Glass Microfiber Filter Research Articles

Low-cost supercapacitor based on multi-walled carbon nanotubes and activated carbon derived from Moringa Oleifera fruit shells

An electric double-layer capacitor (EDLC) was fabricated using multi-walled carbon nanotubes (MWCNT) and activated carbon (AC) derived from Moringa Oleifera fruit shells as electrode material. The carbonization temperature and the weight ratio of the fruit shells to the activating agent were varied to determine the best condition in the fabrication of the electrodes. Activation of the carbonized fruit shells by ZnCl2 resulted in the formation of pores as verified by the scanning electron micrographs. Energy dispersive X-ray analyses show that the washing of the carbonized sample resulted in the removal of zinc and chlorine residues. The supercapacitor electrodes were fabricated by adding polyvinylidene fluoride and N-methylpyrrolidone to the MWCNT-AC mixture to form a slurry and was cast onto a nickel foam. The capacitance of the fabricated electrodes was determined using a potentiostat. The activated carbon with a carbonization temperature of 800 °C and a 1:2 weight ratio between the fruit shells and ZnCl2 was observed to have the highest capacitance of 130 F g−1 and was duplicated to fabricate the supercapacitor electrodes. A glass microfiber filter was soaked in 3 M KOH and placed in between the two electrodes. The specific capacitance of the EDLC was found to be 122 F g−1 at a current density of 0.5 A g−1, average energy density of 17 W h kg−1, average power density of 1.5 kW kg−1 and an equivalent series resistance of 1.6 Ω. After 100 scans with a scan rate of 0.1 V s−1, the percent decrease in capacitance was calculated to be 2.65 % of its original capacitance.

Absorbance and EEM fluorescence of wastewater: Effects of filters, storage conditions, and chlorination.

Aim of this study was to delineate sample handling procedures for accurate fluorescence and UV absorbance measurements of wastewater organic matter. Investigations were performed using different wastewater qualities, including primary, secondary and tertiary wastewater effluents, and a wastewater-impacted surface water. Filtration by 0.7 μm glass microfiber filter, 0.45 μm polyvinylidene fluoride (PVDF) membrane, 0.45 μm cellulose nitrate membrane, and 0.45 μm polyethersulfone (PES) syringe filter released manufacture impurities in water that affected fluorescence measurements. However, pre-washing of filter by Milli-Q water was able to eliminate these interferences. Different storage conditions were tested, including storage of filtered and unfiltered samples under different temperatures (25 °C, 4 °C,-20 °C). According to the obtained results, the best practice of wastewater samples preservation was sample filtration at 0.7/0.45 μm immediately after collection followed by storage at 4 °C. However, the time of storage that assured changes of these spectroscopic measurements that do not exceed the 10% of the original value was dependent on water quality and selected wavelengths (i.e., selected fluorescing organic matter component). As a general rule, it is advisable to perform fluorescence and UV absorbance measurements as soon as possible after collection avoiding storage times of filtered water longer than 2 days. Finally, addition of chlorine doses typical for wastewater disinfection mainly affected tryptophan-like components, where changes that exceed the 10% of the fluorescence intensity measured in the unchlorinated sample were observed even at very low doses (≥1 mg/L). On the contrary, tyrosine-like and humic-like components showed changes <10% at chlorine doses of 0.5-5 mg/L.

Thermally self-sustaining tubular SOFC power generator with no moving parts

Hydrocarbon fuels is roughly 50 times higher energy density compared to commercial batteries. However, scaling down electrical power generators for portable devices have been far from successful due to the difficulties of minimizing heat and friction losses. Hence, an alternate solution without moving parts incorporating a micro-tubular solid oxide fuel cell (mT-SOFC), thermal transpiration (gas pumping in a nanoporous medium from temperature gradient) and catalytic combustion on platinum surface is proposed. The concept involves having thermal transpiration membrane utilizes the temperature gradient created by mT-SOFC and catalytic combustion to supply reactants at high temperature to mT-SOFC for its operation. With this concept, catalytic combustion modeling and thermal transpiration membrane modeling were studied individually and integrated together for an airbreathing cylindrical chamber. The chamber design involves an aluminum cylinder wrapped with glass microfiber filter as transpiration membrane. Aluminum structure provides practically uniform temperature on inside surface of the membranes. Platinum mesh was used as a catalyst for rich butane-air combustion, the products of which supply the mT-SOFC. It was found that the temperature, fuel flow rate and equivalence ratio can be varied over mT-SOFC operation range. The integrated system demonstrates capability in self-sustaining power generation using hydrocarbon fuel without moving parts.

