Characterisation of polycyclic aromatic hydrocarbons associated with indoor PM0.1 and PM2.5 in Hanoi and implications for health risks.

Polycyclic aromatic hydrocarbons (PAHs) associated with indoor PM pose a high risk to human health because of their toxicity. A total of 160 daily samples of indoor PM2.5 and PM0.1 were collected in Hanoi and analysed for 15 PAHs. In general, the concentrations of carcinogenic PAHs (car-PAHs) accounted for 21% ± 2%, 19.1% ± 2%, and 26% ± 3% of the concentrations of 15 PAHs in PM2.5, PM0.1-2.5, and PM0.1, respectively. Higher percentages of car-PAHs were found in smaller fractions (PM0.1), which can be easily deposited deep in the pulmonary regions of the human respiratory tract. The concentrations of 15 PAHs were higher in winter than in summer. The most abundant PAH species were naphthalene and phenanthrene, accounting for 11%-21% and 19%-23%, respectively. The PAH content in PM0.1 was almost twice as high as those in PM2.5 and PM0.1-2.5. Principal component analysis found that vehicle emissions and the combustion of biomass and coal were the main outdoor sources of PAHs, whereas indoor sources included cooking activities, the combustion of incense, scented candles, and domestic uses in houses. According to the results, 60%-90% of the PM0.1-bound BaP(eq) was deposited in the alveoli region, whereas 63%-75% of the PM2.5-bound BaP(eq) was deposited in head airways (HA), implying that most of the particles deposited in the HA region were PM0.1-2.5. The contributions of dibenz[a,h]anthracene and benzo[a]pyrene were dominant and contributed from 36% to 51% and 31%-50%, respectively, to the carcinogenic potential, whereas benzo[a]pyrene contributed from 30% to 49% to the mutagenic potential for both size fractions. The incremental lifetime cancer risk, simulated by Monte Carlo simulation, was within the limits set by the US EPA, indicating an acceptable risk for the occupants. These results provide an additional scientific basis for protecting human health from exposure to indoor PAHs.

Adsorption and transformation of tetracyclines on alpha alumina particles with surface modification by anionic surfactant.

The adsorption and transformation of tetracyclines (TCs) antibiotics, including oxytetracycline (OTC), chlortetracycline (CTC), and tetracycline (TC), on the sodium dodecyl sulfate (SDS) surfactant-modified α-Al2O3 particles were comprehensively investigated in this study. The TCs adsorption was significantly enhanced by using the modified adsorbents compared with the use of the unmodified adsorbents. The experimental conditions were systematically optimized and found to be pH 4, NaCl 1 mM, the contact time of 180 min, and the adsorbent dosage of 25 mg. mL-1. The high maximum adsorption capacities were approximately 320, 85, and 91 mg. g-1 for TC, OTC, and CTC, respectively. Meanwhile, the great removal efficiencies of the three antibiotics TC, OTC, and CTC were correspondingly 91.85, 88.4, and 98.3%. The TCs adsorption isotherm and kinetics on the SDS-modified α-Al2O3 particles mainly governed by the electrostatic and hydrophobic interactions were clarified by a suitable two-step model, the Fourier transform infrared spectroscopy (FT-IR) and zeta potential measurements. Meanwhile, the TCs structural transformation determined by the liquid chromatography with tandem mass spectrometry (LC-MS/MS) measurement was promoted through the adsorption on the α-Al2O3 surface. The TCs transformation rates strongly affected by the TCs adsorption were in the order of CTC > TC > OTC. The found results are promised that the SDS-modified α-Al2O3 particles might behave as high-performance adsorbents to remove the TCs from aqueous solutions.

Analysis of Polycyclic Aromatic Hydrocarbon in Airborne Particulate Matter Samples by Gas Chromatography in Combination with Tandem Mass Spectrometry (GC-MS/MS).

Polycyclic aromatic hydrocarbons (PAHs), the family of organic contaminations, have been shown to have negative effects on human health. However, until now, the comprehension on occurrence, distribution, and risk assessment of human exposure to PAHs has been limited in Vietnam. In this work, a capillary gas chromatography coupled with electron impact ionization tandem mass spectrometry (GC-EI-MS/MS) has been introduced for analysis of 16 PAHs in some particulate matter samples. PAHs have been separated on the TG 5 ms capillary gas chromatographic column and detected by tandem mass spectrometry in multiple reaction monitoring mode. The PAHs in the particulate matter (PM 2.5 and PM 10) samples were extracted by ultrasonic-assisted liquid extraction and cleaned up by an acidic silica gel solid phase extraction. The linearity range of all analyzed PAHs was from 5 to 2000 ng mL-1 with R 2 ≥0.9990. Limit of detection (LOD) of PAHs in particulate matter sample was from 0.001 ng m-3 (Br-Naph) to 0.276 ng m-3 (Fln). The recovery of PAHs was investigated by international proficiency testing samples. The recoveries of PAHs in proficiency testing sample ranged from 79.3% (Chr) to 109.8% (IcdP). The in-house validated GC-EI-MS/MS method was then applied to analysis of some particulate matter samples that were collected in the Hanoi areas. The total concentrations of PAHs in several brands of samples collected from Hanoi were found in the range of 226.3 ng m-3-706.43 ng m-3. Among the studied compounds, naphthalene was found at high frequency and ranged from 106.5 ng m-3 to 631.1 ng m-3. The main distribution of the PAHs in particulate matter samples was two-ring and three-ring compounds.

