) in SRM 1945 (whale blubber), SRM 1946 (fish tissue), SRM 1947 (fish tissue), and SRM 1974b (mussel tissue) were 126 +/- 7, 79 +/- 3, 134 +/- 5, and 7.9 +/- 0.2 ng/g of wet wt, respectively. The sigmaPBDE concentrations were 54 +/- 2 and 163 +/- 4 ng/g of dry wt for SRM 2977 (mussel tissue) and SRM 2978 (mussel tissue), respectively. Among the three kinds of marine animals, mussel tissue had the lowest total concentration of PBDEs. These values can provide an informal reference or benchmark to laboratories who measure these compounds.     

Evaluation of accelerated solvent extraction for butyltin speciation in PACS-2 CRM using double-spike isotope dilution-GC/ICPMS

Pressurized liquid extraction using the accelerated solvent extractor (Dionex ASE 200) has been evaluated for the determination of mono-, di- and tributyltin (MBT, DBT, and TBT, respectively) in PACS-2 certified reference material. A double-enriched spike containing 119Sn-enriched MBT and TBT and 118Sn-enriched DBT allowed for the simultaneous determination of the three butyltin species and the factors governing species interconversion. The stability of the spike was evaluated by reverse isotope dilution experiments covering more than one year with satisfactory results. Quantitative recoveries using ASE for TBT and DBT were obtained at temperatures above 110 degrees C. The effect of the extraction time and number of static cycles was evaluated. Results suggest that extraction efficiency was quantitative with extraction times as low as 10 min for all butyltin species at 110 degrees C. Decomposition reactions were only detected at the higher temperatures assayed (140 and 175 degrees C) and that was only for the degradation of DBT to MBT (approximately 4%). The results found for MBT were approximately 25% higher than the certified value for the PACS-2 sediment reference material in agreement with previous results obtained by ultrasonic and microwave assisted extraction.     

Simultaneous determination of halogenated derivatives of alkylphenol ethoxylates and their metabolites in sludges, river sediments, and surface, drinking, and wastewaters by liquid chromatography-mass spectrometry

A quantitative solid-phase extraction-liquid chromatography/mass spectrometry (SPE-LC/MS) method is described for the simultaneous analysis of halogenated byproducts of alkylphenolic compounds and their degradation products formed during chlorine disinfection in the presence of bromide ions. Compounds analyzed include brominated and chlorinated nonylphenol ethoxylates (XN-PEOs); octylphenol ethoxylates (XOPEOs); nonylphenols (XNP); nonylphenoxycarboxylates (XNPECs) and their precursors nonionic surfactants, alkylphenol ethoxylates (APEOs); and their metabolites formed during sewage treatment, alkylphenoxycarboxylates (APECs) and alkylphenols (APs). Target compounds were concentrated from water samples using a C18 SPE procedure. Extracts were analyzed using reversed phase LC/MS. The performances of both atmospheric pressure chemical ionization (APCI) and electrospray (ESI) interfaces were compared. ESI offered better sensitivity and specificity for a higher range of oligomers. Detection limits (LODs) for water samples were from 20 to 100 ng/L; and for sediment samples, from 2 to 10 microg/kg. Slightly higher LODs were obtained for sludge samples (5-25 microg/kg). Halogenated byproducts were found in sludge from Barcelona drinking water treatment plant in concentrations of 220 microg/kg for BrNP, 430 microg/kg for BrNPEOs (nEO = 1 - 2), and 1600 microg/kg for BrNPEOs (nEO = 3 - 15). The concentration of ClNPEOs was estimated to be in the order of 660 microg/kg (assuming the same response as BrNPEOs). Halogenated OPEOs were also identified, and their concentration was approximately 50 times lower than the concentration of NPEOs analogues. To our knowledge, this is the first method described that allows simultaneous determination of alkyphenol ethoxylates and halogenated derivatives, including degradation products.     

