首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Solid-phase microextraction (SPME) and solid-phase extraction (SPE) procedures were coupling with microwave-assisted micellar extraction for organochlorine pesticides residues determination in seaweed samples. They were optimized, compared and discussed.Preliminary experiments were performed in order to study experimental conditions for the extraction of pesticides from spiked seaweed samples with microwave-assisted micellar extraction (MAME) using a non-ionic surfactant (Polyoxyethylene 10 Lauryl Ether). After that, SPME and SPE were used to clean-up and preconcentrate MAME extract prior the analysis by liquid chromatography with photodiode array (PDA) detection.Excellent results were obtained for both procedures. Average pesticide recoveries between 80.5 and 104.3% for MAME-SPME and between 73.9 and 111.5% for MAME-SPE were obtained. Relative standard deviations (RSDs) were lower than 10.3% and 5.3% respectively for all recoveries tested, and LOD between 138–348 ng g− 1 for MAME-SPME and 2–38 ng g− 1 for MAME-SPE were obtained. The method was validated using Soxhlet extraction procedure.Both methods were applied to analyse target organochlorine pesticides in several seaweed samples and results were compared. These results show the great possibilities of combining MAME-SPE-HPLC-UV for the analysis of seaweed samples, improving the selectivity and sensitivity in the determination of organochlorine pesticides analysis for this kind of samples.  相似文献   

2.
Microwave assisted micellar extraction (MAME) coupled with solid phase microextraction (SPME) and HPLC-UV determination have been used for the determination of five organochlorine pesticides from agricultural soil samples. A non-ionic surfactant, Polyoxyethlylene 10 Lauryl Ether was used, and the different variables for the optimization of MAME and SPME procedures were studied. This method was applied successfully to the determination of these pesticides in several kinds of agricultural soil samples with different characteristics. Most of the compounds studied can be recovered in good yields with R.S.D. lower than 9% and detection limit ranged between 56-96 ng g−1 for the pesticides studied.  相似文献   

3.
An ultra-preconcentration technique composed of solid-phase extraction (SPE) and dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography–flame photometric detection (GC–FPD) was used for determination of thirteen organophosphorus pesticides (OPPs) including phorate, diazinon, disolfotane, methyl parathion, sumithion, chlorpyrifos, malathion, fenthion, profenphose, ethion, phosalone, azinphose-methyl and co-ral in aqueous samples. The analytes were collected from large volumes of aqueous solutions (100 mL) into 100 mg of a SPE C18 sorbent. The effective variables of SPE including type and volume of elution solvent, volume and flow rate of sample solution, and salt concentration were investigated and optimized. Acetone was selected as eluent in SPE and disperser solvent in DLLME and chlorobenzene was used as extraction solvent. Under the optimal conditions, the enrichment factors were between 15,160 and 21,000 and extraction recoveries were 75.8–105.0%. The linear range was 1–10,000 ng L?1 and limits of detection (LODs) were between 0.2 and 1.5 ng L?1. The relative standard deviations (RSDs) for 50 ng L?1 of OPPs in water with and without an internal standard, were in the range of 1.4–7.9% (n = 5) and 4.0–11.6%, respectively. The relative recoveries of OPPs from well and farm water sat spiking levels of 25 and 250 ng L?1 were 88–109%.  相似文献   

4.
A microwave-assisted extraction method followed by clean-up with solid-phase extraction (SPE) combined with large-volume injection gas chromatography–tandem mass spectrometry (LVI-GC-MS/MS) for the analysis of 17 pesticides in wild and aquaculture edible seaweeds has been developed. An experimental central composite design was employed to evaluate the effects of the main variables potentially affecting the extraction (temperature, time, and solvent volume) and to optimize the process. The most effective microwave extraction conditions were achieved at 125 °C and 12 min with 24 mL of hexane/ethyl acetate (80:20). SPE clean-up of the extracts with graphitized carbon and Florisil, optimized by means of the experimental design, proved to be efficient in the removal of matrix interferences. The analytical recoveries were close to 100% for all the analytes, with relative standard deviations lower than 13%. The limits of detection ranged from 0.3 to 23.1 pg g−1 and the limits of quantification were between 2.3 and 76.9 pg g−1, far below the maximum residue levels established by the European Union for pesticides in seaweed. The results obtained prove the suitability of the microwave-assisted extraction for the routine analysis of pesticides in aquaculture and wild seaweed samples.  相似文献   

