High performance liquid chromatographic method for residue determination of sulfosulfuron

A method was developed for sulfosulfuron [(1-(2-ethylsulfonylimidazo [1,2-a] pyridin-3-ylsulfonyl)-3-(4,6-dimethoxy pyrimidin-2yl)] and its three major metabolites by HPLC utilizing photodiode array detector. The method makes use of Lichrosphere RP-8 column and acetonitrile:water:orthophosphoric acid (80:20:0.1 v/v/v) as mobile phase at a flow rate of 1 ml min(-1). Using these condition sulfosulfuron, and compounds II, III and IV were resolved with distinct Rt of 2.088, 2.216, 2.302 and 2.476 minutes, respectively. Sulfosulfuron residues were analysed in soil, wheat grain and straw samples by extracting with a mixture of acetonitrile and 2 M ammonium carbonate (100 ml, 9:1, v/v) using horizontal shaker for soil and Soxhlet apparatus for wheat grain and straw samples. The extracts were cleaned up by partitioning with dichloromethane in case of soil and hexane followed by dichloromethane for plant samples. The percent recovery ranged between 71 to 75.2 for soil and 70.8 to 74.7 for plant samples. The limit of determination of sulfosulfuron was 0.25 microg g(-1).     

Wet scrubber analysis of volatile organic compound removal in the rendering industry

The promulgation of odor control rules, increasing public concerns, and U.S. Environmental Protection Agency (EPA) air regulations in nonattainment zones necessitates the remediation of a wide range of volatile organic compounds (VOCs) generated by the rendering industry. Currently, wet scrubbers with oxidizing chemicals are used to treat VOCs; however, little information is available on scrubber efficiency for many of the VOCs generated within the rendering process. Portable gas chromatography/mass spectrometry (GC/MS) units were used to rapidly identify key VOCs on-site in process streams at two poultry byproduct rendering plants. On-site analysis was found to be important, given the significant reduction in peak areas if samples were held for 24 hr before analysis. Major compounds consistently identified in the emissions from the plant included dimethyl disulfide, methanethiol, octane, hexanal, 2-methylbutanal, and 3-methylbutanal. The two branched aldehydes, 2-methylbutanal and 3-methylbutanal, were by far the most consistent, appearing in every sample and typically the largest fraction of the VOC mixture. A chlorinated hydrocarbon, methanesulfonyl chloride, was identified in the outlet of a high-intensity wet scrubber, and several VOCs and chlorinated compounds were identified in the scrubbing solution, but not on a consistent basis. Total VOC concentrations in noncondensable gas streams ranged from 4 to 91 ppmv. At the two plants, the odor-causing compound methanethiol ranged from 25 to 33% and 9.6% of the total VOCs (v/v). In one plant, wet scrubber analysis using chlorine dioxide (ClO2) as the oxidizing agent indicated that close to 100% of the methanethiol was removed from the gas phase, but removal efficiencies ranged from 20 to 80% for the aldehydes and hydrocarbons and from 23 to 64% for total VOCs. In the second plant, conversion efficiencies were much lower in a packed-bed wet scrubber, with a measurable removal of only dimethyl sulfide (20-100%).     

Adsorption and desorption of selected VOCs in dust collected on air filters

Adsorption and desorption properties of the dust accumulated on air filters were examined by using a small-scale test apparatus with model compounds. The dust samples were loaded with the model compounds either by adsorption from a constant concentration in air flow or by direct injection into the dust. Desorption was measured at three different relative humidities of air (4–5%, 40–50%, 70–80%). Results indicated that constant relative humidity (RH) of air did not affect the rate of desorption in the test conditions. However, an increase in humidity substantially increased desorption of the model compounds. Similar results were obtained when experiments were conducted using dirty filters without added model compounds. In addition, emission products from clean and dusty filter materials were analyzed at two temperatures (50°C and 100°C) by using an automatic thermodesorption device. The main compounds released were carboxylic acids, aldehydes and terpenes. The emission profiles were similar for the pre-filters and main filters, but the emissions were higher from pre-filters than from the main filters. This result is consistent with the earlier findings of higher odor emissions from pre-filters.     

