An improved selectivity method for the simultaneous determination of four benzotriazoles (benzotriazole, 4-methylbenzotriazole, 5-methylbenzotriazole, and 5,6-dimethyl-1H-benzotriazole) and six benzothiazoles (benzothiazole, 2-hydroxybenzothiazole, 2-benzothiazolamine, mercaptobenzothiazole, 2-methylbenzothiazole, and 2-methylthiobenzothiazole) in aqueous matrices has been developed. Under optimal conditions, analytes are concentrated using a MAX solid-phase extraction (SPE) cartridge, based on divinylbenzene-N-vinylpyrrolidone functionalized with quaternary amine groups, which allows reversed-phase interactions in combination with ionic exchange. Selected compounds are recovered with methanol–acetone 7:3 (v/v) whereas acidic interferences remained attached to the sorbent, and as determined by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), LOQs for surface, urban and industrial wastewater are in the range of 0.002-0.29 ng/mL. Figures of merit of the method revealed good precision (RSD% <12%), linearity (R2 > 0.99) and accuracy (%R = 80-100%) for surface waters and effluents allowing direct external standard quantification. For more complex samples, such as urban and industrial raw wastewater, either the standard addition method or pseudo-external standard calibration using matrix matched standards are recommended. Analysis of different real samples, surface, urban wastewater and, for the first time, metal industry wastewater, reflected concentrations up to 310 ng/mL. The methylbenzotriazole isomers ratio was also determined.

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A sensitive procedure for the determination of five ultraviolet (UV) absorbers, belonging to the benzotriazole class, in environmental water samples is proposed. Analytes were first extracted and concentrated from the matrix and then selectively determined by gas chromatography in combination with tandem mass spectrometry detection. The high lipophilic character of some of the investigated species resulted in a strong trend to remain sorbed on solid surfaces, even after addition of considerable percentages of methanol (up to 30%) to water. Thus, minimizing sample handling during the enrichment step is mandatory in order to obtain acceptable accuracy and precision. Solid-phase microextraction (SPME), as sample preparation approach, fulfilled the above requirement and provided acceptable figures of merit for the determination of target species in environmental water samples, including raw wastewater. Optimization of SPME conditions showed that the combination of headspace extraction, with a sample temperature of 100 degrees C and addition of 15 mg of NaCl per milliliter of sample rendered the best compromise in terms of extraction efficiency for all species. Considering a sampling time of 30 min with a poly(dimethylsiloxane)-divinylbenzene-coated SPME fiber, limits of quantification below 2 ng l(-1) and relative standard deviations between 5% and 12% were achieved. Three of the five species included in this research were determined in raw wastewater with a maximum concentration of 57 ng l(-1) for the Tinuvin 326 UV absorber.

Stir-bar sorptive extraction and liquid desorption followed by large volume injection-gas chromatography coupled to mass spectrometry under selected ion monitoring mode acquisition (SBSE-LD/LVI-GC-MS(SIM)) was applied for the determination of six benzotriazole UV stabilizers (Tinuvin P, Allyl-bzt, Tinuvin 320, Tinuvin 326, Tinuvin 327 and Tinuvin 328) in wastewater matrices. Parameters affecting the performance of extraction and desorption steps were thoroughly evaluated using uni- and multivariate optimization strategies, based on the use of experimental factorial designs. Assays performed with stir bars, coated with 24 μL of polydimethylsiloxane, on 25 mL of ultra-pure water samples spiked at the 0.5 ng/mL level, yielded recoveries ranging from 47.9±1.4% (Tinuvin P) to 103.1±3.6% (Tinuvin 326), under optimized experimental conditions. When applied to complex matrices (e.g. wastewater), the methodology showed also excellent linear dynamic ranges (0.02-10.00 ng/mL) for the six benzotriazole UV stabilizers studied with correlation coefficients higher than 0.9970, limits of quantification in between 0.004 and 0.015 ng/mL, suitable repeatability (RSD<12.7%) and reproducibility (RSD<4.5%). The application of the proposed methodology to urban sewage waters from Spain and Portugal wastewater plants revealed the presence of low contents of some benzotriazole UV stabilizers.