An in vitro method for determining of the amount of a processed Clostridial Neurotoxin polypeptide in a solution comprising processed Clostridial Neurotoxin polypeptide and partially processed and/or unprocessed Clostridial Neurotoxin polypeptide, the method comprising the steps of: a) contacting a first portion of said solution comprising processed Clostridial Neurotoxin polypeptide and partially processed and/or unprocessed Clostridial Neurotoxin polypeptide, with a first capture antibody which specifically binds to the light chain of processed, partially processed and unprocessed Clostridial Neurotoxin polypeptide under conditions which allow for binding of said first capture antibody to said light chain of processed, partially processed and unprocessed Clostridial Neurotoxin polypeptide, thus forming a first antibody complex, b) contacting said first antibody complex with a detection antibody which specifically binds to the heavy chain of said processed, unprocessed and partially processed Clostridial Neurotoxin polypeptide in the antibody complex formed in step a), whereby a first detection complex is formed, c) contacting a second portion of said solution comprising processed Clostridial Neurotoxin polypeptide and partially processed and/or unprocessed Clostridial Neurotoxin polypeptide, with a second capture antibody which specifically binds to the linker of said partially processed or unprocessed Clostridial Neurotoxin polypeptide under conditions which allow for binding of said second capture antibody to said partially processed or unprocessed Clostridial Neurotoxin polypeptide, wherein said second capture antibody specifically binds to a peptide epitope consisting of an amino acid sequence as shown in any one of SEQ ID NO: 1 to 16, thus forming a second antibody complex, d) contacting said second antibody complex with a detection antibody which is different from the detection antibody in step b) and which specifically binds to the antibody complex formed in step c), whereby a second detection complex is formed, e) determining the amount of the first detection complex formed in step b) and the amount of the second detection complex formed in step d), and f) calculating the amount of processed Clostridial Neurotoxin polypeptide, based on the amounts of the first and second detection complex determined in step e). a) contacting a first portion of said solution comprising processed Clostridial Neurotoxin polypeptide and partially processed and/or unprocessed Clostridial Neurotoxin polypeptide, with a first capture antibody which specifically binds to the light chain of processed, partially processed and unprocessed Clostridial Neurotoxin polypeptide under conditions which allow for binding of said first capture antibody to said light chain of processed, partially processed and unprocessed Clostridial Neurotoxin polypeptide, thus forming a first antibody complex, b) contacting said first antibody complex with a detection antibody which specifically binds to the heavy chain of said processed, unprocessed and partially processed Clostridial Neurotoxin polypeptide in the antibody complex formed in step a), whereby a first detection complex is formed, c) contacting a second portion of said solution comprising processed Clostridial Neurotoxin polypeptide and partially processed and/or unprocessed Clostridial Neurotoxin polypeptide, with a second capture antibody which specifically binds to the linker of said partially processed or unprocessed Clostridial Neurotoxin polypeptide under conditions which allow for binding of said second capture antibody to said partially processed or unprocessed Clostridial Neurotoxin polypeptide, wherein said second capture antibody specifically binds to a peptide epitope consisting of an amino acid sequence as shown in any one of SEQ ID NO: 1 to 16, thus forming a second antibody complex, d) contacting said second antibody complex with a detection antibody which is different from the detection antibody in step b) and which specifically binds to the antibody complex formed in step c), whereby a second detection complex is formed, e) determining the amount of the first detection complex formed in step b) and the amount of the second detection complex formed in step d), and f) calculating the amount of processed Clostridial Neurotoxin polypeptide, based on the amounts of the first and second detection complex determined in step e).