Endocrine-disrupting nonylphenols--ultra-trace analysis and time-dependent trend in mussels from the German bight

A very sensitive and efficient analytical procedure is presented for the determination of 4-nonylphenols (NP) in blue mussels by use of off-line coupling of high-performance liquid chromatography (HPLC) and gas chromatography with mass spectrometric detection (GC-MS). Combined steam distillation and solvent extraction were used to extract the analytes from the mussel samples. Before quantification by GC-MS the raw extracts were purified by normal-phase HPLC. 4-n-Nonylphenol was used as internal standard. The detection limit was 15 ng NP absolute, calculated from the blank value. The method was applied to the determination of NP in blue mussel samples from the German North Sea sampled over a period of 10 years. Collection, homogenization, and storage of the mussels were performed according to the Standard Operating Procedures of the German Environmental Specimen Bank since 1985. The total NP concentrations in the mussels decreased significantly from 1985 (4 microgram kg (-1)) to 1995 (1.1 microgram kg (-1)).