RESUMEN
With the aim of monitoring water quality according to the regulations established by the European Union it would be necessary to implement analytical methodologies capable of simultaneously determining a broad range of organic pollutants at ultra-trace levels, allowing for increased sample throughput. In addition, the high number of samples to be analyzed requires a particular focus on setting up fully automated analytical methodologies. In view of that, this study is aimed at the development of a complete automated procedure for the ultra-trace determination of certain pesticides, polycyclic aromatic hydrocarbons (PAHs), brominated diphenyl ethers (BDEs) and polychlorinated biphenyls (PCBs) in surface waters. The proposed method is based on an on-line combination of solid phase microextraction (SPME) and gas chromatography coupled to double-focusing magnetic sector high resolution mass spectrometry (GC-HRMS). SPME as well as GC-HRMS conditions were optimized to achieve maximum extraction efficiency and sensitivity, which was reinforced by using multiple ion detection (MID) as acquisition mode. Using only 19mL of water and with minimum sample manipulation, the method allowed for the determination of 53 compounds exhibiting good linearity (R2>0.99), recoveries between 84 and 118% and relative standard deviation (RSD) values <20% for intra-day and inter-day precision. In addition, the method provides quantification limits (LOQs) between 0.1-50ngL-1, lower than the Environmental Quality Standards (EQS) fixed by Directive 2013/39/EC. Finally, the method was successfully applied to determine target contaminants in Almería surface water compartments, detecting dioxin-like PCBs, BDEs and some pesticides.
Asunto(s)
Monitoreo del Ambiente/métodos , Cromatografía de Gases y Espectrometría de Masas , Microextracción en Fase Sólida , Dioxinas/análisis , Éteres Difenilos Halogenados/análisis , Plaguicidas/análisis , Bifenilos Policlorados/análisis , Hidrocarburos Policíclicos Aromáticos/análisis , Contaminantes Químicos del Agua/análisisRESUMEN
A wide range of pesticides used to control pests in vegetables have been determined in agricultural plant waste from beans, watermelons, and melons grown in greenhouses located in a predominantly agricultural area in Southeast Spain (Almería). Analysis of the pesticides was carried out by low-pressure gas chromatography (LP-GC) with mass spectrometry in tandem (MS-MS) mode, after extraction of the lyophilized samples with dichloromethane. The influence of the sample matrix on the analysis was avoided by use of matrix-matched standards. Linearity, detection limit ( LOD), quantitation limit ( LOQ), recovery, and precision for each pesticide were calculated. The most frequently encountered pesticides were endosulfan (>73% of the analyzed samples) and buprofezin (>55% of the samples), followed by cypermethrin, pirimifos-methyl, bifentrin, and chlorpyrifos (>30% of the samples). The pesticide found at the highest concentration level was endosulfan (223.33 mg kg(-1)) in a watermelon sample.
Asunto(s)
Alimentación Animal/análisis , Cromatografía de Gases y Espectrometría de Masas/métodos , Plaguicidas/análisis , Plantas/química , Calibración , Citrullus/química , Cucumis/química , Contaminantes Ambientales/análisis , Fabaceae/química , Hojas de la Planta/química , Tallos de la Planta/química , Presión , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , España , Factores de TiempoRESUMEN
A fast method for the determination of eight organotin compounds (OTs), monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), tetrabutyltin (TeBT), monophenyltin (MPhT), diphenyltin (DPhT), triphenyltin (TPhT) and tetraphenyltin (TePhT), in water, sediments and mussels, was developed using low-pressure gas chromatography/tandem mass spectrometry (LPGC/MS/MS). The method is based on sodium diethyldithiocarbamate (DDTC) complexation of the ionic organotins, followed by extraction of the target matrices and derivatization by a Grignard reagent, as described in a previously published method for water samples. Solid-phase extraction was selected as extraction method from water samples after comparison with liquid-liquid extraction, but extraction of the OTs from sediment and mussel samples was performed using toluene. Matrix-matched calibration standards were used to minimize matrix effects. The analytical process was validated by the analysis of spiked blank samples. Performance characteristics such as linearity, detection limit (LOD), quantitation limit (LOQ), precision, and recovery were determined. Recoveries of OTs in spiked matrices ranged from 86-108% in water and from 78-110% in sediments and mussels, with precision values lower than 18%. Detection limits ranged from 0.1-9.6 ng L(-1) in water, and 0.03-6.10 microg kg(-1) in the other matrices. The present implementation of LPGC rather than conventional capillary GC permitted use of large-volume injection and reduced analysis time by a factor of two. The proposed methodology was applied to the determination of OTs in real samples of water, marine sediments and mussels from the west coast of the Mediterranean Sea (Spain).