Wet Scrubber Analysis of Volatile Organic Compound Removal in the Rendering Industry

Abstract

The promulgation of odor control rules, increasing public concerns, and U.S. Environmental Protection Agency (EPA) air regulations in nonattainment zones necessitates the remediation of a wide range of volatile organic compounds (VOCs) generated by the rendering industry. Currently, wet scrubbers with oxidizing chemicals are used to treat VOCs; however, little information is available on scrubber efficiency for many of the VOCs generated within the rendering process. Portable gas chromatography/mass spectrometry (GC/MS) units were used to rapidly identify key VOCs on-site in process streams at two poultry byproduct rendering plants. On-site analysis was found to be important, given the significant reduction in peak areas if samples were held for 24 hr before analysis. Major compounds consistently identified in the emissions from the plant included dimethyl disulfide, methanethiol, octane, hexanal, 2-methylbutanal, and 3-methylbutanal. The two branched aldehydes, 2-methylbutanal and 3-methylbutanal, were by far the most consistent, appearing in every sample and typically the largest fraction of the VOC mixture.

A chlorinated hydrocarbon, methanesulfonyl chloride, was identified in the outlet of a high-intensity wet scrubber, and several VOCs and chlorinated compounds were identified in the scrubbing solution, but not on a consistent basis. Total VOC concentrations in noncondensable gas streams ranged from 4 to 91 ppmv. At the two plants, the odor-causing compound methanethiol ranged from 25 to 33% and 9.6% of the total VOCs (v/v). In one plant, wet scrubber analysis using chlorine dioxide (ClO2) as the oxidizing agent indicated that close to 100% of the methanethiol was removed from the gas phase, but removal efficiencies ranged from 20 to 80% for the aldehydes and hydrocarbons and from 23 to 64% for total VOCs. In the second plant, conversion efficiencies were much lower in a packed-bed wet scrubber, with a measurable removal of only dimethyl sulfide (20–100%).     

Identification of substances with potential for long-range transport as possible substances of very high concern

According to the European legislation, REACH, organic compounds are considered as substances of very high concern (SVHC) if they are persistent, bioaccumulative and toxic (PBT). A substance's long-range transport potential (LRTP) may also pose a risk to remote regions. This is, however, not yet explicitly included. For identification of compounds, which are not PBT according to REACH criteria, but show LRTP, we investigated 22,438 compounds from the Canadian Domestic Substance List (CDSL). The CDSL was searched for organic, neutral compounds. Substance properties were estimated with EPI Suite v4.00. Next, the substance list was edited in two ways: (1) The half-life criterion in air for LRTP as defined in the Stockholm Convention was applied. (2) For all compounds, indicators for persistence and LRTP were calculated with the multimedia model ELPOS v2.2. Applying the half-life criterion, we identified 594 substances, which are prone to LRT but are not PBT (non-PBT-L substances). In contrast, investigations with ELPOS lead to a shorter list of 188 substances, which are non-PBT-L substances. Finally, the list was compared with potential Arctic contaminants identified in previous literature. Our results show that there is a large number of organic chemicals which would not be considered as SVHC since they are not, at the same time, persistent, bioaccumulative and toxic according to REACH criteria. Nevertheless, they show LRTP according to different screening approaches and thus a potential hazard to remote regions.     

Removing perfluorooctane sulfonate and perfluorooctanoic acid from solid matrices, paper, fabrics, and sand by mineral acid suppression and supercritical carbon dioxide extraction

The removal of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) from solid matrices has received considerable attention because of the environmental persistence, bioaccumulation, and potential toxicity of these compounds. This study presents a simple method using concentrated HNO₃ as a suppression agent, and methanol-modified supercritical carbon dioxide (Sc-CO₂) extraction for removing PFOS and PFOA from solid matrices. The optimal conditions were 16 M HNO₃ and 20% (v/v) methanol containing Sc-CO₂, under a pressure of 20.3 MPa and a temperature of 50 °C. Extraction time was set at 70 min (40 min for static and 30 min for dynamic extraction). PFOA and PFOS were identified and quantitated by liquid chromatography/mass spectrometry. The extraction efficiencies (with double extractions) were close to 100% for PFOA and 80% for PFOS for both paper and fabric matrices. The extraction efficiencies for sand were approximately 77% for PFOA and 59% for PFOS. The results show that this method is accurate, and effective, and that it provides a promising and convenient approach to remediate the environment of hazardous PFOA and PFOS contamination.     

