An investigation was undertaken to check the difference in isotopic content between two boron samples measured earlier in this laboratory by using different methods of sample preparation from those used in the previous investigation. Yields of preparation were measured throughout. Measurements using methyl borate and boron trifluoride indicated a difference of slightly over 2% in the isotopic content of the samples, whereas the difference found in the previous investigation was 3.5%. / Thesis / Master of Science (MS)