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1.
Summary A fast and simple procedure for the analysis of aqueous samples by on-line membrane disk extraction and capillary gas chromatography (GC) is presented. As an example, organophosphorus pesticides are preconcentrated from aqueous samples on three 0.5 mm thick, 4.2 mm diameter extraction disks. The layers are dried by a stream of nitrogen (10–15 min; ambient temperature). Desorption of the analytes is carried out with ethyl acetate which is directly introduced into a retention gap under partially concurrent solvent evaporation conditions, using an early solvent vapour exit. The final analysis is carried out by GC with thermionic detection. The technique is applied to the determination of a series of organophosphorus pesticides in tap water and water from two European rivers. With a sample volume of only 2.5 ml, detection limits of 10–30 ppt are achieved in tap water and of 50–100 ppt in river water.  相似文献   

2.
The efficiency of polyaniline (PANI), coated gold wire was investigated for use as a fiber for solid-phase microextraction (SPME). Aniline monomers were electropolymerized on gold wires by applying a constant current to an acetate buffer containing NaClO4 as supporting electrolyte for 30 min. These fibers were used for the extraction of some aliphatic alcohols from gaseous samples. The results obtained proved the ability of PANI fiber for sampling organic compounds from gaseous samples. From this work, optimum conditions for preparation and conditioning of fibers and for the extraction of analytes from gaseous samples were obtained. Under optimum conditions, one fiber was used for several equivalent analyses and the relative standard deviations (RSD) were <7% (n=6). However, fiber to fiber reproducibility was <9% (n=6). This fiber is firm and durable and is simply prepared. Calibration graphs were linear in the range: 0.1–10 g mL–1 for aliphatic alcohols; the detection limit range was 15–75 ng mL–1 (S/N=3) using a flame ionization detector.  相似文献   

3.
A multiresidue method was developed for the determination of nitrogen- and phosphorous-containing pesticides (amines, anilides, phosphorothioates, and triazines) by solid-phase microextraction (SPME) in-line coupled to gas chromatography—mass spectrometry (GC/MS). The 85-µm polyacrylate fiber was first dipped into the aqueous sample for a given time and then directly introduced into the heated injector of the gas chromatography—mass spectrometer, where the analytes are thermally desorbed. The method was evaluated with respect to the limit of detection, linearity, and precision. The limit of detection [selected ion monitoring (SIM) mode] depends on the compound and varies from 5 to 90 ng/L. The method is linear over at least 3 orders of magnitude with coefficients of correlation usually ≥0.996. In general, the coefficient of variation (precision) is <10%. The partitioning of the analyte between the aqueous phase and the polymeric phase depends on the hydrophobicity of the compound as expressed by the octanol—water partitioning coefficient P ow. The addition of sodium chloride has a strong effect on the extraction efficiency. This effect increases with decreasing hydrophobicity (increasing polarity) of the compound. The triazines atrazine, simazine, and terbuthylazine were first identified and quantified in water samples from the effluent of sewage plants by SPME-gas chromatography—nitrogen—phosphorus detection (GC/NPD). For such a complex matrix GC/NPD is not sufficiently selective for an unambiguous identification at low levels (<1 ppb) of pesticides. Selectivity may be enhanced by using SMPE-GC/MS in the SIM mode with three characteristic ions for each pesticide. This method allows an unequivocal identification and quantification at low levels of pesticides in environmental samples. At a target limit of detection below 100 ng/L, SPME-GC/MS represents a very simple, fast, selective, and solvent-free multimethod for the extraction and determination of these nitrogen- and phosphorous-containing pesticides from aqueous samples.  相似文献   

