Method for estimating an amount of analyte in a fluid

A method for estimating an amount of an analyte in a fluid sample containing particles, the method including the following steps:

• a) mixing the sample with a first reagent able to form a color indicator in the presence of said analyte, in the sample,
• b) following this mixing, illuminating the sample using a light source able to emit light toward the sample,
• c) acquiring, using an image sensor, an image of light transmitted or reflected by the sample,
• d) estimating, depending on said image, an amount of said analyte, by way of the following substeps:
• i) selecting a measuring zone in said image, said measuring zone comprising a plurality of pixels,
• ii) determining, inside the measuring zone, a region of interest and at least one region of exclusion,
• iii) estimating the amount of analyte from a quantity representative of the intensity of the pixels in said region of interest, without taking into account the intensity of the pixels of each region of exclusion,
• the method also including mixing the sample with a second reagent, referred to as the lysis reagent, able to lyse said particles, each region of exclusion corresponding to the trace of an air bubble, said air bubble being formed following the lysis of said particles.