A Membrane-based Disposable Well-Plate for Cyanide Detection Incorporating a Fluorescent Chitosan-CdTe Quantum Dot.

A novel approach to building a membrane-based disposable well-plate, here applied to cyanide detection, is described. Chitosan encapsulated CdTe quantum dots with a maximum emission at 520 nm (CS-QD520) were used as fluorophores. The CS-QD520 nanoparticle was specifically quenched by copper(II), and the quenched CS-QD520 (Cu-CS-QD520) was deposited onto a glass microfiber filter (GF/B). Subsequent introduction of cyanide ion resulted in fluorescence recovery. The "signal-ON" fluorescence linearly correlated to cyanide concentrations in the range of 38.7 to 200 μM with a limit of detection of 11.6 μM. The assay was incorporated into a membrane-based well-plate format to enhance sample throughput. A three-layer paper/glass microfiber well plate design was cut using a laser cutter and assembled using a polycaprolactone (PCL) as a bonding agent in a low-cost laminator. The experimental conditions were optimized and applied to detect cyanide in drinking water with rapid, high-throughput, low-cost analysis.

Effect of surface wettability on filtration performance of gas-liquid coalescing filters

A low-pressure plasma technology was applied for the first time to modify the surface of filter media used for separation of liquid particles from air streams without affecting their bulk properties. The effect of surface wettability on the filtration performance and internal liquid distribution of glass microfiber filters was investigated experimentally. It was found that typical jump and channel characteristics existed in the evolution of both pressure drop and penetration of the filters, which means that in the jump stage of pressure drop, the penetration of oleophobic filters decreased steeply with loading time and the rate of decrease was greater in low-efficiency grade media. However, the variation trends of penetration were opposite in high- and low-efficiency grade oleophilic filters; that is, increased and decreased, respectively. In the channel stage of pressure drop, the penetration increased gradually with loading time in the oleophilic filters but changed little in the oleophobic ones. The oleophobic filters demonstrated lower jump pressure drop, film thickness, equilibrium saturation and loss of efficient fibers compared with their oleophilic counterparts. Furthermore, the oleophobic filters exhibited a remarkable advantage in overall filtration performance due to their comparable pressure drop and significantly higher filtration efficiency at steady state compared with their oleophilic counterparts. It was demonstrated that the most penetrating particle size remained almost constant for filters with the same structure but different wettabilities, although the filtration efficiency for particles across the whole size range was improved in oleophobic filters. Additionally, the dependence of filter performance on the surface modification method was also explored using an oleophilic medium as the control. The results showed that different approaches were capable of changing the media wettability to various degrees. Compared with the unmodified filter or those modified only by nanoparticles or fluoride copolymer, the filters modified by the combination of nanoparticles and fluoride copolymer had the overall best filtration performance.

Dimethyl phthalate. Determination in workplace air

Dimethyl phthalate (DMP) is a colourless liquid with a slight aromatic odour. It is used in industry as a plasticizer of plastics, as an ingredient of fragrances in the production of cosmetics and detergents. Occupational exposure to DMP can occur through inhalation, or ingestion. The aim of this study was to validate a method for determining DMP concentration in workplace air in the range from 1/10 to 2 MAC values, in accordance with the requirements of standard PN-EN 482. The study was performed using a gas chromatograph (GC) with a flame ionization detector (FID) equipped with a capillary column HP-INNOWAX (60 m x 0.25 mm, 0.15 µm). This method is based on the sorption of dimethyl phthalate vapours on a glass microfiber filter, desorption with ethanol, and analyzed by GC-FID. The average desorption efficiency of DMP from filter was 98%. Application of HP-INNOWAX column allows selective determination of DMP in the presence of other solvents. The measurement range was 0.5 – 10 mg/m3 for a 120-L air sample. Limit of detection: 0.02 µg/ml and limit of quantification: 0.06 µg/ml. The analytical method described in this paper enables a selective determination of DMP in workplace air in the presence of other solvents at concentrations from 0.5 mg/m3 (1/10 MAC value). The method is characterized by good precision and accuracy and meets the criteria for the performance of procedures for the measurement of chemical agents, listed in EN 482. The method may be used for the assessment of occupational exposure to DMP and the associated risk to workers’ health. The developed method of determining DMP has been recorded as an analytical procedure (see appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engineering.

