EPA Method 8021B Internal Standard Back Catalog number: 19394 Manufacturer: ABSOLUTE STANDARDS Availability: In the manufacturer's stock Price on request - + Recommended 55312WV WP Fluoride Price on request 70650 Diflubenzuron Price on request 3492.10-100 Propetamphos, 100µg/mL, Solvent-c.hexane or ac.nitrile, Unit 1mL, # of units-1, Cas.no. 31218-83-4 Price on request