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.
With the increased use of chemicals in agriculture for crop protection and improvement of yield, the contamination of water is currently a serious health concern. This study used solid-phase extraction with ultra-high-performance liquid chromatography–tandem mass spectrometry to evaluate the presence of 23 carbamate pesticides in waters from Cameroon. The separation was achieved in 5.5?min using a C18 column (50?×?2.1?mm, 1.8?µm) with a mobile phase composed of water and methanol each containing 0.01% formic acid. The analytes were determined in positive multiple reaction monitoring mode. The recoveries for fortified water were from 75 to 99%, with relative standard deviations below 13%. The limits of detection ranged from 0.003 to 0.397?µg?L?1. The reported method is simple, sensitive, and accurate, and is a suitable alternative for routine monitoring of pesticide residues at ultra-trace levels. The analysis revealed the presence of propoxur at a concentration of 0.072?µg?L?1 in stream water.  相似文献   

2.
Atrazine and simazine are endocrine-disrupting herbicides that may be transported to surface water, unbalancing ecosystems. Sensitive and low-cost methods are required for monitoring the residues of these compounds. Although several highly sensitive chromatographic methods coupled to tandem mass spectrometry are available, these methods use high-cost instrumentation. Ultraviolet detection usually does not provide the sensitivity and selectivity for monitoring these herbicide residues at the maximum concentrations levels permitted by regulatory agencies, so that extraction and concentration steps are required. Cloud-point extraction in Triton X-114 micelles was investigated to extract and preconcentrate atrazine and simazine. Treatment of 10?mL of sample solutions with 5?mL of 5% (m v?1) Triton X-114 in the presence of NaCl (0.3?g) with heating at 60°C for 30?min led to phase separation and the transfer of herbicides to the surfactant-rich phase, which was dissolved in 90:10 methanol:water for liquid chromatography analysis with ultraviolet detection. The linear dynamic range was 1–50?µg?L?1 for the herbicides. The limits of detection were 0.13 and 0.27?µg?L?1 for simazine and atrazine, respectively. The methodology was applied to water samples fortified with 1, 5, 15, and 50?µg?L?1 of the analytes, resulting in recoveries between 86 and 132% with relative standard deviations less than 6%. The method is low cost and uses small volumes of toxic solvents with useful application in trial studies.  相似文献   

3.
《Analytical letters》2012,45(8):1421-1433
A sensitive high performance liquid chromatography–tandem mass spectrometry method was developed for the determination of residues of carbadox, mequindox, olaquindox, quinocetone, cyadox, quinoxaline-2-carboxylic acid, and 3-methylquinoxaline-2-carboxylic acid in environmental water samples. The samples were freeze-dried at ?80°C, re-dissolved in 1.0 mL methanol-water (5:95), then purified with N-propyl ethylenediamine. The separation of the analytes was performed on a column (150 × 2.1 mm i.d., 5.0 µm) using acetonitrile and 0.1% formic acid as mobile phases. The target compounds were confirmed and quantified by tandem mass spectrometry in multiple reaction monitoring mode. The results showed that there were linear relationships between peak area and concentrations of these compounds with correlation coefficients exceeding 0.99. The average recoveries at the spiked levels of 0.25, 0.5, 1.0, and 2.0 µ g L?1 ranged from 68.7% to 109% with relative standard deviations less than 14% except cyadox. The limits of detection of the analytes were between 2.0 and 6.0 ng L?1. This method meets the requirements for the determination of drug residues in environmental water samples.  相似文献   