Asunto(s)
Bivalvos/química , Cromatografía de Gases y Espectrometría de Masas/métodos , Sedimentos Geológicos/química , Compuestos Orgánicos/análisis , Agua de Mar/química , Compuestos de Estaño/análisis , Animales , Calibración , Estructura Molecular , Presión , Reproducibilidad de los ResultadosRESUMEN
An alternative to conventional capillary gas chromatography (GC) is evaluated as a new approach to determine pesticide residues in vegetables. Low-pressure gas chromatography-tandem mass spectrometry (LP-GC-MS-MS) is proposed after a fast and simple extraction of the vegetable samples with dichloromethane and without clean up. The use of the above-mentioned GC technique reduced the total time required to determine 72 pesticides to less than half the present time (31 min), increasing the capability of a monitoring routine laboratory. The use of guard column and plug of carbofrit into the glass liner in combination with LP-GC was evaluated. The method was validated with limits of quantitation low enough to determine the pesticide residues at concentrations below the maximum residue levels stated by legislation. In order to assess its applicability to the analysis of real samples, 25 vegetable samples previously determined using conventional-capillary GC-MS-MS were analysed by LP-GC-MS-MS. The results obtained with the compared techniques showed differences lower than 0.01 mg kg(-1).
Asunto(s)
Cromatografía de Gases y Espectrometría de Masas/métodos , Residuos de Plaguicidas/análisis , Verduras/química , Presión , Reproducibilidad de los ResultadosRESUMEN
A new analytical method was devised using gas chromatography with tandem mass spectrometry (GC-MS-MS) for the routine analysis of 31 multi-class pesticide residues and approximately 8000 fresh fruit and vegetable samples (green bean, cucumber, pepper, tomato, eggplant, watermelon, melon, and marrow). Extraction of the pesticides with dichloromethane was carried out. The optimal ionization mode, either electron impact or chemical ionization, was selected for each pesticide in the same run. Carbofrit was used in the liner and combined with the selectivity of the detector this avoided additional clean-up. Thus, not only was money and time saved, the uncertainty of the method was decreased in its application to routine analysis. The average recoveries in cucumber obtained for each pesticide ranged between 71 and 119% at two different fortification levels (n=10 each) that ranged between 7 and 300 ng g(-1) (depending on the pesticide). The relative standard deviation was lower than 19% for all compounds tested. The calculated limits of detection and quantification were typically <1 ng g(-1) which were much lower than the maximum residue levels established by European legislations.
Asunto(s)
Frutas/química , Cromatografía de Gases y Espectrometría de Masas/métodos , Plaguicidas/análisis , Verduras/química , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
A rapid multiresidue method for the analysis of 72 pesticides has been developed using a single injection with low-pressure gas chromatography/tandem mass spectrometry (LP-GC/MS/MS). The LP-GC/MS/MS method used a short capillary column of 10 m x 0.53 mm i.d. x 0.25 microm film thickness coupled with a 0.6 m x 0.10 mm i.d. restriction at the inlet end. Optimal LP-GC conditions were determined which achieved the fastest separation in MS/MS detection mode. Also MS/MS conditions were optimized in order to increase sensitivity and selectivity. The analytical parameters of the LP-GC/MS/MS method were compared with those obtained by GC/MS/MS using a conventional capillary column (30 m x 0.25 mm i.d. x 0.25 microm film thickness). Better precision and sensitivity values were obtained with the LP-GC/MS/MS approach. The limits of detection (LOD) of the compounds ranged from 0.1 to 14.1 microg L(-1) for LP-GC/MS/MS, lower than those obtained for conventional GC/MS/MS that ranged from 0.1 to 17.5 microg L(-1). The peak widths obtained with the short column in LP-GC are similar to those obtained using conventional capillary GC columns, and the peaks can be successfully identified by MS/MS detection with the conventional scan speed of ion-trap instruments. In addition, the analysis time was significantly reduced with LP-GC/MS/MS (32 min) versus GC/MS/MS (72 min), allowing the number of samples analyzed per day in a routine laboratory to be doubled.
