Patent ID: 7885767

Claim:
A method to quantify an initial population of nucleic acids in a sample of interest subjected to a population amplification reaction comprising a succession of repeated amplification cycles, the method comprising performing by means of an apparatus experimental measurements representative of a current size of the population of the sample of interest during the repeated amplification cycles and further comprising the following steps: a) providing a model of the yield of the amplification reaction, this model corresponding to the variation of the yield in function of the number of amplification cycles and being represented by a curve having: a first constant portion corresponding to a first part of the succession of repeated amplification cycles; a second non-constant portion corresponding to a second part of the succession of repeated amplification cycles; and a changeover region uniting the first and second portions of the curve, said region having a changeover index C equal to a corresponding number of amplification cycles; b) determining a relationship between the changeover index C EEP and a parameter No representative of the initial population size in the sample of interest from the following formula: N n+1 =N 0 ×(1 +E 0 ) C EEP ×function( C EEP ,n+ 1) where N n+1 is a parameter representative of the population size at the current amplification index, E 0 is the value of the yield at the first constant portion of the yield model, the term function (C EEP , n+1) is a particular function characterizing the second non-constant portion of the yield model and that depends at least on the changeover index C EEP and on the current amplification index n+1, and (C EEP −1) is the last index of the amplification reaction during which the yield is still constant; and c) determining an experimental variation of the yield and a changeover index value from the experimental measurements performed by said apparatus during the repeated amplification cycles, and d) determining the initial population size in the sample of interest from the changeover index value by means of the relationship between the changeover index and the said parameter representative of the initial population size.