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1.
I-Fang Mao Yu-Yu Lu 《International journal of environmental analytical chemistry》2013,93(10):713-722
Nonylphenol (NP), octylphenol (OP), nonylphenol monoethoxylate (NP1EO) and nonylphenol diethoxylate (NP2EO) are products of the biodegradation of alkylphenol polyethoxylates (AP n EO) which are used worldwide as detergents and surfactants. NP and OP are categorized as definitely endocrine disruptors. 2,4-Tert-butylphenol (BP) is extensively used for anti-oxidant of rubber and plastics. This work proposed a simple and stable method for simultaneously determining the concentration of NP, OP, BP, n-NP1EO and n-NP2EO in meat and fish, without requiring the complex pretreatments of current methods. This study used liquid extraction with acetonitrile and hexane and solid extraction using Florisil, in that order to pretreat samples. The sample solutions were analyzed to identify NP, OP, BP, n-NP1EO and n-NP2EO by HPLC with fluorescence detection. The mean recoveries were 85.3?±?3.32% for OP, 87.5?±?6.01% for BP, 90.9?±?4.72% for NP, 86.4?±?4.81% for n-NP2EO and 90.9?±?4.84% for n-NP1EO. The average coefficients of variation were about 6%. The method's detection limits were 5.4?ng?g?1 for OP, 5.2?ng?g?1 for BP, 8.9?ng?g?1 for NP, 8.7?ng?g?1 for n-NP2EO and 8.1?ng?g?1 for n-NP1EO. This work analyzed 5 kinds of usual foodstuffs of meat and fish that are frequently consumed by residents of Taiwan. All of these samples contained NP, but not detectable levels n-NP1EO. Only salmon was contaminated with n-NP2EO. The NP level was highest in cod (198.41?±?129.34?ng?g?1, wet weight). The fried chicken had the highest BP level (48.0?±?41.3?ng?g?1, wet weight), and the uncooked chicken had the highest OP level (66.6?±?53.0?ng?g?1, wet weight). 相似文献
2.
Julia Martín Dolores Camacho-MuñozJuan Luis Santos Irene AparicioEsteban Alonso 《Analytica chimica acta》2013
A dispersive liquid–liquid microextraction (DLLME) method followed by high-performance liquid chromatography–triple quadrupole mass spectrometry has been developed for the simultaneous determination of linear alkylbenzene sulfonates (LAS C10, C11, C12, and C13), nonylphenol (NP), nonylphenol mono- and diethoxylates (NP1EO and NP2EO), and di-(2-ethylhexyl)phthalate (DEHP). The applicability of the method has been tested by the determination of the above mentioned organic pollutants in tap water and wastewater. Several parameters affecting DLLME, such as, the type and volume of the extraction and disperser solvents, sample pH, ionic strength and number of extractions, have been evaluated. Methanol (1.5 mL) was selected among the six disperser solvent tested. Dichlorobenzene (50 μL) was selected among the four extraction solvent tested. Enrichment factor achieved was 80. Linear ranges in samples were 0.01–3.42 μg L−1 for LAS C10–13 and NP2EO, 0.09–5.17 μg L−1 for NP1EO, 0.17–9.19 μg L−1 for NP and 0.40–17.9 μg L−1 for DEHP. Coefficients of correlation were higher than 0.997. Limits of quantitation in tap water and wastewater were in the ranges 0.009–0.019 μg L−1 for LAS, 0.009–0.091 μg L−1 for NP, NP1EO and NP2EO and 0.201–0.224 μg L−1 for DEHP. Extraction recoveries were in the range from 57 to 80%, except for LAS C10 (30–36%). The method was successfully applied to the determination of these pollutants in tap water and effluent wastewater from Seville (South of Spain). The DLLME method developed is fast, easy to perform, requires low solvent volumes and allows the determination of the priority hazardous substances NP and DEHP (Directive 2008/105/EC). 相似文献
3.
