Determination of benzotriazoles in water samples by concurrent derivatization-dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry

Concurrent acetylation-dispersive liquid-liquid microextraction (DLLME) combined with gas chromatography-mass spectrometry (GC-MS) has been proposed for the sensitive determination of five polar benzotriazolic compounds (1H-benzotriazole, BTri; 4 and 5-methyl-1H-benzotriazole, 4-TTri and 5-TTri; 5,6-dimethyl-1H-benzotriazole, XTri; and 5-chloro-1H-benzotriazole, 5-ClBTri) in water samples. Under optimized conditions, samples (10 mL volume) were combined with I mL of Na2HPO4 (8%, w/v) and mixed with the ternary acetylation-microextraction mixture, consisting of 100 mu L of acetic anhydride, 1.5 mL of acetonitrile and 60 mu L of toluene. Thus, analytes were simultaneously acetylated and transferred to the dispersed droplets of toluene. The proposed methodology achieved limits of quantification (LOQs) between 0.007 ng mL(-1) and 0.080 ng mL(-1), enrichment factors between 93 and 172 times, good reproducibility, with relative standard deviations lower than 10%, and linearity with determination coefficients above 0.9991 for all compounds in the range between LOQs and 20 ng mL(-1). Pseudo-external calibration, with fortified ultrapure water samples submitted to the acetylation-DLLME procedure, proved to be adequate for the accurate quantification of complex aqueous matrices such as surface or wastewater, providing recoveries comprised between 86% and 112%. BTri, 4-TTri and 5-TTri were measured in environmental samples up to a concentration of 1.9 ng mL(-1) for BTri in raw wastewater. (C) 2014 Elsevier B.V. All rights reserved.