Abstract: Compositions and methods are provided for determining thiols or disulphides in which a sulfur containing analyte is combined with a thiol-specific reagent to produce an intermediate, and the intermediate is combined with a solvent insoluble compound to produce a solid state complex. In one aspect of preferred embodiments the intermediate comprises a chromophore, and in especially preferred embodiments the chromophore is detectable with the naked eye. In another aspect of preferred embodiments the thiol-specific reagent comprises a nitroso-donor, and more preferably Na-nitroprusside. In yet another aspect of preferred embodiments, the solvent insoluble compound comprises a basic or acidic metallic compound, or a polymeric matrix. Still more preferred solvent insoluble compounds comprise Zn-hydroxide, Ni-hydroxide or Al-hydroxide. These compositions and methods are more sensitive and reliable method than that previously available, especially for the determination of homocysteine.