Duyệt theo Tác giả "Nguyen, Nu My Ha"

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  • Hình ảnh thu nhỏ
    Tài liệu
    Determination of cyclic volatile methylsiloxanes in sludge samples collected from To Lich River, Ha Noi, Vietnam
    (Nguyen Tat Thanh University, 2023) Tran, Manh Tri; Nguyen, Nu My Ha; Vu, Manh Trung; Tong, Cam Le; Le, Quang Huong; Do, Quang Trung; Pham, Thi Phuong
    Cyclic volatile methylsiloxanes (cVMSs) are synthesis chemicals used widely in consumer products such as building materials, households, electrical and medical devices, and personal care products. Due to being used in many applications, cVMSs are released into various micro-environments. Recently, the pollution level of cVMSs in the environment including sewage sludge has been gradually concerned. In this work, four typical cVMSs: hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylhexasiloxane (D6) were measured in 20 sludge samples collected from a sewage river (To Lich River) in Ha Noi metropolitan by using the gas chromatography-tandem mass spectrometry (GC-MS) method. The method detection limits (MDLs) and the method qualification limits (MQLs) of cVMSs in sewage sludge were a range of (1.20-3.00) ng/g-dw (dry weight) and (3.60-9.00) ng/g-dw, respectively. Recoveries of the surrogate compound (tetrakis-(trimethyl siloxane)-silane: M4Q) in blank and real samples were from (89.4 to 112) % (RSD: 9.2 %). The total concentrations of cVMSs in sewage sludge samples from To Lich River ranged from (260 to 13,800) ng/g-dw. Among the studied cVMSs, D5 was found at the highest levels in a range of (150-6,040) ng/g-dw. To our knowledge, this is the first report on the occurrence of cVMSs in sewage sludge samples in Ha Noi as well as Vietnam. The results indicate that the distribution of cVMSs in environments is significantly high and further studies should be conducted.
  • Hình ảnh thu nhỏ
    Tài liệu
    Study on determination of PAEs in water samples by using solid phase extraction combined with gas chromatography-mass spectrometry
    (Nguyen Tat Thanh University, 2023) Tran, Manh Tri; Ta, Anh Ngoc; Le, Minh Thuy; Nguyen, Nu My Ha; Nguyen, Thi Thanh Huyen; Dang, Minh Huong Giang; Chu, Ngoc Chau
    Phthalic acid diesters (PAEs) are industrial chemicals used as plasticizers in a variety of commercial products. Due to wide usage, PAEs have been found in various environments and their human exposure risks have also attracted a lot of concerns. However, little information about the distributions of PAEs in the water samples collected from Vietnam was reported. In this study, the method for the determination of nine typical PAEs in water samples by using the solid phase extraction (SPE) combined with gas chromatography-mass spectrometry (GC-MS) technique was optimized. The method detection limits (MDLs) and method quantitation limits (MQLs) of PAEs in water samples were in ranges of 0.2–0.4 ng/L and (0.6-1.2) ng/L, respectively. The recoveries of surrogate compounds in blank and real samples ranged from (74.8 to 93.9) %, with RSD < 9.2 %. The calibration curve for all standards was linear over a concentration range of (1.0-1,000) ng/mL (with R2 ≥ 0.998). The total concentrations of PAEs measured in bottled water of six brands were ranged from 10.0 ng/L to 6,690 ng/L. Among the studied PAEs, di-(2-ethylhexyl) phthalate (DEHP) was found at the highest frequencies and concentrations. Overall, the distribution of PAEs in plastic bottled water is significantly lower than the permitted regulations (only with DEHP) in drinking water by the Ministry of Health of Vietnam in 2011.