Comparison of ASE and SFE with Soxhlet, Sonication, and Methanolic Saponification Extractions for the Determination of Organic Micropollutants in Marine Particulate Matter

The methods of accelerated solvent extraction (ASE) and supercritical fluid extraction (SFE) of polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons, and chlorinated hydrocarbons from marine samples were investigated. The results of extractions of a certified sediment and four samples of suspended particulate matter (SPM) were compared to classical Soxhlet (SOX), ultrasonication (USE), and methanolic saponification extraction (MSE) methods. The recovery data, including precision and systematic deviations of each method, were evaluated statistically. It was found that recoveries and precision of ASE and SFE compared well with the other methods investigated. Using SFE, the average recoveries of PAHs in three different samples ranged from 96 to 105%, for ASE the recoveries were in the range of 97-108% compared to the reference methods. Compared to the certified values of sediment HS-6, the average recoveries of SFE and ASE were 87 and 88%, most compounds being within the limits of confidence. Also, for alkanes the average recoveries by SFE and ASE were equal to the results obtained by SOX, USE, and MSE. In the case of SFE, the recoveries were in the range 93-115%, and ASE achieved recoveries of 94-107% as compared to the other methods. For ASE and SFE, the influence of water on the extraction efficiency was examined. While the natural water content of the SPM sample (56 wt %) led to insufficient recoveries in ASE and SFE, quantitative extractions were achieved in SFE after addition of anhydrous sodium sulfate to the sample. Finally, ASE was applied to SPM-loaded filter candles whereby a mixture of n-hexane/acetone as extraction solvent allowed the simultaneous determination of PAHs, alkanes, and chlorinated hydrocarbons.     

Improvement of measurement precision of SPME-GC/MS determination of tributyltin using isotope dilution calibration

A unique approach was developed to improve the precision of quantification of tributyltin (TBT) in sedimentsby solid phase microextraction (SPME) using isotope dilution GC/MS. The precision of the analytical technique was initially evaluated using standard calibration solutions. In selective ion monitoring (SIM) mode, the relative standard deviation (RSD) obtained for TBT based on peak area response was 18% (n = 11). When an internal standard, tripropyltin (TPrT), was used, the RSD decreased to 12%. A significant improvement in the precision using SPME was noted when a 117Sn-enriched TBT spike was employed; the RSD decreased 4-fold to 3%. Detection limits of 0.2 and 20 ng(Sn) L(-1) were achieved with SPME sampling and liquid-liquid extraction, respectively. Six analyses were performed for determination of TBT in PACS-2 sediment Certified Reference Material using both standard additions and isotope dilution procedures. For the latter, a 117Sn-enriched TBT spike was used. A concentration of 0.88 +/- 0.03 microg g(-1) (RSD 3.4%) obtained using standard additions was in good agreement with the certified value of 0.98 +/- 0.13 microg g(-1) as tin. Concentrations found using isotope dilution were 0.895 +/- 0.015 microg g(-1) (RSD 1.73%) as tin and 0.874 +/- 0.014 microg g(-1) (RSD 1.66%) as tin using a liquid-liquid extraction and SPME sampling, respectively. A 2-fold improvement in the precision of TBT concentration measurement using isotope dilution was clearly achieved, demonstrating its superiority in providing more accurate and precise results as compared to the method of standard additions. The isotope dilution technique eliminated the problem of poor reproducibility, which typically plagues SPME.     

Evaluation of an ultrasonic acid digestion procedure for total heavy metals determination in environmental and biological samples

In this study, a sample preparation method based on ultrasonic assisted acid digestion (UAD) has been evaluated for total heavy metals (Cd, Cr, Ni and Pb) determination in different environmental (soil, sediment and sewage sludge), and biological (fish muscles, vegetables and grains) samples, using electrothermal atomic absorption spectrometry (ETAAS). The investigated parameters influencing UAD such as presonication time, sonication time, temperature of ultrasonic bath, and different acid mixtures were fully optimized, whereas power was maintained constant at 100% of nominal power of ultrasonic bath. Six different sets of above parameters were applied on six certified reference materials (CRMs) having different matrices. The accuracy of the method was also tested by comparing the results with those obtained from conventional hot plate assisted acid digestion method on same CRMs. Analytical results for HMs by both methods showed no significant difference at 95% confidence limit (p<0.05). Recoveries of HMs ranging from 96.2% to 102% and 96.3% to 98.6% were obtained from biological and environmental samples, respectively. The average relative standard deviation of UAD method varied between 3.5% and 8.2%, depending on the analyte.     

