Ten fishmeal samples (hidden duplicates of 4 meals plus 2 high-protein meals as a Youden pair), @entity2340 , and @entity1670 were analyzed by 18 laboratories using the Dumas method. Thirteen of the laboratories also analyzed the same 12 samples using their current Kjeldahl method. Recoveries (+/-SR) of @entity2340 and @entity1670 were 99.3+/-1.04 and 98.8+/-2.11% by Dumas and 97.1+/-3.03 and 74.6+/-26.76% by Kjeldahl. The Dumas method gave significantly greater values (P < 0.001) than the Kjeldahl method. For fishmeals, Kjeldahl N = 0.989 of Dumas N (P < 0.001). A similar proportionate difference (0.984 of Dumas N) was observed with @entity2340 . Most laboratories failed to determine @entity1670 correctly by Kjeldahl. For fishmeals, the relative standard deviations for repeatability and reproducibility were for Dumas 1.48 and 2.01% and Kjeldahl 1.62 and 2.37%, respectively. A single analysis conducted in 2 laboratories should not differ by more than 5.63% of the mean value when measured by Dumas or by more than 6.64% by Kjeldahl. It is concluded that with fishmeal, Dumas gives a more reliable measure of organic @entity1568 than Kjeldahl, and, therefore, Dumas should be the method of choice.

Repeatability and reproducibility of determination of the XXXX content of fishmeal by the combustion (Dumas) method and comparison with the Kjeldahl method: interlaboratory study.

@entity2340 :: ('CHEBI:27897', 'Chemical') :: ['tryptophan'] @entity1568 :: ('MESH:D009584', 'Chemical') :: ['nitrogen'] @entity1670 :: ('MESH:D009525', 'Chemical') :: ['nicotinic acid']
@entity1568 :: (MESH:D009584,Chemical) :: ['nitrogen']
