Abstract: Provided is a test system, a test method and a test kit based on a test medium comprising Bromothymol Blue or a structurally related indicator.

Abstract: The present invention provides a method for determining the presence or absence of an antibiotic in a fluid comprising: (a) contacting a fluid sample with a test medium comprising a test microorganism and at least one indicator; (b) incubating the test microorganism with the fluid under conditions whereby growth of the test microorganism occurs if no antibiotic is present in the fluid sample; and (c) detecting any growth or inhibition of growth of the test microorganism as appropriate by means of an indicator, characterized in that the ratio of the volume of said fluid sample to the volume of test medium exceeds 2:3 (0.68:1) (v/v).

Abstract: Detection arrangement and method for detecting presence of a residue in a sample by determining color values of the sample, associated with the L*a*b color model, where a value of a composite parameter Z is calculated as follows: Z=wL+waa+wbb where wL, wa, and wb are weighting factors having a value depending on said residue and said sample, and a determination is made whether or not said sample comprises more or less than a predetermined amount of said residue in dependence on said value of said composite parameter Z. In a preferred embodiment, the arrangement is used to detect antibiotic residues, e.g. penicillin-G, in food products, e.g. milk, or body fluids, e.g. blood, urine.