El análisis de aguas residuales con fines epidemiológicos: presente y futuro en España / Wastewater-based epidemiology: present and future in Spain

El análisis de aguas residuales con fines epidemiológicos es actualmente una herramienta fiable y complementaria a las metodologías basadas en indicadores tradicionales para el control de diferentes sustancias entre las que cabe destacar las drogas. Si bien varios países europeos la utilizan como herramienta de trabajo para la monitorización de drogas de abuso, en España su uso se limita principalmente a estudios realizados por diferentes grupos de investigación, tal y como se describe en el caso práctico puesto de ejemplo en el artículo. Sin embargo, el potencial de la metodología ha quedado evidenciado en los estudios científicos llevados a cabo tanto a nivel español como internacional y, aunque son necesarios más estudios para llegar a conocer todo su potencial, se prevé pueda ser incorporada como herramienta de trabajo complementaria a las que habitualmente se utilizan. En este sentido, la Red Española de Análisis de Aguas Residuales (ESAR-Net), creada en 2017 y formada por diferentes grupos de investigación españoles, pretende contribuir al conocimiento y aplicación de esta metodología en España a través de actividades científicas y de divulgación

Wastewater-Based Epidemiology is currently a reliable and complementary tool to methodologies based on traditional indicators for the control of various substances such as drugs. Although several European countries use it as a working tool for the monitoring of drugs of abuse, in Spain its use is mainly limited to studies carried out by different research groups, as described in the case study used as an example in the article. However, the potential of the methodology has been demonstrated in the scientific studies carried out both at the Spanish and international level and, although more studies are necessary to get to know its full potential, it is expected that it could be incorporated as a complementary work tool to those that are usually used. In this sense, the Red Española de Análisis de Aguas Residuales (ESAR-Net), created in 2017 and formed by different Spanish research groups, aims to contribute to the knowledge and application of this methodology in Spain through scientific and outreach activities

Contaminants of emerging concern in freshwater fish from four Spanish Rivers.

This study investigated the occurrence of 135 contaminants of emerging concern (CECs) - pharmaceuticals, pesticides, a set of endocrine disrupting compounds (EDCs) (parabens, bisphenols, hormones, triazoles, organophosphorus flame retardants and triclosan), UV-filters, perfluoroalkyl substances (PFASs) and halogenated flame retardants (HFRs) - in 59 fish samples, collected in 2010 in 4 Spanish Rivers (Guadalquivir, Júcar, Ebro and Llobregat). Of the 135 CECs, 76 including 8 pharmaceuticals, 25 pesticides, 10 EDCs, 5 UV-filters, 15 PFASs and 13 HFRs were detected. Pharmaceuticals were the less frequently found and at lower concentrations. Pesticides, EDCs, UV-filters, PFASs and HFRs were detected more frequently (>50% of the samples). The maximum concentrations were 15 ng/g dry weight (dw) for pharmaceuticals (diclofenac), 840 ng/g dw for pesticides (chlorpyrifos), 224 ng/g dw for EDCs (bisphenol A), 242 ng/g dw for UV-filters (EHMC), 1738 ng/g dw for PFASs (PFHxA) and 64 ng/g dw for HFRs (Dec 602). The contaminants detected in fish are commonly detected also in sediments. In light of current knowledge, the risk assessment revealed that there was no risk for humans related to the exposure to CECs via freshwater fish consumption. However, results provide detailed information on the mixtures of CECs accumulated that would be very useful to identify their effects on aquatic biota.

Shared effects of organic microcontaminants and environmental stressors on biofilms and invertebrates in impaired rivers.

