EPA Method 551.1 Internal Standard Back Catalog number: 32103 Manufacturer: ABSOLUTE STANDARDS Availability: In the manufacturer's stock Price on request - + Recommended 677604 2-Quinoxalinecarboxylic acid, 100mg Price on request 79432 Atrazine Price on request C16178700 Phthalic acid, mono-n-butyl ester, certified, 0.1g Price on request