Single versus Double Coffee-Ring Effect Patterns in Thin-Layer Chromatography Coupled with Surface-Enhanced Raman Spectroscopic Analysis of Anti-Diabetic Drugs Adulterated in Herbal Products.

In thin-layer chromatography coupled with surface-enhanced Raman spectroscopy (TLC-SERS), the coffee ring effect (CRE) describes the formation of a ring-shape spot (blank in the middle and darker on the edge) caused by the aggregation of silver nanoparticles (Ag NPs), alone (single CRE) or with the analytes (double CRE). In this work, the SCRE and DCRE were investigated in two anti-diabetic drugs, hydrophobic glibenclamide (GLB) and more hydrophilic metformin (MET). The SCRE occurred in GLB analysis, as opposed to the DCRE that occurred in MET. It was proven that for optimization of the TLC-SERS analytical procedure, it is necessary to distinguish the CRE patterns of analytes. Additionally, MET and GLB were analyzed with the developed TLC-SERS method and confirmed by another validated method using high-performance liquid chromatography. Four herbal products collected on the market were found to be adulterated with GLB or/and MET; among those, one product was adulterated with both MET and GLB, and two products were adulterated with GLB at a higher concentration than the usual GLB prescription dose. The TLC-SERS method provided a useful tool for the simultaneous detection of adulterated anti-diabetic herbal products, and the comparison of the SCRE and DCRE provided more evidence to predict CRE patterns in TLC-SERS.

Use of artificial sweeteners and caffeine in a population of Hanoi: An assessment by wastewater-based epidemiology.

Monitoring the consumption of artificial sweeteners in the population is essential to help public health authorities understand the level of sugar consumption. There is a gap in knowledge of patterns and levels of artificial sweetener consumption in Vietnam. Using wastewater-based epidemiology (WBE), this study aims to evaluate the use of artificial sweeteners in an urban population in Hanoi, Vietnam. A total of 184 wastewater samples were collected at two sampling sites in an urban canal, receiving sewage from over 400,000 people in three different periods between 2018 and 2020. The population normalized per capita consumption of the five detected artificial sweeteners varied from 0.87 mg d-1 p-1 (sucralose) to 5.2 mg d-1 p-1 (aspartame). The daily consumption of artificial sweeteners was found to be stable throughout the week, however the consumption of artificial sweeteners was influenced by season with higher consumption in summer. Significant correlations (p < 0.01) were found among levels of artificial sweeteners and caffeine in urban canal samples, suggesting these chemicals had common sources. Population-weighted consumption load of artificial sweeteners and caffeine was compared in Vietnam, China and Australia, and the per capita consumption load mainly depended on the habitual of tea/coffee drinking in different countries. This was the first study that provided information on the artificial sweetener consumption by wastewater analysis in Vietnam. However, several sources of uncertainty (sample collection, population estimation, other sources of artificial sweeteners in wastewater, etc.) were acknowledged in this study. Further investigations on the spatial-temporal variation of artificial sweetener consumption with more intensive sampling scheme in Vietnam are recommended.

Assessing changes in nicotine consumption over two years in a population of Hanoi by wastewater analysis with benchmarking biomarkers.

Monitoring the actual change in consumption of nicotine (a proxy for smoking) in the population is essential for formulating tobacco control policies. In recent years, wastewater-based epidemiology (WBE) has been applied as an alternative method to estimate changes in consumption of tobacco and other substances in different communities around the world, with high potential to be used in resource-scarce settings. This study aimed to conduct a WBE analysis in Hanoi, Vietnam, a lower-middle-income-country setting known for high smoking prevalence. Wastewater samples were collected at two sites along a sewage canal in Hanoi during three periods: Period 1 (September 2018), Period 2 (December 2018-January 2019), and Period 3 (December 2019-January 2020). Concentrations of cotinine, 3-hydroxycotinine, and nicotine ranged from 0.73 µg/L to 3.83 µg/L, from 1.09 µg/L to 5.07 µg/L, and from 0.97 µg/L to 9.90 µg/L, respectively. The average mass load of cotinine estimated for our samples was 0.45 ± 0.09 mg/day/person, which corresponds to an estimated daily nicotine consumption of 1.28 ± 0.25 mg/day/person. No weekly trend was detected over the three monitoring periods. We found the amount of nicotine consumption in Period 1 to be significantly lower than in Period 2 and Period 3. Our WBE estimates of smoking prevalence were slightly lower than the survey data. The analysis of benchmarking biomarkers confirmed that cotinine was stable in the samples similar to acesulfame, while paracetamol degraded along the sewer canal. Further refinement of the WBE approach may be required to improve the accuracy of analyzing tobacco consumption in the poor sewage infrastructure setting of Vietnam.

Prevalence of illicit drug consumption in a population of Hanoi: an estimation using wastewater-based epidemiology.