5.
《Microchemical Journal》2011,97(2):348-351
A sensitive and selective preconcentration method using solid-phase extraction (SPE) disk, namely multiwalled carbon nanotubes (MWCNTs) disk, is proposed for the determination of atrazine and simazine in water samples. Atrazine and simazine were extracted on MWCNTs disk and then determined by gas chromatography–mass spectrometry (GC/MS). Several parameters on the enrichment factor of the analytes were investigated. The experimental results showed that it was possible to obtain quantitative analysis when the solution pH was 5 using 200 mL of validation solution containing 0.1 μg of triazines and 5 mL of acetone as an eluent. The maximum enrichment factors for atrazine and simazine were 3900 ± 250 and 4000 ± 110, respectively when 200 mL of sample solution volume was used. Relative standard deviations for seven determinations were 6.9% (atrazine) and 3.0% (simazine) under optimum conditions. The linear range of calibration curves were 0.1 to 1 ng mL 1 for each analyte with good correlation coefficients. The detection limits (3S/N) were 2.5 and 5.0 pg mL 1 for atrazine and simazine, respectively. The proposed method was successfully applied to the determination of atrazine and simazine in environmental water samples with high precision and accuracy.  相似文献   

6.
Liquid phase extraction with back extraction (LPE-BE) combined with high performance liquid chromatography-diode array detection (HPLC-DAD) was applied for the extraction and determination of erythromycin A, B and C in fermentation broths. According to this procedure, the fermentation broth with the adjustment pH at a fixed value of 10 was first mixed with organic solvent (Vbroth/Vorg = 1.0). After shaking, the mixture was separated into two phases by microfuging at 13,000 rpm for 15 min. Then back extraction was performed into the acidic aqueous phase with pH 5.0 (Vorg/Vaq = 1.0). After centrifugation at 3000, the two phases were separated and 50 μL of the acidic aqueous phase was injected into the HPLC. The effects of different variables such as the nature of extraction solvent and the pH of samples and buffer were investigated. At the most appropriate conditions, dynamic linear ranges of 0.5–8, 0.1–0.9 and 0.1–0.9 mg mL−1 and limits of detection of 0.03, 0.003 and 0.002 mg mL−1 were obtained for erythromycin A, B and C, respectively. Relative standard deviations (RSDs) of the proposed method were less than 9.5%. The mean recoveries were 99.5%. The proposed method is simple and sensitive with highly clean-up effect and it can be used for monitoring the progress of erythromycin fermentation.  相似文献   

7.
Liquid chromatography–inductively coupled plasma-mass spectrometry (LC–ICP-MS) was used for arsenic speciation analysis in tissues of bivalve mollusks (Anomalocardia brasiliana sp. and Macoma constricta sp.). Microwave and ultrasound radiation, combined with different extraction conditions (solvent, sample amount, time, and temperature), were evaluated for As-species extraction from the mollusks' tissues. Accuracy, extraction efficiency, and the stability of As species were evaluated by analyzing certified reference materials (DORM-2, dogfish muscle; BCR-627, tuna fish tissue; and SRM 1566b, oyster tissue) and analyte recovery tests. The best conditions were found to be microwave-assisted extraction using 200 mg of samples and water at 80 °C for 6 min. The agreement of As-species concentration in samples ranged from 97% to 102%. Arsenobetaine (AsB) was the main species present in bivalve mollusk tissues, while monomethylarsonic acid (MMA) and arsenate (As(V)) were below the limit of quantification (0.001 and 0.003 μg g 1, respectively). Two unidentified As species also were detected and quantified. The sum of the As-species concentration was in agreement (90 to 104%), with the total As content determined by ICP-MS after sample digestion.  相似文献   