Asunto(s)
Cromatografía de Gases y Espectrometría de Masas/métodos , Residuos de Plaguicidas/análisis , Cromatografía de Gases y Espectrometría de Masas/instrumentación , Residuos de Plaguicidas/clasificación , Sensibilidad y Especificidad , Factores de Tiempo , Carga de TrabajoRESUMEN
The use of gas chromatography/tandem mass spectrometry (GC/MS/MS) applied to determine multiple pesticide residues in fresh vegetables has been thoroughly studied. A single injection method to detect, confirm and quantify 54 multiclass pesticides has been developed and applied in a routine analysis laboratory. The proposed method consists of a rapid extraction of 15 g of vegetable sample with dichloromethane. An additional clean-up step is not necessary even when injecting 10 microL of extract. Instead the gas chromatograph was fitted with a carbofrit inserted into the glass liner and a guard column. In addition, the detection mode chosen (MS/MS) provides additional selectivity. The method has been validated and applied to 1300 samples in a routine laboratory following specified quality criteria. The recovery efficiencies obtained for all the pesticides ranged between 70.2 and 110.8% at two different fortification levels. The relative standard deviation for quantification (RSD) was lower than 16.7% for all the compounds. Important experimental parameters, such as the conditioning of carbofrit, overload of the analytical column, and cleanliness of the ion trap, were evaluated for their influence on the performance of the method.
Asunto(s)
Cromatografía de Gases y Espectrometría de Masas/métodos , Residuos de Plaguicidas/análisis , Verduras/química , Cromatografía de Gases y Espectrometría de Masas/instrumentación , Espectrometría de Masa por Ionización de Electrospray/instrumentación , Espectrometría de Masa por Ionización de Electrospray/métodosRESUMEN
A new analytical method for determining 6-chloronicotinic acid (6-ClNA) in human urine is proposed. 6-ClNA is the main metabolite in warm-blooded animals after exposure to the insecticide imidachloprid. 6-ClNA was extracted from human urine using solid phase extraction (SPE) with laboratory-made cartridges of Amberlite XAD-4. A clean-up step and a derivatization process were carried out prior to gas chromatography-tandem mass spectrometric (GC-MS-MS) determination. A study on the influence of pH in the extraction process revealed that it affects the analyte extraction efficiency. A working pH zone was defined between 0.8 and 2.8. Calibration curves were studied in the concentration range of 0.5-100 ng mL(-1) and showed good linearity. Limits of detection and determination of the method were 16 and 56 pg mL(-1) respectively. The mean recovery at 10 and 100 ng mL(-1) was between 97.2 and 102.1% and the repeatability was lower than 5.4% in all cases. The analysis of urine samples of five agricultural workers from Almería (Spain) did not detect the metabolite.
Asunto(s)
Agricultura , Imidazoles , Ácidos Nicotínicos/orina , Exposición Profesional , Plaguicidas , Cromatografía de Gases y Espectrometría de Masas/métodos , Humanos , Neonicotinoides , NitrocompuestosRESUMEN
The reduction in residue levels of endosulfan with time after treatment of tomatoes, green beans, peppers and cucumbers grown in different types of commercial greenhouses (flat- and asymmetric-roof greenhouses) in Almería (Spain) was investigated. A study of the major and minor degradation products of endosulfan in peppers and cucumbers (endosulfan-sulfate, -ether and -lactone) was carried out using gas chromatography-tandem mass spectrometry (GC-MS/MS). To establish the influence of environmental conditions on the degradation of endosulfan, several field trials have been carried out in which crops were sprayed at different rates (full, half- and quarter- of those rates recommended) during two seasons (spring and winter). For statistical purposes, the disappearance of endosulfan with time was considered to follow a pseudo-first-order reaction. Analysis of variance (ANOVA) has been applied to the results obtained. Half-lives of residue disappearance were 4.03-4.68 days in green beans, 4.03-4.20 days in tomatoes, 8.22 days in peppers and 7.97 days in cucumbers. Half-lives in spring were shorter than in the winter season. The application rate and the type of greenhouse did not influence the half-lives.
Asunto(s)
Endosulfano/análisis , Hidrocarburos Clorados , Insecticidas/análisis , Residuos de Plaguicidas/análisis , Verduras/química , Biodegradación Ambiental , Endosulfano/química , Ambiente Controlado , Semivida , Insecticidas/química , Modelos Biológicos , España , Análisis Espectral , Verduras/efectos de los fármacosRESUMEN
A new analytical method combining solid-phase extraction and gas chromatography-tandem mass spectrometry (GC-MS-MS) is proposed to determine the insecticide endosulfan as well as its metabolites endosulfan-ether, -lactone, and -sulfate in human serum. Most matrix interferences are avoided using a cleanup step included in the sample treatment and an instrumental technique such as GC-MS-MS, which presents a high sensitivity and selectivity. Recoveries of spiked compounds range between 94.8 and 100.4% and 93.4 and 99.7% at fortification levels of 10 and 30 ng/mL, respectively. The relative standard deviation is lower than 17.6% in all cases, and the limits of detection calculated range from 6 to 19 pg/mL. Serum samples of nine agricultural workers that spray endosulfan into greenhouses in Almería (Spain) and two nonoccupationally exposed people are analyzed, and endosulfan is found in all the samples studied.
