Acute metobromuron poisoning with severe associated methemoglobinemia. Identification of four metabolites in plasma and urine by LC-DAD, LC-ESI-MS, and LC-ESI-MS-MS

J Anal Toxicol. 2000 Apr;24(3):157-64. doi: 10.1093/jat/24.3.157.


A case of self poisoning with metobromuron, a urea derivative used as a herbicide, is reported. Severe methemoglobinemia observed at the admission (80%) disappeared only at day 11, and hemolysis appeared at day 4 and decreased slowly to day 12. Metobromuron was analyzed by liquid chromatography with diode-array detection. Initial plasma concentration and elimination half-life were 4.9 mg/L and 5 h, respectively. Several metabolites were also detected, and four of those were identified by liquid chromatography-electrospray mass spectrometry. Normetobromuron, bromophenylurea, and bromoacetanilide were detected in plasma, but only N-methyl bromophenylurea was detected in urine. Bromoacetanilide probably results from acetylation of the intermediate bromoaniline. Methemoglobinemia could result from metabolization of metobromuron to bromoaniline and bromoacetanilide.

Publication types

  • Case Reports

MeSH terms

  • Acetanilides / analysis*
  • Acute Disease
  • Adult
  • Aniline Compounds / analysis*
  • Chromatography, High Pressure Liquid / methods*
  • Half-Life
  • Herbicides / pharmacokinetics
  • Herbicides / poisoning*
  • Humans
  • Male
  • Mass Spectrometry
  • Methemoglobinemia / blood
  • Methemoglobinemia / chemically induced*
  • Methemoglobinemia / urine
  • Molecular Structure
  • Phenylurea Compounds / pharmacokinetics
  • Phenylurea Compounds / poisoning*
  • Spectrophotometry, Ultraviolet
  • Suicide, Attempted


  • Acetanilides
  • Aniline Compounds
  • Herbicides
  • Phenylurea Compounds
  • 4-bromoaniline
  • bromoacetanilide
  • metobromuron