Abstract
Because the carbon and nitrogen content of soil and organic matter using SUMIGRAPH (NC-22F, Sumika Chemical Analysis Service) was underestimated by the prescribed method, we clarified the reason and the solution. Incomplete combustion occurred when the amount of introduced sample of soil and organic matter was large, and this resulted in underestimation. Increasing the burning time could solve this problem. From these results, it is possible to perform appropriate analysis by setting the sample weight and burning time (PUMP) within the following range when using this device:
1) For PUMP as 60 seconds→Upper limit of weighing: A layer sample 50 mg, B layer and below sample 100 mg, organic matter 20 mg
2) For PUMP as 120 seconds→Upper limit of weighing: A layer sample 100 mg, B layer and below sample 200 mg, organic matter 20 mg
In order to make sure the sample perfectly burned, it is recommended to check the residual in the quartz cell. The analytical error among the three organizations was small, this result indicating that the analytical error due to the difference in equipment was small.