Marc P. Fernandez Tania-Noelia Noguerol Silvia Lacorte Ian Buchanan Benjamin Piña 《Analytical and bioanalytical chemistry》2009,393(3):957-968
We developed a toxicity identification fractionation (TIF) procedure to determine estrogenic compounds in wastewaters and
sludge. The procedure consisted in fractionation of samples through a C18 solid-phase extraction cartridge, in which Fraction I contained nonylphenol (NP) and its mono (NPEO1) and diethoxylate (NPEO2) and the markers of faecal exposure, Fraction II contained bisphenol A (BPA) and synthetic and natural hormones, and Fraction
III contained the hormone conjugates. These three fractions were analyzed in parallel using gas or liquid chromatography coupled
to mass spectrometry and recombinant yeast assay (RYA). Water samples collected daily throughout a whole week contained from
0.45 to 7.22 μg L−1 of NP > NPEO1 > NPEO2 and were responsible for the estrogenicity of these samples. Fractions II and III were not estrogenic and that was due to
the low ng L−1 level of hormones and hormone conjugates found, respectively. The biological treatment sewage treatment plant (STP) was capable
to eliminate from 52 to 100% of the compounds, with bisphenol A being the least removed. Only alkylphenols were accumulated
in sludge with concentrations from 8.69 to 26.3 mg kg−1 dw of NPEO1 > NPEO2 > NP. The integrated procedure herein proposed can be used as a screening method to evaluate estrogenic compounds in STPs
and to survey faecal elimination. 相似文献
4.
In this work, we present the development and application of a microwave assisted extraction followed by liquid chromatography-tandem mass spectrometry methodology (MAE-LC-MS/MS) for the determination of various estradiol-mimicking compounds in sewage sludge samples. For the purification of the MAE extracts, we have employed a solid phase extraction (SPE) clean-up procedure, previously optimised. The entire method provides recoveries between 71.7% and 103.1%, with relative standard deviation lower than 11.1% and limits of detection ranging from 0.6 to 3.5 ng g−1. The developed method was applied to samples from three wastewater treatment plants (WWTPs) located in Las Palmas of Gran Canaria (Spain), two of which had a conventional activated sludge treatment (AST), whereas the third treatment plant had an advanced membrane bioreactor treatment (MBR). All of the analytes in the study, including (nonylphenol (NP), octylphenol (OP), and some of their ethoxylated chains APnEOs (n ≤ 7), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE) and bisphenol-A (BPA)), were found in almost all samples in concentrations ranging from 0.9 to 710.2 ng g−1. 相似文献
5.
An analytical method has been developed for the simultaneous extraction and determination of trace tertiary octylphenol (t-OP), technical nonylphenol isomers (NP), nonylphenol monoethoxylate isomers (NP1EO) and seven phthalates in the atmosphere using gas chromatography-mass spectrometry (GC-MS). High volume samples were collected using a high-volume pump equipped with a PUF/XAD-2 column for air and glass fiber filter for particles. The detection limits of the method for alkylphenols (APs) and the phthalates ranged from 0.0006 to 0.034 ng m−3 in air. The recoveries of t-OP, NP, NP1EO and the phthalates for the entire procedure were satisfactory (>69%). The method was successfully applied to the determination of the analytes in the atmosphere samples collected over land and the ocean. The concentrations of t-OP, NP, NP1EO showed decline trends from land to the open sea, and the phthalates present over land and the North Sea were comparable. It is suggested that the atmosphere is a significant pathway for the transport of alkylphenols and the phthalates in the environment. 相似文献
6.
