EPA Method 528 Internal Standard Back Catalog number: 93188 Manufacturer: ABSOLUTE STANDARDS Availability: In the manufacturer's stock Price on request - + Recommended 673467 Triforine, 100 µg/ml, Acetonitrile, 5ml Price on request XA16173010CY Phthalic acid, bis-2-ethylhexyl ester D4, 100µg/mL in Cyclohexane, 1ml Price on request V094750 Valproic Acid, 1g Price on request