Disclosed is a method of detecting the presence of a compound of interest (such as an enzyme), or the spatial distribution within a sample of a compound of interest. The method comprises the step of impregnating or coating a suitable base material with a marker substance capable of reacting or interacting with the compound of interest, the marker substance being labelled in a detectable manner (for example fluorescently, radioactively or being coloured) and having a substantially different affinity for the base material than the product of the reaction or interaction thereof with the compound of interest. The method further comprises the steps of bringing the impregnated base material into contact with the sample under test, to permit the labelled marker substance to react or interact with any target compound present in the sample, removing either unreacted labelled marker substance or labelled reacted product with a suitable solvent, and detecting the presence of labelled marker substance remaining on said base material, or detecting the liberation of labelled reacted product from said base material, to give an indication of the presence or absence of the compound of interest. The marker substance may be an oligosaccharide, oligosaccharidyl-1-amino-1-deoxy-alditols (OADs) being particularly preferred. A method of manufacturing OADs is also disclosed.