Two important air pollutants, sulfur dioxide (SO) and nitrogen dioxide (NO), were sampled and monitored in the spring season in the biggest industrial area of Bhutan. Field measurements of SO and NO were performed using standard colorimetric methods, and air samples were collected using an active sampling technique. Sampling sites were selected to cover all the potential catchment areas like settlements, staff quarters, shops and schools. The main objective of this sampling work was to see the distribution of these two pollutants from the source of emission (small scale industries) and to obtain and establish a baseline data. The active sampler was first tested and validated in a laboratory using liquid and gas standards of SO and NO. Good linearity from 0.050 to 1.0 µg mL for SO and from 0.010 to 1.0 µg mL for NO were obtained (R > 0.99) with limits of detection of 30 and 50 ng mL for SO and NO, respectively. Daylong sampling was done at selected sites with a range of distances away from the sources of emission. The ambient concentration of SO and NO were in the range of 0.45-4.46 and 0.56-5.68 µg m, respectively.

A laboratory-built printed circuit board (PCB) passive sampler used for the monitoring of xylene and styrene in copy print shops was re-validated for detecting benzene, toluene and xylene (BTX) and applied for the sampling of ambient air from Hat Yai city, Songkhla, Thailand, in the month of November 2014. For monitoring, the PCB passive samplers were exposed to target analytes in 16 locations covering high to low exposure areas. After sampling, the samplers were thermally desorbed and the analytes were trapped by multi-walled carbon nanotubes packed into a micro-preconcentrator coupled to a gas chromatograph (GC) equipped with a flame ionization detector. At the optimum GC operating conditions, the linear dynamic ranges for BTX were 0.06-5.6 µg for benzene, 0.07-2.2 µg for toluene and 0.23-2.5 µg for xylene with R(2) > 0.99 with the limits of detection being 6.6, 6.8 and 19 ng for benzene, toluene and xylene, respectively. The concentrations of BTX in the 16 sampling sites were in the range of N.D.-1.3 ± 1.6, 4.50 ± 0.76-49.6 ± 3.7 and 1.00 ± 0.21-39.6 ± 3.1 µg m(-3), respectively. When compared to past studies, there had been an increase in the benzene concentration.

The Soxhlet and maceration methods were used to determine the extract yield in the carotenoid pigment encapsulation for halal natural pigment production. This study aims to obtain halal natural pigment by determining the highest extract yield from the encapsulation of β-carotene in carrots. The carrot was extracted using Soxhlet and maceration method and then continued by oven drying. The n-hexane was selected because of its better volatility than ethanol and provided less solvent residue after extraction. UV-Vis spectroscopy and Thin Layer Chromatography (TLC) were used to characterize the n-hexane yield extract. Encapsulation of the pigment was investigated by adding five grams of maltodextrin to extract n-hexane weights of 0.05, 0.50, 0.75, and 1.0 grams. The maceration method yielded a much higher yield than the Soxhlet extraction method, with 2.24% (w/w) and 0.88% (w/w), respectively. The n-hexane extract absorbed a maximum wavelength of 450 nm with a retention factor (Rf) of 0.62. These values are confirmed by comparing the band's Rf values and absorption spectra with the standard’s. Light absorption spectra at wavelengths 350-500 nm confirmed an intense color expression for encapsulation containing the highest pigment concentration.

The study was conducted during 2020-2021 at the Department of Physical Science, Sherubtse College, Royal University of Bhutan with an objective to find out whether the food items that we consume daily are adulterated or not. Various food items, both locally produced and imported, were purchased from different Dzongkhags and analyzed in the laboratory for the presence of adulterants. Locally produced food items purchased were local butter, local cheese, local honey, local chili powder, beaten rice, etc. and imported food items included pulses, chili powder, turmeric powder, spices, milk, etc. Qualitative analysis of food items for detection of adulterants was done by a simple chemical test as per the standard procedure followed by various researchers. The finding showed that local butter was found to be adulterated with banana and dalda, local honey was adulterated with sugar syrup, and beaten rice was adulterated with chlorophyll pigment. Imported lentils were adulterated with Metanil yellow. Chili powder and some spices were adulterated with artificial colours and dust particles.