Land use type, physical and chemical stressors, and organic microcontaminants were investigated for their effects on the biological communities (biofilms and invertebrates) in several Mediterranean rivers. The diversity of invertebrates, and the scores of the first principal component of a PCA performed with the diatom communities were the best descriptors of the distribution patterns of the biological communities against the river stressors. These two metrics decreased according to the progressive site impairment (associated to higher area of agricultural and urban-industrial, high water conductivity, higher dissolved organic carbon and dissolved inorganic nitrogen concentrations, and higher concentration of organic microcontaminants, particularly pharmaceutical and industrial compounds). The variance partition analyses (RDAs) attributed the major share (10%) of the biological communities' response to the environmental stressors (nutrients, altered discharge, dissolved organic matter), followed by the land use occupation (6%) and of the organic microcontaminants (2%). However, the variance shared by the three groups of descriptors was very high (41%), indicating that their simultaneous occurrence determined most of the variation in the biological communities.

Presence of pharmaceuticals and heavy metals in the waters of a Mediterranean coastal wetland: Potential interactions and the influence of the environment.

The occurrence of 17 relevant pharmaceuticals and 7 heavy metals in the waters of the Pego-Oliva Marsh Natural Park (Valencia Community, Spain) were monitored. Thirty four zones (including the lagoon and the most important irrigation channels), covering the main land uses and water sources, were selected for sampling. Thirty three of them were contaminated with at least one pharmaceutical. Ibuprofen and codeine were the pharmaceuticals more frequently detected, in concentrations between 4.8 and 1.2 ng/L and a maximum of 59 ng/L and 63 ng/L, respectively. Regarding metals, Zn showed values under the detection limit in all the samples, while Cd, Co, Cr, Cu, Ni and Pb were detected at concentrations lower than the WHO and EU maximum levels for drinking waters. Ni showed significant direct correlations with diazepam, norfloxacin, ofloxacin and fenofibrate, and inverse relationships with ibuprofen, at 99 and 95% of significance. Cu, Co and Cr also showed significant correlations with some of the pharmaceuticals. These interactions could favor the synergistic/antagonistic interactions among pharmaceuticals and metals in the marsh, which can affect its aquatic fauna and flora or even human health. The influences of the water sources, land uses and spatial distribution of both types of contaminants were also studied.

Invertebrate community responses to emerging water pollutants in Iberian river basins.

Chemical pollution is one of the greatest threats to freshwater ecosystems, especially in Mediterranean watersheds, characterized by periodical low flows that may exacerbate chemical exposure. Different groups of emerging pollutants have been detected in these basins during the last decade. This study aims to identify the relationships between the presence and levels of prioritary and emerging pollutants (pesticides, pharmaceutical active compounds--PhACs, Endocrine Disrupting Compounds EDCs and Perfluorinated Compounds--PFCs) and the invertebrate community in four Mediterranean basins: the Ebro, the Llobregat, the Júcar and the Guadalquivir. Structural (species composition and density) and functional (catalase activity of the tricopteran Hydropsyche exocellata and the feeding activity of the cladoceran Daphnia magna) variables were analyzed to determine which of the pollutants would greatly influence invertebrate responses. EDCs and conductivity, followed by PhACs, were the most important variables explaining the invertebrate density changes in the studied basins, showing a gradient of urban and industrial pollutions. Despite this general pattern observed in the four studied basins - impoverishment of species diversity and abundance change with pollution - some basins maintained certain differences. In the case of the Llobregat River, analgesics and anti-inflammatories were the significant pollutants explaining the invertebrate community distribution. In the Júcar River, fungicides were the main group of pollutants that were determining the structure of the invertebrate community. Functional biomarkers tended to decrease downstream in the four basins. Two groups of pollutants appeared to be significant predictors of the catalase activity in the model: EDCs and PhACs. This study provides evidence that the information given by functional biomarkers may complement the results found for the structural community descriptors, and allowed us to detect two emerging contaminant groups that are mainly affecting the invertebrate community in these basins.

Application of ultra-high pressure liquid chromatography linear ion-trap orbitrap to qualitative and quantitative assessment of pesticide residues.

