The HANNA chloride test kit  is quick, easy to use and portable. The design makes the kit easy to handle and, except for mercuric nitrate solution, practically prevents accidental injury or damage due to spills.  The pH is lowered to approximately 3 by addition of nitric acid. Mercuric ions react with chloride ions to form mercuric chloride; when excess mercuric ions is present, it complexes with diphenylcarbazone to form a purple solution. The color change from yellow to purple determines the end point of this titration.