Novel miniaturized passive sampling devices based on liquid phase microextraction equipped with cellulose-grafted membranes for the environmental monitoring of phthalic acid esters in natural waters.

Phthalic acid esters (PAEs) are considered endocrine disruptors and potential carcinogens. Consequently, efficient and accurate environmental monitoring of trace levels of these organic pollutants is necessary to protect the population against their hazardous effects. Passive sampling techniques have gained notoriety for environmental monitoring and have been proven highly sensitive to temporal variations. This study developed a miniaturized passive sampling device (MPSD) based on hollow fiber liquid-phase microextraction (HF-LPME). The devices were calibrated in the laboratory using an automated calibration system. The results demonstrated the first-order uptake ranges for Diethyl phthalate (DEP), Diisobutyl phthalate (DiBP), Dibutyl phthalate (DBP), Benzyl butyl phthalate (BBP) and Bis(2-ethylhexyl phthalate) (DEHP) between 30 min and 24 h with sampling rates equivalent to 0.009; 0.021; 0.033; 0.085 and 0.003 mL h-1 respectively (R2 between 0.88 and 0.99). The calibrated devices were deployed in 12 marginal lagoons, stretching approximately 330 km along the main river. The extracts recovered from the devices were analyzed by gas chromatography (GC), resulting in the identification and quantification of DEP (0.697-13.7 ng L-1), DiBP (0.100-4.43 ng L-1), DBP (0.014-1.21 ng L-1), BBP (0.218-5.67 ng L-1), and DEHP (0.002-2.24 ng L-1). Despite being frequently identified, DEHP concentrations were well below the maximum established limits, revealing a good water quality in terms of the target PAEs. In contrast, screening the extracts using GCxGC was possible to detect other hazardous pollutants such as pesticides, drugs, and their metabolites. The described device was effective and reliable, providing accurate PAE measurements following short exposure periods. In this sense, its deployment during emergency operations, such as accidental discharges of industrial effluents into natural waters, could continuously and cost-effectively monitor water quality.

Assessment of pesticides in water using time-weighted average calibration of passive sampling device manufactured with carbon nanomaterial coating on stainless steel wire.

The continued contamination of water sources by pesticides is a problem that involves the life of aquatic organisms and human health, especially in countries whose economy is based on agriculture. The need to know the quality of drinking water under these circumstances is a priority for the public health of any community. Passive sampling methods allow the determination of long-term environmental pollutants through a single sample collection, reducing time and cost of analyses. One advantage of passive sampling is that it is possible to calculate a time-weighted average (TWA) concentration value or an equilibrium concentration value, depending on the type of device used and the exposure time. Passive sampling techniques using carbon nanomaterials (CNMs) have a high potential for pesticide sampling in aquatic systems. A device for passive sampling manufactured with CNMs in a microextraction system and recyclable materials was calibrated in laboratory exposure conditions over 15 days. The calibration results showed linear accumulation periods between 5 and 10 days. Sampling rates were between 0.014 and 0.146 mL day-1. The sampler was field-tested in the San Francisco river basin in the state of Minas Gerais in Brazil for 7 days. This research allowed for the detection and calculation of TWA concentrations for organochlorine pesticides such as α-HCH, 4,4-DDE, and 4,4-DD in water sources. The manufactured device demonstrated greater sensitivity than the grab sampling processes for the detection of pesticides. The performed passive sampling system using gas chromatography/mass spectrometry (GC/MS) technique allowed for the collection, detection, identification, and quantification of 26 pesticides.

A new carbon nanomaterial solid-phase microextraction to pre-concentrate and extract pesticides in environmental water.

This research describes a solid-phase microextraction device using carbon nanomaterials supported on steel threads. The device was used to pre-concentrate and extract 24 pesticides in water. The carbon nanomaterials were obtained by a chemical vapor deposition (CVD) process, using methane and acetonitrile as carbon source. The different pesticides were separated, detected, and quantified using gas chromatography coupled to mass spectrometry (GC-MS). The system, optimized and validated in the laboratory, presented good results. Linearity was between 0.0007 and 50.00 µg L-1, with determination coefficients greater than 0.9. The detection and quantification limits were in the range of 0.0002-1.1309 µg L-1 and 0.0007-3.7320 µg L-1, respectively. The studied pesticides presented recovery values in the range of 70 ± 8 to 123 ± 18%. Carbon nanomaterials exhibited high thermal and mechanical resistance, as the same fiber could be used for approximately 300 extractions. The device was applied to analyze environmental water samples collected from the São Francisco river basin in Brazil and in the Chinampas in Mexico City.

New passive sampling device for effective monitoring of pesticides in water.

The extensive use of pesticides promotes environmental contamination, mainly in surface and ground waters. However, they remain at very low concentration and present wide degradation level requiring the use of efficient devices for pesticides passive sampling. In this study, a new in situ passive sampling device was developed for monitoring and estimating time-weighted average (TWA) of pesticides in waters. The device was made with simple, recyclable and cheap materials. The sampling system involves the liquid phase microextraction technique with hollow fiber in two-phases mode. Pesticides determination was done by gas chromatography coupled to mass spectrometry. The method was optimized and validated for the determination of 29 pesticides in water, showing good linearity in the range between 0.012 and 40.00 µg L-1 with determination coefficients of R2 > 0,9649. Limit of detection (LOD) ranged from 0.009 to 0.557 µg L-1 and limit of quantification (LOQ) from 0.012 to 0.802 µg L-1. The recoveries of spiked pesticides in water samples were in the range from 96 to 130%. The method was applied to forty environmental water samples collected at São Francisco river basin, Brazil. The highest detection frequency was found for the pesticides 4,4-DDE, 4,4-DDD and propazine. They were detected in more than 20 percent of the samples.