Mist filters: How steady is their “steady state”?

This paper addresses the phenomenon of a slow Δp increase (“creep”) sometimes observed in mist filters during their so-called steady-state operation, especially at relatively high flow rates and aerosol loads (Kolb et al., 2017). This creep phenomenon draws into question the concept of steady state and awaits a physical explanation on the basis of more systematic data. The present study was performed with conventional glass microfiber filter media at filter face velocities in the range of 1–70 cm/s, using submicron oil aerosol at loading rates up to 1.1 g/(m2 s). Experiments started either with a dry filter (designated as S0 = 0, where S stands for the liquid saturation level), or with a completely pre-saturated filter (designated as S0 = 1). The S0 = 0 runs reached “steady state” (defined here as the onset of drainage) after approximately 0.3 h and were then loaded continually for another 100 h. Runs starting at S0=1 reached a steady state very quickly.With regard to Δp, all filters featured Δp creep when starting from S0 = 0. For coarse filter grades, Δp creep effectively ended in less than 40 h at moderate flow velocities; finer grades crept further and did not stop creeping within any reasonable loading time. When starting from S0 = 1, a steady Δp endpoint was reached rapidly, but was considerably higher than the level attained by creep. It was further shown that creep is associated with a slow increase in the saturation level and that S approached the (higher) level of pre-saturated filters. The increase in S during creep was associated with the formation of additional fine oil channels. Conversely, oil channels were completely absent in pre-saturated filters and the liquid was uniformly dispersed. Using simple theoretical considerations for flow in porous media, the observed differences in Δp are explained in part by the difference in S betweenS0 = 0 and S0 = 1 filters, and in additionally also by taking into account the different liquid distribution patterns.We conclude that the onset of drainage under steady external conditions – the stage conventionally viewed as the beginning of steady-state operation – does not automatically represent an internal steady state with regard to saturation levels or pressure drop; and presumably also not for the oil distribution pattern. The internal saturation reaches a stable endpoint sooner than the pressure drop, which may continue to creep for the lifetime of the filter. Of and when a transition from channel patterns to homogeneous oil distribution occurs during steady operation is not known. However, the transition can be forced rather quickly by operating the filter intermittently at a very low flow velocity.

Investigation of Thermal Properties of Graphene-Coated Membranes by Laser Irradiation to Remove Biofoulants.

In the present study, we take advantage of the high thermal conductivity of graphene nanomaterials to develop a filter that can be easily cleaned via laser irradiation after biofouling occurs. In this investigation, the intensity of the laser beam and the amount of graphene used for membrane coating were investigated with Bacillus subtilis to achieve the most efficient removal of biofoulants. Thermographic measurements of glass microfiber filters coated with 500 μg of graphene showed an increase in temperature of about 328 ± 9 °C in about 6 s when the filters were irradiated with a 21.6 W/cm-2 laser intensity, which allowed successful removal of biofoulants. The thermal cleaning was effective for at least four filtrations without impacting the subsequent microbial removals, which were of ∼5 log for each filtration step followed by laser irradiation. Additionally, the permeability of the coated filters only dropped from 17.8 to 15.9 L/m2s after the laser cleaning procedure. The cleaning procedure was validated by using bayou water with a complex composition of biofoulants. Graphene-coated membranes coupled with laser irradiation afford a very fast and nonhazardous approach to clean biofoulants on graphene-coated membranes.