The analysis of pesticides residues using a last generation high resolution and high mass accuracy hybrid linear ion trap-Orbitrap mass spectrometer (LTQ-Orbitrap-MS) was explored. Pesticides were extracted from fruits, fish, bees and sediments by QuEChERS and from water by solid-phase with Oasis HLB cartridges. Ultra-high pressure liquid chromatography (UHPLC)-LTQ-Orbitrap mass spectrometer acquired full scan MS data for quantification, and data dependent (dd) MS(2) and MS(3) product ion spectra for identification and/or confirmation. The regression coefficients (r(2)) for the calibration curves (two order of magnitude up to the lowest calibration level) in the study were ≥0.99. The LODs for 54 validated compounds were ≤2ngmL(-1) (analytical standards). The relative standard deviation (RSD), which was used to estimate precision, was always lower than 22%. The recovery of extraction and matrix effects ranged from 58 to 120% and from -92 to 52%, respectively. Mass accuracy was always ≤4ppm, corresponding to a maximum mass error of 1.6millimass units (mmu). This procedure was then successfully applied to pesticide residues in a set of the above-mentioned food and environmental samples. In addition to target analytes, this method enables the simultaneous detection/identification of non-target pesticides, pharmaceuticals, drugs of abuse, mycotoxins, and their metabolites.

Multiresidue analysis of organic pollutants by in-tube solid phase microextraction coupled to ultra-high performance liquid chromatography-electrospray-tandem mass spectrometry.

In this work, in-tube solid phase microextraction (IT-SPME) coupling with ultra-high-pressure liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) multiresidue analytical method has been proposed for the first time for on-line enrichment of 9 analytes included in Water Frame Directive 2000/60/EC (WFD). The device was equipped with a GC TRB-5 capillary column, used as pre-concentration loop, and two conventional six-port injection valves. Water sample and desorption solvent volumes were tested. The optimum conditions were 4mL of processed sample followed by elution with 40µL of methanol. The analytes were detected with a mass spectrometer after being ionized positively using an electrospray ionization (ESI) source. The method presents good linearity over the range assayed, 0.025-2.5µg/L for chlorpyriphos and 0.25-25µg/L for the other tested compounds and LODs between 0.025µg/L and 2.5µg/L. Enrichment factors ranged from 2.5 to 10. Intra and inter-day variation coefficients were <26 and 31.6% respectively. Once validated, the method was applied to several water samples from different sources demonstrating that it achieves the on-line enrichment of the analytes with the advantage of minimum sample manipulation, and the identification and quantification of some organic pollutants in water samples in the range of low parts-per-billion. The method provided similar analytical characteristics as those obtained in the established couple IT-SPME-Capillary Liquid Chromatography (CapLC).

Combined use of liquid chromatography triple quadrupole mass spectrometry and liquid chromatography quadrupole time-of-flight mass spectrometry in systematic screening of pesticides and other contaminants in water samples.

As a suitable way for routine screening of pesticides and control of other organic contaminants in water, the combination of liquid chromatography triple quadrupole tandem mass spectrometry (LC-QqQ-MS/MS) and liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) has been applied to the analysis of 63 surface and waste water samples after conventional solid-phase extraction (SPE). The extracts were screened for 43 pesticides or degradation products by LC-QqQ-MS/MS achieving limits of detection (LOD) ranged from 0.04 to 2 ng L(-1). Of the 43 selected pesticides, 33 were detected in water samples. The ESI-QTOF MS instrument was run using two simultaneous acquisition functions with low and high collision energy (MS(E) approach) and acquiring the full mass spectra. A home-made database containing more than 1100 organic pollutants was used for substance identification. Around 250 of these compounds were available at the laboratory as reference standards. Five pesticides and 3 of their degradation products, different to those selected in the QqQ method, were detected by QqTOF-MS. Thirteen pharmaceuticals and two drugs of abuse were also identified in the samples. In practice, the sample preparation proved to be suitable for both techniques and for a wide variety of substances with different polarity. Mutual confirmation and evidence of co-occurrence of several other organic contaminants were the main advantages of the combination of both techniques.

