Butyrylcholinesterase BuChE EC 3.1.1.8., 10–20 U mg , Pseudocholinesterase, from horse serum , Bovine serum albumin BSA , trichlorfon, butyrylcholine chloride and PAM-2 pyridine-2-aldoxime methiodide were pur chased from Sigma France . PVA-SbQ SPP-H-13 was given kindly as gift by Toyo Gosei Kogyo Japan . 25% V rV glutaraldehyde GA solution was from Fluka Buchs, . Switzerland . All of the other reagents were of analytical grade.