HPLC, Biogenic Amine Determination, Amino Acid Determination, EIA, RIA, Catecholamines, Acetylcholine, Placental Transfer. As manager of the Center's Neurochemistry Core, directed by Randy Blakely, Ph.D., Ray Johnson brings more than 30 years' experience at Vanderbilt. He works with Center investigators to review experimental needs and to establish protocols to provide rapid and reliable assay results.