Diatoms are a well-established and standardized test-organism in the field of ecotoxicology for e.g. the testing of (heavy) metals. In terms of living cells, a high cell-to-cell variability is present within one cell population. Bulk metal analysis is not sufficient in this regard. For (eco-)toxicological as well as life-science issues, however, information like cell growth, accumulated concentrations on single-cell level are essential. Single cell analysis addresses this point. Instead of bulk analysis of a total cell-population single cell approaches provide cell-to cell information. This can be achieved with a mass spectrometer comprising an inductively coupled plasma as ion source. For this purpose, the sample is diluted and introduced into the plasma via a slow sample flow. Thereby each time only a single cell is analyzed. Low dwell times in the low millisecond range allow for a short measurement time. A measurement time of two minutes already provides sufficient information to depict a cell population’s composition. However, the largest challenge is to reduce the time needed for tedious sample preparation as well as manual analysis. The combination of a High-Performance Liquid Chromatography-System (HPLC) as autosampler operated in flow-injection mode combined with a syringe pump as well as a 10-port switching valve on-line with ICP-MS enables the design of an automated system for single diatom analysis. To remove ionic matrix components from the diatoms an in-line filter was installed within the flow path. Algae were collected, washed, and flushed into the plasma of the mass spectrometer. This allows for a fully automated diatom analysis on single cell basis within 11 minutes.
Development of an automated on-line purification HPLC single cell-ICP-MS approach for fast diatom analysis
Marcus von der Au, M. Schwinn, K. Kuhlmeier, C. Büchel, Björn Meermann
Analytica Chimica Acta 1077, pages 87-94, 2019
BAM Inorgnic Trace Analysis division