Biodesulfurization of dibenzothiophene by growing cells of Pseudomonas putida CECT 5279 in biphasic media

Several studies have proven that natural or genetically modified bacteria, such as Pseudomonas putida strain, degrade recalcitrant organic sulfur compounds. However, from a practical point of view, the biodesulfurization (BDS) process has to be performed with really high proportions of organic solvents. In this work, the dibenzothiophene (DBT) was selected as recalcitrant model compound, and hexadecane as model organic solvent. It has been observed that P. putida CECT 5279 was able to desulfurize DBT even in the presence of 50% (v/v) of hexadecane. A concentration of 400 ppm of DBT was converted at a specific rate of generation of desulfurized final product, 2-hydroxybiphenyl (HBP), of 2.3 and 1.5 mg HBP L-1 (g DC L-1 h)-1 for 27% and 50% (v/v) of hexadecane, respectively. Finally, the Haldane kinetic model was used to describe the process evolution. The study is relevant as it has been proven that the strain CECT 5279 is a potential biocatalyst for developing an efficient BDS process.     

Relationship of properties of polycyclic aromatic hydrocarbons to sequestration in soil.

A study was conducted to determine whether the sequestration of 21 polycyclic aromatic hydrocarbons (PAHs) in soil was correlated with their properties. From 22 to 58% of the PAHs was not extracted with n-butanol after their addition to soil. After 28 days of aging, the percentage of the PAHs remaining in the soil increased to 47-77%; however, nearly all of each compound was recovered by Soxhlet extraction. Correlations were based on the amounts of aged compound extracted with butanol. Properties of compounds used in the correlations included Kow, molecular length and molecular-connectivity indices (MCIs). No one property, including log Kow, resulted in an R2 value greater than 0.26. A chain MCI (2 chi vCH) together with log Kow or a first-order MCI (1 chi) resulted in R2 values of 0.49 and 0.54, respectively. The data suggest that the properties tested are not important to predicting the sequestration of PAHs in soil.     

Spiking of performance reference compounds in low density polyethylene and silicone passive water samplers

A method for spiking performance reference compounds (PRCs) into low density polyethylene (LDPE) and silicone polymers is described. This method is based on equilibration of the polymers in aqueous/methanolic solutions of PRCs. Equilibration times range from minutes to hours for perdeuterated polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) with a hydrophobicity in the range 3.9 < logKow < 7.7. Best results were obtained for methanol-water ratios of 80/20 (v/v). The method allows for the use of PRCs for in situ calibration of the uptake kinetics of these solvent-free sampling phases in a similar way as for semipermeable membrane devices (SPMDs).     

Spatial and Geographical Variations of Urban, Suburban and Rural Atmospheric Concentrations of Phenols and Nitrophenols (7 pp)

