LC-MS/MS and GC-MS profiling, antioxidant, enzyme inhibition, and antiproliferative activities of Thymus leucostomus H ausskn. & V elen. extracts.

The chemical composition as well as antioxidant, antiproliferative, and enzyme inhibition activities of extracts from aerial parts of Thymus leucostomus H ausskn. & V elen. obtained with hexane, methanol, and water were evaluated. Results showed that the methanol extract had significantly (p < 0.05) the highest total phenolic content (TPC; 107.80 mg GAE/g) and total flavonoids content (TFC; 25.21 mg RE/g) followed by the aqueous extract (102.72 mg GAE/g and 20.88 mg RE/g, respectively). LC-MS/MS-guided profiling of the three extracts revealed that rosmarinic acid (34.8%), hesperetin (42.9%), and linoleic acid (18%) were the dominant compounds in the methanol, aqueous and hexane extracts, respectively. GC-MS analysis of the hexane extract showed that É£-sitosterol (29.9%) was the major constituent. The methanol extract displayed significantly (p < 0.05) the highest Cu++ , Fe+++ , and Mo(VI) ions scavenging and reducing properties while the aqueous extract exerted significantly (p < 0.05) the highest metal chelating power (42.51 mg EDTAE/g). Both the hexane and methanol extracts effectively inhibited the acetylcholinesterase enzyme (2.63 and 2.65 mg GALAE/g, respectively) while the former extract exerted significantly (p < 0.05) the highest butyrylcholinesterase (2.32 mg GALAE/g), tyrosinase (19.73 mg KAE/g), and amylase (1.16 mmol ACAE/g) inhibition capacity. The aqueous extract exhibited the best glucosidase inhibition property (0.49 mmol ACAE/g). The methanol and hexane extracts exerted a higher cytotoxic effect on HT-29 (IC50 : 8.12 µg/mL) and HeLa (IC50 = 8.08 µg/mL) cells, respectively. In conclusion, these results provide valuable insight into the potential use of T. leucostomus bioactive extracts in different pharmaceutical applications.

Phytochemical prospection and larvicidal bioactivity of the janaguba (Himatanthus drasticus) Mart. Plumel (Apocynaceae) latex against Aedes aegypti L. (Diptera: Culicidae).

The aim of this study was to carry out phytochemical prospecting and evaluate the larvicidal activity of Himatanthus drasticus latex extracts against Aedes aegypti. The extracts were obtained by maceration from 5 g of latex powder concentrated separately in 100 mL of methanol, ethyl acetate, and hexane solvents. The concentrations of 100, 200, 300, 400, and 500 ppm of each extract were tested in triplicate with a solution of pyriproxyfen as the positive control and distilled water and dimethylsulfoxide as the negative control. The phytochemical prospection of the methanolic extract showed the presence of phenolic compounds, such as anthocyanins, anthocyanidins, catechins, chalcones, aurones, leucoanthocyanidins, and condensed tannins. The insecticidal bioactivity was most significant for the methanolic extract. The methanolic extract lethal concentrations (LC) of 50 and 90% were 190.76 and 464.74 ppm, respectively. After 48 hours of exposure, the extracts using methanol, ethyl acetate, and hexane at their highest concentrations (500 ppm) caused larval mortality of 100, 73.33, and 66.67%, respectively. These extracts also promoted changes in the external morphology of the larvae, such as damage to the anal papillae, darkening of the body, and reduction in the number of bristles. The methanolic extract showed greater expressivity for morphological changes. The latex of H. drasticus has larvicidal activity against third-stade larvae of A. aegypti and it is more significant when obtained through maceration in methanol. The methanolic extract of H. drasticus latex contains phenolic compounds with insecticidal activity against A. aegypti larvae.

Toxicity of Ocimum americanum L. extracts against Aedes aegypti larvae (Diptera: Culicidae) and their impact on insecticide resistance.

Mosquitoes are a key threat to millions of people worldwide. They spread the pathogens that cause deadly diseases among humans and animals. Synthetic pesticides are the best agents to control mosquitoes, but they cause several problems for the environment as well as public health. Continuous usage of commonly available insecticides develops multiple resistances among pests. In search of alternatives to synthetic pesticides, botanicals could be one of the best alternatives to control mosquitoes. The present study explores the insecticidal activity of Ocimum americanum against Aedes aegypti larvae and their effect on detoxification enzymes. Leaves of O. americanum were sequentially extracted using hexane, chloroform, and methanol. Among these, hexane extract showed 100% larvicidal activity at 1 g/L concentration for 24 h and the LC50 value was 0.3 g/L. The phytochemical screening of hexane extract was performed through gas chromatography-mass spectrometry analysis, which showed 27 compounds. The major compounds are squalene (13.03%), camphor (9.77%), and 1-Iodohexadecane (8.02%). The toxicity of active hexane extract was tested against third instar larvae of Chironomus costatus (nontarget organism). Results revealed less toxicity (12.2%) at 1 g/L concentration on the nontarget organism. The enzyme activity of acetylcholinesterase and ß-carboxylesterase was significantly inhibited by the hexane extract. The present study reveals the insecticidal potential of O. americanum with minimum effects on nontarget organisms. The O. americanum extract inhibited the activity of A. aegypti's major insecticide-resistant enzymes. O. americanum could be one of the best alternatives to controlling mosquitoes.

