A method for assaying enzymatic activities of nine lysosomal enzymes, comprising: (a) contacting a sample with a first solution to provide a solution comprising nine lysosomal enzymes, wherein the nine lysosomal enzymes are: α glucosidase; α galactosidase; α L iduronidase (IDUA); β glucocerebrosidase; β galactocerebrosidase (GALC); sphingomyelinase; iduronate 2-sulfatase (ID2S); N-acetylgalactosamine 6-sulfatase (GAL6S); and N-acetylgalactosamine 4-sulfatase (GAL4S); (b) adding an enzyme substrate for each lysosomal enzyme to be analyzed to the solution comprising the enzymes and incubating the substrates with the enzymes in an enzyme reaction solution for a time sufficient to provide a solution comprising an enzyme product for each lysosomal enzyme present in the sample, wherein the enzyme reaction solution comprises: (i) a metal cation effective for precipitating sulfate ions, wherein the metal cation is a Ba 2+ ion; (ii) a metal cation effective for precipitating phosphate ions, wherein the metal cation is a Ce 3+ ion; (iii)a maltase glucoamylase inhibitor, wherein the maltase glucoamylase inhibitor is acarbose; (iv)a beta-N-acetylhexosaminidase inhibitor, wherein the beta-N-acetylhexosaminidase inhibitor is 2-acetamido-2-deoxy-D-glucono-1,5-lactone; (v) one or more surfactants, and (vi) optional buffer; (c) optionally quenching the enzyme reaction; and (d) determining the quantities of the enzyme products. (a) contacting a sample with a first solution to provide a solution comprising nine lysosomal enzymes, wherein the nine lysosomal enzymes are: α glucosidase; α galactosidase; α L iduronidase (IDUA); β glucocerebrosidase; β galactocerebrosidase (GALC); sphingomyelinase; iduronate 2-sulfatase (ID2S); N-acetylgalactosamine 6-sulfatase (GAL6S); and N-acetylgalactosamine 4-sulfatase (GAL4S); α glucosidase; α galactosidase; α L iduronidase (IDUA); β glucocerebrosidase; β galactocerebrosidase (GALC); sphingomyelinase; iduronate 2-sulfatase (ID2S); N-acetylgalactosamine 6-sulfatase (GAL6S); and N-acetylgalactosamine 4-sulfatase (GAL4S); (b) adding an enzyme substrate for each lysosomal enzyme to be analyzed to the solution comprising the enzymes and incubating the substrates with the enzymes in an enzyme reaction solution for a time sufficient to provide a solution comprising an enzyme product for each lysosomal enzyme present in the sample, wherein the enzyme reaction solution comprises: (i) a metal cation effective for precipitating sulfate ions, wherein the metal cation is a Ba 2+ ion; (ii) a metal cation effective for precipitating phosphate ions, wherein the metal cation is a Ce 3+ ion; (iii)a maltase glucoamylase inhibitor, wherein the maltase glucoamylase inhibitor is acarbose; (iv)a beta-N-acetylhexosaminidase inhibitor, wherein the beta-N-acetylhexosaminidase inhibitor is 2-acetamido-2-deoxy-D-glucono-1,5-lactone; (v) one or more surfactants, and (vi) optional buffer; (i) a metal cation effective for precipitating sulfate ions, wherein the metal cation is a Ba 2+ ion; (ii) a metal cation effective for precipitating phosphate ions, wherein the metal cation is a Ce 3+ ion; (iii)a maltase glucoamylase inhibitor, wherein the maltase glucoamylase inhibitor is acarbose; (iv)a beta-N-acetylhexosaminidase inhibitor, wherein the beta-N-acetylhexosaminidase inhibitor is 2-acetamido-2-deoxy-D-glucono-1,5-lactone; (v) one or more surfactants, and (vi) optional buffer; (c) optionally quenching the enzyme reaction; and (d) determining the quantities of the enzyme products.