Goal, Scope and Background Atmospheric sampling (gas and particles) of 5 phenols (phenol, m-cresol, p-cresol, o-cresol, pentachlorophenol) and 15 nitrophenols (3-methyl-2-nitrophenol, 3-nitrophenol, 4-methyl-2-nitrophenol, 5-methyl-2-nitrophenol, 2-methyl-3nitrophenol, 3-methyl-4-nitrophenol, 2,6-dinitrophenol, bromoxynil, 2,5-dinitrophenol, 2,6-dinitro-p-cresol, 2,4-dinitrophenol, ioxynil, DNOC, 3,4-dinitrophenol, dinoseb) on XAD-2 resin (20 gr) and glass fibre filters, respectively, were performed in 2002 by using 'Digitel DA80' high volume samplers. These measurements were undertaken in order to show spatial and geographical variations of concentrations and the role of traffic in the emissions of these compounds to the atmosphere. Methods Sampling were performed in Strasbourg (eastern France), in its vicinity (Schiltigheim) and in Erstein. Sites were chosen to be representative of urban (Strasbourg), suburban (Schiltigheim) and rural (Erstein) conditions. Field campaigns were undertaken simultaneously in urban and suburban sites during all the seasons during 4 hours at a flow rate of 60 m3.h-1, which gives a total of 240 m3 of air per sample. Period of sampling varied between 06h00 to 10h00, 11h00 to 15h00 and 18h00 to 22h00 in order to evaluate a variation of concentration during automobile traffic between urban, suburban and rural areas. Gas and particle samples were separately Soxhlet extracted for 12 h with a mixture of CH2Cl2 / n-hexane (50:50 v/v), concentrated to about 1 mL with a rotary evaporated and finally dried under nitrogen. Dry extracts were dissolved in 1 mL of CH3CN. Before analysis, extracts were sylilated by using MTBSTFA. Analysis was performed by GC/MSD in the SIM mode. Results and Discussion Partitioning of phenolic compounds between gas and particle phases seems to be mainly correlated with vapour pressure. Among phenolic compounds analysed, phenol, p-cresol, pentachlorophenol and 2.4-dinitrophenol were detected in all samples and emissions from traffic seems to be the major source for the presence of these compounds to the atmosphere. No increase of concentrations in autumn tend to confirm this hypothesis since, with the use of domestic heating in colder months, increases of PAHs concentrations were observed and these compounds are known to be emitted by all combustion processes. Pentachlorophenol is a special case since this molecule is only used as wood preservative. Its presence in all atmospheric samples, whatever the locations and the period of time is the consequence of its persistence. Conclusions and Perspectives These measurements demonstrate that phenols and nitrophenols are emitted to the atmosphere and further measurements, in order to confirm their sources, their behaviour and their potential impact to the air quality and to human health should be undertaken especially since the literature collected is relatively old. Concentrations of pentachlorophenol measured are very low and, due to its toxicity, further investigations should be undertaken. - * The basis of this peer-reviewed paper is a presentation at the 9th FECS Conference on 'Chemistry and Environment', 29 August to 1 September 2004, Bordeaux, France.     

Reliable QSAR for estimating Koc for persistent organic pollutants: correlation with molecular connectivity indices

Several recent studies have shown that n-octanol/water partition coefficients may not be a good predictor for estimating soil sorption coefficients of persistent organic pollutants (POPs), defined here as chemicals with log Kow greater than 5. Thus, an alternative QSAR model was developed that seems to provide reliable estimates for the soil sorption coefficients of persistent organic pollutants. This model is based on a set of calculated molecular connectivity indices and evaluated soil sorption data for 18 POPs. The chemical's size and shape, quantified by 1chi, 3chiC and 4chiC(v) indices, have a dominant effect on the soil sorption process of POPs. The developed QSAR model was rationalized in terms of potential hydrophobic interactions between persistent organic pollutants and soil organic matrix. Its high predictive power has been verified by an extensive internal and external validation procedure.     

The efficiency of two standardized procedures for extracting mutagenic chemicals from soils

A major technical limitation to monitoring the fate of mutagenic compounds in soil is the lack of an established extraction procedure. This study was conducted to evaluate the efficiency of the blender extraction procedure for extracting benzo(a)pyrene (BAP) or 2-nitrofluorene (2NF) from a Weswood silt loam or a Bastrop clay loam soil. Extracted residues were evaluated using the Salmonella/microsome mutagenicity assay and high performance liquid chromatography (HPLC) to quantify recovery of the two chemicals from soil. In addition, a limited study using only the mutagenicity assay was conducted to compare the efficiency of the Blender and Soxhlet extraction procedures for recovering organic mutagens from both soils amended with a wood preserving bottom sediment waste.Extracted residues were dissolved in dimethylsulfoxide to concentrations that could be detected in the bioassay. Over all treatment levels and for both soils, the extraction efficiency of the blender procedure for BAP was greater than 80% for 12 of 16 treatments as measured using both bioassay and HPLC analysis; while, for 2NF the extraction efficiency was greater than 90% for all 15 treatments as measured by HPLC, and greater than 80% for twelve of 15 treatments as measured by bioassay. These results indicate that blender extraction provided efficient recovery of the pure compounds tested. When the efficiency of the blender and Soxhlet procedure for extracting the wood-preserving bottom sediment and waste amended soil were compared, significantly greater levels of mutagenic activity were detected in the fractions extracted using the blender extraction than were detected using the Soxhlet extraction.     

