Colloidal particle-size determination by gel filtration.

The particle sizes of technetium-99m sulfur colloid and technetium-99m antimony sulfide colloid are determined by gel filtration. These results are compared with those obtained by electron microscopy and by ultrafiltration. It is shown that gel filtration is suitable for particle-size determination below 100 nm, whereas above this size ultrafiltration provides the most convenient method.