A composition comprising an isolated antibody or a binding fragment thereof, which binds to quetiapine, the isolated antibody or a binding fragment thereof comprising: a) a light chain CDR1 sequence comprising amino acid residues 43 to 58 of SEQ ID NO:19, a light chain CDR2 sequence comprising amino acid residues 74 to 80 of SEQ ID NO:19, a light chain CDR3 sequence comprising amino acid residues 113 to 121 of SEQ ID NO:19, a heavy chain CDR1 sequence comprising amino acid residues 45 to 54 of SEQ ID NO:20, a heavy chain CDR2 sequence comprising amino acid residues 69 to 85 of SEQ ID NO:20, and a heavy chain CDR3 sequence comprising amino acid residues 118 to 129 of SEQ ID NO:20; b) a light chain CDR1 sequence comprising amino acid residues 43 to 58 of SEQ ID NO:23, a light chain CDR2 sequence comprising amino acid residues 74 to 80 of SEQ ID NO:23, a light chain CDR3 sequence comprising amino acid residues 113 to 121 of SEQ ID NO:23, a heavy chain CDR1 sequence comprising amino acid residues 45 to 54 of SEQ ID NO:24, a heavy chain CDR2 sequence comprising amino acid residues 69 to 85 of SEQ ID NO:24, and a heavy chain CDR3 sequence comprising amino acid residues 123 to 129 of SEQ ID NO:24; or c) a light chain CDR1 sequence comprising amino acid residues 43 to 58 of SEQ ID NO:27, a light chain CDR2 sequence comprising amino acid residues 74 to 80 of SEQ ID NO:27, a light chain CDR3 sequence comprising amino acid residues 113 to 121 of SEQ ID NO:27, a heavy chain CDR1 sequence comprising amino acid residues 45 to 54 of SEQ ID NO:28, a heavy chain CDR2 sequence comprising amino acid residues 69 to 85 of SEQ ID NO:28, and a heavy chain CDR3 sequence comprising amino acid residues 123 to 129 of SEQ ID NO:28. a) a light chain CDR1 sequence comprising amino acid residues 43 to 58 of SEQ ID NO:19, a light chain CDR2 sequence comprising amino acid residues 74 to 80 of SEQ ID NO:19, a light chain CDR3 sequence comprising amino acid residues 113 to 121 of SEQ ID NO:19, a heavy chain CDR1 sequence comprising amino acid residues 45 to 54 of SEQ ID NO:20, a heavy chain CDR2 sequence comprising amino acid residues 69 to 85 of SEQ ID NO:20, and a heavy chain CDR3 sequence comprising amino acid residues 118 to 129 of SEQ ID NO:20; b) a light chain CDR1 sequence comprising amino acid residues 43 to 58 of SEQ ID NO:23, a light chain CDR2 sequence comprising amino acid residues 74 to 80 of SEQ ID NO:23, a light chain CDR3 sequence comprising amino acid residues 113 to 121 of SEQ ID NO:23, a heavy chain CDR1 sequence comprising amino acid residues 45 to 54 of SEQ ID NO:24, a heavy chain CDR2 sequence comprising amino acid residues 69 to 85 of SEQ ID NO:24, and a heavy chain CDR3 sequence comprising amino acid residues 123 to 129 of SEQ ID NO:24; or c) a light chain CDR1 sequence comprising amino acid residues 43 to 58 of SEQ ID NO:27, a light chain CDR2 sequence comprising amino acid residues 74 to 80 of SEQ ID NO:27, a light chain CDR3 sequence comprising amino acid residues 113 to 121 of SEQ ID NO:27, a heavy chain CDR1 sequence comprising amino acid residues 45 to 54 of SEQ ID NO:28, a heavy chain CDR2 sequence comprising amino acid residues 69 to 85 of SEQ ID NO:28, and a heavy chain CDR3 sequence comprising amino acid residues 123 to 129 of SEQ ID NO:28.