Asunto(s)
Endosulfano/sangre , Cromatografía de Gases y Espectrometría de Masas/métodos , Hidrocarburos Clorados , Insecticidas/sangre , Adulto , Humanos , Persona de Mediana Edad , Exposición Profesional , Sensibilidad y EspecificidadRESUMEN
New analytical gas chromatographic-tandem mass spectrometric approaches have been developed for assessing both potential and actual exposure of agricultural workers to malathion. The metabolites alpha- and beta-malathion monocarboxylic acids have been determined after a derivatisation process in order to obtain their hexafluoroisopropyl esters. Whole body dosimetry was used for potential dermal exposure assessment. Potential exposure by inhalation was estimated using personal air samplers and polyurethane foam plugs as sorbents. The intern dose measurements were carried out by analysing samples of urine after solid-phase extraction with C18. The recoveries of the analytes of the three matrices were between 90 and 102%. Quantification limits were lower than 0.24 ng L(-1). The proposed methods have been applied to evaluate potential and actual exposure of applicators spraying malathion in greenhouses.
Asunto(s)
Agricultura , Cromatografía de Gases y Espectrometría de Masas/métodos , Insecticidas/análisis , Malatión/análisis , Exposición Profesional , Humanos , Exposición por Inhalación , Insecticidas/efectos adversos , Malatión/efectos adversos , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
Gas chromatography (GC) with electron-capture detection (ECD), mass spectrometry (MS) and tandem mass spectrometry (MS-MS) were employed for the identification of 12 pesticides in water samples. For this purpose, a solid-phase extraction procedure with C18 cartridges was used, optimising the breakthrough volume and the saturation concentration. In GC-MS-MS, the lowest detectable concentrations for the pesticides were between 2 and 26 ng l(-1), recoveries ranged from 70 to 133% in water samples spiked at 100 ng l(-1) and the relative standard deviations were in the range 5.3 to 17.4%. The proposed analytical methodology was applied to analyse pesticides in wetland samples from Almería (Spain).
Asunto(s)
Cromatografía de Gases y Espectrometría de Masas/métodos , Plaguicidas/análisis , Agua/análisis , Sensibilidad y EspecificidadRESUMEN
A study of endosulfan excretion in human urine was carried out by using an agricultural worker involved with spraying, wearing protective overall, gloves and breathing mask. The urine samples were extracted with Solid Phase Extraction (SPE) cartridges and the compounds were separated and detected using Gas Chromatography-Tandem Mass Spectrometry (GC-MS/MS) due to their high sensitivity and selectivity in preventing most matrix interferences. The alpha- and beta-isomers of endosulfan were detected (total concentrations ranged between 5368 and 2239 pg/ml) but endosulfan-ether, -lactone or -sulphate were not found above the detection limits. The results obtained were compared with the concentrations found for a non-occupational exposed man. Statistical interpretation of the excretion-rate of the insecticide was performed by assuming that it can be described as a first-order kinetic. The constant rate and the half-lives were determined.
Asunto(s)
Endosulfano/orina , Monitoreo del Ambiente , Hidrocarburos Clorados , Insecticidas/orina , Exposición Profesional , Control de Plagas , Adulto , Humanos , MasculinoRESUMEN
A method was developed for determining the occupational exposure to endosulfan and its main metabolites (endosulfanether, -lactone and -sulfate) in human urine using dieldrin as an internal standard. Solid phase extraction (SPE) and gas chromatography-tandem mass spectrometry (GC-MS-MS) have been used due to their high sensitivity and selectivity in avoiding most matrix interferences. The recovery efficiencies of the tested compounds yielded more than 89.2% at the fortification level of 10 ng ml(-1) in urine and their relative standard deviations were between 9.1 and 12.8%. The detection limit of each compound ranged between 6 and 18 pg ml(-1). Urine samples from nine pest control operators were analysed and total endosulfan concentrations between 94 and 2038 pg ml(-1) were found.