Analysis of rubber-derived contaminants in surface water and snow by liquid chromatography coupled with a hybrid linear ion-trap-Orbitrap high-resolution mass spectrometry.

Analytical methods were developed to quantify eight rubber-derived organic contaminants, including four p-phenylenediamine-derived quinones (PPDQs), 1,3-diphenylguanidine (DPG), 1,3-diphenylurea (DPU), N,N-dibutylbutan-1-amine (TBA), and 1,3-dicyclohexylurea (DCU) in the dissolved phase and suspended particulate matter (SPM) of surface water and melted snow. Dissolved-phase samples were prepared using solid-phase extraction with hydrophilic-lipophilic balance cartridges and a 3/7 (v/v) mixture of acetonitrile and dichloromethane as elution solvents. SPM samples underwent ultrasonic-assisted extraction using the same solvent mixture. Reduced glutathione was added before extraction to improve recovery and reduce variability of target compounds. Quantification was performed using ultra-high-performance liquid chromatography coupled with a hybrid linear ion-trap-Orbitrap high-resolution mass spectrometry (UHPLC/ESI-LTQ-Orbitrap) in positive electrospray ionization and full-scan mode (m/z 100-500). Method detection limits for surface water ranged from 0.2 to 7.0 ng/L in the dissolved phase and 0.1-2.6 ng/L in SPM. For melted snow, detection limits ranged from 0.2 to 5.0 ng/L in the dissolved phase and from 0.1 to 5.4 ng/L in SPM. Sample storage tests (4°C and -20°C) indicate that the dissolved phase should be extracted on the sample collection day, while SPM samples (filters stored at -20°C) should be extracted within seven days. Three of the eight target compounds, including DPG, DCU, and 2-((4-methylpentan-2-yl)amino)-5-(phenylamino)cyclohexa-2,5-diene-1,4-dione (6PPDQ), were detected in environmental surface water and snowmelt samples from Quebec, Canada. This is the first reported method using UHPLC/ESI-LTQ-Orbitrap to simultaneously determine these eight contaminants in the dissolved and SPM phases of surface water and melted snow.