A method was developed for determination of Cu(II) ions quantitatively by measuring fluorescent intensity of pheophytin-a (Pheoa) solution. The Pheoa was obtained by de-intercalation of magnesium from the porphyrin ring of chlorophyll-a (Chla) extracted from fresh spinach leaves. Its two UV-Vis absorption peaks at 505 and 535 nm in acetone solution have been observed but disappeared when the acetone solution of Pheoa was mixed with a Cu(II) ion aqueous solution. A fluorescence quenching phenomen