4.
Summary Organosphosphate pesticides have been found extractable by headspace solid-phase microextraction (SPME), and the best conditions of their extraction from human whole blood and urine samples have been investigated. The body fluid samples containing nine pesticides (IBP, methyl parathion, fenitrothion, malathion, fenthion, isoxathion, ethion, EPN and phosalone) were heated at 100°C in a septum-capped vial in the presence of various combinations of acid and salts, and SPME fiber was exposed to the headspace of the vial to allow adsorption of the pesticides before capillary gas chromatography (GC) with nitrogen-phosphorus detection. The heating with distilled water/HCl/(NH4)2SO4/NaCl and with distilled water/HCl gave the best results for urine and whole blood, respectively. Recoveries of the nine pesticides were 0.8–10.6% except for phosalone (0.03%) for whole blood, and 3.8–40.2% for urine. The calibration curves for the pesticides showed linearity in the range of 50–400 ng/0.5 mL for whole blood except for malathion (100–400 ng/0.5 mL whole blood) and 7.5–120 ng/0.5 mL for urine except for phosalone (15–120 ng/0.5 mL urine) with detection limits of 2.2–40 ng/0.5 mL for whole blood and 0.8–12 ng/0.5 mL for urine.  相似文献   

5.
Ming-Chi Wei 《Talanta》2007,72(4):1269-1274
The novel pretreatment technique, microwave-assisted heating coupled to headspace solid-phase microextraction (MA-HS-SPME) has been studied for one-step in situ sample preparation for polycyclic aromatic hydrocarbons (PAHs) in aqueous samples before gas chromatography/flame ionization detection (GC/FID). The PAHs evaporated into headspace with the water by microwave irradiation, and absorbed directly on a SPME fiber in the headspace. After being desorbed from the SPME fiber in the GC injection port, PAHs were analyzed by GC/FID. Parameters affecting extraction efficiency, such as SPME fiber coating, adsorption temperature, microwave power and irradiation time, and desorption conditions were investigated.Experimental results indicated that extraction of 20 mL aqueous sample containing PAHs at optional pH, by microwave irradiation with effective power 145 W for 30 min (the same as the extraction time), and collection with a 65 μm PDMS/DVB fiber at 20 °C circular cooling water to control sampling temperature, resulted in the best extraction efficiency. Optimum desorption of PAHs from the SPME fiber in the GC hot injection port was achieved at 290 °C for 5 min. The method was developed using spiked water sample such as field water with a range of 0.1-200 μg/L PAHs. Detection limits varied from 0.03 to 1.0 μg/L for different PAHs based on S/N = 3 and the relative standard deviations for repeatability were <13%. A real sample was collected from the scrubber water of an incineration system. PAHs of two to three rings were measured with concentrations varied from 0.35 to 7.53 μg/L. Recovery was more than 88% and R.S.D. was less than 17%. The proposed method is a simple, rapid, and organic solvent-free procedure for determination of PAHs in wastewater.  相似文献   

6.
Solid-phase microextraction (SPME) coupled to ultrasonic extraction was evaluated for extracting trace amounts of two agrochemical fungicides, vinclozolin and dicloran, in soil samples. Extraction was performed following two experimental approaches prior to the submission of the aqueous extracts to SPME-GC analysis. In the first approach, extraction involved sample homogenization with a water solution containing 5% (v/v) acetone and centrifugation prior to fiber extraction. In the second approach, the extraction of the fungicides from the soil samples was conducted using acetone as organic solvent which was then diluted with water to give a 5% (v/v) content. The pesticides were isolated with fused silica fiber coating with 85 μm polyacrylate. Parameters that affect both the extraction of the fungicides by the soil samples and the trapping of the analytes by the fiber were investigated and their impact on the SPME-GC-MS was studied. The procedures with respect to repeatability and limits of detection were evaluated by soil spiked with both analytes. Repeatability was between 5.6 and 14.2% and the limits of detection were 2-13 ng g−1. The efficiency of acetone/SPME was generally better than that for water/SPME procedure showing good linearity (R2>0.99) with coefficient variations below 9%, recoveries higher than 91% and limits of detection between 2 and 3 ng g−1. Finally, the recoveries obtained with acetone/SPME procedure were compared with the conventional liquid-liquid extraction using real soil samples. The acetone/SPME method was shown to be an inexpensive, fast and simple preparation method for the determination of target analytes at low nanogram per gram levels in soils.  相似文献   