Multiresidue Pesticides Analysis of Vegetables in Vietnam by Ultrahigh-Performance Liquid Chromatography in Combination with High-Resolution Mass Spectrometry (UPLC-Orbitrap MS).

An ultrahigh-performance liquid chromatography in combination with high-resolution mass spectrometry Thermo Q-Extractive Focus Orbitrap MS has been introduced for analysis of multiclass pesticides in vegetable samples collected in Hanoi, Vietnam. Multiclass pesticides were separated on the Thermo Hypersil Gold PFP column utilizing a gradient of the mobile phase consisting of 5 mM ammonium formate, 0.1% formic acid in deionized water, and methanol. The target analytes were detected in the full-scan mode on Thermo Scientific Q-Exactive Focus Orbitrap MS for quantitation at the optimum operating conditions. These conditions included, but not limit to, the resolution of 70000 at the full width at half maximum in both positive and negative mode, mass range from 80 to 1000 m/z, and optimized parameters for the heated electrospray ionization source. The identification of the analytes in real samples was based on retention times, mass to charge ratios, mass accuracies, and MS/MS spectra at the confirmation mode with the inclusion list of target analytes. The mass accuracies of target analytes were from -4.14 ppm (dinotefuran) to 1.42 ppm (cinosulfuron) in the neat solvent and from -3.91 ppm (spinosad D) to 1.29 ppm (cinosulfuron) in the matrix-matched solution. Target analytes in the vegetable-based matrix were extracted by the QuEChERS method. Some critical parameters of the analytical method such as linearity, repeatability, limit of detection, and limit of quantitation have been evaluated and implemented. Excellent LOD and LOQ of the developed method were achieved at the range of 0.04-0.85 and 0.13-2.9 µg·kg-1, respectively. Intraday and interday repeatability of the analytical signal (peak area, n=6) of the developed method were below 3% and 10%, correspondingly. The matrix effect, extraction recovery, and overall recovery were fully investigated by spiking experiments. Experimental results demonstrated that the ionization suppression or enhancement was the main contribution on the overall recoveries of target analytes. Finally, the in-house validated method was applied to pesticides screening in vegetables samples in local villages in Hanoi, Vietnam. The concentrations of all target analytes were below limit of quantitation and lower than US-FDA or EU maximum residue levels.

Residue concentrations and profiles of PCDD/Fs in ash samples from multiple thermal industrial processes in Vietnam: Formation, emission levels, and risk assessment.

The residue concentrations and congener profiles of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) were examined in fly ash and bottom ash released from different thermal industrial processes in Vietnam. PCDD/F concentrations and toxic equivalents (TEQs) in the ash samples varied greatly and decreased in the following order: steel making > aluminum recycling > medical waste incinerator > boilers > municipal waste incinerator > tin production > brick production > coal-fired power plant. Both the precursor and de novo synthesis were estimated as possible formation mechanisms of dioxins in the ash, but the latter pathway was more prevalent. The highest emission factors were estimated for the ash released from some steel-making plants, aluminum-recycling facilities, and a medical waste incinerator. The emission factors of PCDD/Fs in ash released from some steel plants of this study were two to six times higher than the UNEP Toolkit default value. The annual emission amount of ash-bound dioxins produced by 15 facilities in our study was estimated to be 26.2 to 28.4 g TEQ year-1, which mainly contributed by 3 steel plants. Health risk related to the dioxin-containing ash was evaluated for workers at the studied facilities, indicating acceptable risk levels for almost all individuals. More comprehensive studies on the occurrence and impacts of dioxins in waste streams from incineration and industrial processes and receiving environments should be conducted, in order to promote effective waste management and health protection scheme for dioxins and related compounds in this rapidly industrializing country.

Chemical Composition of Clausena lansium (Lour.) Skeels Leaves and Antifungal Activity

The first study on chemical constituents and biological activities of Clausena lansium (Lour.) Skeels (Rutaceae) growing in Vietnam has been done. Phytochemical investigation of n-hexane extract led to the isolation of five compounds: dihydroindicolactone (1), 8-geranyloxy psoralen (2), imperatorin (3), heraclenol (4) and indicolactone (5), in which this is the first report on the presence of dihydroindicolactone (1). Their structures were elucidated based on LC/MS/NMR hyphenated techniques as well as comparison with those of literature data. The n-hexane extract and its subfractions, ethanol 95% extract and several isolated compounds were evaluated for antifungal activity.