Ethylenediaminetetraacetate (EDTA) is commonly used as an anticoagulant in blood-collection procedures. In this experiment for the instrumental analysis laboratory, students determine the quantity of EDTA in commercial collection tubes by coulometric titration with electrolytically generated Cu[superscript 2+]. The endpoint is detected spectrophotometrically using a UV-vis spectrophotometer equipped with a fiber optic probe. Students gain experience with two instrumental methods and learn about a practical application of complexation chemistry. (Contains 1 table and 1 figure.)