Development of an in vitro method to determine rumen undigested aNDFom for use in feed evaluation

A portion of the forage cell wall, defined as neutral detergent fiber (NDF), is indigestible to anaerobic microbial digestion in ruminants. This fraction has been characterized by surface area relationships between acid detergent lignin, but recently, data have been published describing the dynamic nature of this relationship. In situ approaches have been described to estimate indigestible NDF, recovering the undigested NDF after long-term fermentations (uNDF). To be applicable to nutritionists and diet formulation, determining uNDF needs to be conducted in a commercial laboratory similar to other routine analyses of forage chemistry. A series of studies were conducted to evaluate an in vitro approach, to describe uNDF, which is repeatable and adaptable for routine feed evaluation. One hundred and two forages of several species were analyzed for NDF, acid detergent lignin, and uNDF. The uNDF was estimated by several approaches involving long-term fermentations and filtration steps to evaluate the length of time necessary to exhaust the digestible NDF and a filtration method necessary to maintain sample integrity by ensuring low sample loss and uniform recovery with residues from long-term in vitro fermentation. To determine uNDF, in vitro fermentations were conducted on 0.50 or 0.75 g of dry matter samples, in triplicate, at multiple time points up to 504 h and initially used Gooch crucibles with Celite (Thermo Fisher Scientific, Waltham, MA) as a filtering aid. The final method utilized a 1.5-µm pore size glass microfiber filter, which allowed for increased repeatability and improved sample recovery (lowest standard deviation). In this study, in vitro fermentations of 240 h were adequate to characterize and identify uNDF, which was repeatable among conventional forages provided the samples, after NDF analyses, were filtered through the same glass fiber filter. This approach could be adapted by commercial laboratories and would provide opportunities to develop near-infrared reflectance spectroscopy equations and calibrations.

Rapid, field-deployable method for collecting and preserving plant metabolome for biochemical and functional characterization.

Study of plant metabolome is a growing field of science that catalogs vast biochemical and functional diversity of phytochemicals. However, collecting and storing samples of plant metabolome, sharing these samples across the scientific community and making them compatible with bioactivity assays presents significant challenges to the advancement of metabolome research. We have developed a RApid Metabolome Extraction and Storage (RAMES) technology that allows efficient, highly compact, field-deployable collection and storage of libraries of plant metabolome. RAMES technology combines rapid extraction with immobilization of extracts on glass microfiber filter discs. Two grams of plant tissue extracted in ethanol, using a specially adapted Dremel® rotary tool, produces 25–35 replicas of 10 mm glass fiber discs impregnated with phytochemicals. These discs can be either eluted with solvents (such as 70% ethanol) to study the metabolomic profiles or used directly in a variety of functional assays. We have developed simple, non-sterile, anti-fungal, anti-bacterial, and anti-oxidant assays formatted for 24-multiwell plates directly compatible with RAMES discs placed inside the wells. Using these methods we confirmed activity in 30 out of 32 randomly selected anti-microbial medicinal plants and spices. Seven species scored the highest activity (total kill) in the anti-bacterial (bacteria from human saliva) and two anti-fungal screens (Fusarium spp. and Saccharomyces cerevisiae), providing functional validation of RAMES technology. RAMES libraries showed limited degradation of compounds after 12 months of storage at -20°C, while others remained stable. Fifty-eight percent of structures characterized in the extracts loaded onto RAMES discs could be eluted from the discs without significant losses. Miniaturized RAMES technology, as described and validated in this manuscript offers a labor, cost, and time-effective alternative to conventional collection of phytochemicals. RAMES technology enables creation of comprehensive metabolomic libraries from various ecosystems and geographical regions in a format compatible with further biochemical and functional studies.

A comprehensive protocol for chemical analysis of flame combustion emissions by secondary ion mass spectrometry.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is used to provide detailed information on the surface chemical composition of soot. An analytical protocol is proposed and tested on a laboratory flame, and the results are compared with our previous measurements provided by two-step laser mass spectrometry (L2MS). This work details: (1) the development of a dedicated apparatus to sample combustion products from atmospheric flames and deposit them on substrates suitable for TOF-SIMS analysis; (2) the choice of the deposition substrate and the material of the sampling line, and their effect on the mass spectra; (3) a method to separate the contributions of soot and condensable gas based on impact deposition; and finally (4) post-acquisition data processing. Compounds produced during flame combustion are detected on the surface of different deposition substrates and attributed a molecular formula based on mass defect analysis. Silicon and titanium wafers perform similarly, while the surface roughness of glass microfiber filters results in a reduced mass resolution. The mass spectra obtained from the analysis of different locations of the deposits obtained by impaction show characteristic patterns that are attributed to soot/condensable gas. A working method for the analysis of soot samples and the extraction of useful data from mass spectra is proposed. This protocol should help to avoid common experimental issues like sample contamination, while optimizing the setup performance by maximizing the achievable mass resolution.