Dietary administration of high doses of pterostilbene and quercetin to mice is not toxic.

The aim of this study is to evaluate possible harmful effects of high doses of t-pterostilbene (t-PTER) and quercetin (QUER) in Swiss mice. Mice were fed during 28 days at doses of 0, 30, 300, and 3000 mg/kg body weight/day of t-PTER, QUER, or a mixture of both, t-PTER + QUER, which are equivalent to 5, 50, and 500 times, respectively, the estimated mean human intake of these polyphenols (25 mg/day). Daily oral administration of QUER, t-PTER, or a mixture of both of them did not cause mortality during the experimental period. There were no differences in food and water consumption on sex. No significant body weight gain in the male or female groups was observed. Red blood cell number and the hematocrit increased after polyphenols administration compared to control groups. Biochemical parameters were not affected. Histopathological examination revealed no alterations in clinical signs or organ weight at any dose.

Pesticide residue determination in surface waters by stir bar sorptive extraction and liquid chromatography/tandem mass spectrometry.

In this stir bar sorptive extraction (SBSE) method, 16 pesticides were extracted from surface water samples by sorption onto 1 mm polydimethylsiloxane layer coated on a 10-mm-length stir bar magnet. After liquid desorption of the analytes with 1 ml of methanol, the detection was performed on a liquid chromatography-tandem mass spectrometry with a triple quadrupole (QqQ) analyzer using selected reaction monitoring mode via electrospray ionization. Parameters affecting SBSE operation, including sample volume, salt addition, extraction time, stirring rate, and desorption conditions, have been evaluated. The optimized SBSE method required two 50 ml aliquots of surface water samples, one aliquot was added of 30% NaCl and stirred at 900 rpm during 1 h for testing five pesticides with log K(o/w) < 3, and the other aliquot was directly extracted following the same procedure for the rest of the pesticides with log K(o/w) > 3. The method was validated in spiked surface water samples at limits of quantifications (LOQs) and ten times the LOQs showing recoveries <62%, and the LOQs reached were from 0.03 microg l(-1) for diazinon to 3 microg l(-1) for simazine. The proposed methodology was applied to the determination of these compounds in samples from Albufera Lake and surrounding channels, showing that SBSE is a powerful tool for routine control analysis of pesticide residues in surface water.

Solid-phase microextraction-liquid chromatography-mass spectrometry applied to the analysis of insecticides in honey.

An approach based on solid-phase microextraction-liquid chromatography-mass spectrometry (SPME-LC-MS) has been developed for determining 12 insecticides (bromophos ethyl, chlorpyrifos methyl, chlorpyrifos ethyl, diazinon, fenoxycarb, fonofos, phenthoate, phosalone, pirimiphos methyl, profenofos, pyrazophos, and temephos) in honey. The influence of several parameters on the efficiency of the SPME was systematically investigated. Under optimal conditions, the procedure provided excellent linearity (>0.990), detection and quantification limits (between 0.001 and 0.1 microg g(-1) and between 0.005 and 0.5 microg g(-1), respectively), and precision (<19% at the quantification limits and from 6 to 14% at ten times higher concentrations). However, recoveries were not so good, ranging from 19 to 92%. Honey samples were found that were contaminated with bromophos ethyl, diazinon, fonofos, pirimiphos ethyl, pyrazophos, and temephos at estimated concentrations from 6.2 +/- 1.2 to 19 +/- 3 ng g(-1).

Real-time quantitative PCR of Staphylococcus aureus and application in restaurant meals.

