A reagent supply apparatus and a microfluidic device comprising a fluid processing area and a slot (110, 230) provided in a body portion of the microfluidic device for receiving the reagent supply apparatus therein, said microfluidic device comprising openings (116, 117) in the body portion for exposing the reagent supply apparatus at locations (11, 13) thereof which coincide with said openings (116, 117), the microfluidic device further comprising a pipetting nozzle having a liquid dispensing end and an array of inlets each of which are in fluid communication with the fluid processing area, wherein said pipetting nozzle is moveable vertically so that the liquid dispensing end is adjacent to or in contact with a solid support, or reagent thereon, and wherein the pipetting nozzle is further horizontally moveable so as to overly respective inlets in turn; and wherein said reagent supply apparatus comprises: the solid support formed from a material being non-soluble; at least one dry reagent stored on a surface of the support at a reagent location or locations; wherein said support material is sufficiently porous to allow liquid flow through the material of the solid support from the surface on which said reagent is stored to an opposite side of the support, the support being configured to filter liquid containing dissolved or suspended reagent as the liquid flows through the solid support into the fluid processing area of the microfluidic device, and being further configured to filter liquid containing a biological sample, the support being fibrous and its surface being impregnated with chemicals, said chemicals including a weak base, a chelating agent, an anionic surfactant, and/or a chaotropic agent, and being configured for storing the biological sample in a dry state at a sample location or locations, spaced from the reagent location or locations, wherein the biological sample comprises or consists of i) endogenous moieties; ii) biopharmaceutical or biotech drugs or other pharmaceutical agents; (iii) nucleic acids; (iv) peptides, proteins or antibodies; v) cells or tissue, comprising or consisting of dried: blood; blood plasma, or other blood components; urine; cerebral culture media; cell samples; cell culture; or tissue exudate. the solid support formed from a material being non-soluble; at least one dry reagent stored on a surface of the support at a reagent location or locations; wherein said support material is sufficiently porous to allow liquid flow through the material of the solid support from the surface on which said reagent is stored to an opposite side of the support, the support being configured to filter liquid containing dissolved or suspended reagent as the liquid flows through the solid support into the fluid processing area of the microfluidic device, and being further configured to filter liquid containing a biological sample, the support being fibrous and its surface being impregnated with chemicals, said chemicals including a weak base, a chelating agent, an anionic surfactant, and/or a chaotropic agent, and being configured for storing the biological sample in a dry state at a sample location or locations, spaced from the reagent location or locations, wherein the biological sample comprises or consists of i) endogenous moieties; ii) biopharmaceutical or biotech drugs or other pharmaceutical agents; (iii) nucleic acids; (iv) peptides, proteins or antibodies; v) cells or tissue, comprising or consisting of dried: blood; blood plasma, or other blood components; urine; cerebral culture media; cell samples; cell culture; or tissue exudate.