Patent ID: 7288414

Claim:
A diagnostic reagent kit useful for the measurement of calcium, comprising: a) a compound of formula I: wherein R 1, R 2, R 3, R 4, R 5, R 6, R 7, and R 8 are selected from the group consisting of H, C 1-6 alkyls, C 1-6 etheralkyls, C 1-6 branched alkyls, C 3-8 cycloalkyls and halogens; b) one or more magnesium chelating agents selected from the group consisting of malonic acid, malonic acid salt, oxalic acid, oxalic acid salt, succinic acid, 8-hydroxyquinoline, phthalic acid, tartaric acid and phenylphosphonic acid; and c) a buffer selected from the group consisting of malonate, BES, DIPSO, MES, MOPS, MOPSO, BIS-TRIS, Imidazole, TES, ADA, ACES and TAPSO.