Determination of trace levels of aquaculture chemotherapeutants in seawater samples by SPME-GC-MS/MS

Effects of nanoparticles in species of aquaculture interest

Recently, it was observed that there is an increasing application of nanoparticles (NPs) in aquaculture. Manufacturers are trying to use nano-based tools to remove the barriers about waterborne food, growth, reproduction, and culturing of species, their health, and water treatment in order to increase aquaculture production rates, being the safe-by-design approach still unapplied. We reviewed the applications of NPs in aquaculture evidencing that the way NPs are applied can be very different: some are direclty added to feed, other to water media or in aquaculture facilities. Traditional toxicity data cannot be easily used to infer on aquaculture mainly considering short-term exposure scenarios, underestimating the potential exposure of aquacultured species. The main outputs are (i) biological models are not recurrent, and in the case, testing protocols are frequently different; (ii) most data derived from toxicity studies are not specifically designed on aquaculture needs, thus contact time, exposure concentrations, and other ancillary conditions do not meet the required standard for aquaculture; (iii) short-term exposure periods are investigated mainly on species of indirect aquaculture interest, while shrimp and fish as final consumers in aquaculture plants are underinvestigated (scarce or unknown data on trophic chain transfer of NPs): little information is available about the amount of NPs accumulated within marketed organisms; (iv) how NPs present in the packaging of aquacultured products can affect their quality remained substantially unexplored. NPs in aquaculture are a challenging topic that must be developed in the near future to assure human health and environmental safety. Graphical abstract ᅟ.

Optimizing Mass Spectrometry Analyses: A Tailored Review on the Utility of Design of Experiments

Mass spectrometry (MS) has emerged as a tool that can analyze nearly all classes of molecules, with its scope rapidly expanding in the areas of post-translational modifications, MS instrumentation, and many others. Yet integration of novel analyte preparatory and purification methods with existing or novel mass spectrometers can introduce new challenges for MS sensitivity. The mechanisms that govern detection by MS are particularly complex and interdependent, including ionization efficiency, ion suppression, and transmission. Performance of both off-line and MS methods can be optimized separately or, when appropriate, simultaneously through statistical designs, broadly referred to as "design of experiments" (DOE). The following review provides a tutorial-like guide into the selection of DOE for MS experiments, the practices for modeling and optimization of response variables, and the available software tools that support DOE implementation in any laboratory. This review comes 3 years after the latest DOE review (Hibbert DB, 2012), which provided a comprehensive overview on the types of designs available and their statistical construction. Since that time, new classes of DOE, such as the definitive screening design, have emerged and new calls have been made for mass spectrometrists to adopt the practice. Rather than exhaustively cover all possible designs, we have highlighted the three most practical DOE classes available to mass spectrometrists. This review further differentiates itself by providing expert recommendations for experimental setup and defining DOE entirely in the context of three case-studies that highlight the utility of different designs to achieve different goals. A step-by-step tutorial is also provided.

Development of a field sampling method based on magnetic nanoparticles for the enrichment of pesticides in aqueous samples

A field sampling method based on magnetic core–shell silica nanoparticles was developed for field sampling and the enrichment of low concentrations of pesticides in aqueous samples.

Controllable preferential-etching synthesis of ZnO nanotube arrays on SiO2 substrate for solid-phase microextraction

An improved route to obtain ZnO nanotube arrays and its first application to headspace solid-phase microextraction (HSSPME) as an adsorptive coating were described. The ZnO nanotube arrays were synthesized by a two-step chemical process including the hydrothermal synthesis of ZnO nanorod arrays on the surface of silica fiber (SiO(2)) in the first step, and the formation of ZnO nanotubes by selectively etching in NH(3)·H(2)O solution in the second step. The influence of NH(3)·H(2)O concentration, etching time, reaction temperature, and aging time in the ZnO nanotubes formation process was investigated, and arrays of ZnO nanotube with tailored dimensions (250 nm external diameters, 70 nm wall thicknesses and 2 μm lengths) could be obtained by varying the conditions. In addition, the feasibility of ZnO nanotube arrays adopted for HSSPME was evaluated by extracting volatile organic compounds (VOCs) by use of benzene, toluene, ethylbenzene, o-, m-and p-xylene (BTEX) as model compounds and the results showed that the coating has good extraction capability. The analytes were linear in the range of 10-600 μg L(-1) (r > 0.9960) and the detection limits were about 0.005-0.01 μg L(-1), lower than that obtained with ZnO nanorod arrays. The relative standard derivations (RSD) for the repeatability of single fiber and fiber-to-fiber were lower than 9.5% and 13.8%, respectively. The prepared coating showed good recoveries in the range of 87%-108% and long lifetime (more than 50 times), implying to be a potential absorbent for the VOCs in water samples.

Analysis, occurrence, and toxic potential of pyrethroids, and fipronil in sediments from an urban estuary

Eight pyrethroids and fipronil and its three major degradates were analyzed in urban estuarine sediments that exhibited a range of toxic effects to an amphipod test species. Sediments from Ballona Creek, an urban estuary in Southern California (USA), collected during three dry season events were analyzed by gas chromatography with electron capture and negative chemical ionization mass spectrometric detection (GC-ECD and GC-NCI-MS). The two detection methods were in agreement for intermediate levels of pyrethroid contamination (10-50 ng/g dry wt) but deviated for both low and high concentrations (< 5 and > 50 ng/g). Sediments contained total pyrethroids as high as 473 ng/g with permethrin, bifenthrin, and cypermethrin as the most abundant compounds. In contrast, fipronil and its desulfinyl, sulfide, and sulfone degradates were detected at much lower levels (<or= 0.18-16 ng/g). Toxic units estimated for these compounds revealed that bifenthrin and cypermethrin were likely contributors to the mortality observed in tests with the estuarine amphipod Eohaustorius estuarius. Although fipronil was not a likely contributor to the observed mortality, the concentrations detected may be of concern for more sensitive crustacean species. Furthermore, the spatial pattern of pyrethroid contamination and potential toxicity was highly correlated with fine-grained substrate, which shifted to downstream stations within a three-month period during the dry season.