Identification and determination of chlorinated azoles in sludge using liquid chromatography quadrupole time-of-flight and triple quadrupole mass spectrometry platforms

- LC-QTOF-MS comprehensive search of chlorinated species in sludge extracts.
- Compounds identified using their accurate product ion scan spectra.
- Five novel chlorinated azolic drugs and fungicides identified in sludge.
- Sensitive determination by LC-MS/MS using a triple quadrupole instrument.
- Ubiquity of the novel identified pollutants in municipal sludge.

Four antimycotic drugs (tioconazole, TCZ; sertaconazole, STZ; fenticonazole, FTZ and itraconazole, ITZ) and the fungicide imazalil (IMZ) are determined in sludge from sewage treatment plants (STPs) following a bottom-up analytical strategy. First, sludge extracts, obtained under different sample preparation conditions, were analyzed by liquid chromatography (LC) quadrupole time-of-flight (QTOF) mass spectrometry (MS). A non-target search strategy, combined with the use of the chlorine mass filter, permitted to detect several chlorinated pollutants including the above referred azoles, which either had not been previously reported (TCZ, STZ, FTZ and ITZ), or scarcely investigated (IMZ), in this environmental compartment. Then, the sample preparation procedure was validated using standards of these compounds and their sensitive and selective determination was performed by LC-MS/MS, based on a QqQ system. Under final working conditions, quantitative extraction yields were attained with negligible changes in ionization efficiencies between sample extracts and standards; therefore, the above compounds were quantified against authentic standard solutions, with absolute recoveries in the range from 75 to 124%, achieving a limit of quantification of 2 ng g−1. Analysis of sludge from 10 municipal STPs demonstrated the ubiquity of the identified chlorinated azoles with average concentrations from 31 ng g−1, for IMZ, to more than 200 ng g−1, for ITZ.