Acyl-Nω-methylserotonins and Branched-chain Acylserotonins in Lemon and Other Citrus Seeds-New Lipids with Antioxidant Properties and Potential Pharmacological Applications.

We have found 15 previously unknown compounds in seeds of lemon and other citrus species, such as tangerine, grapefruit and pomelo. The structure of these compounds was characterized by HR-MS spectrometry, fluorescence spectroscopy and chemical synthesis. These compounds were predominantly long-chain (C20-C25), saturated acyl-Nω-methylserotonins with the main contribution of C22 and C24 homologues, usually accounting for about 40% and 30% of all acylserotonins, respectively. The other, previously undescribed, minor compounds were branched-chain acylserotonins, as well as normal-chain acylserotonins, recently found in baobab seed oil. Within the seed, acylserotonins were found nearly exclusively in the inner seed coat, where probably their biosynthesis proceeds. On the other hand, lemon seedlings contained only trace amounts of these compounds that were not found in adult leaves. The compounds identified in the present studies were shown to have antioxidant properties in vitro, using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. In the investigated reaction in hexane, Me-C22 and Me-C24-serotonins were less active than n-C22 and n-C24-serotonins and δ-tocopherol, while branched-chain acylserotonins (iso-C21 and -C25) showed higher antioxidant activity than all the normal-chain compounds. On the other hand, all these compounds showed a similar but considerably lower antioxidant activity in acetonitrile than in hexane.

[Determination of polychlorinated naphthalenes in ambient air by isotope dilution gas chromatography-triple quadrupole mass spectrometry].

Polychlorinated naphthalenes (PCNs) have a structure similar to that of polychlorinated biphenyls (PCBs) and represent a new type of persistent organic pollutants (POPs) that are widely present in the environment and biological communities. PCNs can migrate and transform via different environmental media, which severely affects the health of humans and organisms. Researchers have devoted considerable focus on ambient air pollution. Although the current ambient air quality has not yet limited the concentration of PCNs, the Stockholm Convention has required parties to prohibit and eliminate their production and use. As one of the contracting parties, China is obligated to improve its environmental monitoring. In other words, the development of a method for monitoring PCNs in ambient air is important for understanding ambient air quality and safeguarding human health. PCNs are generally present at trace levels (pg/m3) in ambient air. To achieve accurate quantification of PCNs, high demands are raised on the methods for extraction, purification, and instrumental analysis, which can directly affect the efficiency, accuracy, and sensitivity of a method. Considering the trace-level presence of PCNs in ambient air and the high efficiency and accuracy of the analytical method, accelerated solvent extraction (ASE), combined with column chromatography using a multilayer silica gel column and a neutral alumina column, was established for the extraction and purification of PCNs in ambient air. The important parameters involved in the aforementioned steps, such as the type of extraction and volume of elution solvent, were optimized. The results indicated that dichloromethane-hexane (1∶1, v/v) was the best extraction solvent for the recovery of PCNs. Hexane and dichloromethane-hexane (5∶95, v/v) were used as the elution solvents for the multi-silica gel column and neutral alumina column, respectively. Isotope dilution gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) was used to quantify the target compounds. Gas chromatographic parameters, such as temperature program conditions and inlet temperature, were also optimized. The oven temperature program was as follows: 80 ℃ for 1 min, 80 ℃ to 160 ℃ at 15 ℃/min, 160 ℃ to 265 ℃ at 3 ℃/min, and 265 ℃ to 280 ℃ at 5 ℃/min, followed by holding the temperature at 280 ℃ for 10 min. The inlet temperature was set at 260 ℃. The optimal characteristics of ion pair, collision energy, and ion source temperature were determined by optimizing the key mass spectrometry parameters. The developed instrumental method, combined with suitable sample preparation techniques, was used to determine the concentrations of PCNs in ambient air samples. Quality control (QC) and quality assurance (QA) were performed by adding isotope internal standards before sampling, extraction, and injection analysis to monitor the entire analysis process. The relative standard deviations (RSDs) of the relative response factors (RRFs) for trichloronaphthalene to octachloronaphthalene were less than 16% in the concentration range of 2-100 ng/mL. The method detection limits (MDLs) for PCN homologues were in the range of 1-3 pg/m3(calculated using a sample volume of 288 m3). The precision and accuracy of this method for determining PCNs in ambient air samples were evaluated using a spiked matrix. The average spiked recoveries of trichloronaphthalene to octachloronaphthalene were 89.0%-119.4%, 98.6%-122.5% and 93.7%-124.5% at low, medium, and high spiked concentrations (20, 50, and 90 ng/mL), respectively. The RSDs of the assay results were 1.9%-7.0%, 1.6%-6.6%, and 1.0%-4.8%, respectively. During the entire analysis process, the average recoveries of the sampling and extracted internal standards were 136.2%-146.0% and 42.4%-78.1%, respectively, and the corresponding RSDs were 5.6%-7.5% and 2.7%-17.5%. Thus, this method meets the requirements of trace analysis and exhibits good parallelism, high sensitivity, high accuracy, and good precision, and it is suitable for the accurate quantitative determination of trichloronaphthalene to octachloronaphthalene in ambient air.