Staphylococcus aureus is considered the second most common pathogen to cause outbreaks of food poisoning, exceeded only by Campylobacter. Consumption of foods containing this microorganism is often identified as the cause of illness. In this study, a rapid, reliable, and sensitive real-time quantitative PCR was developed and compared with conventional culture methods. Real-time quantitative PCR was carried out by purifying DNA extracts of S. aureus with a Staphylococcus sample preparation kit and quantifying it in the LightCycler system with hybridization probes. The assay was linear from a range of 10 to 10(6) S. aureus cells (r2 > 0.997). The PCR reaction presented an efficiency of >85%. Accuracy of the PCR-based assay, expressed as percent bias, was around 13%, and the precision, expressed as a percentage of the coefficient of variation, was 7 to 10%. Intraday and interday variability were studied at 10(2) CFU/g and was 12 and 14%, respectively. The proposed method was applied to the analysis of 77 samples of restaurant meals in Valencia (Spain). In 11.6% of samples S. aureus was detected by real-time quantitative PCR, as well as by the conventional microbiological method. An excellent correspondence between real-time quantitative PCR and microbiological numbers (CFU/g) was observed with deviations of < 28%.

Application of matrix solid phase dispersion to the determination of imidacloprid, carbaryl, aldicarb, and their main metabolites in honeybees by liquid chromatography-mass spectrometry detection.

A method based on matrix solid phase dispersion (MSPD) using C18 as dispersant and dichloromethane-methanol as eluent and liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) has been developed for the simultaneous determination of imidacloprid, 6-chloronicotinic acid, carbaryl, aldicarb, aldicarb sulfoxide, and aldicarb sulfone in honeybees. The proposed method was compared with liquid-liquid extraction (LLE) combined with LC-APCI-MS analysis. Spiked blank samples were used as standards to counteract the matrix effect observed in the chromatographic determination. Recovery studies were performed at different fortification levels. Average recoveries by MSPD varied from 61% of 6-chloronicotinic acid to 99% of aldicarb sulfoxide and relative standard deviations were equal or lower than 14%. Limit of detections ranged from 0.004mgkg(-1) for imidacloprid to 0.09mgkg(-1) for 6-chloronicotinic acid. Results obtained by both methods were compared, MSPD showed higher recoveries and sensitivity than LLE for most pesticides, except for carbaryl. As MSPD is easier to perform, faster, consumes less sample and organic solvents than LLE, its application for pesticide analysis in honeybees is suggested.

Quantification of Listeria monocytogenes in salads by real time quantitative PCR.

A real time quantitative PCR (RTQ-PCR) was carried out purifying DNA extracts of Listeria monocytogenes using a High Pure Listeria Sample Preparation Kit and quantifying in a LightCycler system with hybridisation probes. A standard curve was constructed with serial dilutions. A range linear relationship, from 10 to 10(5)L. monocytogenes colony forming units (CFU), was observed between threshold cycle (Ct) and logarithmic concentration of the serial dilutions. The assay was linear in a range from 10 to 10(5)L. monocytogenes CFU and the coefficient of determination (r2) was >0.98. RTQ-PCR presented an efficiency of >85%. The accuracy of the PCR-based assay, expressed as % bias, ranged from 9% to 26% and the precision, expressed as % CV, ranged 9-22%. Intraday and interday variabilities were studied at 10(2) CFU/g and resulted in 12% and 14%, respectively. The proposed RTQ-PCR method and classical cultural methods were applied to analyse 77 salads from restaurants in Valencia (Spain). All culture positive samples were also RTQ-PCR positive.

Occurrence and distribution of pesticides in the province of Bologna, Italy, using honeybees as bioindicators.