4.
ABSTRACT

The aim of this work was to develop and validate a method using online solid-phase extraction and ultra-high-performance liquid chromatography coupled to tandem mass spectrometry to determine residues of 22 veterinary drugs including sulfonamides, amphenicols, fluoroquinolones, benzimidazoles, trimethoprim (TMP) and oxytetracycline (OTC) in water from fee-fishing ponds. The optimal analytical conditions were as follows: XBridge C8 SPE column, Acquity UPLC CSH C18 analytical column, sample loading with water:methanol (98:2, v/v), mobile phase of water with 0.1% acetic acid:methanol (with gradient elution) and eluent flow rate of 0.3 mL min?1. Quantification was performed in selected reaction monitoring mode and sulfadimethoxine-d6, ciprofloxacin-d8, florfenicol-d3 and albendazole-d3 were used as internal standards. Water samples collected from 11 fee-fishing ponds showed the presence of residues of FF (0.42–0.74 µg L?1), albendazole (0.05–0.31 µg L?1) and thiabendazole (0.45 µg L?1). Thiamphenicol and TMP were detected at concentrations lower than the limits of quantification of the method (0.1 and 0.001 µg L?1, respectively).  相似文献   

5.
A procedure for the determination of As, Cd, Cr, Ni, Pb, and V in phytotherapy medicines by inductively coupled plasma–tandem mass spectrometry is reported. The use of tandem mass spectrometry with oxygen into an octopole reaction system at various gas flow rates and the combination of on-mass and mass-shift modes was evaluated. Cadmium, Cr, Ni, and Pb were determined as free atomic ions while As and V were determined as the oxides AsO+ and VO+ in the same run. Samples were prepared by microwave-assisted digestion with dilute nitric acid and hydrogen peroxide. Two plant-certified reference materials (apple leaves and tomato leaves) were used to check the accuracy. For tandem mass spectrometry with 0.5?mL min?1 O2, recoveries in the 85–113% were typically obtained and no statistical differences were observed at the 95% confidence level (t-test) in comparison with the certified values. Using these conditions, the limits of detection for the method were 0.01, 0.0002, 0.008, 0.008, 0.003, and 0.002?µg g?1 for As, Cd, Cr, Ni, Pb, and V, respectively. The procedure was used for the analysis of four phytotherapic drugs and the determined concentrations were up to 0.168?µg g?1 As, 0.03?µg g?1 Cd, 0.82?µg g?1 Cr, 1.18?µg g?1 Ni, 0.52?µg g?1 Pb, and 2.4?µg g?1 V with average precision values of 8% as the relative standard deviation. The found concentrations were compared with limits proposed in official guidelines and, in most cases, the values were below the maximum limits allowed.  相似文献   

6.
A new method for the simultaneous determination of 12 volatile organic compounds (trans-1,2-dichloroethene, 1,1,1-trichloroethane, benzene, 1,2-dichloroethane, trichloroethene, toluene, 1,1,2-trichloroethane, tetrachloroethene, ethylbenzene, m-, p-, o-xylene) in water samples by headspace solid phase microextraction (HS–SPME)–gas chromatography mass spectrometry (GC–MS) was described, using a 100?µm PDMS (polydimethylsiloxane) coated fibre. The response surface methodology was used to optimise the effect of the extraction time and temperature, as well as the influence of the salt addition in the extraction process. Optimal conditions were extraction time and temperature of 30?min and ?20°C, respectively, and NaCl concentration of 4?mol?L?1. The detection limits were in the range of 1.1?×?10?3–2.3?µg?L?1 for the 12 volatile organic compounds (VOCs). Global uncertainties were in the range of 4–68%, when concentrations decrease from 250?µg?L?1 down to the limits of quantification. The method proved adequate to detect VOCs in six river samples.  相似文献   