8.
Simultaneous determination of nimesulide, phenylpropanolamine, chlorpheniramine and caffeine in rat plasma by reversed-phase high performance liquid-chromatography (RP–HPLC) with photodiode array (PDA) detection method was developed and validated. Sample preparation based on a simple extraction procedure consisting of deproteination and extraction with methanol solution followed by volume make up with the aqueous component of the mobile phase obtained best recoveries of the analytes. The chromatographic conditions were optimized and the analytes were separated on XBridge™ C18 (3.5 μm, 4.6 × 150 mm) column in isocratic elution with the mobile phase composition of acetonitrile and 10 mM ammonium acetate buffer (pH 4.0, 0.1% formic acid) (18:82 v/v%) at the flow rate of 1 mL min−1 and the effluents were monitored in the wavelength range of 220–275 nm. The method was linear for all analytes over the following concentration (ng mL−1) ranges: nimesulide 250–4000; phenylpropanolamine 100–1500; chlorpheniramine 20–500; and caffeine 10–100. Acceptable precision, accuracy and recoveries were obtained for quality control (QC) samples at three concentrations (low QC, middle QC and high QC). The percentage of relative standard deviation (% RSD) of Inter and intra-run precision of all molecules was <15% and the percentage of accuracy was 100 ± 10. The analytes were more stable in rat plasma at different storage conditions. Finally the method was efficiently applied to pharmacokinetics study in rat plasma.  相似文献   

9.
We developed a simple strategy for designing a sensitive electrochemical stripping voltammetric sensor for organophosphate pesticides (OPs) based on solid-phase extraction (SPE) using nanosized Pt intercalated Ni/Al layered double hydroxides (labeled as NanoPt-LDHs). By assembling NanoPt with LDHs together, the resulting NanoPt-LDHs are highly efficient to capture OPs. It dramatically facilitates the enrichment of OPs onto their surface and realizes the sensitive stripping voltammetric detection of methyl parathion (MP) as a model of OPs. The stripping analysis shows highly linear over MP concentration ranges of 0.001–0.15 and 0.3–1.0 μg mL? 1 with a detection limit of 0.6 ng mL–1 (S/N = 3). The combination of NanoPt, LDHs, SPE, and square-wave voltammetry (SWV) provides a fast, simple, and sensitive electrochemical method for OPs.  相似文献   

10.
A rapid, specific and sensitive multiresidue method based on dispersive solid phase extraction sample preparation and gas chromatography with the mass spectrometric detection for the analysis of 234 pesticides in Korean herbs (Acanthopanax senticosus, Morus alba L., Hovenia dulcis) has been developed. Method recoveries were found to be between 62 and 119% with relative standard deviation lower than 21% for all compounds in the concentration range of 0.05 to 0.400 mg kg? 1. Limits of quantification of most compounds are below 0.050 mg kg? 1. The data demonstrate that this method was successfully used for analysis of 234 pesticides in Korean herbs.  相似文献   

11.
A highly sensitive, selective and rapid method for the determination of cobalt based on the rapid reaction of cobalt(II) with 5-(2-benzothiazolylazo)-8-hydroxyquinolene BTAHQ and the solid phase extraction of the Co(II)-BTAHQ complex with C18 membrane disks were developed. In the presence of pH = 6.4 buffer solution and cetylpyridenium chloride (CPC) medium, BTAHQ reacts with cobalt to form a deep violet complex with a molar ratio of 1:1 (cobalt to BTAHQ). This complex was enriched by the solid phase extraction with C18 membrane disks. An enrichment factor of 100 was obtained by elution of the complex from the disks with a minimal amount of isopentyl alcohol. In isopentyl alcohol medium, the molar absorptivity of the complex is 2.42 × 105 L mol−1 cm−1 at 658 nm. Beer’s law is obeyed in the range of 0.01–0.38 μg mL−1 in the measured solution. The relative standard deviation for 11 replicate samples of 0.20 μg mL−1 level is 1.37%. The detection and quantification limits reach 3.1 and 9.7 ng mL−1 in the original samples. This method was applied for the determination of cobalt in biological, water, soil and pharmaceutical preparation samples with good results.  相似文献   