Low-Cost and Simple Fabrication of Nanoplasmonic Paper for Coupled Chromatography Separation and Surface Enhanced Raman Detection.

Surface-enhanced Raman scattering (SERS) is a powerful analytical tool which enables the detection and identification of analytes adsorbed on nanostructured noble metals. However, SERS analysis of complex mixtures can be challenging due to spectral overlap and interference. In this report, we demonstrate a method to simplify the identification of mixed-analyte samples by coupling SERS detection with chromatographic separation on a nanoplasmonic paper substrate. This "nanopaper" substrate is a silver coated glass microfiber filter paper which possesses large SERS enhancement and can serve as a stationary phase in paper chromatography. Nanopaper is easily synthesized using the silver mirror reaction, making it a highly accessible technology. Nanopaper was successfully used as a combined paper chromatography-SERS (PC-SERS) substrate in the separation and identification of mixed organic dyes. It was further employed to separate and identify lycopene and β-carotene in commercial food products, demonstrating the versatility and utility of nanopaper in the identification of complex mixtures.

Removal of Humic Acid in Water Using Novel Nanomaterials

The present study investigates the effectiveness of the photocatalytic degradation of humic acid (HA) in aqueous suspensions. Initial batch scale experiments and tests performed using the Continuous Flow Photoreactor have enabled the close inspection of the performance of the photocatalysts nano TiO2, and nano ZnO dispersions. These photocatalysts were used in aqueous dispersions employing medium-pressure mercury-vapour lamps emitting UV-A (λ = 400 nm) and UV-C (λ = 250 nm). Moreover, glass microfibre filters were embedded and coated with Laponite RD (synthetic polycrystalline swelling clay) in order to produce catalytic films to be used in small scale experiments to remove HA through filtration. The findings of this study shows that the HA adsorb highly onto the ZnO and TiO2 surface thus initiating photodegradation, the effectiveness of which steadily increases with irradiation time along with an increase in the biodegradability of HA.

Experimental study on aerosol scrubbing efficiency of self-priming venturi scrubber submerged in water pool

Scrubber nozzles are key pieces of equipment used to remove aerosols in a wet-type filtered containment venting system (FCVS). This study deals with the aerosol scrubbing efficiency of a scrubber nozzle operating in self-priming mode. The scrubber nozzle that has been developed in this work consists of a reducer, a throat, a diffuser, a liquid suction slit, and an end cap with a rectangular section area. The aim of this study was to characterize scrubbing efficiency under various thermal hydraulic and aerosol conditions including nozzle inlet pressure (250–600 kPa(g)), nozzle inlet temperature (102–164 °C), nozzle inlet flow rate (air: 42–132 m3/h, steam: 112–269 m3/h), submergence from the nozzle exit (0.7–2.7 m), aerosol size (0.5, 0.7, 3 µm), nozzle inlet aerosol concentration (0.1–3 g/m3), and steam mass fraction in the main carrier gas (0–1). Aerosol scrubbing efficiency was measured based on the inlet and outlet aerosol concentrations of the scrubbing vessel with isokinetic sampling systems including a glass microfiber filter. Experimental results show that the scrubbing efficiency increased with increasing aerosol size, steam mass fraction, nozzle submergence, and inlet aerosol concentration. We also showed that the scrubbing efficiency increased with an increase in inlet pressure at low scrubber nozzle submergence. However, at higher scrubber nozzle submergence, the nozzle inlet pressure did not significantly influence the scrubbing efficiency. The aerosol scrubbing efficiency with the developed self-priming scrubber nozzle submerged in the pool was over 97% for various thermal–hydraulic conditions. Thus, the experimental results can be used to design a wet scrubber system considering upstream conditions such as operation of the FCVS.

