Technical Note: How long can seawater oxygen samples be stored before titration?
M. Lankhorst1, G. Chavez1, S. H. Nam2, and U. Send11Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093, USA 2Research Institute of Oceanography/School of Earth and Environmental Sciences, Seoul National University, Seoul 151-742, Republic of Korea
Received: 08 Oct 2014 – Accepted for review: 08 Oct 2014 – Discussion started: 29 Oct 2014
Abstract. The concentration of dissolved oxygen in seawater is routinely measured using a standardized titration method that involves analysis shortly after the water sample has been collected. However, none of the existing procedural documents are specific about how soon after collection the titration has to be done. Here, we report on a small number of samples where duplicates were collected and one batch was titrated within days after collection, while the other batch was stored for several weeks before titration. In addition, for a subset of the samples a third batch was taken that was stored like the others but with a particular chemical already added before storage. Comparison between the batches confirms that there is no significant difference between the ones that were stored and the ones that were analyzed sooner, indicating that a month-long storage period is acceptable. The implication of this is that such oxygen samples do not necessarily have to be analyzed while still on the ship; instead, it is possible to transport them ashore for analysis there.
Lankhorst, M., Chavez, G., Nam, S. H., and Send, U.: Technical Note: How long can seawater oxygen samples be stored before titration?, Ocean Sci. Discuss., 11, 2447-2459, doi:10.5194/osd-11-2447-2014, 2014.