7.
The use of two modes for mass spectrometry (MS) detection with an ion trap instrument, selected ion storage (SIS) and tandem mass spectrometry (MS/MS), are compared for the solid-phase microextraction (SPME)–gas chromatography (GC) coupled to mass spectrometry (GC-MS) determination of 16 priority organochlorine pesticides (OCPs) in drinking water samples at the ultratrace levels (ng?L?1) required by official guidelines in the European legislation. Experimental parameters investigated for the SPME sample preparation were: the type of coating (100?µm polydimethylsiloxane, PDMS, and 65?µm poly(dimethylsiloxane)–divinylbenzene, PDMS/DVB), SPME modality, extraction and desorption times and desorption temperature and the methanol percentage in the SPME working solution. Under the calculated optimal conditions two methodologies were developed, one for SIS and the other for MS/MS modes. The detection limits, precision and accuracy were evaluated for both alternatives and were appropriate to the official guidelines requirements. The SPME–GC-MS(SIS) methodology offered LODs from 0.2–6.6?ng?L?1, precision below 13% and recoveries between 83 and 110%. The SPME–GC–MS/MS methodology provided limits of detection (LODs) ranging from 0.3 to 7.6 ng?L?1, % RSD were ≤14% and recoveries of 79–108% were achieved. After the results observed within an Interlaboratory Exercise, the latest MS methodology was selected for the pursued analysis in real drinking water samples. Also, the good results in this round-robin exercise validate the proposed SPME–GC–MS/MS methodology.  相似文献   

8.
An ultraviolet-photochemical generator (UV-PVG) capable of post-column on-line transformation of both organic and inorganic mercury species to cold vapor (Hg0) with subsequent detection by quartz tube-atomic absorption spectrometry (QT-AAS) was developed. Mercury(II), methylmercury(I), ethylmercury(I), and phenylmercury(I) were successfully detected after separation by reversed-phase high-performance liquid chromatography (RP-HPLC). Two types of AAS detectors were compared. The first was a commonly used line-source instrument while the second was a high-resolution continuum source (HR-CS) AAS. The latter provided better limits of detection: 0.47?µg?L?1 for Hg(II), 0.84?µg?L?1 for methylmercury(I), 0.80?µg?L?1 for ethylmercury(I), and 2.0?µg?L?1 for phenylmercury(I). The repeatability at 30?μg?L?1 was 3.6%, 4.1%, 6.2%, and 4.5% for these species (n?=?10). These figures of merit were comparable with those reported for more sensitive atomic fluorescence spectrometry. Nine sample extraction procedures were investigated. Extraction by tetramethylammonium hydroxide and HCl at 75?°C was selected as the only method compatible with the proposed separation and detection steps providing high extraction efficiency and no changes in mercury speciation. The applicability of the proposed high-performance liquid chromatography–ultraviolet-photochemical vapor generation–quartz tube-atomic absorption spectrometry method was demonstrated using fish samples and certified reference materials (CRM) DOLT-4 (dogfish liver) and ERM-CE464 (tuna fish). The results were comparable to those obtained by a reference method based on L-cysteine extraction and high-performance liquid chromatography–inductively coupled plasma-mass spectrometry (HPLC–ICP-MS) determination.  相似文献   

9.
A method for determination of 61 organic pollutants (polycyclic aromatic hydrocarbons and organochlorine, organophosphorous and organonitrogen pesticides) is proposed. It is based on solid phase extraction (SPE) and subsequent analysis of the extract by liquid and gas chromatography coupled to tandem mass spectrometry. Method validation yielded to the following values: limits of quantification, from 0.005 to 0.020?µg?L?1; trueness, 95% to 113% and reproducibility (as percent relative standard deviation), 2% to 15%. Additionally, the method performed well in various proficiency tests.  相似文献   

10.
A method for analysis of 20 commonly used pesticides in surface water based on solid-phase extraction and gas chromatography-mass spectrometry was proposed. During method development the key parameters that can affect SPE extraction and determination such as selection of efficient SPE sorbent, pH of water sample, type and volume of elution solvent, breakthrough volume and matrix effects were investigated. The method was validated using spring water spiked with appropriate concentration of pesticides. The obtained correlation coefficients were in range 0.9972–1.000, limits of detection (LOD) were 0.001–0.5?µg?L?1 and the limits of quantification (LOQ) were 0.005–1?µg?L?1 depending on a pesticide. Much higher LOD (20?µg?L?1) and LOQ (50?µg?L?1) values were obtained for bentazone. The influence of matrix was assessed using real water samples spiked with appropriate concentration of pesticide standards solution. Both signal enhancement and suppression were observed, depending on a pesticide, therefore standard addition method was used for pesticides determination. The developed method was applied on real water samples taken in close vicinity of agricultural fields. Many of the targeted pesticides were found in the samples and the results are presented in this article.  相似文献   

