Radiochemical purity and particles number determinations of modified 99mTc-macroaggregated albumin

Abstract

A new procedure for the aggregation of human albumin and 99mTc-labelling of the prepared macroaggregated albumin are presented. Simple methods for quantifying of all the radiochemical impurities existing in 99mTc-MAA were tested. Thus, 85 % methanol was used as the mobile phase in paper and ITL chromatography with Whatman N° 1 and ITLC-SA strips. A system of two solvents (acetone and 1 M NaCl or 0.9 % NaCl) was used for 3 MM paper, ITLC-SA and ITLC-SG strips and silica gel plates as the stationary phase. Low-voltage paper electrophoresis with Whatman 3 MM paper sheets soaked in barbiturate buffer and the gel chromatography column method (Sephadex G-25) were also applied. Filtration through syringe filters, proposed by European and Yugoslav Pharmacopoeia, was performed for comparison. The application of the mentioned tests lead to consistent results for the labelling efficiency (>98.5 %) and percent radiochemical impurities of 99mTc-MAA. Determination of the particles number in a counter chamber and their size distribution under a light microscope with a calibrated ocular scale gave the result of 300000-350000 particles per 1 mg of HA. This confirmed that the human albumin macroaggregates prepared by our new procedure is remarkably improved and convenient for routine diagnostic purposes.