An integrated analytical method for the simultaneous determination of 4-n-nonylphenol (4-n-NP), nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), bisphenol A (BPA) and triclosan (TCS) in wastewater (dissolved and particulate phase) and sewage sludge was developed based on gas chromatography-mass spectrometry. Chromatographic analysis was achieved after derivatization with bis(trimethylsilyl)trifluoroacetamide (BSTFA). Extraction from water samples was performed by solid-phase extraction (SPE). The optimization of SPE procedure included the type of sorbent and the type of the organic solvent used for the elution. Referred to solid samples, the target compounds were extracted by sonication. In this case the optimization of the extraction procedure included the variation of the amount of the extracted biomass, the duration and the temperature of sonication and the type of the extraction organic solvent. The developed extraction procedures resulted in good repeatability and reproducibility with relative standard deviations (RSDs) less than 13% for all the tested compounds for both types of samples. Satisfactory recoveries were obtained (>60%) for all the compounds in both liquid and solid samples, except for 4-n-NP, which gave recoveries up to 35% in wastewater samples and up to 63% in sludge samples. The limits of detection (LODs) of the target compounds varied from 0.03 (4-n-NP) to 0.41 microg l(-1) (NP2EO) and from 0.04 (4-n-NP) to 0.96 microg kg(-1) (NP2EO) for liquid and solid samples, respectively. The developed methods were successfully applied to the analysis of the target compounds in real samples. 相似文献
7.
Shusheng Luo Ling Fang Xiaowei Wang Hongtao Liu Gangfeng Ouyang Chongyu Lan Tiangang Luan 《Journal of chromatography. A》2010,1217(43):6762-6768
A simple and fast sample preparation method for the determination of nonylphenol (NP) and octylphenol (OP) in aqueous samples by simultaneous derivatization and dispersive liquid–liquid microextraction (DLLME) was investigated using gas chromatography–mass spectrometry (GC/MS). In this method, a combined dispersant/derivatization catalyst (methanol/pyridine mixture) was firstly added to an aqueous sample, following which a derivatization reagent/extraction solvent (methyl chloroformate/chloroform) was rapidly injected to combine in situ derivatization and extraction in a single step. After centrifuging, the sedimented phase containing the analytes was injected into the GC port by autosampler for analysis. Several parameters, such as extraction solvent, dispersant solvent, amount of derivatization reagent, derivatization and extraction time, pH, and ionic strength were optimized to obtain higher sensitivity for the detection of NP and OP. Under the optimized conditions, good linearity was observed in the range of 0.1–1000 μg L−1 and 0.01–100 μg L−1 with the limits of detection (LOD) of 0.03 μg L−1 and 0.002 μg L−1 for NP and OP, respectively. Water samples collected from the Pearl River were analyzed with the proposed method, the concentrations of NP and OP were found to be 2.40 ± 0.16 μg L−1 and 0.037 ± 0.001 μg L−1, respectively. The relative recoveries of the water samples spiked with different concentrations of NP and OP were in the range of 88.3–106.7%. Compared with SPME and SPE, the proposed method can be successfully applied to the rapid and convenient determination of NP and OP in aqueous samples. 相似文献
8.
A simple and highly sensitive method called thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS), which is used for the determination of trace amounts of 4-nonylphenol (NP) and 4-tert.-octylphenol (OP) in water samples, is described. NP and OP in samples are extracted from water samples and concentrated by the stir bar sorptive extraction (SBSE) technique. A stir bar coated with polydimethylsiloxane (PDMS) is added to a 2.0 ml water sample and stirring is carried out for 60 min at room temperature (25 °C) in a headspace vial. Then the extract is high sensitively analyzed by TD-GC-MS without any derivatization step. The optimum SBSE conditions are realized at an extraction time of 60 min. The detection limits are 0.02 ng ml−1 for NP and 0.002 ng ml−1 for OP. The method shows good linearity over the concentration range of 0.1-10 ng ml−1 for NP and 0.01-10 ng ml−1 for OP, and the correlation coefficients are higher than 0.999. The average recoveries of NP and OP are higher than 97% (R.S.D.: 3.6-6.2%) with correction using the added surrogate standards, 4-(1-methyl) octylphenol-d5 and deuterium 4-tert.-octylphenol. This simple, accurate, sensitive and selective analytical method may be used in the determination of trace amounts of NP and OP in tap and river water samples. 相似文献
9.