Enzymatic degradation of anthracene, dibenzothiophene and pyrene by manganese peroxidase in media containing acetone

The high hydrophobicity of polycyclic aromatic hydrocarbons (PAHs) greatly hamper their degradation in liquid media. The use of an organic solvent can assist the degradative action of ligninolytic enzymes from white rot fungi. The enzymatic action of the enzyme manganese peroxidase (MnP) in media containing a miscible organic solvent, acetone (36% v/v), was evaluated as a feasible system for the in vitro degradation of three PAHs: anthracene, dibenzothiophene and pyrene. These compounds were degraded to a large extent after a short period of time (7, 24 and 24h, respectively), at conditions maximizing the MnP-oxidative system. The initial amount of enzyme present in the reaction medium was determinant for the kinetics of the process. The order of degradability, in terms of degradation rates was as follows: anthracene>dibenzothiophene>pyrene. The intermediate compounds were determined using gas chromatography-mass spectrometry and the degradation mechanisms were proposed. Anthracene was degraded to phthalic acid. A ring cleavage product of the oxidation of dibenzothiophene, 4-methoxybenzoic acid, was also observed.     

Impact of Alternative Fuels on Vehicle Emissions of Greenhouse Gases

Abstract

The conversion of methane to liquid products, hydrogen (H₂), and ammonia (NH₃) was investigated experimentally using microgap discharge plasma at an environmentally friendly condition. The experimental results indicated that H₂ and NH₃ were detected as the main gas products. The highest yield and production rate of H₂ was 14.4% (v/v) and 2974.6 μmol/min, respectively, whereas the highest yield and production rate of NH₃ was 8000 ppm (v/v) and 165.1 μmol/min, respectively. Particularly, the liquid products were collected on the plate and consisted of pyrrole, 2-methyl-1,4-pentadiene, α-amidopyri-dine, 2,5-dimethylpyrrole, methylpyrazine, 1-hexyne, 1,4-heptadiene, and polycyclic organic compounds. Some liquid products were the intermediates of drug, ?avor, dye, and organic synthesis, as well as edible ?avor. The collection efficiency in mass and energy efficiency were 26.3% at once and 22.9 g/kWh, respectively. The whole reaction process was considered to be in line with green chemistry principles.     

Inhibition of laccase activity from Trametes versicolor by heavy metals and organic compounds

Due to the numerous biotechnological applications of laccase enzyme, it is essential to know the influence of different agents usually present in the natural environment on its enzymatic action, especially for in situ treatment technologies. In the present work, a simple and rapid method to determine the inhibitory or inducer effect of different compounds on laccase activity was developed. The compounds tested were copper-chelating agents and heavy metals. It was found that using syringaldazine as a substrate, all copper-chelating agents (except EDTA) highly inhibited laccase activity (around 100%) at an inhibitor concentration lower than 20 mM. Moreover, 40% of inhibition, which was detected at a concentration of 20 mM for both Cd(2+) and Cu(2+) increased with concentration until nearly complete inhibition at 80 mM.     

