Gas chromatography quadrupole time-of-flight mass spectrometry determination of benzotriazole ultraviolet stabilizers in sludge samples

• Determination of benzotriazole UV stabilizers in sludge.
• Assessment of GC–QTOF-MS performance as selective determination technique.
• Simplified, low cost and solvent consuming sample preparation method.
• Confirmation of benzotriazole UV stabilizers ubiquity in sludge samples and reference materials.

In this research, a simplified procedure for the selective determination of nine benzotriazole UV stabilizers (BUVSs) in sludge from urban sewage treatment plants is presented. Analytes were extracted from the sample using the matrix solid-phase dispersion (MSPD) technique and further determined by gas chromatography (GC) with quadrupole time-of-flight mass spectrometry (QTOF-MS). Highly selective chromatographic records were attained considering a mass window of 0.005 Da, centred in the quantification product ion corresponding to each compound. Moreover, the availability of accurate ion product scan MS/MS spectra permitted to confirm the identities of peaks observed in extracted ion MS/MS chromatograms. As a result, a straightforward sample preparation procedure combining extraction and clean-up in the same step, and consuming just 10 mL of ethyl acetate, sufficed to deal with complex sludge samples. The developed method attained limits of quantification (LOQs) between 2 ng g−1 and 10 ng g−1, referred to freeze-dried sludge, and recoveries from 70% to 111%, with standard deviations from 2% to 13%. Analysis of sludge samples and certified reference materials confirmed the existence of residues of eight out of nine BUVSs. UV-326, UV-328 and UV-234 displayed the highest occurrence frequencies and individual concentrations above 100 ng g−1 in several samples.