EPA Method 624 Internal / Surrogate Standard Back Catalog number: 92559 Manufacturer: ABSOLUTE STANDARDS Availability: In the manufacturer's stock Price on request - + Recommended 71780 N-Phenyl-1,4-phenylenediamine Price on request 50276 pH 6.0 Standard @ 25°C Price on request 71750 p-tert-Amylphenol Price on request