Qualitative analysis of phenols and alcohols in complex samples after derivatization to esters of ferrocene carboxylic acid by gas chromatography with mass spectrometric detection

Phenols and alcohols in complex petrochemical samples are derivatized to esters of ferrocene carboxylic acid in a rapid and simple reaction. These esters show several characteristic ions of high intensity in gas chromatography coupled with electron impact ionization mass spectrometry (GC-EI-MS) which can be used for the identification of the analyte. A differentiation between alcohols and phenols is possible due to the McLafferty rearrangement shown only by the alcohol esters. Selective ion monitoring of m/z 213 yields a phenol-selective chromatogram and m/z 230 an alcohol-selective chromatogram. For all iron containing fragments, the isotopic pattern of iron can be observed which enhances the reliability of the peak identification. The ferrocene esters of 11 alcohols, 20 alkylphenols (including octyl- and nonylphenol), phenylphenol, naphthol and hydroxyphenanthrene, several chloro- and all mononitrophenols were synthesized as well as the esters of pentadeutero- and two fluorinated phenols. Their fragmentation pattern under EI ionization is studied and a GC-ion trap-MS system was optimized for simultaneous use of the full scan mode and an MS/MS experiment in the same run. This provides for a very high selectivity in the detection of the esters and makes available the complete mass spectra without any additional measurements. The benefits of the simple and rapid derivatization procedure in combination with this powerful detection method are demonstrated for selected petrochemical samples. Several alkylphenols could be successfully identified in such samples and molecular information about unknown phenolic components could be easily obtained.