Determination of theobromine and caffeine in some Malaysian beverages by liquid chromatography-time-offlight mass spectrometry

Purpose: To determine the concentration of theobromine (TB) and caffeine (CF) in tea and other beverages using liquid chromatography-time of flight-mass spectrometry (LC-TOF-MS).Methods: The extract of caffeine and theobromine from tea and other beverages was filtered by 0.45 μm nylon micro-syringe and then injected into a LC-ToF-MS system. Theobromine and caffeine were separated using Thermo Scientific C18-column (length 250 mm, width 2.1 mm and diameter 5 μm). Acetonitrile-methanol (ACN – MeOH, 3:1 v/v) was used as mobile phase B, while mobile phase A was 0.1 % FA in DIW. The volume injected was 30 μL at a rate of 0.3 mL/min.Results: Good linearity was obtained in the range of 0.3 – 400 and 0.2 – 200 mg/L for theobromine and caffeine, respectively (regression coefficient (R2) > 0.970). The limits of detection were 0.15 and 0.05 μg/mL for theobromine and caffeine,  respectively. The highest concentrations of caffeine and theobromine determined in tea samples were 159.1 and 255.8 mg/L, respectively.Conclusion: Theobromine and caffeine have been successfully analysed in tea, coffee and soft drinks. LC-TOF-MS is an accurate and promising instrument for the  determination of the studied compounds in beverages.Keywords: Theobromine, Caffeine, Tea, Coffee, LC-TOF/M

Machine learning-based country-level annual air pollutants exploration using Sentinel-5P and Google Earth Engine

Climatic condition is triggering human health emergencies and earth’s surface changes. Anthropogenic activities, such as built-up expansion, transportation development, industrial works, and some extreme phases, are the main reason for climate change and global warming. Air pollutants are increased gradually due to anthropogenic activities and triggering the earth’s health. Nitrogen Dioxide (NO2), Carbon Monoxide (CO), and Aerosol Optical Depth (AOD) are truthfully important for air quality measurement because those air pollutants are more harmful to the environment and human’s health. Earth observational Sentinel-5P is applied for monitoring the air pollutant and chemical conditions in the atmosphere from 2018 to 2021. The cloud computing-based Google Earth Engine (GEE) platform is applied for monitoring those air pollutants and chemical components in the atmosphere. The NO2 variation indicates high during the time because of the anthropogenic activities. Carbon Monoxide (CO) is also located high between two 1-month different maps. The 2020 and 2021 results indicate AQI change is high where 2018 and 2019 indicates low AQI throughout the year. The Kolkata have seven AQI monitoring station where high nitrogen dioxide recorded 102 (2018), 48 (2019), 26 (2020) and 98 (2021), where Delhi AQI stations recorded 99 (2018), 49 (2019), 37 (2020), and 107 (2021). Delhi, Kolkata, Mumbai, Pune, and Chennai recorded huge fluctuations of air pollutants during the study periods, where ~ 50–60% NO2 was recorded as high in the recent time. The AOD was noticed high in Uttar Pradesh in 2020. These results indicate that air pollutant investigation is much necessary for future planning and management otherwise; our planet earth is mostly affected by the anthropogenic and climatic conditions where maybe life does not exist.Validerad;2023;Nivå 2;2023-05-22 (hanlid)</p

Investigation of the environmental transport of human pharmaceuticals to surface water: a case study of persistence of pharmaceuticals in effluent of sewage treatment plants and hospitals in Malaysia

The present work reports the occurrence and monitoring of 11 pharmaceuticals (i.e., caffeine, prazosin, enalapril, carbamazepine, nifedipine, gliclazide, levonorgestrel, simvastatin, hydrochlorothiazide, diclofenac-Na and mefenamic acid) in surface water and in the influent and effluent of sewage treatment plants (STPs) and hospitals (HSPs). A total of 105 water samples were analyzed using solid-phase extraction combined with liquid chromatography-time-of-flight/ mass spectrometry (SPE-LC-TOF/MS). The mean concentrations of the detected pharmaceuticals in STP influent and effluent ranged from limit of quantification (LOQ) to 3909 ng L-1 and 12 to 577 ng L-1, respectively. The mean concentrations of the detected pharmaceuticals in the hospital influent and effluent ranged from 28 to 1644 ng L-1 and 20 to 1540 ng L-1, respectively. The highest concentration detected in the sampling points was 9099 ng L-1 for caffeine in influent STP. The presence of prazosin has never been reported before in literature. In this study, prazosin was detected in all studied samples, and the highest concentration was 525 ng L-1 in influent STP. Chemometric analysis was used to assess the presence of pharmaceuticals in samples

Thermal and Hydraulic Performances of Carbon and Metallic Oxides-Based Nanomaterials

For companies, notably in the realms of energy and power supply, the essential requirement for highly efficient thermal transport solutions has become a serious concern. Current research highlighted the use of metallic oxides and carbon-based nanofluids as heat transfer fluids. This work examined two carbon forms (PEG@GNPs & PEG@TGr) and two types of metallic oxides (Al2O3 & SiO2) in a square heated pipe in the mass fraction of 0.1 wt.%. Laboratory conditions were as follows: 6401 ≤ Re ≤ 11,907 and wall heat flux = 11,205 W/m2. The effective thermal–physical and heat transfer properties were assessed for fully developed turbulent fluid flow at 20–60 °C. The thermal and hydraulic performances of nanofluids were rated in terms of pumping power, performance index (PI), and performance evaluation criteria (PEC). The heat transfer coefficients of the nanofluids improved the most: PEG@GNPs = 44.4%, PEG@TGr = 41.2%, Al2O3 = 22.5%, and SiO2 = 24%. Meanwhile, the highest augmentation in the Nu of the nanofluids was as follows: PEG@GNPs = 35%, PEG@TGr = 30.1%, Al2O3 = 20.6%, and SiO2 = 21.9%. The pressure loss and friction factor increased the highest, by 20.8–23.7% and 3.57–3.85%, respectively. In the end, the general performance of nanofluids has shown that they would be a good alternative to the traditional working fluids in heat transfer requests