12.
In the present work a new, simple, rapid and environmentally friendly dispersive liquid–liquid microextraction (DLLME) method has been developed for extraction/preconcentration of some triazole pesticides in aqueous samples and in grape juice. The extract was analyzed with gas chromatography–flame ionization detection (GC–FID) or gas chromatography–mass spectrometry (GC–MS). The DLLME method was performed in a narrow-bore tube containing aqueous sample. Acetonitrile and a mixture of n-hexanol and n-hexane (75:25, v/v) were used as disperser and extraction solvents, respectively. The effect of several factors that influence performance of the method, including the chemical nature and volume of the disperser and extraction solvents, number of extraction, pH and salt addition, were investigated and optimized. Figures of merit such as linearity (r2 > 0.995), enrichment factors (EFs) (263–380), limits of detection (0.3–5 μg L?1) and quantification (0.9–16.7 μg L?1), and relative standard deviations (3.2–5%) of the proposed method were satisfactory for determination of the model analytes. The method was successfully applied for determination of target pesticides in grape juice and good recoveries (74–99%) were achieved for spiked samples. As compared with the conventional DLLME, the proposed DLLME method showed higher EFs and less environmental hazards with no need for centrifuging.  相似文献   

13.
A method for determining the volatile organic compounds (VOCs) in textiles was developed, by the use of high capacity headspace, solid phase micro extraction (SPME) and gas chromatography–mass spectrometry (GC/MS). The detection targets contained total organic compounds (TVOCs) and six specific substances (toluene, vinylcyclohexene, styrene, 4-phenylcyclohexene, vinylchloride and butadiene), according to Oeko-Tex Standard 100. A designed experiment was used to optimize the headspace–SPME–GC/MS operation, and the method was validated in terms of linearity, limit of detection (LOD) and method precision. It was found that at a loading ratio of 10 m2/m3, the LODs for toluene, vinylcyclohexene, styrene and 4-phenylcyclohexene were 0.0002 mg/m2, 0.01 mg/m2, 0.01 mg/m2 and 0.0001 mg/m2 respectively, while for vinylchloride and butadiene they were both 0.08 mg/m2. SPME exhibited better adsorption performance for toluene, vinylcyclohexene, styrene and 4-phenylcyclohexene, for which the extraction fractions were 10 times of those for vinylchloride and butadiene. The method developed was successfully applied to analyze several commercial textiles, and would be a simple, efficient and promising technique for the analysis of volatile compounds from textiles or other samples (such as polymer materials).  相似文献   

14.
Air quality in the metropolitan region of Rio de Janeiro was evaluated by analysis of particulate matter (PM) in industrial (Santa Cruz) and rural (Seropédica) areas. Total suspended particles (TSP) and fine particulate matter (PM2.5) collected in filters over 24 h were quantified and their chemical composition determined. TSP exceeded Brazilian guidelines (80 μg m 3) in Santa Cruz, while PM2.5 levels exceeded the World Health Organization guidelines (10 μg m 3) in both locations. Filters were extracted with water and/or HNO3, and the concentrations of 20 elements, mostly metals, were determined by inductively coupled plasma mass spectrometry (ICP-MS) and optical emission spectrometry (ICP OES). Water soluble inorganic anions were determined by ion chromatography (IC). To estimate the proportion of these elements extracted, a certified reference material (NIST SRM 1648a, Urban Dust) was subjected to the same extraction process. Concordant results were obtained by ICP-MS and ICP OES for most elements. Some elements could not be quantified by both techniques; the most appropriate technique was chosen in each case. The urban dust was also analyzed by the United States Environmental Protection Agency (US EPA) method, which employs a combination of hydrochloric and nitric acids for the extraction, but higher extraction efficiency was obtained when only nitric acid was employed. The US EPA method gave better results only for Sb. In the PM samples, the elements found in the highest average concentrations by ICP were Zn and Al (3–6 μg m 3). The anions found in the highest average concentrations were SO42  in PM2.5 (2–4 μg m 3) and Cl in TSP (2–6 μg m 3). Principal component analysis (PCA) in combination with enrichment factors (EF) indicated industrial sources in PM2.5. Analysis of TSP suggested both anthropogenic and natural sources. In conclusion, this work contributes data on air quality, as well as a method for the analysis of PM samples by ICP-MS.  相似文献   

