To surely prevent the generation of a precipitate in a level vial, by letting chemical species capable of forming metallic ions and complex ions contained in a sealed solution.
Approximately 1-10mmol of EDTA.2Na (ethylenediaminetetraacetic acid.disodium salt) which is one of representative chemical species of ligands forming lead ions (Pb+ and Pb2+) and complex ions is added to a sealed solution 13. A glass tube 11 of a level vial 10 has lead ions as a component and therefore lead ions are deposited in the sealed solution. However, the reaction actually does not proceed because of an intensity relation of iodine ions I- and ligands based on the ligand field theory, so that the deposition of lead iodide is prevented. The deposition of lead iodide in the vial 10 is thus prevented, whereby the function as a level vial is not damaged. The lead iodide never erroneously elute from the vial 10. The precipitation of lead affecting human bodies is accordingly restricted.
YAMAZAKI NAOJI
HORIUCHI TADAHIKO
ISONO MASARU