On the accuracy of capillary flow porometry for fibrous filter media

Abstract The application of capillary flow porometry by gas-liquid displacement to the measurement of the pore size distribution in identical glass microfiber filter media can lead to surprisingly divergent results. The causes for these differences as well as the factors that influence the over-all reliability of data obtained by this widely used technique are investigated. Among the key factors studied were the volatility and viscosity of four common wetting liquids, the scan rate (i.e. the holding time between increments of differential pressure Δp or volumetric flowrate V ), and the scan sequence (i.e. dry before wet, or wet before dry scan). Most measurements were made with a porometer designed in house, in order to have complete control over all aspects of operation. Data obtained with commercial porometers are also reported. For best comparability, all measurements were made with the same batch of standard glass microfiber media. The largest error source by far was the volatility of fluorinated compounds commonly used as wetting liquids. While the vapor pressures of such compounds may be relatively low, their use in combination with a flow of air through the porous matrix can have an enormous effect on the evaporation rate during a scan. Neglecting this effect (which obviously depends on the scan rate) may ultimately result in an error of almost arbitrary magnitude in the pore size distribution. Silicone oil on the other hand has a negligible volatility and provides reliable results for a wide range of operating conditions. The liquid viscosity in the tested range of 5–100 mm2/s played a comparatively insignificant role. These and other factors of uncertainty are discussed on the basis of experimental data.

Antimicrobial and antibiofilm efficacy of self-cleaning surfaces functionalized by TiO2 photocatalytic nanoparticles against Staphylococcus aureus and Pseudomonas putida

A photocatalytic sol of TiO2 nanoparticles has been used for creating self-cleaning antimicrobial flat and porous glass surfaces. The substrates were irradiated to study their photocatalytic properties and behavior in the presence of biofilm-forming bacteria. Smooth glass surfaces and glass microfiber filters were covered with 1.98×10−3±1.5×10−4gcm−2 and 8.55×10−3±3.0×10−4gcm−2 densities, respectively. Self-cleaning properties were analyzed using the methylene blue 365nm UV-A photodegradation test. TiO2-coated filters achieved rapid and complete photodegradation of methylene blue because of the better TiO2 dispersion with respect to the glass slides. The effect of functionalized surfaces on the growth and viability of bacteria was studied using the strains Staphylococcus aureus and Pseudomonas putida. After irradiation (2h, 11.2Wm−2, 290–400nm), the initially hydrophobic surface turned hydrophilic. The antibacterial effect led to extensive membrane damage and significant production of intracellular reactive oxygen species in all TiO2-loaded irradiated specimens. The reduction of cell viability was over 99.9% (>3-log) for TiO2 on glass surfaces. However, the polymeric extracellular matrix formed before the irradiation treatment was not removed. This study highlights the importance of bacterial colonization during dark periods and the difficulty of removing the structure of biofilms.

Filter Media Comparison for the Removal of Brettanomyces bruxellensis from Wine

<i>Brettanomyces bruxellensis</i> is a wine-spoilage yeast of significant concern to wine producers, and its removal by filtration is not fully understood. The aim of this work was to compare the efficacy of filters, having different compositions and micron ratings, to remove <i>B. bruxellensis</i> from wine. Wines inoculated with a <i>B. bruxellensis</i> strain were used, and the U.S. Food and Drug Administration guidelines for filter validation for aseptic processing were followed. Polypropylene filters of 0.6 and 1.0 µm ratings yielded wines with high <i>Brettanomyces</i> cell counts. No cells were detected in wines filtered through polyethersulfone filters of 0.45, 0.65, and 1.0 µm, or through X grade glass microfiber filter. This work showed that different filter compositions with similar micron ratings result in variable retention of <i>B. bruxellensis</i>, highlighting that filter media are relevant for removal mechanisms, and pointing to the importance of a complete characterization of filter media when addressing <i>Brettanomyces</i> removal from wine.