Arsenic speciation in rice and soil containing related compounds of chemical warfare agents

Diphenylarsinic acid, phenylarsonic acid, methylphenylarsinic acid (MPAA), dimethylphenylarsine oxide (DMPAO), and methyldiphenylarsine oxide (MDPAO) in soil and rice were extracted, separated by reversed-phase chromatography, and quantified by ICPMS with a membrane desolvating system. For the extraction of arsenicals from rice grain and straw, 68% HNO3 provided better extraction efficiency than water, 50% methanol, or 2.0 mol L(-1) trifluoroacetic acid. For the extraction from soil, 68% HNO3 provided better extraction efficiency than H2O, 1 mol L(-1) H3PO4, or 1 mol L(-1) NaOH. The contaminated soil contained all five aromatic arsenicals along with inorganic arsenicals as main species (5.86 +/- 0.19 microg of As kg(-1): 60.8 +/- 2.0% of total extracted As). After pot experiments, rice straw contained mainly DMPAO (7.71 +/- 0.48 microg of As kg(-1): 60.5 +/- 3.7%), MDPAO (0.91 +/- 0.07 microg of As kg(-1): 7.2 +/- 0.5%), and inorganic As (2.85 +/- 0.20 microg of As kg(-1): 22.3 +/- 1.6%). On the other hand, rice grain contained mainly MPAA (1.17 +/- 0.04 microg of As kg(-1): 86.7 +/- 2.7%). The root uptake of each species from the soil and transport from straw to grains were significantly related to the calculated log K(ow) values.     

Elemental speciation analysis by multicapillary gas chromatography with microwave-induced plasma atomic spectrometric detection

Multicapillary column gas chromatography (MC-GC)/microwave-induced plasma atomic emission spectrometry (MIP AES) was developed for fast speciation analysis of organotin compounds in the environment. Ethylated butyltin compounds could be separated isothermally within less than 30 s (instead of ～5-10 min) without sacrificing either the resolution or the sample capacity of conventional capillary GC with oven temperature gradient programming. Careful optimization of the pressure and temperature GC program allowed a comprehensive organotin speciation analysis including phenyltin compounds within less than 2.5 min, increasing the sample throughput 6-fold. Compatibility of MC-GC with an MIP atomic emission detector (MIP-AED) was discussed. MC-GC/MIP-AES was validated for the analysis of sediment (PACS-1 and BCR 462) and biological (NIES11) certified reference materials.     

Multielemental determination of GEOTRACES key trace metals in seawater by ICPMS after preconcentration using an ethylenediaminetriacetic acid chelating resin