7.
The solid‐phase microextraction (SPME) technique using a 100 μm film polydimethylsiloxane (PDMS) coated fiber has been examined with the aim to determine dichlorobenzene in aqueous samples. The feasibility of SPME‐GC‐ECD analysis has been evaluated. Absorption time of 30 min was selected and 1 min was long enough for complete desorption of the analytes in the injection port of the gas chromatograph. Linear ranges from 0.03 to 5 μg/L and method detection limits between 7 and 9 ng/L for dichlorobenzenes were obtained. The relative standard deviations were less than 12% for a spiking level of 3 μg/L. The proposed method was applied to determine dichlorobenzenes in spiked deionized water, ground water, and in industrial effluent samples.  相似文献   

8.
A method was developed for the analysis of volatile polar compounds in a water matrix using open cap vials Solid Phase Micro-Extraction (SPME) and Capillary Gas Chromatography (CGC). Both SPME techniques – direct sampling and headspace – were tested. Optimization of experimental conditions – exposure time, desorption time, with headspace SPME in addition the influence of the temperature and ionic strength of the sample solution on compound sorption, and finally GC response – were investigated. The analytes were extracted by directly immersing the 85 μm polyacrylate fiber in the aqueous sample or in the headspace. The linear range of the preconcentration process and the precision were examined. The amount of polar analytes sorbed on the fiber was determined and was found to be concentration dependent; it amounted to 0.014–0.64% in the concentration range of 0.00425–425 ppm studied in aqueous solution for direct sampling SPME and to 0.011–2.76% for solutions of concentration 0.0425–255 ppm for headspace SPME. The limits of determination were ascertained. Headspace SPME was applied to the analysis of real-life samples.  相似文献   

9.
Solid-phase microextraction method (SPME) coupled to GC/ECD has been developed and validated for the determination of phthalic acid esters (dimethyl-, diethyl-, di-n-butyl-, butylbenzyl-, di-2-ethylhexyl- and di-n-octyl phthalate) in water samples. Two types of coatings (PDMS, PA), altogether four different kinds of fibers have been investigated. Both parameters affecting the partition of analytes between a fiber coating and aqueous phase (i.e. extraction time, extraction temperature, agitation) and conditions of the thermal desorption in a GC injector were optimized. The final SPME method employing the polyacrylate fiber, extraction time 20 min, heating and stirring of the sample enabled the determination of all six phthalates in water samples. The method showed linear response over four orders of magnitude and the limits of quantification of the method ranged between 0.001 and 0.050 μg l−1. The repeatability expressed as R.S.D. was in the range 4-10% for the spiking level 7 μg l−1 of each analyte. The applicability of the developed SPME method was demonstrated for real water samples.  相似文献   

10.
Myung SW  Kim S  Park JH  Kim M  Lee JC  Kim TJ 《The Analyst》1999,124(9):1283-1286
A simple and rapid analytical method is presented for the determination of pethidine (meperidine) and methadone in human urine using solid-phase microextraction (SPME) and gas chromatography with nitrogen-phosphorus detection (GC-NPD). After the analytes had been partitioned between an extracting phase and the aqueous sample matrix, the needle of the coating fiber assembly was injected directly into the GC injector. The analytes were thermally desorbed in the heated injector (240 degrees C) and subsequently separated and detected by the GC-NPD system. The factors influencing the SPME method, such as the salt (NaCl) effect (15%), pH (pH 11), and equilibration time (30 min), were optimized. The calibration graphs for urine samples showed a good linearity. The detection limit was below 1 ng ml-1 for both drugs.  相似文献   

11.
A new sample preparation and preconcentration technique – solid phase microextraction (SPME) – is reported for the application of several tinorganic compounds and tetrabutyllead in aqueous samples. The solvent-free procedure is rapid in comparison with liquid-liquid extraction or SFE but also sensitive. Analytical variables of the extraction such as adsorption and desorption time, stirring rate and temperature has been investigated. The determination has been performed by GC coupled with atomic emission detection (AED). After optimization of the conditions of SPME a calibration was realized on the basis of a multicomponent standard solution, prepared by ethylation of organotin salts directly in the sample using sodium tetraethylborate (NaBEt4) without prior separation of the analytes from the matrix. The method permits preconcentration. Values of about 10 can be reached. A detection limit of 0.09 pg Sn and 0.08 pg Pb can be achieved under optimized conditions. The proposed procedure has been successfully applied to the analysis of organotin compounds in various slurry samples.  相似文献   