Illicit drug use is a serious issue in Vietnam, but information about their prevalence is scarce, mainly based on seizure data. Wastewater-based epidemiology (WBE) is an alternative tool for obtaining such information, especially when stigma related to drug use can hinder survey approaches. The study aimed to apply WBE to assess the prevalence of use of a range of illicit drugs in an urban population of Vietnam. A total of 184 wastewater samples were collected at two different sites along a sewage canal, receiving sewage from over 400,000 people in Hanoi, Vietnam, in three different periods between 2018 and 2020. Illicit drugs and their metabolites were measured by direct injection using liquid chromatography-tandem mass spectrometry. The results were back-estimated, normalised to per capita daily consumption for assessement of consumption patterns and trends. Most drugs were detected in all the samples except cocaine, benzoylecgonine, amphetamine indicating a low prevalence of cocaine and amphetamine use. The estimated consumption level of methamphetamine was varied from 119.5 to 553.5 mg/d/1000 pp. The market of illicit drugs in Vietnam has changed from opiates to amphetamine-type simulants, and methamphetamine has replaced heroin as the No.1 drug, its use can be as much as 3 times more than heroin use. Moreover, we observed the considerable and potentially increasing level of ketamine consumption in Hanoi. No statistical difference was found in daily consumption per capita among days of the week for any drugs, both legal (codeine, methadone) and illegal (methamphetamine, MDMA, ketamine and heroin), suggesting the drugs were consumed mainly by regular users. This study provides important information related the illicit drug consumption in Vietnam, which will help to formulate appropriate drug control policies in this country.

Detection of sildenafil adulterated in herbal products using thin layer chromatography combined with surface enhanced Raman spectroscopy: "Double coffee-ring effect" based enhancement.

Sildenafil is an inhibitor of the phosphodiesterase type 5 which is commonly adulterated in herbal health products. In this study, a rapid, sensitive and selective method using thin layer chromatography (TLC) combined with surface-enhanced Raman spectroscopy (SERS) was developed for identification of sildenafil adulteration in herbal drugs and dietary supplements. TLC separation method was developed and different SERS factors were investigated: nanosilver colloid preparation, concentration and volume, and coffee-ring effect (CRE) enhancement for SERS measurement. "Double CRE" - a newly observed effect that resulted in the redistribution of both silver nanoparticles and sildenafil molecules - was reported for the first time in TLC-SERS applications. This method presented an efficient TLC-SERS performance enhanced by the "hot spots" obtained under double CRE. The method was validated in terms of selectivity on three blank matrixes (capsule, granule, and herbal extract) and sensitivity with a limitation of detection (LOD) of 2 ng/spot for sildenafil. The validated method was implemented on 9 herbal products sold on the market as erectile dysfunction therapy. Two products were detected with sildenafil adulteration by the TLC-SERS method and confirmed by parallel LC-MS/MS analysis. These results exhibited the reliability and feasibility of the developed method in adulteration screening for sildenafil. On the other hand, the novel findings on double CRE provided extra information for CRE optimization in TLC-SERS applications.

Occurrence of antibiotic residues and antibiotic-resistant bacteria in effluents of pharmaceutical manufacturers and other sources around Hanoi, Vietnam.

Pharmaceutical manufacturers in Vietnam are producing a wide variety of antibiotics for human and veterinary use. Consequently, the water discharged from those facilities can contain residues of antibiotics, which could have adverse impact on the environment. However, studies on the occurrence of antibiotics in the wastewater from pharmaceutical manufacturers in Vietnam are almost non-existent. In this study, water samples were collected at around the outlets of four pharmaceutical manufacturing plants as well as from a hospital and an aquaculture farm around Hanoi in 2016 and 2017. Fifteen antibiotics from four major classes (ß-lactam, quinolones, macrolides, sulfonamides) were monitored, using a validated LC-MS/MS method, based on their number of registrations at the Ministry of Health. Ten antibiotics, ampicillin, cefuroxime, cefotaxime, clarithromycin, azithromycin, sulfamethoxazole, trimethoprim, ofloxacin, norfloxacin, and ciprofloxacin were detected in the samples at different concentrations. Notably, sulfonamides and quinolones were occasionally detected at very high concentration, such as sulfamethoxazole (252 µg/L), trimethoprim (107 µg/L), ofloxacin (85 µg/L), and ciprofloxacin (41 µg/L). In this study, concentrations of antibiotic residues in effluent of pharmaceutical plants were higher than those from other sources. The antibiotic-resistance tests indicated the widespread resistance to common antibiotics like quinolone and sulfonamides in the collected samples. This finding suggests that wastewater from pharmaceutical manufacturers could be an important source of antibiotics and antibiotic-resistant bacteria in the aquatic environment of Vietnam.

Antibiotics in the aquatic environment of Vietnam: Sources, concentrations, risk and control strategy.

The presence of antibiotics in the aquatic environment is a serious concern because it may lead to the emergence of antibiotic resistance, thus lowering the therapeutic effect of antibiotics. In Vietnam, the problem is aggravated by the irrational use of antibiotics in different sectors of agriculture and human health service. Moreover, the residues of antibiotics in the aquatic environment can be spread widely due to the lack of proper wastewater treatment systems. In this paper, we aim to comprehensively review all relevant sources that discharge antibiotics to the aquatic environment in Vietnam. Apart from the common source of antibiotics from aquaculture, other activities that release considerable amounts of antibiotics into water environment are also included. Environmental concentrations of antibiotics related to those sources are studied to demonstrate their contributions to the presence of antibiotics in the aquatic environment in Vietnam. As antibiotic-contained water may be used as water supply for irrigation and even human consumption in rural areas, the essence of wastewater treatment is highlighted. Finally, we also discuss the new National Action plan from the Ministry of Health for controlling the issue of antibiotic resistance in Vietnam.