Nonyl- and dinonylphenol polyethoxylates (NPEOs, DNPEOs) and their o-phosphate esters are widely used as surfactants in various industrial, agricultural and domestic applications. An HBr-fission
procedure was developed for cleaving NPEOs, DNPEOs and their o-phosphate esters to nonylphenol (NP) and dinonylphenol (DNP), and their bromine adducts, thereby facilitating the analysis of NP- and DNP contents in complex NPEO- and DNPEO-containing
samples. The procedure includes fission, liquid-liquid extraction and GC-MS analyses of the fission end-products. Using 2
× 2 factorial experimental designs, 2 h cleavage at 120°C was found to provide optimal yields of the target compounds, with
minimal unwanted by-products. The calculated accuracy for the cleavage of NP10EO to NP was 95% and the limit of NP/DNP detection
of the presented method was 5 mg/L. 相似文献
10.
Agnieszka Zgoła-Grześkowiak 《Journal of chromatography. A》2010,1217(11):1761-1766
Dispersive liquid–liquid microextraction (DLLME) coupled with high-performance liquid chromatography with fluorescence detector was applied for the determination of alkylphenols and their short-chained ethoxylates in water samples. Development of DLLME procedure included optimisation of some important parameters such as kind and volume of extracting and dispersing solvents. Under optimised conditions 50 μL of trichloroethylene in 1.5 mL of acetone were rapidly injected into 5 mL of a water sample. After centrifuging the organic phase containing the analytes was taken for evaporation with a gentle nitrogen purge and reconstituted to 50 μL of acetonitrile. The aliquot of this solution was analysed with the use of HPLC. For octylphenol (OP) and octylphenol ethoxylates (OPEOs) linearity was satisfactory in the range 8–1000 μg L−1 and for nonylphenol (NP) and nonylphenol ethoxylates (NPEOs) linearity was in the range from 50 to about 3000 μg L−1. Limit of quantitation was 0.1 μg L−1 for OP and OPEOs and 0.3 μg L−1 for NP and NPEOs. Satisfactory recoveries between 66 and 79% were obtained for environmental samples. The results showed that DLLME is a simple, rapid and sensitive analytical method for the preconcentration of trace amounts of alkylphenols and their ethoxylates in environmental water samples. 相似文献
11.
Single and pauci chain aggregates of isotactic polystyrene (i-PS) were prepared by the freeze-drying process from dilute solutions with the concentration from 1×10−3 to 2×10−5 g/mL. It was found by DSC measurements that the melting point of samples gradually shifted to lower temperatures with the
decrease of the solution concentration used for sample preparation. As a result, the lamella thickness of bulk samples and
the samples prepared by the freeze-drying process from a solution of 2×10−5 g/mL was 19.3 and 12.6 nm, respectively. At 468.3 K the half crystallization time (t
1/2) of samples freeze-dried from a solution of 1×10−4 g/mL was about 36 s, which was merely one tenth of that of the bulk sample. In addition, the growth rate of spherulite (dr/dt) of samples prepared from a solution of 2×10−5 g/mL was faster than that of the bulk sample annealed at 478.3 K. All these results should be attributed to the fewer entanglements
in samples prepared by freeze-drying process from dilute solutions, and presented clear evidence for the influence of chain
entanglements on the crystallization behavior of polymers.
__________
Translated from Chemical Journal of Chinese Universities, 2005, 26(10) (in Chinese) 相似文献
12.
Céspedes R Lacorte S Ginebreda A Barceló D 《Analytical and bioanalytical chemistry》2006,385(6):992-1000
This study presents a quantitative estimation of the analysis and fate of several emerging pollutants, some of them endocrine-disrupting
compounds, in surface water samples collected at several locations along the Ter River and two of its tributaries. Influent
and effluent waters and particulate matter from five sewage treatment plants (STP) that discharge into these rivers were also
studied. The target compounds analyzed were: nonylphenol ethoxylates (NPEO), nonylphenol (NP), octylphenol (OP), bisphenol
A (BPA), phthalates, alcohol ethoxylates (AEO) and benzothiazoles. Chemical analysis by liquid chromatography–mass spectrometry
using an electrospray interface (LC–ESI–MS) revealed the presence of low amounts (between 0.06 and 17.5 μg L−1) of the target compounds NPE1+2O and NP, which were detected in 100% and 84% of the samples respectively. Maximum concentrations occurred in the STPs associated
with the municipalities of Vic and Girona. From the fate and behavior data obtained for the various compounds analyzed in
the STP influent and effluent, we can conclude that the STPs are effective at removing large amounts (more than 70%) of the
compounds studied from the water.
