Estimation of protochlorophyll(ide) contents in plant extracts; re-evaluation of the molar absorption coefficient of protochlorophyll(ide).

In an attempt to solve the controversy about the evaluation of the molar absorption coefficient of PChl(ide), this coefficient is estimated in this work by using an original experimental approach. The calculated molar absorption coefficient of PChl(ide) is 30.4.10(3) 1 mole(-1) cm(-1) at 626 nm in acetone 80%; it is close to that derived from the specific absorption coefficient of Koski and Smith when assuming that the pigment extracted by these authors was the esterified pigment: PChl. Sets of equations for the quantification of Chl(ide) a, Chl b and PChl(ide) in 80% acetone extracts are derived.