11.
In this paper, a procedure for the determination of 11 aromatic hydrocarbon-type sensitisers and their related compounds from water samples, used in the manufacture of thermal paper, is presented. The compounds were extracted using a solid-phase extraction (SPE) cartridge with an octadecyl (C18) or a phenyl-bonded silica (PH) sorbent and then determined by gas chromatography–mass spectrometry (GC–MS). Factors affecting the performance of the extraction steps were thoroughly evaluated, and their effects on the yield of the sample preparation were discussed. Under optimised experimental conditions, SPE cartridges were conditioned with 10?mL hexane followed subsequently by 10?mL methanol, loaded with water sample at 2?mL?min?1, and eluted with 10?mL hexane at 1.5?mL?min?1. The limits of detection and quantification, calculated for signal-to-noise ratios of 3 and 10, were in the range of 1–5?µg?L–1 and 2.5–10?µg?L–1, respectively. Recovery yields of the present method using river water were in the range of 88%–112% with a C18 sorbent and 86%–116% with a PH sorbent. The repeatability, expressed as a relative standard deviation, was in the range of 2.8%–11% with a C18 sorbent and 0.7%–9.7% with a PH sorbent (n?=?4). Analysis of paper mill effluents revealed the presence of aromatic hydrocarbon-type sensitisers with maximum concentrations of up to 5.2?µg?L?1.  相似文献   

12.
《Analytical letters》2012,45(12):1761-1783
Abstract

This article describes a method for the simultaneous analysis of four fungicides—pyrimethanil, penconazol, metalaxyl, and dichlofluanid—in must and wine by solid-phase extraction. Two cartridges (octadecylsilane and polystyrene-divinylbenzene) were evaluated with different elution solvents. The most efficient solid phase was octadecylsilane together with ethyl acetate as elution solvent. Determination was performed by gas chromatography with a nitrogen–phosphorus detector, using metribuzin as internal quantification standard. To reduce quantitative errors from matrix effects, matrix-matched calibration was used. The linear regression coefficients were at least 0.9990. The quality parameters of the proposed method presented good recoveries from spiked must and wine, ranging from 92.3 to 105.5%, and good precision, indicated by relative standard deviations (RSDs) of less than 10%. The limits of quantification varied from 0.27 µg L?1 for penconazol in wine to 9.34 µg L?1 for metalaxyl in wine. An additional confirmation method, gas chromatography with mass spectrometry detection, was used.  相似文献   

13.
A cloud point extraction procedure for pre-concentration and determination of cadmium and lead in drinking water using sequential multi-element flame atomic absorption spectrometry is described. 4-(2-thiazolylazo)-orcinol (TAO) has been used as complexing agent and the micellar phase was obtained using the non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114) and centrifugation. The conditions for reaction and extraction (surfactant concentration, reagent concentration, effect of incubation time, etc) were studied and the analytical characteristics of the method were determined. The method allows the determination of cadmium and lead with quantification limits of 0.30?µg?L?1 and 2.6?µg?L?1, respectively. A precision expressed as relative standard deviation (RSD, n?=?10) of 2.3% and 2.6% has been obtained for cadmium concentrations of 10?µg?L?1 and 30?µg?L?1, respectively, and RSD of 1.3% and 1.7% for lead concentrations of 10?µg?L?1 and 30?µg?L?1, respectively. The accuracy was confirmed by analysis of a natural water certified reference material. The method has been applied for the determination of cadmium and lead in drinking water samples collected in the cities of Ilhéus and Itabuna, Brazil. Recovery tests have also been performed for some samples, and results varied from 96 to 105% for cadmium and 97 to 106% for lead. The cadmium and lead concentrations found in these samples were always lower than the permissible maximum levels stipulated by World Health Organization and the Brazilian Government.  相似文献   

