Green methodology based on active air sampling followed by solid phase microextraction and gas chromatography-tandem mass spectrometry analysis to determine hazardous substances in different environments related to tire rubber

Abstract

A fast, efficient, and simple air sampling methodology was developed to study a high number of volatile and semivolatile organic compounds in air above tire rubber materials and surfaces made of recycled tire rubber. The proposed method, based on active sampling (solid-phase extraction, SPE) using a small quantity of sorbent material (25 mg) followed by solid-phase microextraction (SPME) and gas chromatography-tandem mass spectrometry analysis, was developed with the aim of determining 40 organics substances including polycyclic aromatic hydrocarbons (PAHs), plasticizers, antioxidants, and vulcanization agents. An experimental design was carried out to study the influence of main factors such as type of SPME fibre, solvent addition, headspace volume, stirring, as well as the factor interactions. Method performance showed good linearity in a broad concentration range (0.05 to 200 ng m^-3, for most compounds), with coefficients of determination (R²) higher than 0.9900. Whole method precision (≤ 16 %) and accuracy were also satisfactory, obtaining quantitative recoveries (mean values between 80 and 110 % in most cases). Limits of detection and quantification have also been calculated, yielding values of sub ng m^-3 for most compounds. The validated method was applied to outdoor and indoor air environments including playgrounds, football pitches and warehouses showing the presence of most target compounds in the samples achieving high levels for some PAHs (concentrations up to 51 ng m^-3), benzothiazole (BTZ), diisobutyl- dibutyl- and di-(2-ethylhexyl)- phthalate, among others, reaching concentrations up to hundreds of ng m^-3 (BTZ). This is the first time that the combination of techniques SPE and SPME is applied for these families of chemicals, and it is also the first time that this approach is proposed for the simultaneous multiclass compound extraction of substances of different chemical families. The whole sampling and extraction procedure is performed in a short period of time (61 min) allowing high throughput. The elimination of the use of organic solvents and waste generation by using only 25 mg of sorbent and a SPME fibre than are both reused makes the method sustainable and in consonance with the principles of the green chemistry. The method can be implemented in any routine lab and easily automated using a SPME autosampler.

Keywords: Air analysis; Crumb rubber; Gas chromatography-tandem mass spectrometry; Hazardous compounds; Solid-phase microextraction; Tire rubber materials.