相似文献
13.
Nonylphenol isomers (NP), linear nonylphenol (4-n-NP) and NP short chain ethoxylated derivates (NPEO1 and NPEO2) are degradation products of nonylphenol polyethoxylates, a worldwide used group of surfactants. All of them are considered endocrine disrupters due to their ability to mimic natural estrogens. In this paper, the preparation and evaluation of several 4-n-NP molecularly imprinted polymers (MIPs) for the selective extraction and clean-up of 4-n-NP, NP, NPEO1 and NPEO2 from complex environmental solid samples is described. Among the different combinations tested, a methacrylic acid-based imprinted polymer prepared in toluene provided the better performance for molecularly imprinted SPE (MISPE). Under optimum MISPE conditions, the polymer was able to selectively retain not only linear NP but also the endocrine disruptors NPEO1, NPEO2 and NP with recoveries ranging from 60 to 100%, depending upon the analyte. The developed MISPE procedure was successfully used for the determination of 4-n-NP, NP, NPEO1 and NPEO2 in sediments and sludge samples at concentration levels according to data reported in the literature for incurred samples. Finally, various sludge samples collected at five different sewage treatment plants from Madrid and commercial sludge for agriculture purposes were analysed. The measured concentrations of the different compounds varied from 3.7 to 107.5 mg/kg depending upon the analyte and the sample. 相似文献
14.
Rikke Brix Cristina Postigo Susana González Marta Villagrasa Asuncion Navarro Marina Kuster Maria J. Lopez de Alda Damià Barceló 《Analytical and bioanalytical chemistry》2010,396(3):1301-1309
As a part of a project aiming to assess the potential toxicological effects of contaminants in aquatic ecosystems, the objective
of this work was to determine the occurrence of several selected endocrine-disrupting compounds in water and sediment and
to estimate the estrogenicity of the water. The study consisted of four sampling campaigns at seven sampling points in the
lower Llobregat catchment area (NE Spain). Water and sediment samples underwent chemical target analysis for 19 steroid estrogens
and alkylphenols, which are known to be endocrine-disrupting compounds. In this study, the only estrogens detected in the
water samples were estrone and estrone-sulfate, which were found at low levels (2–5 ng l−1). The alkylphenolic compound showing the highest concentrations was nonylphenol di-ether carboxylate (NP2EC), which was found
at levels up to 30.62 μg l−1 in water samples and 535 ng g−1 in sediment samples. K
d was determined for several alkylphenolic compounds and showed the expected trend of decreasing K
d with increasing polarity. The concentrations of nonylphenol and octylphenol only exceeded the annual average of the European
Union’s environmental quality standards (EQS) in one sampling point. However, the calculated estrogenic potential surpassed
the expected effect concentration in several sampling points, indicating a potential risk. Therefore, we recommend that future
EQS include short-chain alkylphenol ethoxylates and carboxylates. 相似文献
15.