14.
A method for the analysis of the artificial sweetener sucralose in sewage water and recipient water was developed. Extraction and clean up was performed with solid-phase extraction utilising Oasis HLB columns. Detection was made by liquid chromatography electrospray mass spectrometry (LC/MS). The triple-quadrupole mass spectrometer was operated in multiple reaction monitoring (MRM) mode. However, ‘pseudo MRM’ was used, a technique where the two quadrupoles monitor the same m/z. The sodium adduct of sucralose was used for quantification, since lower detection limits were obtained as compared to the sucralose quasi-molecular ion in negative ion mode. The two ions with highest intensity in the chlorine isotope pattern were monitored. The reduction of matrix effects with this approach is discussed. The method limit of quantification (MLOQ) for sewage water was 0.2?µg?L?1, whereas for recipient water MLOQ was 0.02?µg?L?1. The method was used to analyse effluent samples from an experimental sewage treatment plant (STP) to assess the efficiency of tertiary treatment techniques for removal of sucralose. Filtration through activated carbon was shown to be efficient, while ozonation, advanced oxidation techniques and membrane bioreactors were less efficient. Analyses of receiving waters showed low dilution of sucralose emitted from the STPs.  相似文献   

15.
In the present study, room-temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium hexafluorophosphate was used as extraction solvent in a liquid–liquid microextraction (LLME) procedure followed by liquid chromatography for determining 4-nonylphenol (4-NP) and 4-tert-octylphenol (4-t-OP) in environmental water samples. RTIL-based LLME was a simple, inexpensive, and fast sample preparation method, and its parameters such as extraction time, addition of salt, selection of phase ratio, and pH value were optimized. The optimized method had acceptable limits of detection (LOD) and a precision of 2?µg?L?1 and 8.1% for 4-NP and 0.6?µg?L?1 and 3.7% for 4-t-OP, respectively. The proposed method was successfully applied in river water and effluent from a sewage-treatment plant, and the recoveries spiked at 6?µg?L?1 and 25?µg?L?1 levels were in the range of 82–113%.  相似文献   

16.
An on-line pre-concentration system for the sequential determination of cadmium and lead in drinking water by using fast sequential flame atomic absorption spectrometry (FS-FAAS) is proposed in this paper. Two minicolums of polyurethane foam loaded with 2-(6-methyl-2-benzothiazolylazo)-orcinol (Me-BTAO) were used as sorptive pre-concentration media for cadmium and lead. The analytical procedure involves the quantitative uptake of both analyte species by on-column chelation with Me-BTAO during sample loading followed by sequential elution of the analytes with 1.0?mol?L?1 hydrochloric acid and determination by FS-FAAS. The optimisation of the entire analytical procedure was performed using a Box–Behnken multivariate design utilising the sampling flow rate, sample pH and buffer concentration as experimental variables.

The proposed flow-based method featured detection limits (3σ) of 0.08 and 0.51?µg?L?1 for cadmium and lead, respectively, precision expressed as relative standard deviation (RSD) of 1.63% and 3.87% (n?=?7) for cadmium at the 2.0?µg?L?1 and 10.0?µg?L?1 levels, respectively, and RSD of 6.34% and 3.26% (n?=?7) for lead at the 5.0?µg?L?1 and 30.0?µg?L?1 levels, respectively. The enrichment factors achieved were 38.6 and 30.0 for cadmium and lead, respectively, using a sample volume of 10.0?mL. The sampling frequency was 45 samples per hour. The accuracy was confirmed by analysis of a certified reference material, namely, SRM 1643d (Trace elements in natural water). The optimised method was applied to the determination of cadmium and lead in drinking water samples collected in Santo Amaro da Purificação City, Bahia, Brazil.  相似文献   

