Glass impurities and Oceanography

by on 15 April, 2013

Over the last twenty years our understanding of the importance of trace metal concentrations and distributions in the oceans at greatly evolved.  We now recognize that trace metals exist at nanomolar and picomolar concentrations in seawater - orders of magnitude below the concentrations found in terrestrial ecosystems.  Trace metals can have either a positive or negative effect on marine environment:  It is believed that the lack of trace metals may limit phytoplankton growth (1) and indirectly inhibit oxygen production (Marine phytoplankton account for approximately 50% of global photosynthesis).  Conversely, some trace metals have been shown to be toxic to organisms at very low concentrations. For these reasons measuring trace metals in the oceans has grown in importance.

When working with nanomolar and picomolar concentrations it is easy to accidentally contaminate the samples.  For this reason analytical chemists who work with trace elements are very selective about the labware equipment they use.  Fortunately fused silica is an extremely clean glass (unlike, for example, borosilicate and Pyrex glass).  Fused silica in general and Translume’s microfluidic chips in particular can used for metal trace analysis.

(Note that trace metals may also be absorbed in the materials that are in contact with the sample.  This can generally be prevented by adjusting the pH of the seawater samples.(2))

References

  1. "Limitation of productivity by trace metals in the sea", F. Morel, R. Hudson, and N. Price Limnol. Oceanogr., 36(8), 1991, 1742-175
  2.  “Atomic Absorption Spectrometry”, J.E. Cantle, Elsevier, ISBN 0-444-42015-0