For reversed phase (RP) chromatography, a Waters Acquity UPLC HSS Cyano column (1.8 µm particle size, 2.1 mm x 100 mm) equipped with a Waters Acquity UPLC HSS Cyano guard column (1.8 µm particle size, 2.1 mm x 5 mm) was used with 0.1% formic acid in water (Solvent A) and 0.1% formic acid in acetonitrile (Solvent B) at a flow rate of 0.4 mL/min. The HSS Cyano column has previously been used for analysis of compounds in complex marine samples with robust reproducibility of peak size and shape. The column was held at 5% B for 2 minutes, ramped to 100% B over 16 minutes, held at 100% B for 2 minutes, and equilibrated at 5% B for 5 minutes (25 minutes total). The column was maintained at 35 C. The injection volume was 15 µL. When starting a batch, the column was equilibrated at the starting conditions for at least 10 minutes; several water blanks were run before and throughout a batch. After a batch, the column was flushed with 100% acetonitrile for 20 to 30 minutes. For HILIC chromatography, a SeQuant ZIC-pHILIC column (5 um particle size, 2.1 mm x 150 mm, from Millipore) was used with 10 mM ammonium carbonate in 85:15 acetonitrile to water (Solvent A) and 10 mM ammonium carbonate in 85:15 water to acetonitrile (Solvent B) at a flow rate of 0.15 mL/min. This column was compared with a Waters UPLC BEH amide and a Millipore cHILIC column; the pHILIC showed superior reproducibility and peak shapes. The column was held at 100% A for 2 minutes, ramped to 64% B over 18 minutes, ramped to 100% B over 1 minute, held at 100% B for 5 minutes, and equilibrated at 100% A for 25 minutes (50 minutes total). The column was maintained at 30 C. The injection volume was 2 µL for samples and standard mixes. When starting a batch, the column was equilibrated at the starting conditions for at least 30 minutes. To improve the performance of the HILIC column, we maintained the same injection volume, kept the instrument running water blanks between samples as necessary, and injected standards in a representative matrix in addition to standards in water. After each batch, the column was flushed with 10 mM ammonium carbonate in 85:15 water to acetonitrile for 20 to 30 minutes.