Dataset: Size fractionated zooplankton d13C and d15N of individual amino acids from EXPORTS cruise RR1813 in August 2018

Zooplankton were collected using a multiple opening-closing net and environmental sensing system (MOCNESS) on R/V Roger Revelle cruise RR1813 during August-September 2018 (EXPORTS cruise). Onboard, zooplankton were wet-sieved into different size fractions using filtered seawater and 0.2, 0.5, 1.0, 2.0, and 5.0 mm mesh sieves and frozen at -20ºC. Zooplankton were dried and each fraction ground using a mortar and pestle. Samples were weighed and amino acids were isolated and purified by hydrolysis in 6N hydrochloric acid followed by cation exchange chromatography. The purified amino acids were then treated with isopropanol and trifluoroacetic acid yielding trifluoroacetic amino acid esters. The resulting solution was further purified by liquid-liquid extraction into chloroform before being stored in a dichloromethane-trifluoroacetic acid solution, and then finally transferred into ethyl acetate just prior to mass spectrometric isotopic analysis. CSIA-AA was carried out on a gas chromatograph coupled to an isotope ratio mass spectrometer (GC-IRMS), with all samples measured in triplicate when amino acid concentrations were sufficient.