Method for quantitative optical measurements and laboratory apparatus

The invention is related to a method for the quantitative optical measurement of a characteristic property of at least one analyte in at least one laboratory sample, in particular for the fluorescence measurement of at least one biochemical or biological sample, the method using a laboratory apparatus, which has at least one light source and at least one detector device, the apparatus utilizing at least sensitivity parameter S, which controls the capability of the laboratory apparatus to detect a signal by means of the at lest one detector device, the method using source light for causing the at least one sample to emit a sample light, and the at least one detector device for detecting sample light and utilizing the at least one sensitivity parameter S to detect the corresponding at least one intensity I of the sample light, the method comprising the steps:- determining at least one reference point (S_ref; I_ref); - using at least one first sensitivity parameter S_m1, which is not the same as S_ref, for measuring at least one first intensity I_m1 of sample light as-signed to a first analyte; -determining a quantity Q1, which is a measure for the slope of a line, which is determined by utilizing the at least one reference point (S_ref; I_ref) and the at least one measurement point (S_m1; I_m1); using the quantity Q1 for calculating a first analyte value C_m1, which is dependent on Q1 and which is characteristic for a property of the first analyte, in particular for a concentration of the first analyte in the at least one sample, in particular according to the formula Q1 = (I_m1 - I_ref) / (S_m1 - S_ref). The method, further, is related to a laboratory apparatus, which is configured to apply the method according to the invention.