Vietnam Analytical Sciences Society
Hội Khoa học Kỹ thuật Phân tích Hóa, Lý và Sinh học
COMBINED APPLICATION OF pH REDUCTION AND ACTIVATED CARBON FOR THE REMOVAL OF OFF-FLAVOR COMPOUNDS (GEOSMIN AND 2-MIB) IN FERMENTED CARP-BASED FISH SAUCE
Các hợp chất gây mùi lạ geosmin và 2-methylisoborneol (2-MIB) thường xuất hiện trong cá nước ngọt và các sản phẩm nuôi trồng thủy sản, làm giảm chất lượng cảm quan. Nghiên cứu này đánh giá khả năng loại bỏ các hợp chất đó khỏi nước mắm làm từ cá chép bằng phương pháp kết hợp axit hóa và sử dụng than hoạt tính (PAC và GAC). Thí nghiệm Jar test theo mẻ và cột dòng chảy cho thấy việc hạ pH xuống 4 giúp tăng cường khả năng hấp phụ, trong đó PAC cho hoạt tính hấp phụ mạnh hơn, còn GAC phù hợp với xử lý liên tục ở quy mô lớn. Phương pháp kết hợp axit hóa và than hoạt tính cho thấy hiệu quả khử mùi cao hơn so với từng phương pháp riêng lẻ. Mặc dù carbon hữu cơ hòa tan và axit amin cạnh tranh vị trí hấp phụ, đánh giá cảm quan xác nhận mùi đất – mùi mốc giảm đáng kể trong khi vẫn giữ được vị umami. Kết quả chỉ ra rằng việc tích hợp axit hóa với xử lý bằng than hoạt tính là một phương pháp hiệu quả nhằm nâng cao chất lượng nước mắm từ cá nước ngọt, đồng thời mang lại lợi ích trong việc tận dụng nguồn cá chép xâm hại ở một số khu vực không có thói quen ăn cá chép.
Copyright (c) 2025 Tạp chí Phân tích Hóa, Lý và Sinh học
SEDIMENT–SEAWATER PARTITIONING OF PER- AND POLYFLUOROALKYL SUBSTANCES IN VIETNAMESE COASTAL WATERS: ROLES OF CHAIN LENGTH AND HYDROPHOBICITY
Các chất per- và polyfluoroalkyl (PFAS) đã được phân tích trong nước biển và trầm tích thu thập từ 20 địa điểm dọc theo bờ biển Việt Nam bằng tàu Viện sĩ Oparin. Nồng độ PFAS thay đổi trong khoảng từ 0,97 đến 10,55 ng/L (trung bình: 5,37 ng/L) trong nước biển và từ 0,195 đến 2,165 ng/g TLK (trung bình: 0,755 ng/g TLK) trong trầm tích. Các PFCA chuỗi ngắn (C4–C7, như PFBA, PFPeA, PFHxA) phổ biến trong nước biển, trong khi các PFCA chuỗi dài (≥ C8 như PFOA, PFNA, PFDA, PFUnDA) có xu hướng tích tụ trong trầm tích. Hệ số phân bố trầm tích-nước biển (log KOC) dao động trong khoảng 3,2–4,8, cho thấy mối tương quan đáng kể với chiều dài chuỗi PFAS (R = 0,94, p < 0,05), và thể hiện xu hướng các PFAS chuỗi dài được ưu tiên hấp phụ vào trầm tích. Kết quả cho thấy ô nhiễm PFAS đáng kể ở vùng nước ven biển Việt Nam, có thể là do chất thải công nghiệp và đô thị. Những phát hiện này nhấn mạnh sự cần thiết phải tăng cường giám sát và quản lý để giải quyết tình trạng ô nhiễm PFAS trong môi trường biển nhiệt đới.
ISOLATION AND STRUCTURE ELUCIDATION OF ENT-KAURANE COMPOUNDS FROM THE MESOCARP OF ANNONA GLABRA L.
Từ dịch chiết điều chế từ phần thịt quả của cây Bình bát nước (Annona glabra L.), một số hợp chất diterpenoid thuộc khung ent-kaurane đã được phân lập, bao gồm: 16-H-ent-kaurane-17-oic acid (1), 16-H-ent-kaurane-17,19-dioic acid (2), ent-kaurane-16-en-19-ol (3), 16-H-ent-kaurane-17,18-dioic acid, 17-methyl ester (4), và 16-dihydroxykauran-19-oic acid (5). Cấu trúc của các hợp chất được thực hiện thông qua các phương pháp phân tích phổ, kết hợp với đối chiếu dữ liệu phổ đã được công bố. Đáng chú ý, đây là lần đầu tiên hợp chất 16-H-ent-kaurane-17-oic acid (1) được báo cáo phân lập từ loài Bình bát nước Annona glabra L.
