Search

Abstract Carbon dots (CDs) have attracted much attention in a variety of fields owing to the diversified properties. However, the control of the structure and surface function of CDs are still urgent issues to be addressed for using it in specific application. Herein, the reduced state of carbon nanodots (R-CDs) has been produced through a convenient strategy by reduction of the pure carbon dots products, which was utilized as a good candidate of matrix for direct analysis of bisphenol (BP) analogs in negative-ion surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS). Due to the dominant hydroxyl groups on the surface of R-CDs, they were easier to absorb BPs through hydrogen bonding and van der Waals interactions, resulting in highly efficient detection of BPs. Meanwhile, compared with the organic matrix and raw carbon dots, the superior surface structure and properties of this R-CDs surface provide various advantages including low background noise, outstanding sensitivity and salt tolerance. This work opens a door for developing R-CDs as alternative substrate in SALDI-TOF MS for direct detection of small molecule pollutants. Graphical abstract fx1 Highlights • Reduced carbon nanodots (R-CDs) was used as a novel candidate for detection bisphenol analogs (BPs) in SALDI-TOF MS. • The R-CDs-assisted LDI MS exhibited low background noise, high sensitivity and salt tolerance in analysis of BPs. • This work provides a good alternative substrate to SALDI-TOF MS and expands the CDs’ new application scope. [ABSTRACT FROM AUTHOR]

Abstract A new method for the determination of 19 polyaromatic hydrocarbons (PAHs) and 12 hydroxy-polyaromatic hydrocarbons (OHPAHs) in fine particulate matter (PM 2.5) was developed using atmospheric pressure gas chromatography-tandem mass spectrometry (APGC-MS/MS). Better sensitivity was achieved by APGC-MS/MS than conventional liquid chromatography or gas chromatography coupled with mass spectrometry. The method detection limits (< 0.4 pg m−3 for PAHs and < 0.076 pg m−3 for OHPAHs), recoveries (67.7–120%), repeatability (RSD of 0.9–19.1%) and linearity (R2 > 0.99) were obtained for the analysis of PM 2.5 samples. The content profile of 19 PAHs and 12 OHPAHs were successfully obtained in 55 PM 2.5 samples collected from two major Chinese megacities, Taiyuan and Guangzhou, in both summer and winter by this method. Based on the concentrations, possible emission sources for the pollutants were also identified. Graphical abstract fx1 Highlights • APGC-MS/MS achieved lower LODs of 19 PAHs and 12 OHPAHs in PM 2.5 than previous method. • 19 PAHs and 12 OHPAHs in PM 2.5 all could be detected by APGC-MS/MS. • Pollution characteristics of PAHs/OHPAHs in PM 2.5 were obtained based on determined concentrations. [ABSTRACT FROM AUTHOR]

Abstract Toxic chemicals such as flame retardants are associated with atmospheric fine particles (PM 2.5), which are an important pollutant in the world. In this study, a sensitive method using gas chromatography-tandem triple quadrupole mass spectrometry combined with ultrasonic-assisted extraction and multi-phase column purification was developed for simultaneously determination of 29 flame retardants including halogenated flame retardants (HFRs) and organophosphate flame retardants (OPFRs) in PM 2.5 samples. Extraction time, as well as the type and volume of elution solvent were optimized. The recoveries of all target flame retardants from PM 2.5 samples were in the range of 70%‒130%, with good repeatability and reproducibility (0.39%‒17.4%). The instrumental detection limits (IDLs) and method quantitation limits (MQLs) of HFRs were in the range of 0.004‒5.44 pg and 0.002‒2.52 pg m−3, while those of OPFRs were 0.003‒0.23 pg and 0.07‒5.41 pg m−3, respectively. The developed method has been successfully applied for analysis of target flame retardants in atmospheric PM 2.5 collected from the cities of Guangzhou and Taiyuan, China. HFRs were found at concentrations of 45.7‒1230 pg m−3 and 51.2‒82.3 pg m−3 in Guangzhou and Taiyuan. The concentrations of HFRs were lower than those of OPFRs, which were detected at concentrations of 6004‒49,800 pg m−3 and 16,741‒34,346 pg m−3 in Guangzhou and Taiyuan. Accordingly, the analytical method is robust and useful for further elucidating the contamination profiles of flame retardants in PM 2.5. Graphical abstract fx1 Highlights • A sensitive method for analysis of 17 HFRs and 12 OPFRs in PM 2.5 was developed. • MQLs of most OPFRs by GC-MS/MS were lower than the reported MQLs by GC-MS. • Good performance characteristics were obtained for all target flame retardants. • The method was successfully applied for analysis of PM 2.5 in different areas. [ABSTRACT FROM AUTHOR]