12.
A solid-phase microextraction (SPME)-gas chromatography (GC)-mass spectrometry (MS) analytical method for the simultaneous separation and determination of 16 polycyclic aromatic hydrocarbons (PAHs) from aqueous samples has been developed, based on the sorption of target analytes on a selectively sorptive fibre and subsequent desorption of analytes directly into GC-MS. The influence of various parameters on PAH extraction efficiency by SPME was thoroughly studied. Results show that the fibre exposure time and the use of agitation during exposure are critical in enhancing SPME performance. The presence of colloidal organic matter (as simulated by humic acid) in water samples is shown to significantly reduce the extraction efficiency, suggesting that SPME primarily extracts the truly dissolved compounds. This offers the significant advantage of allowing the differentiation between freely available dissolved compounds and those associated with humic material and potentially biologically unavailable. The method showed good linearity up to 10 μg/l. The reproducibility of the measurements expressed as relative standard deviation (R.S.D.) was generally <20%. The method developed was then applied to extract PAHs from sediment porewater samples collected from the Mersey Estuary, UK. Total PAH concentrations in porewater were found to vary between 95 and 742 ng/l with two to four ring PAHs predominating. Results suggest that SPME has the potential to accurately determine the dissolved concentrations of PAHs in sediment porewater.  相似文献   

13.
Solid-phase microextraction (SPME) is a miniaturized and solvent-free sample preparation technique for chromatographic–spectrometric analysis by which the analytes are extracted from a gaseous or liquid sample by absorption in, or adsorption on, a thin polymer coating fixed to the solid surface of a fiber, inside an injection needle or inside a capillary. In this paper, the present state of practical performance and of applications of SPME to the analysis of blood, urine, oral fluid and hair in clinical and forensic toxicology is reviewed. The commercial coatings for fibers or needles have not essentially changed for many years, but there are interesting laboratory developments, such as conductive polypyrrole coatings for electrochemically controlled SPME of anions or cations and coatings with restricted-access properties for direct extraction from whole blood or immunoaffinity SPME. In-tube SPME uses segments of commercial gas chromatography (GC) capillaries for highly efficient extraction by repeated aspiration–ejection cycles of the liquid sample. It can be easily automated in combination with liquid chromatography but, as it is very sensitive to capillary plugging, it requires completely homogeneous liquid samples. In contrast, fiber-based SPME has not yet been performed automatically in combination with high-performance liquid chromatography. The headspace extractions on fibers or needles (solid-phase dynamic extraction) combined with GC methods are the most advantageous versions of SPME because of very pure extracts and the availability of automatic samplers. Surprisingly, substances with quite high boiling points, such as tricyclic antidepressants or phenothiazines, can be measured by headspace SPME from aqueous samples. The applicability and sensitivity of SPME was essentially extended by in-sample or on-fiber derivatization. The different modes of SPME were applied to analysis of solvents and inhalation narcotics, amphetamines, cocaine and metabolites, cannabinoids, methadone and other opioids, fatty acid ethyl esters as alcohol markers, γ-hydroxybutyric acid, benzodiazepines, various other therapeutic drugs, pesticides, chemical warfare agents, cyanide, sulfide and metal ions. In general, SPME is routinely used in optimized methods for specific analytes. However, it was shown that it also has some capacity for a general screening by direct immersion into urine samples and for pesticides and other semivolatile substance in the headspace mode.  相似文献   