EFFECT OF SUCROSE ON THE PHYSICOCHEMICAL PROPERTIES OF GLYCEROL-BASED FREEZE-DRIED FERROUS SULFATE LIPOSOMES
This study investigated the effect of sucrose as a freeze-drying protectant for glycerol-based ferrous sulfate liposomes at sucrose/lipid mass ratios of 5:1 and 8:1 (w/w) on particle size, polydispersity index (PDI), and zeta potential. Sucrose at a mass ratio of 8:1 proved superior in maintaining the desired properties of the final product, such as reproducibility of size, PDI, and zeta potential, similar to the liposomes before freeze-drying. Furthermore, FTIR-ATR analysis confirmed the incorporation of iron sulfate into the liposome matrix through the reduction of sulfate vibrations and the alteration of phospholipid phosphate bands, indicating the absence of free crystalline salts. FESEM images confirmed the formation of freeze-dried ferrous sulfate liposomes as spherical structures. Furthermore, short-term stability assessment after 7 days at 4°C showed that the sucrose/lipid ratio = 8 : 1 effectively preserved the integrity of the liposomes after freeze-drying. These results highlight the important role of sucrose in stabilizing glycerol-based ferrous sulfate liposomes.
Copyright (c) 2026 Tạp chí Phân tích Hóa, Lý và Sinh học
RESEARCH ON DISTINGUISHING THE GEOGRAPHICAL ORIGIN OF HOA LOC MANGO VARIETY IN VIETNAM
Mango (Mangifera indica L.) is a tropical fruit of the Anacardiaceae family, origin in the Indo–Burma – Malay region and later spread to other regions. Vietnam is a major global mango producer; however, the expansion of international trade has increased the prevalence of low-quality and fraudulent products, emphasizing the necessity of origin identification for quality assurance and market integrity. This study investigated the traceability of Vietnamese mangoes, especially the valuable Hoa Loc mango variety, through an integrated analytical approach using principal component analysis (PCA) on inductively coupled plasma mass spectrometry (ICP-MS) elemental concentrations. Mango samples from Tien Giang, Vinh Long, Dong Thap, and Can Tho provinces were evaluated for their elemental composition(Mg, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Hg, and Pb). PCA of the elemental data showed significant differences between regions. Important elements for distinguishing mango samples included Mg, Cu, Rb, Sr, Cs. Notably, Can Tho samples had the highest Mg concentration (140.83 µg/g), while Tien Giang had the lowest concentration (28.30 µg/g). Cu concentration in Tien Giang also the lowest of the 4 provinces (0,21±0,02 µg/g) and Can Tho is the highest (1,96±0,04µg/g). The above differences contributed to the assessment of the origin of mango samples. Other notable elements such as Al, Ti Cr, Fe were also analyzed and evaluated by province. The results of this study demonstrate the effectiveness of applying advanced analytical techniques in traceability and quality control of Hoa Loc mangoes in particular, and agricultural products in general.
APPLICATION OF FORWARD OSMOSIS TECHNOLOGY IN THE CONCENTRATION OF WATERMELON JUICE
This research studied the potential application of forward osmosis technology in the concentration of watermelon juice using different inorganic draw solutions, pursuing the express goal of achieving the final juice concentration of 60 °Brix. Particularly, the influences of various operational conditions-which included: type of draw solutes, draw solution concentration, and watermelon juice concentration-on the concentration efficiency of the investigated forward osmosis system were evaluated through the changes in water flux and reverse draw solute flux. Experimental results suggested that water flux would increase with the rise of draw solution concentration, leading to the respective shortening of operational duration, while specific draw solute loss remained relatively stable. Therefore, it would be optimum to use saturated draw solutions in the forward osmosis concentration of watermelon juice, so that any potential losses of useful phytochemicals could be minimized. Overall, this study provided empirical evidence on the capability of forward osmosis technology in the concentrating watermelon juice, presenting an alternative approach that does not involve the utilization of elevated temperature conditions and consequently better in preserving useful but thermal-sensitive phytochemicals present in watermelon juice.
FLAVONOIDS FROM THE LEAVES OF POLYSCIAS FILICIFOLIA
Four compounds, including 3-O-a-L-rhamnopyranoylkaempferol (Afzelin) (1), 7-O-a-L-rhamnopyranosylkaempferol (2), 3-O-β-D-glucopyranosylkaempferol (astragalin) (3), and 3-O-a-L-rhamnopyranosylquercetin (quercitrin) (4) were obtained from ethyl acetate extract of leaves Polyscias filicifolia. Their chemical structures were elucidated via HR-ESI-MS, NMR, and comparison of their spectroscopic data with previous references. All purified flavonol glycosides were announced for the first time from P. filicifolia.
SYNTHESIS AND CYTOTOXIC ACTIVITY OF N-(BROMOPHENYL)-6-FLUOROQUINAZOLIN-4-AMINE DERIVATIVES AGAINST CANCER CELLS
Quinazoline and its derivatives have demonstrated considerable anticancer potential. The incorporation of halogen atoms into aromatic scaffolds is recognized for enhancing pharmacokinetic properties, including potency, metabolic stability, and target selectivity. In the present work, a series of novel quinazoline-based compounds were synthesized through a concise three-step synthetic route, commencing from 5-fluoro-2-nitrobenzaldehyde. The synthesized compounds were assessed for their in vitro cytotoxicity against two human cancer cell lines: hepatocellular carcinoma (HepG2) and lung adenocarcinoma (A549). Notably, the ortho-brominated derivative (compound Va) exhibited markedly higher anticancer activity compared to its meta- and para-substituted counterparts.
