Gas-to-aqueous Phase Transfer for Three Paint Solvents Injected into an Abiotic, Industrial Biotrickling Filter Measured with a Flame Ionization Detector

This is a knowledge contribution to the unsatisfactory biodegradation problem, when biotrickling filters are purifying mixed paint solvents. A biotrickling filter manufacturer reported low biodegradation rates during the purification of a hydrocarbon pollutant mix from an industrial paint spraying floor. From a gas chromatograph/mass spectrometer analysis both hydrophilic and hydrophobic solvents were found in the polluted air. It is known that biodegradation is retarded, if the pollutant does not transfer from gas to liquid into the biofilm and it was therefore suspected that hydrophobic pollutants do not sufficiently migrate into the water/biofilm. To test this hypothesis, pure, rather than mixed pollutants, were injected into the abiotic biotrickling filter. When hydrophobic paint solvent (xylene) was sprayed into the biotrickling filter, the solvent load at the outlet of the filter was almost as high as at the inlet. But when pure, hydrophilic paint solvent (PGME) was sprayed into the abiotic biotrickling filter, the solvent load measured at the outlet of the filter was zero, indicating complete dissolution into the circulation water. Carbon/solvent loads at the filter outlet and inlet were measured with a portable flame ionization detector instrument. The experiment confirms that the hydrophobic solvent does not migrate into the liquid phase. This poor mass transfer of hydrophobic solvents is likely to be the reason for the low biodegradation rate. The result is highly relevant to the paint spraying industry and manufacturers of exhaust gas treatment equipment alike, who spend millions in non-sustainable incineration of exhaust gases.

Quantifying ethanol in ethanol-based hand sanitizers by headspace gas chromatography with flame ionization detector (HS-GC/FID)

Background The COVID-19 pandemic sharply increased the demand for ethanol-based gel hand sanitizers, leading to a shortage of these products. Consequently, regulatory health agencies worldwide have altered their regulatory guidelines, on ethanol quality, to meet this high demand, raising concern about the products quality. Objective The aim of this study was to quantify ethanol content and to qualitatively assess common impurities in ethanol-based gel hand sanitizers by headspace gas chromatography with flame ionization detector (HS-GC/FID). Methods To quantify the ethanol content, 0.10 g of the sample was weighed in a 20 mL headspace vial and 5 mL of deionized water was added. Regarding the qualitative approach, 0.25 g of the sample was weighed and 4 mL of deionized water and was added. The samples were incubated, and then 400 µL of the headspace was injected into the GC/FID. Forty-eight products purchased in Brazil were analyzed. Results Thirteen products presented at least one nonconformity regarding the ethanol quantity. Two samples presented an average ethanol concentration below the lower limit considered effective. Twelve samples presented acetaldehyde or ethyl acetate. Conclusion The huge demand for ethanol-based gel hand sanitizers may have impacted their quality. Because concern with proper hand hygiene tends to remain an issue for a long period, more studies about quality control of hand sanitizers will be needed. Highlights A simple and fast HS-GC/FID method to quantify ethanol in ethanol-based gel hand sanitizers was developed, validated and applied to commercial samples in Brazil. The regulatory authorities must be more vigilant to ensure that the commercially available products meet the recommended specifications.

Offline Solid-Phase Extraction and Separation of Mineral Oil Saturated Hydrocarbons and Mineral Oil Aromatic Hydrocarbons in Edible Oils, and Analysis via GC with a Flame Ionization Detector

A method was developed for the determination of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) in edible oils, achieving similar limits of quantification than those obtained by online extraction methodologies, i.e., 0.5 mg/kg. The isolation of MOSH and MOAH was performed in a silver nitrated silica gel stationary phase prior to their analysis by gas chromatography–flame ionization detector (GC-FID). To improve the sensitivity, the simulated on-column injection method, using a suitable liner, was optimized. The method was validated at 0.5, 10.0 and 17.9 mg/kg, and recoveries ranged from 80 to 110%. Intra and inter-day precision were evaluated at the same levels, and relative standard deviation (RSD) was lower than 20%. The method was applied to a total of 27 samples of different types of oil previously analyzed in an accredited laboratory, detecting MOSH up to 79.2 mg/kg and MOAH up to 22.4 mg/kg.

Standardization and validation of assay of selected omega-3 and omega-6 fatty acids from phospholipid fraction of red cell membrane using gas chromatography with flame ionization detector

Background Docosahexaenoic acid (DHA) is an important structural component of human brain and retina. Evidence exists linking nutritional status of pregnant mothers and cognitive functions of their born infants. The DHANI (Maternal DHA Supplementation and Offspring Neurodevelopment in India) trial was implemented to evaluate the effect of maternal supplementation with DHA during pregnancy and for 6 months following delivery on motor and mental development of infants at 1 and 12 months. We describe here the standardization and validation of an assay for measurement of selected omega-3 and omega-6 fatty acids from the phospholipid fraction of red blood cells to assess their status in mothers at baseline, delivery and 6 months post-delivery and for infants in cord blood and at 1 and 12 months of age. The validated method has been used for the analysis of samples for DHANI. Methods Lipids were extracted from a pool of red blood cells, separated using thin layer chromatography. The phospholipid fraction was esterified, and fatty acids were separated by gas chromatography using a flame ionization detector. Result The method accuracy for DHA was between 97 - 98% and between 91 - 95% for arachidonic acid (AA) at three different concentrations. The intra-assay and inter-assay coefficient of variation for the fatty acids ranged from 1.19 to 5.7% and 0.78 to 13.0% respectively. Intraclass correlation (ICC), as a measure of reproducibility, ranged between 0.689 and 0.996. A good linearity was observed for all the fatty acids between concentrations of 0.2–4 μg/ml. Conclusion The standardized and validated method is suitable for implementation in large epidemiological studies for evaluation of fatty acids and in nutritional trials for assessment of fatty acid content of various lipid classes.

