Development of a sensitive determination method for benzotriazole UV stabilizers in enviromental water samples with stir bar sorption extraction and liquid desorption prior to ultra-high performance liquid chromatography with tandem mass spectrometry : Sample Preparation

Stir bar sorptive extraction (SBSE) was introduced in 1999 as a solventless sample preparation method for the extraction and enrichment of organic compounds from aqueous matrices. The method is based on sorptive extraction, whereby the solutes are extracted into a polymer coating on a magnetic stirring rod. The extraction is controlled by the partitioning coefficient of the solutes between the polymer coating and the sample matrix and by the phase ratio between the polymer coating and the sample volume. For a polydimethylsiloxane coating and aqueous samples, this partitioning coefficient resembles the octanol-water partitioning coefficient. In comparison to solid phase micro-extraction, a larger amount of sorptive extraction phase is used and consequently extremely high sensitivities can be obtained as illustrated by several successful applications in trace analysis in environmental, food and biomedical fields. Initially SBSE was mostly used for the extraction of compounds from aqueous matrices. The technique has also been applied in headspace mode for liquid and solid samples and in passive air sampling mode. In this review article, the principles of stir bar sorptive extraction are described and an overview of SBSE applications is given.

Benzophenones and benzotriazoles are widely used as ultraviolet (UV) light filters and stabilizers in cosmetics, skin creams, and body lotions and as corrosion inhibitors in building materials, automobile components, and automotive antifreeze cooling systems. Benzophenones and benzotriazoles have been reported to occur in the environment. Some of these UV filters have been reported to possess significant estrogenic activity. Despite this, very few studies have examined their occurrence and profiles in the environment. In this work, we determined five benzophenone-type UV filters and two benzotriazole-type corrosion inhibitors, namely, 2-hydroxy-4-methoxybenzophenone (2OH-4MeO-BP), 2,4-dihydroxybenzophenone (2,4OH-BP), 2,2'-dihydroxy-4-methoxybenzophenone (2,2'OH-4MeO-BP), 2,2',4,4'-tetrahydroxybenzophenone (2,2',4,4'OH-BP), 4-hydroxybenzophenone (4OH-BP), 1H-benzotriazole (1H-BT), and 5-methyl-1H-benzotriazole (5Me-1H-BT), in sediment and sewage sludge samples, using liquid-liquid extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS). In addition, four benzotriazole-type UV stabilizers, namely, 2-(3-t-butyl-2-hydroxy-5-methylphenyl)-5-chlorobenzotriazole (UV-326), 2,4-di-t-butyl-6-(5-chloro-2H-benzotriazole-2-yl) phenol (UV-327), 2-(2H-benzotriazole-2yl)-4,6-di-t-pentylphenol (UV-328), and 2-(5-t-butyl-2-hydroxyphenyl) benzotriazole (TBHPBT) were determined by gas chromatography (GC)-mass spectrometry (MS). The limits of quantitation (LOQ) were in the ranges of 0.06-0.33 ng g⁻¹ dry weight (dw) and 0.1-1.65 ng g⁻¹ dw for sediment and sludge samples, respectively. Recoveries of target compounds spiked into sample matrices and passed through the entire analytical procedure ranged from 70% to 116% (RSD: 3.32-13.8%) and from 82% to 106% (RSD: 2.89-8.09%) for the compounds analyzed by LC-MS/MS and GC-MS, respectively. The methods were applied to the analysis of sediment samples from the Songhua, Saginaw, and Detroit Rivers; the sum concentrations of target compounds were 3.29-9.93, 5.81-22.5, and 190-389 ng g⁻¹ dw, respectively. Five sludge samples collected from five wastewater treatment plants in northeastern China contained the sum concentrations of target compounds in the range of 104-6370 ng g⁻¹ dw. The concentration of UV-328 in sludge was the highest (mean: 1300 ng g⁻¹ dw) among the target compounds. To our knowledge, this is the first work to report the occurrence of 2OH-4MeO-BP, 2,4OH-BP, 2,2'OH-4MeO-BP, 2,2',4,4'OH-BP, and 4OH-BP in sediment and sludge samples.