Abstract
The investigation has been carried out to find a proper sample preparation and a proper standard material for accurate determination of oxygen in organic substances by fast neutron activation analysis, wherein a serious systematic error due to Q-ray self-absorption is always in problem. It was confirmed from the present work that the error mainly depended on the difference in density between a sample and a standard material and that it was effectively eliminated by using a mixture of stearic acid and solid paraffin as a standard and also diluting the sample with solid paraffin. For most of organic samples, eight times dilution was found to be enough to lower the relative systematic error down to 2%.
