Patent ID: 6882425

Claim:
A method for measuring a concentration of hemoglobin and bilirubin in a sample of blood serum or blood plasma before analysis of said sample by an in vitro diagnostic method, in order to determine whether an amount of hemoglobin, bilirubin or lipid present in that sample can interfere with a measurement of a target analyte contained in said sample by means of said diagnostic method, said method for measuring comprising sequentially carrying out the following method steps: (a) carrying out a first method step for determining the concentration of hemoglobin in said sample, said first method step including: i) measuring a first extinction spectrum E 1 (λ) of said sample in a first selected wavelength range λ rh =λ 1,1 to λ 1,n , the contribution of bilirubin to the extinction spectrum being much smaller than the contribution of hemoglobin within the first selected wavelength range, and ii) fitting a first approximated spectrum Ē 1 (λ) to said first measured extinction spectrum E 1 (λ), said first approximated spectrum Ē 1 (λ) being a combination of: a predetermined first approximation function E d1 (λ, a 0h , a 1h ) for a background extinction, with a 0h , a 1h being coefficients, and a predetermined extinction spectrum E H (C H , λ) of pure hemoglobin having a concentration C H to be determined, said fitting of said first approximated spectrum Ē 1 (λ) to said first measured extinction spectrum E 1 (λ) being performed by varying said concentration C H of hemoglobin and said coefficients a 0h , a 1h , so that a deviation between said first measured extinction spectrum E 1 (λ) and said first approximated spectrum Ē 1 (λ) is minimized in order to determine the concentration C H of hemoglobin, and (b) carrying out a second method step for determining the concentration of bilirubin in said sample, said second method step including: i) measuring a second extinction spectrum E 2 (λ) of said sample in a second selected wavelength range λ rb =λ 2,1 to λ 2,n , ii) fitting a second approximated spectrum Ē 2 (λ) to said second measured extinction spectrum E 2 (λ), said second approximated spectrum Ē 2 (λ) being a combination of: a predetermined second approximation function E d2 (λ,a 0b , a 1b ) for a background extinction, with a 0b , a 1b being coefficients, a predetermined extinction spectrum E H (C H , λ) of hemoglobin having a concentration C H determined in said first method step, and a predetermined extinction spectrum E B (C B , λ) of pure bilirubin having a concentration C B to be determined, said fitting of said second approximated spectrum Ē 1 (λ) to said second measured extinction spectrum E 1 (λ) being performed by varying said concentration C B of bilirubin and said coefficients a 0b , a 1b , so that a deviation between said second measured extinction spectrum E 2 (λ) and said second approximated spectrum Ē 2 (λ) is minimized in order to determine the concentration C B of bilirubin.