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Veröffentlichung A collaborative evaluation of LC-MS/MS based methods for BMAA analysis: soluble bound BMAA found to be an important fraction(2016) Faassen, Elisabeth J.; Antoniou, Maria G.; Beekman-Lukassen, Wendy; Blahova, Lucie; Chernova, Ekaterina; Christophoridis, Christophoros; Combes, Audrey; Edwards, Christine; Fastner, Jutta; Harmsen, Joop; Hiskia, Anastasia; Ilag, Leopold L.; Kaloudis, Triantafyllos; Lopicic, Srdjan; Lürling, Miquel; Mazur-Marzec, Hanna; Meriluoto, Jussi; Porojan, Cristina; Viner-Mozzini, Yehudit; Zguna, NadezdaExposure to â-N-methylamino-l-alanine (BMAA) might be linked to the incidence of amyotrophic lateral sclerosis, Alzheimers disease and Parkinsons disease. Analytical chemistry plays a crucial role in determining human BMAA exposure and the associated health risk, but the performance of various analytical methods currently employed is rarely compared. A CYANOCOST initiated workshop was organized aimed at training scientists in BMAA analysis, creating mutual understanding and paving the way towards interlaboratory comparison exercises. During this workshop, we tested different methods (extraction followed by derivatization and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis, or directly followed by LC-MS/MS analysis) for trueness and intermediate precision. We adapted three workup methods for the underivatized analysis of animal, brain and cyanobacterial samples. Based on recovery of the internal standard D3BMAA, the underivatized methods were accurate (mean recovery 80%) and precise (mean relative standard deviation 10%), except for the cyanobacterium Leptolyngbya. However, total BMAA concentrations in the positive controls (cycad seeds) showed higher variation (relative standard deviation 21%-32%), implying that D3BMAA was not a good indicator for the release of BMAA from bound forms. Significant losses occurred during workup for the derivatized method, resulting in low recovery (<10%). Most BMAA was found in a trichloroacetic acid soluble, bound form and we recommend including this fraction during analysis.Quelle: http://www.mdpi.comVeröffentlichung What Colin Reynolds could tell us about nutrient limitation, N:P ratios and eutrophication control(2020) Chorus, Ingrid; Spijkerman, EllyColin Reynolds exquisitely consolidated our understanding of driving forces shaping phytoplankton communities and those setting the upper limit to biomass yield, with limitation typically shifting from light in winter to phosphorus in spring. Nonetheless, co-limitation is frequently postulated from enhanced growth responses to enrichments with both N and P or from N:P ranging around the Redfield ratio, concluding a need to reduce both N and P in order to mitigate eutrophication. Here, we review the current understanding of limitation through N and P and of co-limitation. We conclude that Reynolds is still correct: (i) Liebig's law of the minimum holds and reducing P is sufficient, provided concentrations achieved are low enough; (ii) analyses of nutrient limitation need to exclude evidently non-limiting situations, i.e. where soluble P exceeds 3-10 (my)g/l, dissolved N exceeds 100-130 (my)g/l and total P and N support high biomass levels with self-shading causing light limitation; (iii) additionally decreasing N to limiting concentrations may be useful in specific situations (e.g. shallow waterbodies with high internal P and pronounced denitrification); (iv) management decisions require local, situation-specific assessments. The value of research on stoichiometry and co-limitation lies in promoting our understanding of phytoplankton ecophysiology and community ecology. © The Author(s) 2020