Samples of honeybees (Apis mellifera, n = 92) from 14 beehive monitoring stations located in 3 townships in the province of Bologna were analyzed from April to October 2000. The concentration of 32 organophosphorus pesticides and 5 carbamates was determined through liquid-liquid extraction followed by gas chromatography with a nitrogen-phosphorus detector and liquid chromatography coupled to mass spectrometry using atmospheric pressure chemical ionization in positive and negative ion modes. The most contaminated samples were from Granarolo Emilia where cereals (wheat, sorghum, and corn), sugar beets, and potatoes are the main agriculture products. Thirty-five pesticides were detected, with organophosphorus being the most abundant ones. Malathion was detected in 58% of the samples (mean level 0.360 mg/kg) followed by fenithrothion in 53% of the samples (mean level 0.544 mg/kg) and pirimiphos methyl in 48% of the samples (mean level 0.006 mg/kg). Temporal trends showed that the maximum detection frequency occurred in late spring and was associated with the use of treatment products and less rainfall. The obtained results demonstrated the feasibility of using honeybees for assessing pesticide exposure in agriculture settings.

Determination of organochlorine pesticide residues in honey from the central zone of Portugal and the Valencian community of Spain.

In this study nine organochlorine pesticide residues (alpha-, beta-, and gamma-hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), aldrin, p,p'-DDE, p,p'-DDD, o,p'-DDT, and p,p'-DDT) in forty nine samples of honey collected from markets of Portugal and Spain during 2001 and 2002, respectively, were evaluated. For this evaluation, three analytical procedures were studied. The analytical procedure, based on LLE extraction with ethyl acetate followed by gas chromatography-electron-capture detection (GC-ECD) for quantification, and mass spectrometry (GC-MS) for confirmation, has been selected. Recoveries of spiked samples ranged from 68%, for beta-HCH, and 126% for p,p'-DDT, for fortification levels between 10 and 100 microg/kg, and 64%, for alpha-HCH, and 143% for gamma-HCH for fortification levels between 20 and 200 microg/kg. Limits of quantification, using GC-ECD, were from 0.01 and 0.10mg/kg, and limits of detection between 0.001 and 0.02 mg/kg. Fourteen Valencian samples were contaminated, containing residues of HCB or/and HCH isomers. The frequency of detection was 56% for Spanish samples. In Portugal, 23 samples were contaminated, what means 95.8%. In Spanish samples, concentrations range from nd to 0.03 mg/kg for HCB, and nd to 2.24 mg/kg for HCH-total. The mean concentration and standard deviation were 0.017+/-0.011 mg/kg for HCB, and 0.579+/-0.747 mg/kg for HCH-total, contributing the gamma isomer with the highest values. The samples from Portugal showed higher levels. Levels of HCB ranged from nd to 0.39 mg/kg. HCH-total ranged from nd to 4.86 mg/kg, and DDT-total from nd to 0.658 mg/kg. Mean concentration and standard deviation were 0.09+/-0.116 mg/kg for HCB, 1.357+/-1.30 mg/kg for HCH-total, and 0.143+/-0.193 mg/kg for DDT-total.

Comparison of solid-phase microextraction and stir bar sorptive extraction for determining six organophosphorus insecticides in honey by liquid chromatography-mass spectrometry.

Two approaches based on sorptive extraction, solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE), in combination with liquid chromatography (LC)-atmospheric pressure chemical ionization mass spectrometry (MS) have been assayed for analyzing chlorpyriphos methyl, diazinon, fonofos, phenthoate, phosalone, and pirimiphos ethyl in honey. In both, SPME and SBSE, enrichment was performed using a poly(dimethylsiloxane) coating. Significant parameters affecting sorption process such as sample volume, sorption and desorption times, ionic strength, elution solvent, and dilution (water/honey) proportion were optimized and discussed. Performance of both methods has been compared through the determination of linearity, extraction efficiencies, and limits of quantification. Relative standard deviations for the studied compounds were from 3 to 10% by SPME and from 5 to 9% by SBSE. Both methods were linear in a range of at least two orders of magnitude, and the limits of quantification reached ranging from 0.04 to 0.4 mg kg(-1) by SBSE, and from 0.8 to 2 mg kg(-1) by SPME. The two procedures were applied for analyzing 15 commercial honeys of different botanical origin. SPME and SBSE in combination with LC-MS enabled a rapid and simple determination of organophosphorus pesticides in honey. SBSE showed higher concentration capability (large quantities of sample can be handled) and greater accuracy (between 5 and 20 times) and sensitivity (between 10 and 50 times) than SPME: thus, under equal conditions, SBSE is the recommended technique for pesticide analysis in honey.