ENHANCING THE STABILITY AND REUSABILITY OF Ag3PO4 PHOTOCATALYST THROUGH A COMPOSITE FILM STRUCTURE WITH POLYVINYL ALCOHOL
In this study, Ag3PO4 (APO) was combined with polyvinyl alcohol (PVA) in order to overcome two major limitations of pristine APO: the difficulty of recovery and the susceptibility to photocorrosion. APO/PVA composites were fabricated at different ratios (10:1, 20:1, 30:1, and 40:1) and characterized by XRD, Raman, SEM, and UV–Vis techniques. The results indicated that the PVA coating did not disrupt the crystal lattice structure of APO, while significantly influence on the particle morphology and optical properties. Photocatalytic tests for the degradation of methylene blue (MB) under simulated solar light revealed that APO/PVA-40/1 exhibited the highest activity, whereas APO/PVA-10/1 showed a slower degradation rate but demonstrated superior reusability and durability. After three cycles, APO/PVA-10/1 retained approximately 75% of its MB degradation efficiency, whereas pristine APO, although achieving nearly 100% degradation within 10 minutes in the first cycle, declined sharply to about 45% by the third cycle. Furthermore, the APO/PVA composite in film form could be easily recovered and reused without centrifugation or filtration. These findings confirmed that PVA provided a simple yet effective approach to enhance the practical applicability of APO, thereby opening a pathway for the development of “floating sheet” materials for real-world treatment of organic wastewater.
DEVELOPMENT OF AN UV-Vis SPECTROPHOTOMETRIC METHOD BASED ON THE SCANDIUM-PLUMBAGIN COMPLEX FOR THE DETERMINATION OF SCANDIUM IN INORGANIC FERTILIZER SAMPLES
An UV-Vis spectroscopic method based on the complex formation reaction between Sc3+ ions and plumbagin was developed to determine scandium content in inorganic fertilizers. The formation of the Sc-Plumbagin complex was confirmed through UV-Vis absorption spectroscopy with a characteristic absorption band at 500 nm. Factors influencing the complex formation process and measurement were systematically investigated; the optimal conditions were determined including pH 5.5, plumbagin concentration of 10-3 M, complexation time of 5 minutes with a stability of at least 45 minutes, and an acetonitrile:water solvent system at a ratio of 1:2 (v/v). Under these conditions, the absorbance of the complex showed a good linear relationship with Sc3+ concentration in the range of 1-45 ppm, with a correlation coefficient R2 = 0.9988. The method had a detection limit of 0.24 ppm, a quantification limit of 0.71 ppm, and the repeatability and accuracy met the requirements of quantitative analysis. Analysis of real-world inorganic fertilizer samples showed that the proposed method was feasible, low-cost, and suitable for the determination of scandium by UV-Vis spectroscopy.
STUDY ON THE SIMULTANEOUS DETERMINATION OF POLYBROMINATED DIPHENYL ETHERS AND SOME ALTERNATIVE BROMINATED FLAME RETARDANTS BY GAS CHROMATOGRAPHY - MASS SPECTROMETRY METHOD (GC-MS)
Studies on the characterization of detailed profiles of brominated flame retardants (BFRs), including both legacy and alternative compounds, are still limited in Vietnam. In this study, concentrations of 41 polybrominated diphenyl ethers (PBDEs), hexabromobiphenyl (BB-153), pentabromoethylbenzene (PBEB), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), and decabromodiphenyl ethane (DBDPE), were determined using a gas chromatography - mass spectrometry (GC-MS) method with electron capture negative ionization and selected ion monitoring mode (ECNI-SIM). Several fluorine-labeled compounds (FBDEs) were used as surrogates and internal standards, showing their ability to replace expensive isotope-labeled compounds (13C12-PBDEs). A specific capillary column with relatively short length (15 m) and thinner stationary phase (0.10 μm) was used to prevent thermal degradation of BFRs, especially high-brominated compounds such as decabromodiphenyl ether (BDE-209) and DBDPE. Good chromatographic separation was achieved for most BFRs and labeled compounds. The quantification method showed high accuracy, linearity (R2 > 0.99), and sensitivity (detection limits from 0.13 to 5.0 ng/mL). Concentrations of the target compounds and recoveries of the surrogates were calculated using relative response factors with the internal standard/isotope dilution approach. The validated GC-MS method was successfully applied to analyze BFR concentrations in some settled dust samples collected from northern Vietnam. The total BFR levels ranged from 78 to 57,000 ng/g, with the most predominant compounds as BDE-209 (36–34,000 ng/g) and DBDPE (33–17,000 ng/g). These results indicated the co-occurrence of legacy BFRs (i.e., PBDEs) and their replacement formulations in the environment, suggesting the need for comprehensive monitoring of multiple BFR classes in Vietnam.
