Study of the peak splitting in an alternative method for the radiochemical purity measurement of 99mTechnetium-sestamibi

One of the alternative methods for the measurement of radiochemical purity (RCP) of 99mTechnetium-sestamibi uses Whatman 3MM paper as the stationary phase and ethyl acetate as the mobile phase. However, alternative method shows peak splitting and shouldering of the radiopharmaceutical. This could be