FAQ: “… I just need to find a way to better condition the samples for consistency. I can get some pretty consistent results on my own, but once it’s in a general QC lab, it’s going to need some standardization.”
These APHA/Pt-Co/Hazen liquid color standards were originally developed as references for visual APHA/Pt-Co/Hazen Color comparison to samples. Their role with instrumental APHA/Pt-Co/Hazen Color measurement is primarily as a performance qualification check of the instrument prior to measuring liquid product samples, or to validate the instrumental-to-visual correlation.
HunterLab instruments have their own internal diagnostic standards to verify instrument performance. Measurement verification on these liquid color standards serves as an application diagnostic, affirming that the instrument has been configured correctly and is reading APHA/Pt-Co/Hazen color in the range of the samples closely and consistently over time.
There are many suppliers of APHA/Pt-Co/Hazen liquid color standards. Just make sure that their liquid color standards conform to ASTM D1209. Also some APHA/Pt-Co/Hazen color standards come in a small volumes sealed in glass intended for visual comparison purposes rather than instrumental measurement.
Typically a client orders a Platinum Cobalt 500 Color Standard and mixes it down to intermediate levels such as an APHA/Pt-Co/Hazen 30 that are close to the product color.
While there are other industry test methods that reference the Platinum Cobalt 500 Color Standard Solution, also known as APHA/Pt-Co/Hazen Color Standard, preparation of the liquid standard is best defined in ASTM D1209 Standard Test Method for Color of Clear Liquids (Platinum Cobalt Scale). Instruction for preparing intermediate APHA/Pt-Co/Hazen standards below 500 by dilution is found in ASTM D1209 Table 1. This method also provides advice on how best to perform visual comparisons to these liquid color standards.
Sources for Liquid APHA/Pt-Co/Hazen Color Standards
Ricca Chemical Company, Arlington, TX 76094 USA +817-461-5601 www.riccachemical.com can be ordered through Fisher Scientific www.fishersci.com with worldwide distribution (search under Analytical Reagents for “Color Standard APHA/Hazen” conforming to ASTM D1209).
RICCA manufactures the liquid APHA/Pt-Co/Hazen 500 Color Standard, as will also prepare the intermediate standards, and certify them. They also sell a liquid APHA/Pt-Co/Hazen 1000 Color Standard for rare cases where the product color exceeds 500.
Fluka sells the 500 Color Standard along with sets (2 ml and 10ml) for 20 different intermediate APHA/Pt-Co/Hazen standards, sealed in vials and intended for visual comparison.
Paragon is a European supplier of APHA/Pt-Co/Hazen color standards (fixed 5, 10. 15, 30, 50, 100, 500 color standards only with certification). Please note that Paragon offers an APHA/Pt-Co/Hazen color standard that represents 0. As this is just certified distilled water, purchase is not recommended.
Reagecon is a European supplier of APHA/Pt-Co/Hazen, Gardner, Saybolt and ASTM D1500 liquid color standards in accordance with ASTM D1209, ASTM D6166 and ASTM D6045 methods.
Hach bought Dr. Lange (Germany) and with it got their LICO color measurement instruments that include measuring APHA/Pt-Co/Hazen and Gardner Color. Dr. Lange also had a side business of supplying liquid color standards for instrument performance qualification. Hach UK has picked this business up in Europe.
The ADDISTA Colour Set of 6 certified standard colour solutions for LICO (LZM282 consists of 3×50 ml APHA/Pt-Co/Hazen liquid color standards (levels of 20, 100, 200) and 3×50 ml Gardner liquid color standards (levels of 2, 5, 8).
Our EasyMatch QC software has a built-in 10 mm correlation for measuring both APHA/Pt-Co/Hazen and Gardner Color simultaneously on the same sample with the 10 mm cell path length filled with distilled water being APHA/Pt-Co/Hazen and Gardner = 0, representing no color.
There are no physical liquid standards specifically designed to verify the Yellowness Index of liquid samples over time. Yellowness Index is defined as a mathematical function such that a perfect clear of 100% transmission, typically represented by the transmission cell filled with DI water, will have a YI value of 0.
However, a good workaround solution is to use a very stable APHA/Pt-Co liquid standard in the yellowness range of your product as an application diagnostic to monitor your liquid measurement over time. Continue reading
Presses used for molding plastic plaques and sheets from pellets typically have heating/cooling platens and a programmable controller. Continue reading
The original references were written by Allen Hazen, a chemist who first defined APHA/Pt-Co/Hazen color scale for the evaluation of water quality on behalf of the American Public Health Association:
Hazen, A. A new color standard for natural waters, American Chemist Journal (14:300), 1892.
Hazen, A. The measurement of the colors of natural waters, American Chemist Journal (18:264), 1896.
Industrial Test Methods referencing the Hazen Color Scale
ISO 2211:1973 Liquid chemical products – Measurement of colour in Hazen units (platinum cobalt scale) is an ISO method that references both Hazen and platinum cobalt color and was subsequently replaced by DIN EN ISO 6271.
“APHA” stands for American Public Health Association Color Scale, the organization responsible for the original definition and implementation of this visual color scale as a standard method for rating water quality. Continue reading
FAQ: ” We are currently using a 10 mm path length and read in the 0 – 50 region for APHA/Pt-Co/Hazen Color, usually in the area of 10. Would you recommend a 10 mm path length with our equipment for this application?” Continue reading
When used with industrial and commercial products, there is more than one definition of “opacity” as an optical property.