Samaras VG Thomaidis NS Stasinakis AS Lekkas TD 《Analytical and bioanalytical chemistry》2011,399(7):2549-2561
This article presents an analytical method based on solid-phase extraction (SPE) and gas chromatography coupled with mass
spectrometry for the simultaneous determination of the most frequently used acidic pharmaceutical residues, ibuprofen, diclofenac,
naproxen and ketoprofen (KFN), and phenolic endocrine disruptors, bisphenol (BPA), triclosan (TCS), nonylphenol, nonylphenol
monoethoxylate and nonylphenol diethoxylate, in wastewater and sewage sludge samples. In the first phase of the study, each
compound has been characterized individually and afterwards in mixture as a trimethylsilyl derivative in order to identify
the characteristic ions (m/z ratio) constituting the mass spectrum and to choose the ions for quantification and confirmation. Subsequently, derivatization
was evaluated by testing different variables such as the volume of the derivatization solvent bis(trimethylsilyl)trifluoroacetamide
and the effect of each catalyst, pyridine and 1% trimethyl chlorosilane, in the derivatized solution. For the analysis of
wastewater samples, two commercial SPE cartridges, C18 and Oasis HLB, were compared for their extraction efficiency of the
target compounds. The key parameter of extraction procedure included the effect of pH (2.5, 5.3 and 7) of the loading solution.
For solid samples, parameters such as the extracted biomass, the volume of the extraction organic solvent and the effect of
matrix interferences in chromatographic analysis were evaluated. By using C18 cartridges as purification procedure and ultrasound
sonication, satisfactory mean relative recoveries with BPA-d16 and meclofenamic acid as surrogates were obtained ranging from
91% to 117% for wastewater and 84% to 107% for sewage sludge samples. Nine-point calibration of the standard mixture was performed
by linear regression analysis with a correlation coefficient >0.99 for all the tested compounds. Limits of detection for the
developed methods were established between 0.3 (KFN) and 14.8 (BPA) ng L−1, and 15.0 (TCS) and 32.9 (BPA) ng g−1 for wastewater and sewage sludge, respectively. Application to real samples of the wastewater treatment plant in Athens,
the capital of Greece, demonstrated the presence of all tested compounds in most of the samples. 相似文献
16.
Thermal analysis of soil amended with sewage sludge and biochar from sewage sludge pyrolysis 总被引:1,自引:0,他引:1
The main objective of the present study is to study the behaviour of sewage sludge and biochar from sewage sludge pyrolysis
after addition to soil in a context of a temperate agricultural soil. For this, an incubation experiment was designed during
200 days. Carbon mineralization of soil amended with sewage sludge and biochar at two different rates (4 and 8 wt%) was evaluated.
Differential thermal analysis, thermogravimetry and the first derivate of the TG were performed in oxidizing conditions on
soil samples before and after incubation. Biochar obtained from sewage sludge pyrolysis at 500 °C was more stable in soil
than original sewage sludge. After incubation experiment, the reduction of soil organic matter content was significantly lower
in soil amended with biochar than in soil amended with sewage sludge. The thermostability index WL3/WL2 decreases after incubation in soil amended with biochar, however it increases in case of soil treated with sewage sludge. 相似文献
17.
Lara-Martín PA González-Mazo E Brownawell BJ 《Analytical and bioanalytical chemistry》2012,402(7):2359-2368
Surfactants and their metabolites can be found in aquatic environments at relatively high concentrations compared with other
micropollutants due in part to the exceptionally large volumes produced every year. We have focused our attention here on
the most widely used nonionic surfactants, alcohol ethoxylates (AEOs), and on nonylphenol ethoxylate (NPEO) degradation products
(short-chain nonylphenol ethoxylates, NP1-3EO, nonylphenol, NP, and nonylphenol ethoxycarboxylates, NP1-2EC), which are endocrine-disrupting
compounds. Our main objective in this work was to develop a methodology aimed at the extraction, isolation, and improved analysis
of these analytes in environmental samples at trace levels. Extraction recoveries of target compounds were determined for
sediment samples after ultrasonic extraction and purification using HLB or C18 solid-phase extraction minicolumns. Recovery
percentages were usually between 61 and 102% but were lower for longer AEO ethoxymers. Identification and quantification of
target compounds was carried out using a novel ultra-performance liquid chromatography coupled to tandem mass spectrometry
(UPLC–MS-MS) approach, a combination that provides higher sensitivity and faster analysis than prior methods using conventional
high-performance liquid chromatography–mass spectrometry. Limits of detection were usually below 0.5 ng/g, being higher for
monoethoxylate species (>5 ng/g) because of poor ionization. The method was used for analyzing surface sediment samples collected
at Jamaica Bay (NY) in 2008. The highest values (28,500 ng/g for NP, 4,200 ng/g for NP1-3EO, 22,400 ng/g for NP1-2EC, and
1,500 ng/g for AEOs) were found in a sampling station from a restricted water circulation area that is heavily impacted by
wastewater discharges. 相似文献
18.