14.
Yan CT  Shih TS  Jen JF 《Talanta》2004,64(3):650-654
Microwave-assisted desorption (MAD) coupled to in situ headspace solid-phase microextraction (HS-SPME) was first proposed as a possible alternative pretreatment of samples in absorbent collected from workplace monitoring. Aniline collected on silica gel was investigated. Under microwave irradiation, the aniline was desorbed from silica gel and directly absorbed onto the SPME fiber in the headspace. Having been sampled on the SPME fiber, and desorbed in the GC injection port, aniline was analyzed using a GC-FID system. Parameters that affect the proposed extraction efficiency, including the extraction media and its pH, the microwave irradiation power and the irradiation time as well as desorption parameters of the GC injector, were investigated. Experimental results revealed that the extraction of a 150-mg silica gel sample using a 0.8-ml aqueous solution (pH 12) and a PDMS/DVB fiber under medium-high-powered irradiation (345 W) for 3 min maximized the efficiency of extraction. Desorption of aniline from the SPME fiber was optimal at 230 °C held for 3 min. The detection limit was 0.09 ng. The proposed method provided a simple, fast, and organic solvent-free procedure to analyze aniline from a silica gel matrix.  相似文献   

15.
Solid-phase microextraction (SPME) represents a very simple and rapid method for the extraction of organophosphorus, triazine and 2,6-dinitroaniline pesticides from aqueous samples without making use of any solvents. The same fiber can be used repeatedly. Moreover, a sample volume as small as 3 mL can be employed with no loss in sensitivity. 34 compounds have been extracted from aqueous samples by SPME using a 85 m polyacrylate fiber. For organophosphorus pesticides, a 100 m polydimethylsiloxane fiber has been used additionally for comparison. The fibers were directly introduced into the heated split/splitless injector of the gas chromatograph and determined using a nitrogen-phosphorus detector. The method was evaluated with respect to the limit of detection (LOD), linearity and precision. The limit of detection (LOD) depends on the compound and varies from 0.005–0.09 g/L. The method is linear over at least three orders of magnitude with coefficients of correlation usually >0.999. For triazines and 2,6-dinitroanilines the coefficient of variation (precision) is <8% while for organophosphorus compounds it may reach values up to 18% (however, if the latter compounds are extracted using the polydimethylsiloxane phase considerably higher precision is achieved). The partitioning of the analyte between the aqueous phase and the polymeric phase depends on the hydrophobicity of the compound as expressed by the octanol/water partitioning coefficient (Pow). For triazines it was shown that there is a linear dependence of the logarithm of the analyte response on the log(Pow) i.e. the higher the hydrophobicity, the higher the affinity of the analytes to the polymeric phase of the fiber and the higher the response. Salt addition has a strong effect on the extraction efficiency. This effect increases with decreasing hydrophobicity (increasing polarity) of the compound. The triazines ametryn, atrazine, propazine, simazine and simetryn have been identified in a ground water well sample by SPMEGC/NPD.  相似文献   

16.
Organometal compounds of tin, mercury and lead were simultaneously determined in environmental water and sediment samples by CGC-ICPMS. Instead of classical liquid/liquid extractions, solid phase microextraction was used as sampling technique. In this method, the organometallic compounds arein situ derivatised in the aqueous phase and simultaneously extracted onto a polydimethylsiloxane fiber, so that organic solvents are no longer necessary. The sorbed organometals are subsequently released from the fiber in the GC injection liner by thermal desorption. By sampling from the headspace, only the species of interest are sampled and no interfering matrix components are coextracted. With this new method, derivatisation, extraction, preconcentration and injection into the GC takes only 10 min with a minimum of handling steps. Owing to the very low detection limits (0.13–3.7 ng/1 as metal) only small sample amounts (25 ml of water, 0.5 g of sediment) are needed for one analysis. Finally, SPME is an inexpensive sampling technique that can be used with standard split/splitless injection systems.  相似文献   

17.

Solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) was optimized for the analysis of hexachlorocyclohexanes, DDD, DDE, DDT and other organochlorine pesticides in aqueous samples. Higher extraction efficiency was observed with the SPME fibre coated with 100 µm polydimethylsiloxane than with the fibres coated with 85 µm polyacrylate or 65 µm polydimethylsiloxane/divinylbenzene. Equilibration times were longer than 60 min, except for the hexachlorocyclohexanes, in spite of rapid stirring of the sample. However, precise quantitative analysis could be performed also under non-equilibrium conditions: i.e. repeatability standard deviations below 20%. Salt addition had a positive effect on the response for the hexachlorocyclohexanes, whereas the extraction of the other analytes was affected negatively. The pH of the sample solution did not influence the extraction efficiency. The desorption was performed for 5 min at 275°C directly in the GC injector. At shorter desorption times or lower temperatures a significant carry-over was observed for the heavier analytes. Generally, detection limits in the ng/L range were obtainable.  相似文献   

