Reagents, methods, and kits for assaying enzymes associated with lysosomal storage diseases MPS-I, MPS-II, MPS-IIIA, MPS-IIIB, MPS-IV A, MPS-VI, and MPS VII. In one aspect, the invention provides methods for assaying one or more enzymes associated with a lysosomal storage disease. In a first embodiment, the method includes: (a) contacting a sample with a first solution to provide a solution comprising one or more lysosomal enzymes； (b) contacting the one or more lysosomal enzymes in solution with an enzyme substrate for each lysosomal enzyme to be analyzed and incubating the substrates with the enzymes for a time sufficient to provide a solution comprising an enzyme product for each lysosomal enzyme present in the sample.
