GFS Chemicals Sells water calibration equipment, reagents and quality standards. Page includes online catalog. Based in Powell, Ohio, USA. AMCO Clear® is an EPA approved primary standard for calibration of turbidity sensors that is safe, nontoxic and disposable. It is easytouse with no dilution or resuspension, and it is available in a wide range of values. It is NIST traceable to particle sizedistribution and optical density, and its inherent stability means it does not settle from suspension. It has a guaranteed one year shelf life even if youve opened the bottle and happened not to have recapped it tightly. The convenient submicron polymer suspensions are nontoxic primary calibration standards approved by the US EPA for drinking water analysis for turbidity, and preferred by the U. S. Geological Survey for turbidity and sediment transport analysis.

Website: http://www.amcoclear.com/