SURVEY OF CHEMICAL COMPOSITION AND ACTIVITY OF ESSENTIAL OILS OF EUCALYPTUS GLOBULUS AND EUCALYPTUS CITRIODORA COLLECTED IN DONG THAP PROVINCE
Cây bạch đàn Eucalyptus globulus và cây bạch đàn chanh Eucalyptus citriodora rất phổ biến ở Việt Nam và nhiều quốc gia trên thế giới. Tinh dầu của 2 loài này được sử dụng rộng rãi trong đời sống hàng ngày với nhiều công dụng hữu ích bảo vệ sức khỏe như sát khuẩn, kháng viêm, bảo vệ da, trị mụn, giảm stress,… Mặc dù là 2 loài cùng chi với nhiều đặc điểm tương đồng về cảm quan và công dụng, tuy nhiên kết quả phân tích GC-MS cho thấy chúng hầu như khác biệt về thành phần đơn hương, trong đó thành phần chính của tinh dầu lá E. globulus là α–phellandrene (36.9%), cymol (34.2%) trong khi thành phần chính của tinh dầu lá E. citriodora là citronellal (67.54%), isopulegol (10.09% ), (R)–(+)–β–citronellol (9.9%). Cả 2 loại tinh dầu đều thể hiện hoạt tính kháng oxy hóa yếu đối với gốc tự do DPPH và ABTS•+ trong khi hoạt tính kháng khuẩn tốt trên 5 dòng vi khuẩn Bacillus cereus, Bacillus subtilis,Staphylococcus aureus, Pseudomonas aeruginosa và Escherichia coli.
SURVEY of CONDITIONS for SPORE FORMATION of Geobacillus stearothermophilus ATCC 7953
Biological indicators are considered the gold standard for sterilization process control, one of the criteria for evaluating autoclaves, and a measure that directly reflects the effectiveness of sterilization. In Vietnam, the use of biological indicators to proactively control the effectiveness of the sterilization process has not received due attention and has not been implemented regularly, especially in local medical facilities. Research on Geobacillus stearothermophilus bacteria that create biological indicators is still very limited. This study investigated 16 conditions for the spores formation of G. stearothermophilus ATCC 7953 from 4 culture mediums NA-CaKMgMn, NA-CaMn, YMMn, PCA; 2 pH conditions of 7.0 and 8.5; 2 incubation temperatures of 55oC and 61oC. The research results showed that at pH 8.5 and incubation temperature of 61oC, the rate and proportion of G. stearothermophilus ATCC 7953 spores formation were superior to those at pH 7.0 and 55oC. The four spore formation conditions NA-CaKMnMg/ 8.5/ 61oC, NA-CaMn/ 8.5/ 61oC, YMMn/ 7.0/ 61oC and YMMn/ 8.5/ 61oC had a spore formation rate of over 95% and a spore yield of over 105 cfu/mL. Of which, the condition YMMn/8.5/ 61oC had the fastest rate of G. stearothermophilus ATCC 7953 spores formation, reaching 90% after 4 days. The results of the research could be the premise for further research to create biological indicators that meet ISO standards.
INITIAL RESEARCH ON PHYTOCHEMICAL SCREENING AND BIOCHEMICAL ACITIVITY OF ABELMOSCHUS MOSCHATUS IN THAI NGUYEN PROVINCE
Vong vang (Abelmoschus moschatus) is a medicinal plant that has been widely used in Vietnamese folk medicine. This study presents some initial preliminary research results on the chemical composition and antibacterial ability of stem parts, leaves, and roots of Vong vang plants collected in Dai Tu, Thai Nguyen. Vong Vang leaf extract exhibits better antibacterial activity than stem and root extract against all three bacteria: Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. Vong vang leaf extract shows good ability to inhibit the proliferation of gastric cancer (AGS) and liver cancer (HepG2) cells, IC50 were 27  3 and 35  2 µg/mL, respectively. At concentration 100 µg/mL, the effectiveness of inhibiting AGS and HepG2 cancer cell proliferation is 86.25  0.59 % and 87.30  1.44 %, respectively. These results are a reliable scientific basis for folk remedies as well as the potential for application in the medical field of the Abelmoschus moschatus plant.
RESEARCH ON SEPARATION AND PURIFICATION OF ABRIN FROM THE SEEDS OF ABRUS PRECATORIUS IN VIETNAM
Abrin is a natural lectin found in the seeds of Abrus precatorius. The structure of abrin consists of two chains (Chain A and chain B) with a molecular weight about 65 kDa. Abrin is highly toxic to humans and animals, so it is considered as a dangerous biological agent that can be used in terrorism or biological warfare. This article introduces the process of isolating abrin from the seeds of Abrus precatorius and purifying abrin by ion exchange chromatography and gel filtration chromatography. Purified abrin is used in determining toxicity in animals, testing the sensitivity of rapid detection tests and immunological studies.
