Leitf?higkeitstitrationen

Ohne Zusammenfassung     

Determination of methylmercury in organic matrices with gas chromatography/ atomic absorption spectrometry

Determinations of methylmercury in biological tissues by gas chromatography with electron-capture detection are often disturbed by electron-capturing compounds simultaneously eluting with the organo-mercury compound.Identification and quantification of methylmercury is improved by interfacing the gas chromatograph to the gas cell of a flameless atomic absorption spectrometer. The construction of the transfer line used is described.     

Photosynthetic energy conversion in the diatom <Emphasis Type="Italic">Phaeodactylum tricornutum</Emphasis>

Isothermal microcalorimetry can be used to investigate the photosynthetic energy conversion of autotrophic organisms. In this study, for the first time a diatom alga was used to compare the calorimetrically measured heat flux with measurements of the photosynthetic performance by oxygen evolution and pulse-amplitude modulated fluorescence. The presented experimental setup proved suitable to compare calorimetric data with those of conventional methods of the determination of photosynthesis rates. Special attention was paid to the contribution of energy dissipation via non-photochemical quenching (NPQ) of chlorophyll fluorescence to the metabolic energy balance. This was achieved by a combination of different light conditions and the use of an inhibitor of NPQ. Although NPQ is an important photoprotective mechanism in diatoms, the inhibition of NPQ resulted in an activation of alternative, energy dissipating pathways for absorbed radiation which completely compensated for the fraction of energy dissipation by NPQ.