The certified value and uncertainty were based on the analytical results of eight labs by non-dispersive infra-red method. 其标准值和不确定度由多家实验室用非分散红外法进行分析测定，并经数理统计处理后确定的。
Method to check whether a particular value can be added to the standard values collection. 方法以检查某个特定值是否可以添加到标准值集合中。