GEOTRACES is an international research project on marine biogeochemical cycles of trace elements and their isotopes. GEOTRACES key trace metals in seawater are Al (8-1000 ng/kg), Mn (4-300 ng/kg), Fe (1-100 ng/kg), Cu (30-300 ng/kg), Zn (3-600 ng/kg), and Cd (0.1-100 ng/kg), of which global oceanic distribution will be determined on a number of research cruises. This work introduces a novel method of solid-phase extraction to determine Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb in seawater by adjusting the pH of the sample to 6 and carrying out a single preconcentration step. The trace metals were collected from approximately 120 mL of seawater using a column of a chelating resin containing the ethylenediaminetriacetic acid functional group and eluted with approximately 15 mL of 1 M HNO3. Mn and Fe in the eluate were measured by inductively coupled plasma mass spectrometry (ICPMS) using the dynamic reaction cell mode, and the other metals were measured using the standard mode. Using this procedure, the trace metals were collected quantitatively, while >99.9% of alkali and alkaline earth metals in seawater were removed. The procedural blank was <7% of the mean concentration in deep ocean waters, except 16% for Pb. The overall detection limit was <14% of the mean concentration in deep ocean waters. The RSD was <9%. Our values for the trace metals in the certified reference materials of seawater NASS-5 and nearshore seawater CASS-4 agreed with the certified values (except that there is no certified value for Al). This method was also successfully applied to the reference materials of open-ocean seawater produced by the SAFe program. Our Fe concentrations were 5.9 +/- 0.7 ng/kg for surface water (S1) and 50.4 +/- 2.9 ng/kg for deep water (D2), which are in agreement with the interlaboratory averages of 5.4 +/- 2.4 and 50.8 +/- 9.5 ng/L, respectively. The data for other metals were oceanographically consistent.     

Determination of gamma-emitting radionuclides in the inter-tidal sediments off Balochistan (Pakistan) Coast, Arabian Sea

Natural radionuclide contents of 226Ra, 228Ra and (40)K were studied for inter-tidal sediments collected from selected locations off the745 km long Balochistan Coast using HPGe detector based gamma-spectrometry system. The sampling zone extends from the beaches of Sonmiani (near Karachi metropolis) through Jiwani (close to the border of Iran). The natural radioactivity levels detected in various sediment samples range from 14.4 +/- 2.5 to 36.6 +/- 3.8 Bq kg(-1) for 226Ra, 9.8 +/- 1.2 to 35.2 +/- 2.0 Bq kg(-1) for (228)Ra and 144.6 +/- 9.4 to 610.5 +/- 23.9 Bq kg(-1) for (40)K. No artificial radionuclide was detected in any of the marine coastal sediment samples. 137Cs, (60)Co, 106Ru and 144Ce contents in sediment samples were below the limit of detection. The measured radioactivity levels are compared with those reported in the literature for coastal sediments in other parts of the world. The information presented in this paper will serve as the first ever local radioactivity database for the Balochistan/Makran Coastal belt of Pakistan. The presented data will also contribute to the IAEA's, Asia-Pacific Marine Radioactivity Database (ASPAMARD) and the Global Marine Radioactivity Database (GLOMARD).     

Microwave-assisted steam distillation for simple determination of polychlorinated biphenyls and organochlorine pesticides in sediments

A novel sample extraction technique for polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) analysis using microwave-heating device is developed. In this study, microwave-assisted extraction (MAE) and steam distillation techniques were combined. Desorption of the anatytes from solid matrixes was accelerated with water vapor which was generated by microwave irradiation. A sample holder in a commercial microwave extraction cell kept the sample from direct contact with the organic solvent for analytes trapping during the treatment process. Therefore, relatively clean extracts were obtained with small amount of solvents. Without any cleanup steps, the obtained extract could be analyzed with gas chromatograph/mass spectrometers (GC/MS). Six PCB congeners (PCB15, 28, 70, 101, 180, 194, 209) and three OCPs (gamma-HCH, 4,4'-DDE, 4,4'-DDD) in two marine sediment samples (a sediment collected from a bay of Kyusyu Island, Japan, and a certified reference material NIST SRM1944) were analyzed by using this microwave-assisted steam distillation (MASD) technique and another extraction method (exhaustive steam distillation, MAE, and Soxhlet extraction); and comparisons of the results are shown in this report. Although recovery yields of highly chlorinated biphenyls (PCB180, 194, 209) and relatively polar OCPs (gamma-HCH, 4,4'-DDD) were low (30-60%) compared with other analytes (PCB15, 28, 70, 101, 4,4'-DDE; recovery, 80-100%), use of isotope labeled internal standards for the MASD technique gave comparable results with the values obtained by other extraction methods and the certified values in the samples.     