15.
Multiwalled carbon nanotube (MWCNT) was developed as a new sorbent for solid-phase extraction (SPE) of organophosphate (OP) pesticides. A combination of SPE with square-wave voltammetric (SWV) analysis resulted in a fast, sensitive, and selective electrochemical method for determination of OP pesticide using methyl parathion (MP) as a representative. Because of the strong affinity of MWCNT for phosphoric group, nitroaromatic OP compounds can strongly bind to the MWCNT surface. The macroporosity and heterogeneity of MWCNT allow extracting a large amount of MP less than 5 min. The stripping response was highly linear over the MP range of 0.05–2.0 μg/mL, with a detection limit of 0.005 μg/mL. The determination of MP in garlic samples showed acceptable accuracy. The fast extraction ability of MWCNT makes it promising sorbent for various solid-phase extractions.  相似文献   

16.
Citric acid was used as a chemical modifier for Pb determination by graphite furnace atomic absorption spectrometry in dietary supplement samples (calcium carbonate, dolomite and oyster shell samples) and its efficiency was compared to the use of palladium. Pyrolysis and atomization curves were established without use of chemical modifier, with the addition of 20, 100 and 200 μg of citric acid, and with 3 μg of palladium. The citric acid modifier made possible the interference-free Pb determination in the presence of high concentrations of Ca and Mg nitrates. Acid sample digestion involving closed vessels (microwave-assisted and conventional heating) and acid attack using polypropylene vessels at room temperature were compared. All digestion procedures presented similar results for calcium carbonate and dolomite samples. However, for oyster shell samples accurate results were obtained only with the use of closed vessel systems. Analyte addition and matrix-matched standards were used for calibration. The characteristic mass for Pb using citric acid and palladium were 16 and 25 pg, respectively. The relative standard deviation (RSD) was always less than 5% when citric acid was used. The relative and absolute limits of detection were 0.02 μg g 1 and 8 pg with citric acid and 0.1 μg g 1 and 44 pg with the Pd modifier, respectively (n = 10, 3σ). The recovery of Pb in spiked calcium supplement samples (10 μg l 1) was between 98% and 105%. With the use of 100 μg of citric acid as chemical modifier, problems such as high background absorption and high RSD values were minimized in comparison to the addition of 3 μg of palladium.  相似文献   

17.
Cu was determined in a wide range of petroleum products from crude oil distillation using flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma mass spectrometry (ICP-MS). Different procedures of sample preparation were evaluated: (i) mineralization with sulfuric acid in an open system, (ii) mineralization in a closed microwave system, (iii) combustion in hydrogen–oxygen flame in the Wickbold's apparatus, (iv) matrix evaporation followed by acid dissolution, and (v) acidic extraction. All the above procedures led to the transfer of the analyte into an aqueous solution for the analytical measurement step. It was found that application of FAAS was limited to the analysis of the heaviest petroleum products of high Cu content. In ICP-MS, the use of internal reference method (with Rh or In as internal reference element) was required to eliminate the matrix effects in the analysis of extracts and the concentrated solutions of mineralized heavy petroleum products. The detection limits (in original samples) were equal to, respectively, 10, 86, 3.3, 0.9 and 0.4 ng g 1 in procedures i–v with ETAAS detection and 10, 78, 1.1 and 0.5 ng g 1 in procedures i–iii and v with ICP-MS detection. The procedures recommended here were validated by recovery experiments, certified reference materials analysis and comparison of results, obtained for a given sample, in different ways. The Cu content in the analyzed samples was: 50–110 ng g 1 in crude oil, < 0.4–6 ng g 1 in gasoline, < 0.5–2 ng g 1 in atmospheric oil, < 6–100 ng g 1 in heavy vacuum oil and 140–300 ng g 1 in distillation residue.  相似文献   