SOME COMPOUNDS ISOLATED FROM THE SEAGRASS HALODULE UNINERVIS
From the methanol extract of the seagrass Halodule uninervis, five pure compounds were isolated for the first time from this species using a combination of various chromatographic techniques. The chemical structures of these compounds were elucidated based on the analysis of mass spectrometry data (ESI-MS) and nuclear magnetic resonance spectroscopy (¹H-NMR, ¹³C-NMR, DEPT, HMBC, HSQC, and COSY), in conjunction with comparisons to previously published literature. The identified compounds include 3,3’,4’ tri-O-methylellagic acid, catechin, naringenin-4’,7-dimethyl ether, quercetin and quercetin-3-O-rutinoside
STUDY ON DETERMINATION OF β-ECDYSTERONE AND CHEMICAL CONSTITUENTS FROM THE ROOT OF ACHYRANTHES BIDENTATA BLUME, COLLECTED IN HUNGYEN
In this study, we have developed a quantitative method β-ecdysterone in root samples of Achyranthes bidentata Blume colleted in Hungyen. Only a sample (NT03) had β-ecdysterone content of 0.051 ± 0.001 %, while the others were below 0.03%. Four compounds including acutoside A (1), calendoloside E (2), β ecdysterone (3) and daucosterol (4) were isolated from NT03 sample. Their chemical structures were determined by MS, 1D-, 2D-NMR spectral methods, which were compared with the data reported in previous literature.
EVALUATION OF GREEN ULTRASOUND-ASSISTED EXTRACTION OF SULFAMETHOXAZOLE FROM SOIL WITH LC-MS ANALYSIS
This study aimed to optimize the extraction conditions for sulfamethoxazole (SMX) from soil matrices using green ultrasound-assisted extraction combined with LC-MS analysis. Two buffer systems, phosphate and Mcllvaine, at different concentrations (1 mM and 10 mM) and pH values ranging from 3 to 7 were evaluated. A three-way ANOVA revealed that soil type, buffer type, and pH significantly influenced SMX recovery, with notable interactions among these factors (p < 0.001). Both phosphate and Mcllvaine buffers at 1 mM concentration and pH 3 provided the highest and most stable SMX recovery (>100%) across two contrasting soils (S1 and S2). Conditions of low ionic strength and acidic pH significantly enhanced the desorption efficiency of sulfamethoxazole (SMX). In contrast, increasing the buffer concentration – especially when using Mcllvaine buffer—resulted in reduced recovery rates, likely due to the formation of metal-ligand complexes and ion suppression effects. The findings highlight phosphate 1 mM and Mcllvaine 1 mM at pH 3 as optimal green extraction solutions for SMX analysis in diverse soil environments, providing a reliable and environmentally friendly approach for monitoring antibiotic residues in agricultural soils.
RESEARCH TO DETERMINE OF THE CONTENT OF SOME HEAVY METALS IN OCIMUM TENUIFLORUM IN THE NORTH CENTRAL REGION BY ATOMIC ABSORPTION SPECTROSCOPY (AAS)
The content of some heavy metals such as cadmium, copper, iron, manganese, nickel, lead, and zinc (Cd, Cu, Fe, Mn, Ni, Pb, Zn) in Ocimum Tenuiflorum grown in the two provinces of Nghe An and Ha Tinh in the North Central region of Vietnam has been determined using atomic absorption spectroscopy with flame atomization (F-AAS) after sample digestion in microwave oven. The analysis results were compared with the agricultural crop guidelines of FAO/WHO, showing that the heavy metal content was within the limits. The analysis results were also compared with some other studies on Ocimum Tenuiflorum finding that the content of Cu, Fe, Mn, Zn was higher, while the content of Cd, Ni, Pb was lower. According to WHO standards on medicinal herbal ingredients, the content of Cd, Cu, Mn, Pb below the permissible limits in all samples; the content of Fe in HN1, HN3, HN5 samples exceeded the recommended value; the content of Zn in the HN4 sample exceeded the permissible limits. The concentration range of heavy metals varies, with the levels of toxic metals such as Cd, Pb, and Ni all below the detection limit for all samples. For other heavy metals, the content of Fe and Mn in sample HN1 (191.606; 96.429 mg/kg); the content of Cu and Zn in sample HN4 (16.597; 133.561 mg/kg) is the highest. The analysis method used has a low detection limit, achieving thresholds lower than 59 ppb for Cd, Fe, Mn, Ni, Pb, Zn and 0.1 ppm for Cu. The relative standard deviation (% RSD) of 10 repeat measurements of low-concentration heavy metal content is all less than 3.530%; and the recovery of elements are in the range from 87.652 to 109.812%, which meets AOAC requirements for trace.