17.
A novel method for the online extraction and preconcentration of four sulfonamides was developed using column switching liquid chromatography. Sulfadiazine, sulfathiazole, sulfamethoxypyridazine and sulfamethoxazole were analysed in water samples and preconcentrated in a C18 guard column. Suitable validation parameters were obtained, such as precision, accuracy and relative recovery, in accordance with the validation guidelines of the Food and Drug Administration. Low limits of detection (0.05–0.09 µg L?1) and quantification (0.30 µg L?1, for all of them) were obtained. The quadratic polynomial model was used to adjust the calibration data, and the coefficients of determination were higher than 0.999 for all the analytes. The method was shown to be robust to the assayed parameters according to Youden’s test. The proposed method was successfully used to determine sulfonamides in 11 different fish farming water samples, in which sulfadiazine (0.732 µg L?1), sulfamethoxazole (0.531 µg L?1), sulfathiazole (0.546–1.856 µg L?1) and sulfamethoxypyridazine (0.369–1.509 µg L?1) were found.  相似文献   

18.
《Analytical letters》2012,45(10):1597-1606
In this work, a method to determine the concentration levels of organochlorine pesticides in water samples from the Mandacaru stream in the region of Maringá- Paraná was validated, using the technique of solid phase extraction associated with gas chromatography coupled to mass spectrometry. In the optimization of the method, parameters such as injector temperature and splitless time were evaluated. The analytical curves showed linear correlation values greater than 0.99 (R2 > 0.99) for all compounds. The detection limits of 0.243 µg L?1 to 1.200 µg L?1 and quantification of 5.0 µg L?1 were obtained for pesticides and the recovery values were between 88.25 and 127.3%. Values of relative standard deviation were less than 6.79%. In the water samples analyzed were found four organochlorine pesticides, two with concentrations within the limits set by national legislation and two with concentrations above these limits.  相似文献   

19.
Speciation of mercury was accomplished by using a simple interface with photo-induced chemical vapour generation in a high performance liquid chromatography—atomic fluorescence spectrometry (HPLC-AFS) hyphenated system. Acetic acid and 2-mercaptoethanol in the mobile phase were used as photochemical reagent. The operating parameters were optimized to give limits of detection of 0.53 µg L?1, 0.22 µg L?1, 0.18 µg L?1 and 0.25 µg L?1 for inorganic mercury, methylmercury, ethylmercury and phenylmercury, respectively. The method was validated with the certified reference material DORM-2 and applied to the analysis of seafood samples. The HPLC-AFS hyphenated system is simple, environmentally friendly, and represents an attractive alternative to the conventional peroxothiosulfate-borohydride method.  相似文献   

20.
In this study, a simple and efficient method of ligandless-ultrasound-assisted emulsification microextraction (LL-USAEME) followed by inductively coupled plasma-optical emission spectrometry (ICP-OES) has been developed for simultaneous extraction, preconcentration and determination of manganese, cadmium, cobalt and nickel in water samples. In the proposed approach, tetrachloroethylene was selected as extraction solvent. The effect of important experimental factors such as volume of extraction solvent, pH, sonication time, salt concentration, and temperature was investigated by using a fractional factorial design (25?1) to identify important factors and their interactions. In the next step, a Box-Behnken design (BBD) was applied for optimisation of significant factors. The obtained optimal conditions were: 30?µL for extraction solvent, 12 for pH, 5?min for sonication time, and 5% w/v for salt concentration. The limits of detections (LODs) for Cd(II), Co(II), Mn(II) and Ni(II) were 0.20, 0.13, 0.21 and 0.28?µg?L?1, respectively. Relative standard deviations (RSD, C?=?200.0?µg?L?1, n?=?9) were between 3.4–7.5% and the calibration graphs were linear in the range of 0.25 to 1000.0?µg?L?1 for Mn, 0.5–1000.0?µg?L?1 for Co and Ni and 1.0–250.0?µg?L?1 for Cd. The determination coefficients (R 2) of the calibration curves for the analytes were in the range of 0.993 to 0.999. The proposed method was validated by using two certified reference materials, and also the method was applied successfully for the determination of heavy metals in different 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