In vitro anti-HIV and cytotoxic effects of pure compounds isolated from Croton macrostachyus Hochst. Ex Delile.

Croton macrostachyus is an important plant in traditional African medicine, widely utilized to treat a variety of diseases. In Kenya, HIV-infected patients use leaf and root decoctions of the plant as a cure for cough, back pain, bleeding, skin diseases, warts, pneumonia, and wounds. This study aimed to evaluate the anti-HIV activities and cytotoxic effects of extracts and chemical constituents isolated from C. macrostachyus. In our previous study we demonstrated that the hexane, CH2Cl2, ethyl acetate and methanol soluble fractions of a 1:1 v/v/ CH2Cl2/MeOH crude extracts of the leaves and stem bark of C. macrostachyus exhibited potent anti-HIV activities against HIV-1 with IC50 values ranging from 0.02-8.1 µg/mL and cytotoxicity effects against MT-4 cells ranging from IC50 = 0.58-174 µg/mL. Hence, hexane soluble extract of 1:1 v/v/ CH2Cl2/MeOH crude extract of the leaves of C. macrostachyus, that was more potent against HIV-1 at IC50 = 0.02 µg/mL was subjected to column chromatography leading to the isolation of 2-methoxy benzyl benzoate (1), lupenone (2), lupeol acetate (3), betulin (4), lupeol (5), sitosterol (6) and stigmasterol (7). Lupenone (2), lupeol acetate (3) and betulin (4) exhibited anti-HIV-1 inhibition at IC50 = 4.7 nM, 4.3 and 4.5 µg/mL respectively. The results obtained from this study support the potential of C. macrostachyus, as a source of anti-HIV constituents.

Composition, Antioxidant and Anti-inflammatory activities of Hexane and Methanol extracts of Acmella uliginosa from Terai region of Uttarakhand

Abstract Acmella uliginosa, an edible herb belonging to Asteraceae family, was collected from the Terai region of Uttarakhand, India. Methanol and hexane extracts of the whole plant were prepared using soxhlet apparatus. The GC-MS analysis of plant extracts identifies 22 and 35 major compounds of methanol and hexane extracts which comprises of 74.21% and 73.20% of the total composition of extracts, respectively. The major compound in hexane was 2, 4-heptadienal (7.99%) whereas trans, trans-9, 12-octadecadienoic acid propyl ester (16.96%) was major compound in methanol extract. The extracts were evaluated for antioxidant and anti-inflammatory properties. Methanol extract showed higher free radical scavenging and reducing power activities with IC50 value 153.82±1.69 µg/mL and RP50 value of 152.28±0.41 µg/mL, respectively. The metal chelating activity was higher in hexane extract as compared to methanol extract i.e., 62.08±0.25 µg/mL. The anti-inflammatory activity assessed by its ability to inhibit denaturation was higher in methanol having IB50 value 87.33±0.15 µg/mL. The total phenolic content (TPC), total flavonoid content (TFC) and ortho-dihydric phenol content (ODP) of methanol and hexane extracts were also evaluated. TPC, TFC and ODP was higher in methanol extract having value of 122.23±0.22, 35.01±0.29 and 8±0.86 mg/mL, respectively. Acmella uliginosa, might be considered as a natural source for antioxidant and anti-inflammatory properties

[Detection of Residual Solvents in Commercial Supplements Using Headspace (HS)-GC-MS].