DEVELOPMENT OF LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY (LC-MS/MS) METHOD FOR DETERMINATION OF CERTAIN PER- AND POLYFLUOROALKYL SUBSTANCES (PFAS) IN FOOD
PFAS are a large, complex group of synthetic chemicals that are highly resistant to degradation in the environment. They may cause cancer and adverse effects on the reproductive and immune systems. In this study, 16 PFAS compounds were determined in food samples (fish, meat, vegetables) using the LC-MS/MS method to assess contamination levels and support food safety risk control. A reversed-phase C18 chromatography column (150 mm × 2.1 mm; ID 3.5 µm) was used to separate the 16 compounds. The mobile phase consisted of (A) 2 mM ammonium acetate (CH3COONH4 )/methanol (MeOH) (9/1, v/v) and (B) MeOH. The extraction solvent was 1% formic acid (HCOOH)/acetonitrile (ACN), and the extraction salt compositions contained 6 g MgSO₄ combined with 2 g NaCl. Samples were cleaned up by d-SPE composition of 1.2 g MgSO₄ combined with 0.2 g PSA and 0.2 g C18, and SPE using Polymeric Weak Anion SPE cartridge. The calibration curves for the 16 substances, within a concentration range of 0.1–5.0 µg/kg, showed correlation coefficients (R²) greater than 0.995. The method achieved recoveries ranging from 75.7% to 110%, with relative standard deviations (RSDs) between 1.46% and 9.72%. The method detection limit (MDL) and method quantitation limit (MQL) were 0.03 µg/kg and 0.1 µg/kg, respectively. This method was applied to the analysis of 20 food samples, and the results showed that 5 of these samples tested positive for specific PFAS compounds. This study may lay the foundation for developing quantitative procedures for PFAS groups in various food matrices.
ISOLATION OF PHENOLIC COMPOUNDS FROM THE AERIAL PARTS OF EXCOECARIA COCHINCHINENSIS
Cây Đơn lá đỏ (Excoecaria cochinchinensis) thuộc họ Thầu dầu (Euphorbiaceae), từ lâu đã được sử dụng rộng rãi trong y học dân gian để điều trị các bệnh ngoài da như nhọt, phát ban, cũng như đau bụng, tiêu chảy, viêm khớp, rối loạn da và một số bệnh nhiễm trùng. Trong nghiên cứu này, từ dịch chiết methanol của E. cochinchinensis thu hái tại tỉnh Hòa Bình, sáu hợp chất đã biết đã được phân lập, bao gồm kaempferol (1), quercetin (2), kaempferol 3-O-β-D-xylopyranoside (3), scopoletin (4), methyl protocatechuate (5) và methyl gallate (6). Cấu trúc của các hợp chất này được xác định thông qua phổ NMR và so sánh với tài liệu tham khảo. Đặc biệt, hai hợp chất số 3 và 5 lần đầu tiên được phân lập từ cây này.
CHITOSAN-BASED MICROCAPSULES FOR ESSENTIAL OIL VIA IONIC GELATION
Nghiên cứu tập trung tổng hợp polymer sinh học Chitosan (CS) có nguồn gốc từ Chitin và các hạt Microcapsule Chitosan bọc tinh dầu sả chanh(CSO) được điều chế bằng phương pháp gel ion để tạo liên kết ion giữa CS với Sodium Tripolyphosphate (STPP). Các đặc trưng của hạt CS, CS – STPP, CSO được xác định bằng kính hiển vi điện tử quét (SEM), kính hiển vi quang học (OM) và đánh giá phân bố kích thước hạt bằng tán xạ ánh sáng động (DLS). Ảnh hưởng của các thông số pH và thời gian phản ứng giữa CS và STPP cũng như vai trò của STPP đến quá trình hình thành hạt Microcapsule CSO đã được nghiên cứu. Kết quả chỉ ra hạt Microcapsule có khả năng bao bọc lấy tinh dầu bên trong khi STPP tạo liên kết ngang với CS bằng liên kết ion. Kích thước hạt CSO phân bố nhiều nhất từ 40 – 80 m. Thông số thực nghiệm để tạo CS STPP tối ưu là nồng độ STPP 1% ở môi trường pH 9 và thời gian phản ứng tối ưu là 2h.
STUDY ON THE METHOD FOR ANALYSIS OF PARABENS IN SWIMMING POOL WATER SAMPLES
Nghiên cứu đã phát triển phương pháp xác định đồng thời 7 hợp chất paraben trong mẫu nước bằng phương pháp sắc ký lỏng ghép nối khối phổ (LC-MS/MS) kết hợp với kỹ thuật chiết pha rắn. Paraben được tách sắc ký trên cột C18 (Kinetex: 150 mm x 2,1 mm, 2,6 µm, P/N 00F-4462-AN), với pha động (A): acetic acid (AcOH) 0,05% và (B): Methanol (MeOH). Mẫu nước được axít hóa đến pH~3 bằng axít formic. 100 ng mỗi chất đồng hành (13C-MeP and 13C-BuP) được thêm vào 100 mL nước. Mẫu nước sau đó được cho qua cột SPE (Oasis HLB 500 mg), đã được hoạt hóa trước đó lần lượt bằng 3 mL MeOH và 3 mL nước siêu tinh khiết. Các chất phân tích được rửa giải bằng 5 mL MeOH. Dung dịch sau rửa giải được cô đặc đến 1 mL dưới dòng khí nitrogen. Dung dịch cuối cùng được lọc qua giấy lọc Whatman (kích thước lỗ: 0,2 µm) và tiến hành phân tích trên thiết bị LC-MS/MS. Đường chuẩn của các chất phân tích được xây dựng trong khoảng nồng độ 0,5-200 ng/mL (R2 > 0,997). Độ thu hồi của các chất đồng hành 13C-MeP và 13C-BuP tương ứng trong khoảng 85,5–105% (RSD < 9,5) và 88,0–110% (RSD < 8,0). Giới hạn phát hiện của phương pháp đối với các chất paraben trong mẫu nước nằm trong khoảng 0,2 đến 1,6 ng/mL. Phương pháp tối ưu đã được áp dụng để xác định nồng độ các paraben trong 24 mẫu nước bể bơi thu tại khu vực Hà Nội và bước đầu đánh giá mức độ phân bố của paraben trong các bể bơi.
