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APHA/Hazen (Platinum-Cobalt) Color Scale

Originally created for the waste water industry, the APHA color scale has expanded to the chemical, pharmaceutical, beverage, plastic and petroleum industries. This color scale is also known as the Hazen scale as well as the PtCo scale. The APHA scale is typically used to identify purity of an end product, in many cases the goal is <10 APHA or “water white”. GFS Chemicals manufactures APHA 500 which can be diluted to create the necessary APHA values for your application. Some applications call for a visual check using sight sticks while others use UV/Vis spectrophotometers. 
Pre-made dilutions are also available upon request. 
Specification provided with all 500 APHA standards:
1. Absorbance (1 cm) @ 430 nm 0.110-0.120
2. Absorbance (1 cm) @ 455 nm 0.130-0.145
3. Absorbance (1 cm) @ 480 nm 0.105-0.120
4. Abosrbance (1 cm) @ 510 nm 0.055-0.065
The GFS Chemicals APHA standards are all NIST traceable and made with class A glassware. 
 Check out the In-Spec website for more information: or contact Rachel Stapf at or 1-800-838-5567 ext. 121.
In-Spec® is a registered trademark of GFS Chemicals