Determination of the quaternary ammonium surfactant ditallowdimethylammonium in digested sludges and marine sediments by supercritical fluid extraction and liquid chromatography with postcolumn ion-pair formation

To study the phasing-out of the quaternary ammonium surfactant ditallowdimethylammonium cation (DTDMAC), concentrations of the cation in anaerobically stabilized sewage sludges were determined before and after its replacement by better degradable compounds. DTDMAC was quantitatively extracted from digested sludges using 380 atm of supercritical CO(2) modified with 30% methanol at 100 °C. Determination of DTDMAC was performed by normal-phase HPLC with postcolumn ion-pair formation and extraction with no sample cleanup. Mean concentrations of DTDMAC in sludges from five different municipal sewage treatment plants in Switzerland decreased from 3.67 g/kg (in 1991) to 0.96, 0.47, and 0.21 g/kg of dry sludge in 1992, 1993, and 1994, respectively. The precision of the method in digested sludge for 0.1-6.0 g/kg of dry matter, as indicated by the relative standard deviation, was typically 7%. The influence of the sample matrix was studied by performing supercritical fluid extraction (SFE) in coastal marine sediments. While SFE and a conventional liquid extraction method gave equal DTDMAC concentrations in sludges, the extraction of marine sediment samples yielded 30-40% higher DTDMAC values for SFE compared to those obtained by liquid extraction. The 94% drop in DTDMAC concentrations in digested sludges is due to the replacement of this substance and is a clear result of the producers' voluntary ban on its use in Europe.     

Using speciated isotope dilution with GC-inductively coupled plasma MS to determine and unravel the artificial formation of monomethylmercury in certified reference sediments

Speciated isotope-dilution mass spectrometry (SID-MS) is claimed to be an absolute method; however, it has been found to be affected by artifact monomethylmercury (MMHg) formation in sediments. The determination of MMHg in sediments was carried out by SID-MS after open-focused microwave extraction. The extracted mercury species were then ethylated and separated by capillary gas chromatography (CGC). Isotope ratios (peak area ratios at different masses) were measured by on-line ICP-MS detection of the CGC-separated compounds. Reproducibility of 202Hg/201Hg isotope ratio measurements were 0.60% for MeEtHg and 0.69% for Et2Hg; for 202Hg/199Hg, 0.43 and 0.46%, respectively, were determined. The absolute detection limits for CGC-ICPMS measurements were better than 26 fg for 202Hg, 20 fg for 201Hg, and 24 fg for 199Hg. For the direct determination of MMHg in sediment reference materials (CRM 580, IAEA 356, and IAEA 405), higher values than the certified were always found. Systematic experiments were carried out to localize the sources of the unintentional abiotic methylmercury formation during analysis. Different spiking and derivatization procedures (either ethylation, propylation, or derivatization by Grignard reagents) were tested. In addition, isotopically enriched inorganic mercury was spiked. The amount of inorganic mercury initially present in the sample was found to be the critical factor that should be known and carefully controlled. A simple solvent extraction technique involving no critical cleanup steps was applied in order to reduce high Hg2+ amounts. The method was applied to the determination of MMHg in sediment reference material IAEA-405 with satisfactory results after organic solvent extraction. The limitations of applicability of the proposed method are evaluated as related to inorganic mercury, organic carbon, and sulfur contents. The results obtained confirmed that available sediment reference materials are adequate to achieve traceable mercury speciation analysis and to detect potential sources of MMHg artifact formation.     

碳黑比表面积标准物质的研制

选择商品化的碳黑作为比表面积标准物质候选材料,利用交叉缩分的方法对碳黑样品进行分装。经均匀性、稳定性(18个月)检验,碳黑标准物质样品具有良好的均匀性和稳定性。按照国际公认的氮气物理吸附BET方法,联合测量能力经确认过的8家实验室对碳黑标准物质样品进行定值(104.6、29.9、8.96 m2/g)。与国内外同类标准物质比较表明:研制的3种碳黑比表面积标准物质的相对不确定度(2.1%、2.3%和3.2%)达到国际同类标准物质的先进水平。     

