A method for detecting at least two different non-nucleic acid analytes in a sample, the method comprising: providing to a reaction vessel: (i) at least one solid substrate comprising one or more immobilisation agents, wherein the substrate comprises a plastic surface or a hydrophobic surface; (ii) the sample; (iii) at least two different capture agents that bind to at least two different analytes and the at least two different capture agents can be immobilised on the at least one solid substrate, wherein the at least two different capture agents comprise an antibody; (iv) at least two different detectable agents that bind to the at least two different analytes, wherein the at least two different detectable agents comprise an antibody; and detecting the at least two different analytes in the sample by detecting the presence of the at least two different analytes bound to the at least one solid substrate, wherein the detecting of the at least two different analytes comprises no washing of the at least one solid substrate after contacting of the at least one solid substrate with the sample, one or more of the at least two different capture agents and one or more of the at least two different detectable agents; wherein the one or more immobilisation agents is passively bound to the at least one solid substrate; wherein one or more of the at least two different capture agents comprises a ligand for the one or more immobilisation agents, wherein the ligand is bound to one or more of the at least two different capture agents; wherein the ligand and one of the one or more immobilisation agents are a binding pair comprising a peptide-tag and an anti-peptide antibody; and wherein the at least two different analytes are detected simultaneously, wherein one or more of the at least two different analytes are selected from the group consisting of a protein, a component of a cell signaling pathway, a cytokine, a tumour suppressor, or an antibody. providing to a reaction vessel: (i) at least one solid substrate comprising one or more immobilisation agents, wherein the substrate comprises a plastic surface or a hydrophobic surface; (ii) the sample; (iii) at least two different capture agents that bind to at least two different analytes and the at least two different capture agents can be immobilised on the at least one solid substrate, wherein the at least two different capture agents comprise an antibody; (iv) at least two different detectable agents that bind to the at least two different analytes, wherein the at least two different detectable agents comprise an antibody; and (i) at least one solid substrate comprising one or more immobilisation agents, wherein the substrate comprises a plastic surface or a hydrophobic surface; (ii) the sample; (iii) at least two different capture agents that bind to at least two different analytes and the at least two different capture agents can be immobilised on the at least one solid substrate, wherein the at least two different capture agents comprise an antibody; (iv) at least two different detectable agents that bind to the at least two different analytes, wherein the at least two different detectable agents comprise an antibody; and detecting the at least two different analytes in the sample by detecting the presence of the at least two different analytes bound to the at least one solid substrate, wherein the detecting of the at least two different analytes comprises no washing of the at least one solid substrate after contacting of the at least one solid substrate with the sample, one or more of the at least two different capture agents and one or more of the at least two different detectable agents; wherein the one or more immobilisation agents is passively bound to the at least one solid substrate; wherein one or more of the at least two different capture agents comprises a ligand for the one or more immobilisation agents, wherein the ligand is bound to one or more of the at least two different capture agents; wherein the ligand and one of the one or more immobilisation agents are a binding pair comprising a peptide-tag and an anti-peptide antibody; and wherein the at least two different analytes are detected simultaneously, wherein one or more of the at least two different analytes are selected from the group consisting of a protein, a component of a cell signaling pathway, a cytokine, a tumour suppressor, or an antibody. wherein the one or more immobilisation agents is passively bound to the at least one solid substrate; wherein one or more of the at least two different capture agents comprises a ligand for the one or more immobilisation agents, wherein the ligand is bound to one or more of the at least two different capture agents; wherein the ligand and one of the one or more immobilisation agents are a binding pair comprising a peptide-tag and an anti-peptide antibody; and wherein the at least two different analytes are detected simultaneously, wherein one or more of the at least two different analytes are selected from the group consisting of a protein, a component of a cell signaling pathway, a cytokine, a tumour suppressor, or an antibody.