Filtern
Dokumenttyp
Sprache
- Englisch (2)
Referierte Publikation
- ja (2)
Schlagworte
- Diatoms (1)
- Ecotoxicological Testing (1)
- ICP-TOF-MS (1)
Organisationseinheit der BAM
Recently, first analyses of single sub-micrometre particles, embedded in liquid droplets, by inductively coupled plasma optical emission spectrometry (ICP-OES) with a size-equivalent detection limit of several hundred nanometres were reported.1,2 To achieve lower detection limits which might allow for the analysis of particles in the nanometre size range a more sensitive technique such as mass spectrometry (MS) is required. Various modifications of particle delivery and data acquisition systems commonly used were carried out to install a setup adequate for ICP-MS detection. These modifications enabled us to supply droplets generated by a commercial microdroplet generator (droplet size: 3040 µm) with nearly 100% efficiency and high uniformity to the ICP. Analyses were performed using both standard solutions of dissolved metals at concentrations of 1 (Ag), 2 (Au), 5 (Au), or 10 (Cu) mg L-1 and highly diluted suspensions of gold and silver nanoparticles with sizes below 110 nm. In doing so, detection efficiencies of 10-6 counts per atom could be achieved while size-related limits of quantification were found to be 21 nm and 33 nm for gold and silver, respectively. Furthermore, the advantages of utilizing microdroplet generators vs. conventional nebulizers for nanoparticle analyses by ICP-MS are discussed.
Diatoms play a key role in assessing the eco-toxicology of metals and are already part of several national and international guidelines and regulations. Data on metal uptake and its correlation with a natural metal composition of the diatoms are mostly lacking on a cellular basis - mainly due to the lack of a suitable method on both the preparation and detection side. Therefore, within this work a fully automated approach based on the on-line coupling of a high performance liquid chromatograph (HPLC) and an inductively coupled plasma-time of flight-mass spectrometer (ICP-ToF-MS) was applied to analyze single cells of the alga Cyclotella meneghiniana multi-elementally in order to provide a deeper insight into the metal composition and its response to environmental stress. Multi-elemental analysis in single diatoms also enables assessment of combined toxicity of a set of metals. A set of four fingerprint elements, characteristically for diatoms (Mg, P, Si, Fe), were identified and hence the investigation of environmental stress onto the cells was enabled by performing incubation experiments with environmentally relevant toxic elements. It could be shown at moderate environmental stress caused by increasing the metal concentration in the medium (zinc) that the fingerprint element concentrations remained stable and thus the suitability of the selected elements for algae tracing was demonstrated. With regard to further ecotoxicological assessments, a multivariate approach was successfully applied allowing for cell classification upon different incubation concentration levels. This multivariate approach also facilitated an effective identification of three different diatom species (Cyclotella meneghiniana, Thalassiosira weissflogii and Thalassiosira pseudonana).