APHA Color #3020
Measurement of APHA color either on-line or in a laboratory setting using a photometer. Background: APHA is sometimes referred to as the Platinum Cobalt (Pt/Co) or Hazen scale. Also referred to as a “yellowness index”, the APHA color scale is a common method of comparison of the intensity of yellow-tinted samples to assess the quality of liquids that are clear to yellowish in color. Originally developed to determine the purity of municipal water supplies, it is now used as a metric for purity in the water, chemical, oil, plastics, and pharmaceutical industries. APHA color quantifies the appearance of trace amounts of yellowness, which is a visual indicator of product degradation due to exposure to light or heat; the presence of impurities and negative effects of processing. As such APHA color is often used as a product release specification. APHA is a single number yellowness index. The units are based on a dilution of a 500ppm solution of PtCo.