STUDY STRUCTURE AND THE PHOTOCATALYTIC ACTIVITIES DEGRADATION OF RHODAMINE B ON ZnO/g-C3N4/PVDF MEMBRANE MATERIAL
ZnO/g-C3N4 composites were loaded onto a polyvinylidene fluoride (PVDF) membrane using a phase inversion method to obtain a photocatalytic flat membrane for Rhodamine B(RhB) dye removal. Material properties were studied by modern physicochemical methods of X-ray diffraction (XRD), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and photoluminescence (PL) spectrum. XRD and FT-IR studies confirmed the incorporation of ZnO and g-C3N4 into the PVDF substrate. In addition, the hetero-structures formed between ZnO and g-C3N4 nanosheets promoted the separation of photogenerated electron-holes in the g-C3N4 layer. They improved the photocatalytic and anti-fouling performance of the ZnO/g-C3N4/PVDF composite. The photocatalytic activity of the materials was evaluated through the RhB dye degradation reaction under visible light, resulting in the ZnO/g-C3N4/PVDF composite film with the highest efficiency (90.00%). Therefore, this research is expected to be extended to environmental treatment.
THE STRUCTURE AND OPTICAL INTERACTION WITH SINGLET OXYGEN OF THE Y3+, Eu3+ COMPLEXES CONTAINING 2-THENOYLTRIFLUOROACETONE AND ANTHRACENE LIGANDS
The complexes of Y3+ and Eu3+ rare earth elements with 2-Thenoyltrifluoroacetone (HTFTB) as ligand and N,N-Dimethyl-N'-(9-methylanthracenyl)ethylenediamine (AnMe2) as auxiliary ligand were synthesized. Two new complexes M1, M2 were structurally investigated using infrared and mass spectrometry. The structure of the [Y(TFTB)3AnMe2] (M1) complex was determined by nuclear magnetic resonance spectroscopy. The luminescent property of the [Eu(TFTB)3AnMe2] (M2) complex was investigated using absorption spectroscopy and photoluminescence spectroscopy. The results indicate that Y3+ and Eu3+ ions are coordinated to six oxygen atoms from three TFTB– ligands and two nitrogen atoms of AnMe2 ligand. The Eu3+ complexes exhibit strong absorption in the 220 – 400 nm range. Upon reaction with 1O2 (singlet oxygen), the M2 complex transforms into M2-EPO, which displays a luminescence intensity nearly three times higher than that of M2.
SURVEY OF CHEMICAL COMPOSITION AND ACTIVITY OF ESSENTIAL OILS OF MELALEUCA ALTERNIFOLIA AND MELALEUCA CAJUPUTI COLLECTED IN DONG THAP PROVINCE
Melaleuca Cajuputi and Malaleuca Alternifolia are very popular in Vietnam and many countries around the world. Essential oils distilled from these two plants are commonly used in daily life with many useful applications. This study investigated the chemical composition, antibacterial and antioxidant activities of Melaleuca Cajuputi and Malaleuca Alternifolia collected in Dong Thap province. The results showed that, in terms of chemical composition, they have similar main compounds such as 1,8-cineol, γ-terpinene, terpinen-4-ol, α-terpineol, terpinolene, but with remarkably differences in contents. Both essential oils demonstrated the ability to neutralize DPPH free radicals ((1) IC50 = 42.1 g/ml; (2) IC50 = 69,8 g/ml), ABTS•+ ((1) IC50 = 202.3 g/ml; (2) IC50 = 292.3 g/ml) and antibacterial activity on three bacterial strains E. Coli, B. cereus and S. aureus when tested using the agar disk diffusion method.
