Identification of organic residues in tertiary effluents by GC/EI-MS, GC/CI-MS and GC/TSQ-MS

A method was developed for the analysis of non-volatile dissolved organic residues in tertiary treated wastewater effluents. This method involved concentration of samples by rotary evaporation, propylation using propanol/formic acid/acetyl chloride, and separation, detection and quantitation by capillary GC/EI and CI-MS and GC/TSQ-MS analysis. Ethylenediamine tetraacetic acid (EDTA) was the most prominent compound found in both granular activated carbon (GAC) and chlorinated GAC effluents (110 and 140 μg/L, respectively). Other compounds identified included nitrilotriacetic acid (NTA), carboxyalkylphenoxy ethoxy carboxylates, poly(propoxy), poly(ethoxy) or poly(ethoxy)(propoxy) compounds, small aliphatic dicarboxylic acids and aldehydes, all at μg/L levels. Approximately 80% of all chromatographically separated compounds were positively or tentatively identified. The identified compounds are estimated to account for approximately 10% of the dissolved organic carbon.