Direct field observation of the relative humidity effect on the beta-gauge readings

The effect of ambient relative humidity (RH) on hourly particulate matter (PM10) readings of beta-gauge monitors has been studied using two collocated monitors in the field. The inlet air of monitor 1 was conditioned with water vapor to increase its RH, whereas monitor 2 operated normally in ambient conditions. Experimental data showed that PM10 readings of monitor 1 were nearly the same as monitor 2, as long as the RH of its conditioned incoming air did not exceed approximately 80-85%. However, when the RH exceeded approximately 80-85%, PM10 readings of monitor 1 became higher than monitor 2, and the difference increased with increasing RH. The measurement of pressure drop across the filter was also conducted, and the data revealed that the increase of pressure drop per unit of PM10 concentration decreased when RH was higher than approximately 80-85%, as compared with the case when RH was lower than 80-85%. This is perhaps because of more porous structure of deposited particles in the beta-gauge monitor when RH is greater than approximately 80-85%. The theoretical calculation using an evaporation model and a thermodynamic model has been conducted to simulate the beta-gauge readings. The results show that the theoretical PM10 concentrations using the evaporation model are in better agreement with the actual beta-gauge readings than those using the thermodynamic equilibrium model.     

Rapid resolution liquid chromatography-tandem mass spectrometry method for the determination of endocrine disrupting chemicals (EDCs), pharmaceuticals and personal care products (PPCPs) in wastewater irrigated soils

A multiresidue analytical method was developed for the determination of 9 endocrine disrupting chemicals (EDCs) and 19 pharmaceuticals and personal care products (PPCPs) including acidic and neutral pharmaceuticals in water and soil samples using rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS). Solid phase extraction (SPE), and ultrasonic extraction combined with silica gel purification were applied as pretreatment methods for water and soil samples, respectively. The extracts of the EDCs and PPCPs in water and soil samples were then analyzed by RRLC-MS/MS in electrospray ionization (ESI) mode in three independent runs. The chromatographic mobile phases consisted of Milli-Q water and acetonitrile for EDCs and neutral pharmaceuticals, and Milli-Q water containing 0.01 % acetic acid (v/v) and acetonitrile: methanol (1:1, v/v) for acidic pharmaceuticals at a flow rate of 0.3 mL/min. Most of the target compounds exhibited signal suppression due to matrix effects. Measures taken to reduce matrix effects included use of isotope-labeled internal standards, and application of matrix-match calibration curves in the RRLC-MS/MS analyses. The limits of quantitation ranged between 0.15 and 14.08 ng/L for water samples and between 0.06 and 10.64 ng/g for solid samples. The recoveries for the target analytes ranged from 62 to 208 % in water samples and 43 to 177 % in solid samples, with majority of the target compounds having recoveries ranging between 70–120 %. Precision, expressed as the relative standard deviation (RSD), was obtained less than 7.6 and 20.5 % for repeatability and reproducibility, respectively. The established method was successfully applied to the water and soil samples from four irrigated plots in Guangzhou. Six compounds namely bisphenol-A, 4-nonylphenol, triclosan, triclocarban, salicylic acid and clofibric acid were detected in the soils.     

Acute toxicity of substituted phenols to Rana japonica tadpoles and mechanism-based quantitative structure-activity relationship (QSAR) study.

Acute 12 h and 24 h lethal toxicity (12 h-LC50 and 24 h-LC50) of 31 substituted phenols to Rana japonica tadpoles was determined. Results indicate that toxicity of phenols to tadpoles varied only slightly with length of exposure and the 12-h test could serve as surrogate of the 24-h test. A mechanism-based quantitative structure-activity relationship (QSAR) method was employed and 1-octanol/water partition coefficient (log K(ow))-dependent models were developed to study different modes of toxic action. Most phenols elicited their response via a polar narcotic mechanism and an excellent logK(ow)-dependent model was obtained. Soft electrophilicity and pro-electrophilicity were observed for some phenols and a good log K(ow)-dependent model was also achieved. Additionally, the significant dissociation of carboxyl on benzoic acid derivatives sharply reduced their toxicity. A statistically robust QSAR model was developed for all studied compounds with the combined application of log K(ow), energy of lowest unoccupied orbital (E(lumo)), heat of formation (HOF) and the first-order path molecular connectivity dices (1chi(p)).