Agilent 8900 icp ms

Urine specific gravity was analyzed using a handheld refractometer with automatic temperature compensation (PAL-10S; ATAGO Co Ltd). An Agilent LC 1260 equipped with a Hamilton PRP-100X column interfaced with an Agilent 8900 ICP-MS in collision cell mode was used to measure concentrations of urinary arsenic species, i.e., iAs (arsenite and arsenate), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), and arsenobetaine (AsB), at the Trace Element Analysis Core at Dartmouth College. The arsenic species limit of detection (LOD) ranged from 0.06 to 0.10 μg/L across batches (Table S1). Total arsenic in tap water samples was measured with the Agilent 8900 ICP-MS in direct solution acquisition mode with a LOD of 0.04 μg/L.

Zebrafish samples from vehicle, 0.03, 0.3, and 3 ppm Ag-NP exposure groups were analyzed at 3 and 5 dpf to quantify tissue concentrations of Ag. Samples were analyzed in triplicate with 22 to 26 larval zebrafish/sample obtained from 3 separate spawnings. Zebrafish samples, triplicate method blanks (200 µL 18.2 MΩ/cm water), and triplicate NIST1640a digestion quality control standards (200 µL NIST1640a Trace Elements in Natural Water - National Institute of Standards and Technology) were digested by adding 30 µL concentrated TraceMetal Grade HNO₃ (Fisher Scientific) and 100 µL concentrated TraceMetal Grade HCl (Fisher Scientific) then heating in a hot block that was ramped up to 95 ºC over 30 min, followed by digestion at 95 ºC for 1 h. 550 µL 30% ULTREX II H2O2 (J.T. Baker) was added incrementally to room temperature samples with heating between additions. The following increments were used: 50 µL at 4 ºC for 15 min, 100 µL at 67 ºC for 10 min, 100 µL at 85 ºC for 45 min, 150 µL at 95 ºC for 25 min, and 150 µL at 95 ºC for 1 h. The samples were allowed to cool, then brought to a final volume of 1 mL with 18.2 MΩ-cm water prior to analysis by the Interdisciplinary Center for Plasma Mass Spectrometry at the University of California at Davis (ICPMS.UCDavis.edu) using an Agilent 8900 ICP-MS (Agilent Technologies).