Methane Concentration on Three Mangrove Zones in Ngurah Rai Forest Park, Bali

Mangrove menjadi salah satu ekosistem lahan basah yang berperan penting dalam menyerap karbon. Namun, secara alami ekosistem mangrove juga mampu mengemisikan gas rumah kaca kedalam atmosfer. Metana merupakan salah satu gas rumah kaca yang berdampak signifikan terhadap perubahan iklim. Penelitian tentang siklus metana telah dilakukan di ekosistem mangrove TAHURA Ngurah Rai Bali. Penelitian ini bertujuan untuk mengukur konsentrasi gas metana pada tiga zona ekosistem mangrove. Metode chamber tertutup digunakan dalam pengambilan sampel gas yang kemudian dianalisis dalam gas kromatografi dengan sensor flame ionization detector (FID). Karakter ekologi mangrove yang terdiri dari parameter struktur komunitas mangrove dan lingkungan diukur dari setiap plot kuadrat pengambilan sampel gas. Hasil penelitian menunjukkan konsentrasi gas metana tertinggi ditemukan pada zona darat dengan rata-rata 3,698 ± 0,986 mg. L-1. Walaupun demikian, konsentrasi gas metana pada dua zona lainnya tidak menunjukkan perbedaan yang signifikan dengan zona darat. Variabilitas konsentrasi gas metana tidak berbeda signifikan dengan kondisi struktur komunitas mangrove yang berbeda antar zona. Penelitian ini hanya menemukan variasi nilai potensial redoks (ORP) yang berhubungan signifikan dengan konsentrasi gas metana. Hasil penelitian mengindikasikan bahwa karakter ekologi mangrove yang cukup seragam di kawasan sehingga, tidak menimbulkan perbedaan yang signifikan pada konsentrasi gas metana antar zona. Namun, parameter kondisi substrat lainnya perlu dilibatkan dalam penelitian berikutnya.AbstractMangrove is one of the wetland ecosystems that play an important role in carbon sequestration and storage. However, the ecosystem also emits greenhouse gas into the atmosphere naturally. Methane has been considered as a significant effect on global warming. A preliminary study in a part of the carbon cycle was conducted on the mangrove ecosystem in Ngurah Rai Forest Park Bali. This study was aimed to determine methane gas concentration in three different mangrove zones. Gas samples were collected by closed chamber method and they were analyzed using gas chromatography embedded with the flame ionization detector (FID) sensor. Mangrove ecological parameters i.e. community structure and environmental condition were determined on each quadratic plot where gas samples were collected. The result showed that the highest methane concentration was found in the landward zone at 3,698 ± 0,986 mg. L-1. Even though, the methane concentration of the other zones had not significantly different from the landward zone. In addition, the mangrove community structure among the three zones was not different significantly. The oxidation-reduction potential was the only factor that had a significant correlation with methane concentration. Those results indicated that mangrove ecological conditions among zones were similar to each other, hence the variation of methane concentration was not significant. Nevertheless, substrate abiotic characters need to be involved in greenhouse gas studies in the future.

Coupling a gas chromatograph simultaneously to a flame ionization detector and chemical ionization mass spectrometer for isomer-resolved measurements of particle-phase organic compounds

Atmospheric oxidation products of volatile organic compounds consist of thousands of unique chemicals that have distinctly different physical and chemical properties depending on their detailed structures and functional groups. Measurement techniques that can achieve molecular characterizations with details down to functional groups (i.e., isomer-resolved resolution) are consequently necessary to provide understandings of differences of fate and transport within isomers produced in the oxidation process. We demonstrate a new instrument coupling the thermal desorption aerosol gas chromatograph (TAG), which enables the separation of isomers, with the high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS), which has the capability of classifying unknown compounds by their molecular formulas, and the flame ionization detector (FID), which provides a near-universal response to organic compounds. The TAG-CIMS/FID is used to provide isomer-resolved measurements of samples from liquid standard injections and particle-phase organics generated in oxidation flow reactors. By coupling a TAG to a CIMS, the CIMS is enhanced with an additional dimension of information (resolution of individual molecules) at the cost of time resolution (i.e., one sample per hour instead of per minute). We found that isomers are prevalent in sample matrix with an average number of three to five isomers per formula depending on the precursors in the oxidation experiments. Additionally, a multi-reagent ionization mode is investigated in which both zero air and iodide are introduced as reagent ions, to examine the feasibility of extending the use of an individual CIMS to a broader range of analytes with still selective reagent ions. While this approach reduces iodide-adduct ions by a factor of 2, [M − H]− and [M + O2]− ions produced from lower-polarity compounds increase by a factor of 5 to 10, improving their detection by CIMS. The method expands the range of detected chemical species by using two chemical ionization reagents simultaneously, which is enabled by the pre-separation of analyte molecules before ionization.