Determination of 25 Organophosphate Flame Retardants in Polyurethane Products by Dispersive Solid Phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry

Organophosphate flame retardants (OPFRs) have widely used in the manufacturing of plastics, textiles, foam products and various building materials because of their dual roles of flame retardants and plasticizers. With in-depth studies of toxicology research, the multiple toxicity of OPFRs to human health has been gradually revealed. It is of great significance to establish accurate detection and quantitative methods of OPFRs in various industrial products and pay attention to the presence of OPFRs for understanding the exposure risk of OPFRs. A method of liquid chromatography tandem mass spectrometry was established for the determination of 25 OPFRs in polyurethane products. A convenient ultrasonic extraction method with organic solvent was used to extract OPFRs from samples. In order to improve the accuracy of the method, the pre-treatment processes such as extraction solvents and solid phase extraction methods were optimized. The experimental results showed that acetonitrile extraction has the highest effectiveness. Subsequently, the extraction solution was further dispersed with silica gel (Si, 200 mg) and N-propyl ethylene diamine adsorbent (PSA, 200 mg), which can effectively eliminate the matrix effect and improve the accuracy of the method. The purified solution was separated on a Kinete®C18 column (2.6 μm×3 mm, 150 mm) under the gradient elution of 0.1% formic acid water and methanol, and analyzed by electrospray ionization positive ion mode with multi-reaction monitoring. The results of methodological verification indicated that the calibration curves of 25 OPFRs show an excellent linear correlation (r>0.999) in the specific concentration ranges. The limits of detection (LODs) and the limits of quantitation (LOQs) of the method are 0.02-0.50, 0.05-1.00 mg/kg, respectively. The recoveries of low, medium and high spiked level are between 61.09% and 114.89%. The relative standard deviations (RSDs) range from 0.27% to 13.92%. All the results of method verification can meet the detection requirement. At the meanwhile, while the efficiency of batch sample analysis is improved, the purification process avoids the complicated procedures using commercial solid phase column extraction, and exhibits low cost, short time and simple operation. The method was further applied to detect commercially available polyurethane products. It was found that OPFRs have been widely used in consumer products such as toys and household products, and the concentration of OPFRs in some products should be noticeable. Thus, health risks may be caused with long-term exposure, and more attention should be paid to the presence of OPFRs in such products.