Novel Laser-Assisted Electrospray Ionization Mass Spectrometry (Laser-Assisted ESI-MS): A Sensitive Method for Determining Tetrabromobisphenol A and Its Derivative
Haonan Liu, Xiaoxuan Han, Shuo Gao, Fan Shi, Yong Tian, Ligang Hu, Jianbo Shi, Guibin Jiang
Abstract
Efficient ionization is essential for sensitive mass spectrometry (MS) analysis. Herein, a novel laser-assisted electrospray ionization (laser-assisted ESI) source was developed to efficiently ionize low-polar and thermal unstable compounds. By irradiating the electrospray nozzle with a simple and low-cost laser probe (450 nm, 500 mW), the sample droplets were stimulated with a laser beam as well as the high voltage of the electrospray, which significantly enhanced the ionization efficiency. In positive ionization mode, by further utilizing the reaction of Ag + and tetrabromobisphenol A bis(allyl ether) (TBBPA-BAE), the established laser-assisted ESI strategy was able to efficiently ionize the low-polar and thermal unstable TBBPA-BAE. Specifically, a limit of detection (LOD) of 14 ng L –1, linear range of 0.1–10 μg L –1 (R 2 > 0.99), and relative standard deviations (RSDs) of 2.5% (n = 7, intraday) and 6.2% (n = 3 per day for 5 days, interday) were achieved. In negative ionization mode, laser-assisted ESI also improved the detection sensitivity of tetrabromobisphenol A (TBBPA), achieving a LOD of 3.3 ng L –1, linear range of 0.01–10 μg L –1 (R 2 > 0.99), and RSDs of 4.7% (n = 7, intraday) and 7.3% (n = 3 per day for 5 days, interday). Compared to extractive electrospray ionization mass spectrometry (EESI-MS) and ESI-MS, the LODs achieved with laser-assisted ESI-MS were 54 and 16 times lower for the detection of TBBPA-BAE and TBBPA, respectively. Notably, deep purification and preconcentration were not required to accurately detect TBBPA and TBBPA-BAE in river water and wastewater treatment plant effluent. The spiked recoveries were between 88.0% and 106.0%, demonstrating the high reliability and practicality of this method.