(1188) An Alternative Miniaturized Chromatography System to Evaluate the Radiochemical Purity of technetium-99m Labeled Red Blood Cells

Objectives: Verifying the radiochemical purity (RCP) of radiopharmaceuticals before administration is described as the minimum standard in the USP General Chapter < 825>. The current RCP system for technetium-99m labeled red blood cells (Ultratag® Curium) consists of using a centrifuge. Because a centrifuge is not equipment normally found in a nuclear medicine department or nuclear physician’s office, our facility evaluated a miniaturized chromatography system (MCS) system using silica gel solid phase (ITLC-SG) and acetone as the mobile phase.

Methods: Technetium-99m labeled red blood cells (Tc99m-RBCs) radiolabeling process: in a laboratory setting, whole blood will be collected using heparin at 20 units/mL of blood as an anticoagulant. Using a large-bore needle, 2 mL of anticoagulated whole blood will be added to a sterile pyrogen-free evacuated vial, referred to as a reaction vial. Approximately 200 mcg of stannous chloride, USP will be added to the reaction vial and allowed to react for 5 minutes. At 5 minutes, a 0.1% solution of sterile sodium hypochlorite will be added to the reaction vial and mixed gently while inverting. Next, 5 to 10 mCi of Tc99m sodium pertechnetate will be added and allowed to react for 20 minutes. The RCP will be evaluated by comparing the Ultratag® centrifuge RCP method to the alternative miniaturized chromatography system (MCS) using the solvent acetone with ITLC-SG. Radiochromatography patterns for 99mTc-RBC and 99mTcO4- will be obtained using a Bioscan detector with the alternative method (1 cm x 7 cm ITLC-SG) following strip development. Rf value for each component will be calculated. Ten preparations of Tc99m-RBCs (with RCPs ranging from 5% to 99%) will be assessed using the Ultratag® centrifuge RCP and the alternative ITLC-SG method simultaneously. For each evaluation, triplicate samples will be analyzed and the data statistically summarized.

Results: Project is in progress. Rf and correlation between the RCP values obtained by the standard centrifuge system and the alternative ITLC-SG method is to be determined.

Conclusions: Project is in progress. The alternative MCS using ITLC-SG which is a smaller, less expensive method, if shown to be statistically comparable to the current system using a centrifuge, will enable every department preparing Tc99m-RBCs to meet USP minimal standards.