Liquid chromatography coupled to mass spectrometry (LC-MS) is seen as an integral part of methods of choice for the replacement of animal tests in the determination of lipophilic shellfish toxins. However, these techniques are prone to matrix effects that need to be considered when developing and validating methods. The analysis of shellfish is a challenging task due to the complexity of the shellfish matrix and the number of shellfish species encountered in monitoring laboratories. Therefore, it is crucial that the cause and the extent of matrix effects is fully understood in order to apply corrective measures to the analytical method and to develop efficient sample clean-up steps. This paper presents different approaches to evaluate matrix effects associated with the analysis of okadaic acid (OA), azaspiracid-1 (AZA1) and pectenotoxin-2 (PTX2) in cooked and raw mussel flesh. Post-extraction addition and standard addition experiments were carried out and analysed using various LC-MS methods. Gradient and isocratic elution were compared and ultra-performance liquid chromatography (UPLC), using C8 and C18 Acquity BEH columns, was evaluated for the extent of matrix effects. When matrix effects were observed, OA and PTX2 were always prone to signal enhancement and AZA1 to signal suppression. For all the toxins studied, matrix effects were dependent on chromatographic conditions. UPLC separation using a C8 column significantly reduced matrix effects compared to the other conditions assessed. Furthermore, sample dilution has proven to be an efficient way of reducing matrix effects associated with OA analysis.

Most large carnivores are secretive and threatened, and these characteristics pose problems for research on, and monitoring of, these species across extensive areas. Participatory monitoring, however, can be a useful tool for obtaining long-term data across large areas. Pumas Puma concolor and jaguars Panthera onca are the largest predators in the threatened Upper Paraná Atlantic Forest. To survey the presence of these two species we established a participatory network of volunteers and a partnership with researchers in the three countries that share the Upper Paraná Atlantic Forest (Argentina, Brazil and Paraguay). We trained participants in simple methods of collecting faeces and track imprints of large felids. Between 2002 and 2008 . 100 volunteers helped with monitoring, obtaining 1,633 records identified as pumas or jaguars across c. 92,890 km 2 . We confirmed jaguar presence in a large section of the Misiones Green Corridor in Argentina and in the largest protected areas of Brazil and Paraguay. Pumas exhibited a wider distribution, being recorded throughout Misiones province in Argentina and in some areas of Brazil and Paraguay where jaguars were not detected. Both species, and especially jaguars, were detected mainly in the few remaining medium and large forest fragments in this Forest. Although these carnivores are often in conflict with local people, their charisma and cultural significance makes them flagship species that motivated the participation of volunteers and institutions. Participatory monitoring allowed coverage of a vast area at relatively low cost whilst enhancing collaborative management policies among people and institutions from three countries.