The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 03, 1980
Filed:
Sep. 28, 1978
Sharon S Sloat, Urbandale, IA (US);
HACH Chemical Company, Ames, IA (US);
Abstract
A liquid sample is prepared for measurement of its calcium plus magnesium hardness by adding to the sample an aluminum chelate, preferably aluminum disodium (cyclohexylenedinitrilo) tetra-acetic acid, while maintaining the pH of the sample in the range between about 5 and 8. Interference by iron or copper ions is thereby substantially eliminated without using poisonous substances. The pH of the sample is then raised to between about 9.5 and 11 to insolubilize aluminum ions; a magnesium chelate is added to exchange calcium ions, releasing an equivalent number of magnesium ions; and a dye indicator that forms a colored complex with magnesium ions is added. The calcium plus magnesium hardness is then measured by titration or spectrophotometrically.