| The determination of urea in sea water was performed by an automated method based on the reaction of urea with diacetyl-monoxime. The sensitivity, which has been greatly enhanced compared to previous methods, by using reagents containing thiosemicarbazide and iron III, is 0.044 absorbance units/ g-at urea-N/L with the 50 mm flow cell. The precision is 0.01 g-at urea-N/L and the limit of detection (2 SD) is 0.02 g-at urea-N/L. The absorbance-concentration relationship is linear up to 15 g-at urea-N/L. The analytical blanks have been strictly determined and the interferences studied. Citrulline is the main compound that interferes. However, in attempting to remove this compound from the samples by a chelating resin. we demonstrated its absence from... |
