A simple and automated method to determine macrocyclic musk fragrances in sewage sludge samples by headspace solid-phase microextraction and gas chromatography–mass spectrometry

• For the first time eight macrocyclic musks have been determined in sewage sludge samples.
• HS-SPME has been applied directly to the sewage sludge without any previous pretreatment.
• The absence of sample pretreatment facilitated us the automation of the whole analytical method.
• Method detection and quantification limits were found in the low pg g−1.
• Good values of intra-day and inter-day repeatabilities have been obtained.

For the first time, headspace solid-phase microextraction (HS-SPME) has shown to be a powerful technique to extract macrocyclic musk fragrances directly from sewage sludge. It avoids the need to use additional extraction/preconcentration techniques or clean-up procedure and facilitates the automation of the method. Thus, a simple and fully automated method based on HS-SPME and GC–MS has been developed which allows the determination of eight macrocyclic musk fragrances at ng g−1 (d.w.) levels. The optimal HS-SPME conditions were achieved when a PDMS/DVB 65 μm fibre was exposed for 45 min in the headspace of 0.25 g sewage sludge samples mixed with 0.5 mL of water stirred at 750 rpm at 80 °C. Optimal desorption conditions were found to be 250 °C for 3 min. Method detection limits were found in the low pg g−1 range between 10 pg g−1 (d.w.) and 25 pg g−1 (d.w.) depending on the target analytes. In addition, under optimized conditions, the method gave good levels of intra-day and inter-day repeatabilities in sewage sludge with relative standard deviations varying between 1% to 9% and 6% to 15% respectively (n = 5, 1000 pg g−1 d.w.). The applicability of the method was tested with sewage sludge from three urban sewage treatment plants (STPs). The analysis revealed the presence of the macrocyclic musks studied in several samples, with concentrations ranging between below MQL (method quantification limit) and 0.89 ng g−1 (d.w.)