Abstract: There is disclosed a lateral flow assay device and method of producing the same. The device, which is for identifying carbohydrate antigens in a biological sample comprises a substrate having, a) a sample receiving zone, b) an extraction zone for receiving the sample from said sample receiving zone and which extraction zone comprises immobilised or otherwise absorbed therein at least one or more reactants and reagents which when combined react to form an extraction reagent for a desired antigen in said sample, said sample to be added to said sample receiving zone optionally comprising the remaining reactant required to form said extraction reagent if not present in said extraction zone, c) optionally a neutralising agent capable of bringing the pH of the resulting sample to within the operational pH range of the assay and, d) a detection zone for a labelled specific binding or capture reagent for said antigen to be detected.