The search for an 111In labeled agent for the solid component of gastric emptying

¹¹¹In-labeled solid meal was prepared by chelation of ¹¹¹In with Chelex resin bead. The effect of grinding of normal Chelex bead on ¹¹¹In chelation and retention in solid meal was evaluated in an in vitro system. The Chelex resin beads were ground in a mortar-pestle to form ground Chelex resin beads. Fine particles were removed by resuspension in distilled water and centrifugation (1000 g). One hundred to 150 μCi of ¹¹¹In chloride was diluted with 0.1 N HC1 and mixed with 1 g of Chelex resin beads. Unbound ¹¹¹In was removed by centrifugation (1000 g). The ¹¹¹In-labeled Chelex resin beads were mixed with fresh egg and ¹¹¹In-labeled solid meal was prepared by heating until solid. The meals were digested with HCl-pepsin (1.2mg/mL of pepsin in 0.1 N HC1) for 4 h in a stirrer-bath (37 °C). Aliquots were collected at intervals for determination of ¹¹¹In loss from ¹¹¹In-labeled solid meal.These results suggest that ¹¹¹In Chelex resin beads were retained in solid meals at a higher level than normal Chelex resin beads and other ¹¹¹In-tracers.