Determination of free and ethoxylated alkylphenols in leather with gas chromatography–mass spectrometry

An analytical approach was developed to determine nonylphenol (NP), octylphenol (OP), nonylphenol ethoxylates (NPEOn) and octylphenol ethoxylates (OPEOn) in leather samples involving the conversion of NPEOn and OPEOn into the corresponding NP and OP. The four targets were extracted from samples using ultrasonic-assisted acetonitrile extraction. NP and OP in the extracts were directly isolated with hexane and quantitatively determined with 4-n-nonylphenol as internal standard by gas chromatography–mass spectrometry (GC–MS). For NPEOn and OPEOn in the extracts, they were first converted into NP and OP with aluminum triiodide as cleavage agent, and the yielded NP and OP were determined by GC–MS. The contents of NPEOn and OPEOn were calculated by normalizing to NPEO9 and OPEO9, respectively. This method was properly validated and the real sample tests revealed the pollution significance of leather by NPEOn and OPEOn.