Analysis of nitro musk compounds and their amino metabolites in liquid sewage sludges using NMR and mass spectrometry

A method using HRGC ion trap MS/MS for measuring simultaneously amino metab olites and the parent compounds, the nitro musks, an important group of org anic fragrance components found in sewage sludges, was developed. The monoa mino metabolites were synthesized and characterized by H-1/C-13 NMR and mas s spectroscopy. Among the nitro musks, musk ketone was the major compound, found at an average concentration of 5 mu g/kg of dry mass (dm) whereas mus k xylene was detected in only one sample (30 mu g/kg dm). Three amino metab olites were identified, namely, 1-tert-butyl-3,5-dimethyl-4-amino-2,6-dinit robenzene, 1,1,3,3,5-pentamethyl-4-nitro-6-aminoindane, and 4-acetyl-1-tert -butyl-3,5-dimethyl-2-nitro-6-aminobenzene, the corresponding reduction pro ducts of the nitro musks xylene, moskene, and ketone. These metabolites wer e present in partly higher concentrations in the sludges than the correspon ding nitro musk compounds. Musk xylene and musk moskene were mainly found a s their monoamino metabolites, underlining the importance of anaerobic redu ction processes in the sewage treatment plant.