Determination of brominated alkylbenzenes in nickel industry sludge by capillary gas chromatography

Capillary gas chromatography coupled to both mass spectrometry (GCMS) and atomic emission spectroscopy (GC-AED) was studied for the analysis of bromine-containing alkylbenzenes present in sludge from a nickel refinery. Owing to the high abundance of chlorinated compounds, location of the brominated species was difficult based on GC-MS with electron ionization. In contrast, GC-MS with negative chemical ionization (GC-NCIMS) and GC-AED enabled bromine-selective detection and were utilized for an effective location of the brominated compounds. Bromine-selective detection by GC-NCIMS relied on the monitoring of Br-(m/z 79/81) with CH4 as ionization gas, while atomic emission (827.2 nm) from a helium plasma was utilized in the case of GC-AED. While GC-NCIMS was 30-500 times more sensitive than GC-AED, the latter technique was superior for quantitative purposes. Because the bromine response of the AED was independent of molecular structure, quantification was possible without reference material.