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 1 mL of Na2HPO4 (8%, w/v) and mixed with the ternary acetylation-microextraction mixture, consisting of 100 μL of acetic anhydride, 1.5 mL of acetonitrile and 60 μL 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.