Determination of fatty acids (C8–C22) in urban wastewater by GC-MS

A simple method for determination of fatty acids (C8–C22) in wastewater, extracted with dichloromethane, was developed. The extraction time was drastically reduced using ultrasound. Fatty acids were esterified using BF3 methanolic solution followed by an 11 min run using gas chromatography-mass spectrometry with selected ion monitoring (GC/MS-SIM). A clean-up is not necessary using SIM Mode. Tridecanoic acid was used as a surrogate internal standard. Detection limits go from 0.008 to 0.016 mg l−1. The applicable concentration range was 0.010 to 10 mg l−1. The method was validated by using the Standard Addition Methodology and it was applied satisfactorily to wastewater from Granada (Spain).