A milking system including a milking means, a milk line, and a sampling and analysis device, that includes an analysis tape, with a carrier layer and a reagent tape layer with a reagent that provides a detectable response in the presence of a substance in the sample, a dosing device, an optical radiation source, and an optical sensor device to detect optical response radiation emitted by the reagent tape layer and to analyse the detected optical response radiation to provide an indication of a presence or concentration of the substance in the droplet. The reagent tape layer includes, or is, a material with an asymmetrical porosity, having the largest pore size at a first side where the sample is provided, and the smallest pore size at the opposite side.