Dataset: GN01 As Speciation

0.45 µm filtered seawater samples from the GEOTRACES Carousel/GO-FLO bottles were placed into 500 mL Teflon FEP bottles, refrigerated, and analyzed within 24 hours of collection.

Arsenic speciation was determined using selective hydride generation, liquid nitrogen-cooled trapping, and then revolatilization and determination with gas chromatography/photoionization detection (Cutter et al., 1991; Cutter and Cutter, 2006). Calibration performed daily via the standard additions method, with a minimum of 4 additions of AsIII and AsV. The slope from the linear fit to these data was then applied to all samples for that day. Detection limits were 0.03 nmol/L for As(III) and As(V). Precision was better than 8% RSD. Dimethyl and monomethyl arsenic (DMAS and MMAs) were simultaneously determined using the total inorganic As procedures above, but using a different gas chromatography column (15% OV-3 on Chromasorb W/AW DMCS, 80/100 mesh; Cutter and Cutter, 2006)). Detection limit for the methylated As species were 0.01 nmol/L and the precision was 6% (RSD) at 0.1 nmol/L. Calibration was performed using the standard additions method with a minimum of 4 additions of MMAs and DMAs. The slope from the linear fit to these data was then applied to all samples for that day.