18.
A simple and inexpensive laboratory-built flow injection vapor generation system coupled to atomic absorption spectrometry (FI-VG AAS) for inorganic and total mercury determination has been developed. It is based on the vapor generation of total mercury and a selective detection of Hg2 + or total mercury by varying the temperature of the measurement cell. Only the inorganic mercury is measured when the quartz cell is at room temperature, and when the cell is heated to 650 °C or higher the total Hg concentration is measured. The organic Hg concentration in the sample is calculated from the difference between the total Hg and Hg2 + concentrations. Parameters such as the type of acid (HCl or HNO3) and its concentration, reductant (NaBH4) concentration, carrier solution (HCl) flow rate, carrier gas flow rate, sample volume and quartz cell temperature, which influence FI-VG AAS system performance, were systematically investigated. The optimized conditions for Hg2 + and total Hg determinations were: 1.0 mol l 1 HCl as carrier solution, carrier flow rate of 3.5 ml min 1, 0.1% (m/v) NaBH4, reductant flow rate of 1.0 ml min 1 and carrier gas flow rate of 200 ml min 1. The relative standard deviation (RSD) is lower than 5.0% for a 1.0 μg l 1 Hg solution and the limit of quantification (LOQ, 10 s) is 55 ng g 1. Certified samples of dogfish muscle (DORM-1 and DORM-2) and non-certified fish samples were analyzed, using a 6.0 mol l 1 HCl solution for analyte extraction. The Hg2 + and CH3Hg+ concentrations found were in agreement with certified ones.  相似文献   

19.
The exposure to gamma-irradiation pretreatment increases cell wall permeabilization, resulting in loss of turgor pressure, which led to the increase of extractability of betanin from red beetroot. The degree of extraction of betanin was investigated using gamma irradiation as a pretreatment prior to the solid–liquid extraction process and compared with control beetroot samples. The beetroot subjected to different doses of gamma irradiation (2.5, 5.0, 7.5, 10.0 kGy) and control was dipped in an acetic acid medium (1% v/v) to extract the betanin. The diffusion coefficients for betanin as well as ionic component were estimated considering Fickian diffusion. The results indicated an increase in the diffusion coefficient of betanin (0.302×10−9–0.463×10−9 m2/s) and ionic component (0.248×10−9–0.453×10−9 m2/s) as the dose rate increased (from 2.5 to 10.0 kGy). The degradation constant was found to increase (0.050–0.079 min−1) with an increase gamma-irradiation doses (2.5–10.0 kGy), indicating lower stability of the betanin as compared to control sample at 65 °C.  相似文献   

20.
In this study, dispersive liquid–liquid microextraction (DLLME) combined with ultra-high-pressure liquid chromatography (UHPLC)–tunable ultraviolet detection (TUV), has been developed for pre-concentration and determination of triclosan (TCS), triclocarban (TCC) and methyl-triclosan (M-TCS) in aqueous samples. The key factors, including the kind and volume of extraction solvent and dispersive solvent, extraction time, salt effect and pH, which probably affect the extraction efficiencies were examined and optimized. Under the optimum conditions, linearity of the method was observed in the range of 0.0500–100 μg L?1 for TCS, 0.0250–50.0 μg L?1 for TCC, and 0.500–100 μg L?1 for M-TCS, respectively, with correlation coefficients (r2) > 0.9945. The limits of detection (LODs) ranged from 45.1 to 236 ng L?1. TCS in domestic waters was detected with the concentration of 2.08 μg L?1. The spiked recoveries of three target compounds in river water, irrigating water, reclaimed water and domestic water samples were achieved in the range of 96.4–121%, 64.3–84.9%, 77.2–115% and 75.5–106%, respectively. As a result, this method can be successfully applied for the rapid and convenient determination of TCS, TCC and M-TCS in real water samples.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号