A highly pure 2,4,4,6-tetrabromo-2,5-cyclohexadienone has been prepared in a single pot, eco-friendly procedure in yields of 91-94% from phenol. The longitudinal direction of each finger is orthogonal to the axis of symmetry. The presence of a positive value for the second metric is then used to determine that the first metric is inaccurate or unreliable, after which the first metric may be discarded; otherwise, the first metric is considered accurate. A retractable insertion sheath is provided for covering the transfer needle and the catch needle when the device is inserted into a procedural site.