Data for: Reconsideration of seawater surfactant activity analysis based on an inter-laboratory comparison study.

Data to accompany the manuscript 'Reconsideration of seawater surfactant activity analysis based on an inter-laboratory comparison study'.

These data are the results of an inter-laboratory calibration of concentrations of surfactants, or surface-active substances (SAS), in replicate seawater samples. Data are expressed as total surfactant activity (SA) in equivalents of model surfactant Triton-X-100 (T-X-100 eq. mg/L). The participating laboratories were the Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University of Oldenburg, Germany, The School of Natural and Environmental Sciences, Newcastle University (NU), UK and the Division for Marine and Environmental Research, Ruđer Bošković Institute (RBI), Croatia. SA was quantified on four instruments (ICBM, NU, RBI1 and RBI2) and three calibration protocols were also compared (ICBM, NU1 and RBI (NU2)).