Patent ID: 8617907

Claim:
A method for determining the presence or amount of a silver-labelled species in a sample, the method comprising: applying the sample to a test device in a dry state, the test device comprising dried reagents; causing the metal of the silver-labelled species in the sample to form a soluble electrochemically-active complex which is stable relative to moieties present or potentially present in the sample which moieties will form an insoluble and/or electrochemically-inactive complex with the silver, wherein the electrochemically-active complex is formed by oxidising the silver to form a silver ion and reacting the silver ion with a complexing agent according to the following reaction: Ag + +m(NH4) + +n(SCN) âˆ’ â†’[Ag(NH4) + m(SCN âˆ’ )n] m-n+1 ; and electrochemically measuring the formed complex to provide an indication of the presence or amount of the silver-labelled species.