Ultrasound-assisted extraction of isoflavones from soy beverages blended with fruit juices 总被引:1,自引:0,他引:1
A new method for the fast determination of isoflavones from soy beverages blended with fruit juices without the need of freeze-drying the sample was developed. During the method development, several parameters were studied: solvent (methanol and ethanol), sample:solvent ratio (5:1 to 0.2:1), temperature (10-60 °C) and extraction time (5-30 min). The most important parameter for the extraction of isoflavones from soy drinks was the sample:solvent ratio. The optimized method consists of extracting the sample with ethanol with a sample:solvent ratio of 0.2:1 on an ultrasound bath at 45 °C during 20 min. Also, samples were freeze-dried, extracted using conventional method and compared with the optimized method and no significant difference was observed on total and individual isoflavone concentration. The most representative samples from the Spanish market, with a wide variation of isoflavone concentration were analyzed using the optimized method. Differences between manufacturers reached an almost 10 times fold variation. Overall isoflavone concentration ranged from 6.7 to 58.2 mg L−1. 相似文献
19.
This work describes a methodology for Cd and Pb determination in sewage sludge slurry samples using thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS). The TS-FF-AAS system was equipped with a Ni tube atomizer placed on an oxidizing air/acetylene flame. Two multivariate calibration models based on partial least squares (PLS) were proposed using total peak profiles (recorded during 57 s). Metals concentration in the sewage sludge samples were from 1.87 to 6.26 mg kg−1 for Cd and from 101 to 327 mg kg−1 for Pb. The limits of detection and quantification were, respectively, 0.2 and 0.7 μg kg−1 for Cd and 8 and 26 μg kg−1 for Pb. These values were three times lower than the limits found when these metals were calibrated using linear calibration with aqueous standard solutions. 相似文献
20.
C. Ovalles R. L. Marquez R. Curci L. Prat E. Lujano J. Portillo 《Journal of Dispersion Science and Technology》2013,34(4):353-366
The synthesis of the nonylphenol poly(ethylene carbonate) surfactants derived from nonylphenol (NP), carbon dioxide and ethylene oxide (EO) were carried out with high yields in the presence of alkali metal salts (K2CO3, Na2CO3, K2SnO3 and zinc glutamate) as base catalysts. The synthesis reactions were carried out in a stainless-steel reactor in the temperature range of 150-200°C under an initial pressure of 800 psi, with an initial molar ratio of CO2/EO = 0·21, catalyst concentration of 1 × 103 M for a 24 h-period. The surfactants were characterized by FT-IR and by H-NMR. The percentages of carbon dioxide incorporation were between 7 and 16% indicating that the activation of CO2 is a rather difficult process under the catalytic conditions used L175-200 °C and 800 psi of final pressure) It was found that the most probable mechanism for the synthesis of the surfactants occurs in two steps. The first reaction involves the role of the base as a catalyst for the formation of the cyclic ethylene carbonate from CO2 and ethylene oxide. The next step is the reaction of the nonylphenol in the presence of cyclic ethylene carbonate and ethylene oxide to generate the surface active compounds. This mechanism indicates that for each mol of carbon dioxide incorporated, one mol of EO has to be added. The CMC values of the surfactants decrease (from 200 to 100 mM) with the increase in the molar ratio CO2/EO (from 0·08 to 0·3) which can be attributted to a decrease in the hydrophilic character of the surfactant heads due to the addition of carbonate groups(-O-C(=0)-0-) to the ethoxylated chains (between I to 3 moles). 相似文献