颗粒计数标准物质定值方法研究

为了探讨颗粒计数标准物质研究中缺乏操作性强、量值溯源可靠的颗粒计数标准物质定值方法等主要技术难点,本文中采用量值可溯源至长度基准的显微图象分析仪,配以血球计数板为球形乳胶颗粒计数标准物质定值,在确定标准值同时对于定值的不确定度进行了分析和研究。研究结果表明:采用这种方法的定值不确定度优于10%(k=2)。     

Liquid chromatography quadrupole time-of-flight mass spectrometry analysis of carbosulfan, carbofuran, 3-hydroxycarbofuran, and other metabolites in food

The potential of liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QqTOF-MS) to identify and confirm carbosulfan and seven of its main metabolites (carbofuran, 3-hydroxycarbofuran, 3-ketocarbofuran, 3-hydroxy-7-phenol carbofuran, 3-keto-7-phenolcarbofuran, 7-phenolcarbofuran, dibutylamine) at trace levels from food is explored for the first time. The analytical method developed consists of pressurized liquid extraction (PLE) and LC-QqTOF-MS in positive ion mode, which attains unequivocal identification and quantification of the studied compounds in food, at levels well below of those of concern (0.05 mg/kg for the sum of carbosulfan, carbofuran, and 3-hydroxycarbofuran). PLE recoveries ranged from 55 to 94% with limits of quantification from 10 (for carbosulfan, carbofuran, 3-hydroxycarbofuran, and dibutylamine) to 70 microg/kg (3-keto-7-phenolcarbofuran). The method is precise, with relative standard deviations varying between 5 and 11% for the repeatability (within-day) and 8-13% for the reproducibility (interday). This method was used to monitor the presence and fate of the target compounds in orange, potato, and rice crops treated with a commercial product containing carbosulfan. Field degradation studies show that carbofuran, 3-hydroxycarbofuran, and dibutylamine are the main degradation products formed in the environmental disappearance of carbosulfan.     

系列液体和固体水分标准物质的研制

针对水分检测领域对标准物质的需要,研制了系列水分标准物质,包括4种液体水分标准物质,量值覆盖范围为0.139~47.6 mg/g,不确定度范围为0.012~1.1 mg/g;还包括3种含结晶水化合物水分标准物质,量值覆盖范围为50.7~156.3 mg/g,不确定度范围为0.6~1.3 mg/g,以及3种混合物水分标准物质,量值覆盖范围为0.142~9.90 mg/g,不确定度范围为0.013~0.20 mg/g。该系列液体和固体水分标准物质,适用于卡尔·费休库仑法和容量法水分仪的校准和检定,以及水分测量方法的验证,能够保障我国水分检测的量值准确和等效一致。     

Analysis of octyl- and nonylphenol and their ethoxylates in water and sediments by liquid chromatography/tandem mass spectrometry

The ubiquitous presence of alkylphenol ethoxylates in the environment as well as concern for endocrine disruption effects in biota caused by their degradation products (such as octyl- and nonylphenol) has raised interest in the environmental fate of these compounds. As part of an effort to model their behavior in a subestuary of the Chesapeake Bay, a quantitative method for the analysis of octyl- and nonylphenol, and their ethoxylates (1-5) in water and sediment was developed. Extraction procedures are based on solid-phase extraction techniques. Identification and quantitation of the analytes is done by liquid chromatography coupled to tandem mass spectrometry. Instrument detection limits for the compounds ranged from 0.1 to 9 pg injected on column, which allowed method detection limits of 0.04-3 ng/L in water and 0.2-13 ng/g of dry weight in sediment. The method was used to analyze water and sediment from the Back River, MD, where concentrations for the individual compounds ranged from <8 to 200 ng/L in water and <9 to 6700 ng/g of dry weight in sediment. Additionally, structural information obtained in the mass spectrometer is presented that supports previous observations that nonylphenol and its ethoxylates are composed mainly of isomers with a tertiary alpha-carbon.