Determination of dithiocarbamates and metabolites in plants by liquid chromatography-mass spectrometry.

A quantitative matrix solid-phase dispersion and liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS) method is outlined for the simultaneous analysis of dithiocarbamates (DTCs) and their degradation products in plants. Compounds analyzed are dazomet, disulfiram, thiram and the metabolites ethylenthiourea and propylenthiourea. The performance of two different sample preparation protocols, the proposed one and other based on solid-phase extraction, as well as, of both atmospheric pressure ionization sources, APCI and electrospray, were compared. The effect of several parameters on the extraction, separation and detection was studied. Dithiocarbamates and metabolites were dispersed with carbograph, eluted with a mixture of dichloromethane-methanol, and then, identified by monitoring the base peak of the spectra corresponding to [M + H]+. The method was validated for avocados, cherries, lemons, nuts, oat, oranges, peaches, rice and tomatoes. Average recoveries varied from 33 to 109%, and relative standard deviation were between 4 and 21% with limits of quantification ranged from 0.25 to 2.5 mg kg(-1), except for thiram and disulfiram, which were not recovered from fruits with high acid content. The procedure was applied to the determination of DTCs and their metabolites in fruits, vegetables and cereals taken from different markets of Valencia, Spain.

Revisión de los métodos de determinación de residuos de plaguicidas organofosforados en alimentos / Determination of organophosphorus pesticide residues in food. A review

Los plaguicidas organofosforados han sido ampliamente utilizados en la agricultura desde hace más de 50 años, proporcionado tratamientos económicos y efectivos para un gran número de cultivos. Sin embargo, algunos residuos de estos plaguicidas persisten en los alimentos y constituyen un riesgo importante para la salud humana. Los métodos de análisis de residuos deberán proporcionar una precisión y exactitud adecuadas siendo a la vez rápidos y simples de manera que proporcionen resultados fiables para el análisis de alimentos complejos en un tiempo razonable. Se presenta una revisión relativa a la determinación de plaguicidas organofosforados en alimentos donde se discuten las ventajas e inconvenientes de los métodos de extracción y determinación junto con los desarrollos más recientes en estos campos. Actualmente, la extracción con disolventes orgánicos y la extracción en fase sólida, como partes fundamentales de las tecnologías de preparación de la muestra, están en continua evolución. La cromatografia de gases utilizando detectores selectivos es la técnica más utilizada para la determinación de plaguicidas organofosforados debido a sus cualidades sobre otras técnicas-analíticas (AU)

Application of matrix solid-phase dispersion to the determination of a new generation of fungicides in fruits and vegetables.

A method based on matrix solid-phase dispersion (MSPD) and gas chromatography to determine eight fungicides in fruits and vegetables is described. Fungicide residues were identified and quantified using nitrogen-phosphorus detection and electron-capture detection connected in parallel and confirmed by mass spectrometric detection. The method required 0.5 g of sample, C18 bonded silica as dispersant sorbent, silica as clean-up sorbent and ethyl acetate as eluting solvent. Recoveries from spiked orange, apple, tomato, artichoke, carrot and courgette samples ranged from 62 to 102% and relative standard deviations were less than 15% in the concentration range 0.05-10 mg kg(-1). Detection and quantitation limits ranged 3-30 microg kg(-1) and 10-100 microg kg(-1), respectively, with linear calibration curves up to 10 mg kg(-1). The analytical characteristics of MSPD compared very favourably with the results of a classical multiresidue method, which uses ethyl acetate and anhydrous sodium sulphate for the extraction.