18.
A solid-phase microextraction technique using steel fiber coated with 20 μm polypyrrole (Ppy) doped with polyphosphate was developed for the GC determination of a group of organochlorine pesticides (OCPs) in water. The coating was prepared using a three-electrode electrochemical system from a 10% aqueous sodium polyphosphate solution containing 0.05 M pyrrole by applying a constant potential of 1.2 V for 30 min. In order to obtain an adherent, smooth and stable film of polypyrrole, experimental parameters related to the coating process consisting of the type of dopant or counter-ion, deposition potential, concentration of the monomer, concentration of the counter-ion, and deposition time were optimized. The effects of various parameters on the efficiency of SPME process such as extraction time, extraction temperature, ionic strength, desorption time, and desorption temperature were also studied. The coating was highly stable and extremely adherent to the surface of the steel fiber. The method was linear for at least three orders of magnitude with correlation coefficients varying from 0.9818 to 0.9977. The accuracies found through spiking blank samples showed high recoveries between 82 and 110%. Intra- and inter-day precisions of the method were determined from mixed aqueous solutions containing 1.0 ng ml−1 of each OCP. The intra-day precisions varied from 4.7% for heptachlor to 11.4% for methoxychlor, while the inter-day precisions varied from 6.8% for endosulfan I to 13.0% for p,p′-DDD and o,p-DDD. Limits of detection based on S/N = 3 were in the range 0.015-0.66 pg ml−1. The proposed method was applied to monitor organochlorine pesticides in some well water samples.  相似文献   

19.
We have prepared a fiber for solid-phase microextraction of organochlorine pesticides. A graphene-polyaniline composite was electrochemically deposited on a platinum fiber by exploiting the unique properties of polyaniline and graphene. The modified fiber displays thermal stability up to 320 °C and can be used more than 70 times. It possesses high extraction efficiency due to the high specific surface of graphene. The Pt fiber was used for the extraction and subsequent GC determination of the pesticides heptachlor, aldrin, endrin and p,p’-DDT in aqueous samples. The effects of extraction time, extraction temperature, stirring rate, salinity and headspace volume were optimized. Calibration plots are linear (with an R2 of 0.990) in the 0.2 to 250 μg L–1 concentration range, and the limits of detection are below 11 ng L–1 (at an S/N of 3). The relative standard deviations for three replicate measurements with a single fiber were <11.0 %. The recovery of the pesticides from spiked seawater samples ranged from 81 % to 112 %.
Figure
The graphene–polyaniline (G/PANI) nanocomposite was prepared by simultaneous electropolymerization of G–aniline and used as a new coating for SPME of organochlorine pesticides as model compounds. The large delocalized π-electron system of G and high extraction capability of PANI caused to produce an efficient and sensitive sorbent for SPME  相似文献   

20.
建立了顶空固相微萃取(HS-SPME)/气相色谱-质谱(GC-MS)同时测定液态化妆品中8种邻苯二甲酸酯类增塑剂(PAEs)的分析方法,并对萃取涂层、萃取温度、搅拌速率、盐浓度等参数进行了优化。最终采用65μm聚二甲基硅氧烷/二乙烯基苯(PDMS/DVB)固相微萃取纤维头,调节待萃取液盐浓度为360 g.L-1,在搅拌速率600 r/min及萃取温度90℃条件下萃取60 min,在250℃进样口解吸4 min后供GC-MS分析。结果表明,该方法对除邻苯二甲酸二苯酯(DPhP)外的7种目标化合物的线性范围为10~2 000μg.kg-1,检出限为0.7~13.6μg.kg-1,回收率为83%~97%,相对标准偏差(RSD)为2.5%~10.0%;由于DPhP在萃取涂层上的保留较弱,其回收率为70%,检出限为75μg.kg-1,RSD为13.9%。该方法能很好地富集基体中的目标化合物,满足液态化妆品中多种PAEs的分析要求。  相似文献   

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