| abstract |
A leuco-type color source-containing aqueous solution, wherein a leuco-type color source-containing aqueous solution has at least one substituent selected from the group consisting of nitroso groups and azo groups, and further has a compound having a metal ion coordination ability or a salt thereof. Preservation method; A leuco-type color source, which has a leuco-type color source, coexists in the aqueous solution containing the compound which has at least 1 substituent chosen from the group which consists of a nitroso group, and an azo group, and its metal ion coordination ability, or its salt. Stabilization method; A liquid reagent comprising a leuco-like color source, at least one substituent selected from the group consisting of nitroso groups and azo groups, and a compound having a metal ion coordination ability or a salt thereof. |