Diethyl phthalate Determination in workplace air

Diethyl phthalate (DEP) is an ester of phthalic acid and an ethanol. It is a colorless, oily liquid. This substance is used in industry as a solvent for cellulose acetate and nitrocellulose, and a plasticizer of plastics. It is added to nail polish, perfumes in cosmetics and detergents, food packaging and pharmaceuticals. Diethyl phthalate is a substance which is toxic if inhaled, irritating to eyes and skin, toxic for reproduction (it is suspected that acts harmful to fertility or unborn child). The aim of this study was to develop and validate a method for determining concentrations of diethyl phthalate in workplace air in the range from 1/10 to 2 MAC values in accordance with the requirements of Standard No. PN-EN 482. The study was performed using a gas chromatograph (GC) with a flame ionization detector (FID) with a capillary column HP-INNOWAX (60 m × 0.25 mm, 0.15 µm). The method is based on the adsorption of diethyl phthalate on glass microfiber filter, desorption of analysed compound with ethanol and analysis of the resulting solution with GC-FID. The average desorption efficiency of diethyl phthalate from filter was 90%. Application of column HP-INNOWAX enables selective determination of diethyl phthalate in the presence of other solvents. The measurement range was 0.3  6 mg/m3 for a 240-L air sample. The limit of detection (LOD) and the limit of quantification (LOQ) are 0.09 µg/ml and 0.27 µg/ml, respectively. The analytical method described in this paper enables selective determination of inhalable fraction of diethyl phthalate in workplace air in the presence of other substances at concentrations from 0.3 mg/m3 (1/10 MAC value). The method is precise, accurate and it meets the criteria for procedures for measuring chemical agents listed in Standard No. EN 482. The method can be used for assessing occupational exposure to diethyl phthalate and associated risk to workers’ health. The developed method of determining diethyl phthalate has been recorded as an analytical procedure (see appendix).

Determination and analysis of trace metals and surfactant in air particulate matter during biomass burning haze episode in Malaysia

Trace metal species and surface active agent (surfactant) emitted into the atmosphere from natural and anthropogenic source can cause various health related and environmental problems. Limited data exists for determinations of atmospheric particulate matter particularly trace metals and surfactant concentration in Malaysia during biomass burning haze episode. We used simple and validated effective methodology for the determination of trace metals and surfactant in atmospheric particulate matter (TSP & PM2.5) collected during the biomass burning haze episode in Kampar, Malaysia from end of August to October 2015. Colorimetric method of analysis was undertaken to determine the concentration of anionic surfactant as methylene blue active substance (MBAS) and cationic surfactant as disulphine blue active substance (DBAS) using a UV–Visible spectrophotometer. Particulate samples were also analyzed for trace metals with inductive coupled plasma mass spectrometer (ICP-MS) followed by extraction from glass microfiber filters with close vessel microwave acid digestion. The result showed that the concentrations of surfactant in both samples (TSP & PM2.5) were dominated by MBAS (0.147–4.626 mmol/m3) rather than DBAS (0.111–0.671 mmol/m3) and higher than the other researcher found. Iron (147.31–1381.19 μg/m3) was recorded leading trace metal in PM followed by Al, Zn, Pb, Cd, Cr and others. During the haze period the highest mass concentration of TSP 313.34 μg/m3 and 191.07 μg/m3 for PM2.5 were recorded. Furthermore, the backward air trajectories from Kampar in north of peninsular Malaysia confirmed that nearly all the winds paths originate from Sumatera and Kalimantan, Indonesia.

Mitigation of nitrogen mustard mediated skin injury by a novel indomethacin bifunctional prodrug

Nitrogen mustard (NM) is a bifunctional alkylating agent that is highly reactive in the skin causing extensive tissue damage and blistering. In the present studies, a modified cutaneous murine patch model was developed to characterize NM-induced injury and to evaluate the efficacy of an indomethacin pro-drug in mitigating toxicity. NM (20μmol) or vehicle control was applied onto 6mm glass microfiber filters affixed to the shaved dorsal skin of CD-1 mice for 6min. This resulted in absorption of approximately 4μmol of NM. NM caused localized skin damage within 1 d, progressing to an eschar within 2–3 d, followed by wound healing after 4–5 d. NM-induced injury was associated with increases in skin thickness, inflammatory cell infiltration, reduced numbers of sebocytes, basal keratinocyte double stranded DNA breaks, as measured by phospho-histone 2A.X expression, mast cell degranulation and increases in inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Wound healing was characterized by epidermal hyperplasia and marked increases in basal cells expressing proliferating cell nuclear antigen. A novel indomethacin-anticholinergic prodrug (4338) designed to target cyclooxygenases and acetylcholinesterase (AChE), was found to markedly suppress NM toxicity, decreasing wound thickness and eschar formation. The prodrug also inhibited mast cell degranulation, suppressed keratinocyte expression of iNOS and COX-2, as well as markers of epidermal proliferation. These findings indicate that a novel bifunctional pro-drug is effective in limiting NM mediated dermal injury. Moreover, our newly developed cutaneous patch model is a sensitive and reproducible method to assess the mechanism of action of countermeasures.