1984 Volume 33 Issue 9 Pages T77-T80
Cross check tests were carried out by the members of Association for Environmental Analysis in Osaka, Japan for the purpose of comparison of analytical methods of nitrate and nitrite, ammonia, organic and total nitrogens in environmental water samples. Twenty of authentic samples were prepared, some of them were synthesized by mixing the standard solutions and spiking the standards to natural waters. Eight samples were used for the determination of nitrate and nitrite, four for ammonia and eight for organic and total nitrogens. These samples were distributed to 53 laboratories and the results were compared with respect to mean values, relative standard deviations and accuracy. The following results were obtained by these cross check tests. (1) Good results on nitrate were obtained when the copper-cadmium column reduction method was adopted. However, samples should be diluted before the reduction when they might contain a considerable amount of foreign substances like as silicate. (2) Accurate and precise analytical results were obtained for nitrite and ammonia. Higher results, however, were obtained when the calibration curve was made after the distillation of ammonia. (3) The results on organic nitrogen diversed due to variation in the recovery of nitrogen compounds from their rate of digestion. The satisfied results were obtained when commercial total nitrogen analyzers were used.
