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.
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.
A cost-effective and low solvent consumption method, based on the matrix solid-phase dispersion (MSPD) technique, for the determination of six benzotriazole UV absorbers in sediments is presented. Sieved samples (0.5 g) were first mixed in a mortar with a solid sorbent and then transferred to a polypropylene syringe containing a layer of clean-up co-sorbent. Analytes were eluted with a suitable solvent and further determined by gas chromatography with tandem mass spectrometry (GC-MS/MS). Under final conditions, diatomaceous earth and silica, deactivated to 10%, were used as inert dispersant and clean-up co-sorbent, respectively. Analytes were recovered using just 5 mL of dichloromethane, and this extract was concentrated and exchanged to 1 mL of isooctane. Further removal of co-extracted sulphur was achieved adding activated copper powder to final extracts, which were stored overnight, before injection in the GC-MS/MS system. The accuracy of the method was assessed with river and marine sediment samples showing different carbon contents and spiked at different concentrations in the range from 40 to 500 ng g(-1). Recoveries varied between 78% and 110% with associated standard deviations below 14%. The limits of quantification of the method stayed between 3 and 15 ng g(-1). Levels of target compounds in sediment samples ranged from not detected up to a maximum of 56 ng g(-1) for Tinuvin 328.
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