Determination of 13 Halogenated Organic Additives in Plastics of Electronic Products by Liquid Chromatography-High Resolution Mass Spectrometry

Halogenic organic additives (HOAs) are widely used in plastic components of electronic products to improve product properties. Aiming at environmental and public health issues, a method of ultrasonic-assisted extraction and liquid chromatography-high resolution mass spectrometry (LC-HRMS) was developed for determination of 13 HOAs in plastics of electronic products. The sample extraction, purification procedures, and the detection parameters of LC-HRMS were optimized. The plastic samples were washed with ultrapure water firstly to remove dust from the surface, and then cut into small pieces and ground into fine powder. The plastic powder (0.10 g for each sample) was accurately weighed, followed by addition of isotope labeled internal standards. The sample mixture was allowed to stay still for 5 min in a glass tube for equilibration of the extraction internal standards with the sample mixture. Thereafter, 3 mL methanol-acetonitrile (1:1, V/V) was added into the glass tube, followed by vortex mixing and ultrasonication treatment. After ultrasonication, the sample mixture was centrifugated, and the supernatant was transferred to a clean glass tube. The extraction process was repeated twice more, and all the extracts were merged. The sample extract was blown to near-dryness with a gentle nitrogen stream at 40 ℃. Before LC-HRMS analysis, the sample residue was redissolved with 1 mL H2O-methanol (1:1, V/V). Chromatographic separation was conducted with an ACQUITY UPLC BEH C18 column. A gradient elution program was performed with the mobile phases of acetonitrile and H2O containing 2 mmol/L ammonium acetate. Negative electrospray ionization was applied, and full scan under data-dependent acquisition mode was utilized for HRMS analysis, isotopic internal method was used for quantitative analysis. The results indicated that all the investigated HOAs have excellent linear relationship in the range of 1-1 000 μg/L (R2>0.9909). The limits of quantification of the HOAs are 10 ng/g. The method was validated with mixed plastic samples of electronic products in the spiked concentrations of 80, 800 and 8 000 ng/g. The recoveries of the 13 HOAs range from 62.5% to 107.8%, with the relative standard deviations are not more than 10%. This method is accurate and precisive, and is suitable for rapid detection of HOAs in electronic product plastics. The quantitative analysis of 13 HOAs in 11 plastic samples collected from commonly used electronic products was performed by this method. The results showed that all the electronic products plastics contain various concentrations of HOAs, and the concentrations of individual HOAs in these plastics range from undetectable to 64 686 ng/g. The concentration of tetrabromobisphenol is the highest, and its detection frequency is also the highest (81.8%). The method exhibits good sensitivity and high accuracy, and can be used as a high-throughput screening and quantitative analysis method for HOAs in electronic product plastics.