STUDY ON THE FLUORESCENCE DETERMINATION OF KANAMYCIN USING COMBINATION OF g-C3N4/AuNPs
The risk of exposure to aminoglycoside antibiotic resistance genes increases the incidence of infections caused by drug-resistant bacteria, leading to clinical treatment failure with kanamycin. This situation necessitates the urgent implementation of new strategies to control antibiotic resistance. In this study, we developed a highly sensitive fluorescence “on-off” nanosensor for kanamycin detection based on the interaction between g-C₃N₄ and gold nanoparticles (AuNPs). The addition of AuNPs to the g-C₃N₄ solution resulted in fluorescence quenching (off effect). However, in the presence of kanamycin, the fluorescence signal was restored due to the analyte binding to AuNPs and releasing g-C₃N₄ (on effect). Under optimal conditions (6 mM Na₂SO₄, pH 7.0, incubation time of 15 minutes), the method demonstrated a wide linear range from 10 nM to 500 nM with high accuracy (RSD < 5%). This approach was successfully applied for kanamycin detection in pharmaceutical samples, highlighting its potential for antibiotic residue monitoring and antibiotic resistance mitigation.
INVESTIGATING THE DETERMINATION OF TYRAMINE IN CHEESE USING GOLD NANOPARTICLES (AUNPS) IN COMBINATION WITH NITROGEN-DOPED CARBON QUANTUM DOTS (N-CQDS) SYNTHESIZED BY MICROWAVE-ASSISTED METHOD
Tyramine is a biogenic amine commonly found in products such as cheese, fish sauce, soy sauce, and kimchi due to the decarboxylation of tyrosine during fermentation or decomposition. It is also one of the parameters used to evaluate product quality. In this study, we developed a cost-effective and environmentally friendly method to detect tyramine in food using fluorescence techniques with nitrogen-doped carbon quantum dots (N-CQDs) combined with gold nanoparticles (AuNPs). N-CQDs were synthesized simply from citric acid and urea within 5 minutes using a household microwave. These N-CQDs were then employed as reducing agents to convert Au(III) salts into gold nanoparticles. The N-CQDs exhibited fluorescence quenching in the presence of AuNPs and fluorescence recovery in tyramine. Under optimal conditions, the fluorescence recovery of the N-CQDs/AuNPs system showed a linear relationship with tyramine concentration in the range of 0.02 ppm to 1 ppm. The method demonstrated a relatively low limit of detection (LOD) at 6 ppb, high recovery rates, and good repeatability (RSD < 5%). The method successfully detected tyramine in cheese samples, yielding reliable results.
STUDY ON SELECTIVE ADSORPTION AND ENRICHMENT OF MALACHITE GREEN ON MOLECULARLY IMPRINTED POLYMER (MIP) MATERIALS FOR SEAFOOD ANALYSIS APPLICATION
Malachite Green is a dye with the ability to treat diseases caused by parasites, fungi, and bacteria in aquatic animals. However, due to its toxicity to humans, it has been banned in most countries worldwide, especially in Vietnam. In this study, we synthesized molecularly imprinted polymer (MIP) materials selective for Malachite Green (MG) through a copolymerization reaction between the monomer methacrylic acid (MAA) and the cross-linking agent ethylene glycol dimethacrylate (EGDMA), initiated by azobisisobutyronitrile (AIBN) in an acetonitrile:methanol mixture (3:1, v/v). The maximum adsorption capacity was 23.81 mg. g 1 at optimum conditions, pH 5.0, m = 7mg, t=40 min and the imprinted factor max was 2.3. High adsorption selectivity of MG over other dyes having the same blue color such as Blue Briliant, Fast Green was obtained. The synthesized MIP had enrichment factor of 50 times with high desortpion efficiency of 95.31%; as well as good reusablity of at least 5 times. The application of material to enrich MG in fish samples provided a recovery efficiency reaching 94.9% to 107.3%. The obtained results reflected the selective analytical capability and enrichment potential of MIP for MG.
RESEARCH ON DIOXIN COMPOUNDS IN ASH SAMPLES COLLECTED AT MAN XA ALUMINUM RECYCLING VILLAGE, BAC NINH PROVINCE
The study investigated to determine several dioxin compounds in the ash samples collected at Man Xa aluminum recycling village (Van Mon commune, Yen Phong district, Bac Ninh province). Dioxin compounds were extracted by Thermo ASE 350 Solvent Accelerator (Thermo, USA) and analysed using HRGC/HRMS gas chromatography equipment (Thermo Trace 1310, Thermo, USA) coupled with DFS high resolution mass spectrometry system. Results, the average concentrations of dioxin/furan compounds in fly ash and bottom ash samples were 16.9-979 (ng/kg d.w) and 0.422-10.2 (ng/kg d.w), respectively. The total equivalent toxic concentrations of dioxin/furan compounds in fly ash samples ranged from 284 to 423 ng TEQ/kg d.w, while those in bottom ash samples were from 3.17 to 7.93 ng TEQ/kg d.w. Interestingly, these values are within the permissible limits according to the national technical regulation on hazardous waste thresholds (QCVN 07:2009/BTNMT). However, the exploitation and use of fly ash and bottom ash for different purposes, that can cause environmental pollution and pose potential risks to human health if not controlled and managed appropriately. Therefore, it is necessary to expand research to minimize the impacts of dioxin/furan compounds present in fly ash and bottom ash on the environment and human life, gradually helping authorities have the basis to issue sanctions to better monitor and manage the activities of metal recycling villages in general and Man Xa aluminum recycling village in particular.