Open AccessAutomated cleaning of foraminifera shells before Mg/Ca analysis using a pipette robot
Author(s) -
Johnstone Heather J. H.,
Steinke Stephan,
Kuhnert Henning,
Bickert Torsten,
Pälike Heiko,
Mohtadi Mahyar
Publication year - 2016
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1002/2016gc006422
Subject(s) - globigerinoides , foraminifera , seawater , pipette , calcite , mineralogy , geology , sediment , chromatography , oceanography , chemistry , paleontology , benthic zone
Abstract The molar ratio of magnesium to calcium (Mg/Ca) in foraminiferal calcite is a widely used proxy for reconstructing past seawater temperatures. Thorough cleaning of tests is required before analysis to remove contaminant phases such as clay and organic matter. We have adapted a commercial pipette robot to automate an established cleaning procedure, the “Mg‐cleaning” protocol of Barker et al. (2003). Efficiency of the automated nine‐step method was assessed through monitoring Al/Ca of trial samples (GeoB4420‐2 core catcher). Planktonic foraminifera Globigerinoides ruber, Globigerinoides sacculifer , and Neogloboquadrina dutertrei from this sample gave Mg/Ca consistent with the habitat range of the three species, and 40–60% sample recovery after cleaning. Comparison between manually cleaned and robot‐cleaned samples of G. ruber (white) from a sediment core (GeoB16602) showed good correspondence between the two methods for Mg/Ca (r = 0.93, p < 0001, n = 27). Average Al/Ca in robot‐cleaned samples was 0.05 mmol/mol, showing that the samples are cleaned effectively by the robot. The robot offers increased sample throughput as batch sizes of up to 88 samples/blanks can be processed in ∼7 h with little intervention.