In order to understand the actual state of residual solvents contained in commercial supplements, we performed a simultaneous analysis of residual solvents by headspace (HS)-GC-MS with reference to the Japanese Pharmacopoeia's "Residual Solvents", for 29 products selected from among commercial supplements (e.g., revitalizers, weight loss pills) that are deeply colored or contain coating agents and extract powder. As a result, benzene (class 1) was detected in eight black-colored supplements, and hexane (class 2B) was also detected in one of those products. On the other hand, methanol (class 2A) was detected in four products containing coating agents and extract powders, such as citrus peel extract. None of these residual solvents exceeded the concentration limits set by the Japanese Pharmacopoeia. Benzene was detected at 1.7 µg/g, which was near the concentration limit, in some products. As raw materials used for the manufacture of the black-colored supplements from which benzene was detected commonly included activated carbon, we analyzed the residual solvents contained in activated carbon commercially available for use as food additive and in food production and medicine. As a result, benzene was detected at high concentrations in activated carbon made from hemp (approximately 29 µg/g) and bamboo (approximately 140 µg/g).

Qualitative analysis of flavors and fragrances added to tea by using GC-MS.

A precise identification method was developed to identify the flavors and fragrances added to tea matrix artificially using gas chromatography with mass spectrometry and gas chromatography with quadrupole time-of-flight mass spectrometry. The proposed method was based on the corresponding "three-column retention indices, two exact mass numbers, one mass spectrum matching degree" database of 40 kinds of common flavors and fragrances. The intraday and the interday relative standard deviation of the retention indices were less than 0.048 and 0.093%, respectively. The accuracy of exact mass was between 0.15 and 6.22 ppm. And the validation of the created database was performed by analyzing the tea samples. Thus, the proposed method is suitable for the precise identification of the flavors and fragrances added to tea matrix artificially without standard substances as a reference.

Sequential biodegradation of complex naphtha hydrocarbons under methanogenic conditions in two different oil sands tailings.

Methane emissions in oil sands tailings ponds are sustained by anaerobic biodegradation of unrecovered hydrocarbons. Naphtha (primarily C6-C10; n- iso- and cycloalkanes) is commonly used as a solvent during bitumen extraction process and its residue escapes to tailings ponds during tailings deposition. To investigate biodegradability of hydrocarbons in naphtha, mature fine tailings (MFT) collected from Albian and CNRL tailings ponds were amended with CNRL naphtha at ∼0.2 wt% (∼2000 mg L-1) and incubated under methanogenic conditions for ∼1600 d. Microbial communities in both MFTs started metabolizing naphtha after a lag phase of ∼100 d. Complete biodegradation/biotransformation of all n-alkanes (except partial biodegradation of n-octane in CNRL MFT) followed by major iso-alkanes (2-methylpentane, 3-methylhexane, 2- and 4-methylheptane, iso-nonanes and 2-methylnonane) and a few cycloalkanes (derivatives of cyclopentane and cyclohexane) was observed during the incubation. 16S rRNA gene pyrosequencing showed dominance of Peptococcaceae and Anaerolineaceae in Albian MFT and Anaerolineaceae and Syntrophaceae in CNRL MFT bacterial communities with co-domination of Methanosaetaceae and "Candidatus Methanoregula" in archaeal populations during active biodegradation of hydrocarbons. The findings extend the known range of hydrocarbons susceptible to methanogenic biodegradation in petroleum-impacted anaerobic environments and help refine existing kinetic model to predict greenhouse gas emissions from tailings ponds.

Hexane Extract of Echinops spinosissimus Turra subsp. spinosus from Tunisia: A Potential Source of Acetylated Sterols - Investigation of its Biological Activities.

The hexane extract of Echinops spinosissimus Turra subsp. spinosus flower heads was analyzed for its fatty acid and sterol composition. Its physicochemical characteristics were also studied. The saponification, iodine and peroxide values were determined as 255 mg KOH/g, 42.57 g I2 /100 g and 110 m equiv. O2 /kg of oil, respectively. The oleic (C18:1; 61.14%), palmitic (C16:0; 21.36%) and linoleic (C18:2; 10.45%) acids were the dominant fatty acids. This extract was also found to contain high levels of ß-sitosterol and stigmasterol (44.97% and 34.95% of total sterols, respectively). On the other hand, the identification of terpenoid compounds was investigated by using GC/MS, which revealed fourteen major terpenoids mainly taraxasterol, lupeol, pseudotaraxasterol, lup-22(29)-en-3-yl acetate, taraxasteryl acetate, α-amyrin, ß-amyrin, pseudotaraxasteryl acetate, hop-20(29)-en3-ß-ol, α-amirenone, along with ß-sitosterol and stigmasterol. Moreover, we have evaluated the in vitro antibacterial and antifungal activities of the unsaponifiable matter and a fraction isolated from this extract. These activities were conducted using the diffusion disc methods and broth microdilution assay. The resulted fraction from this extract showed the highest antibacterial activity with significant minimum inhibitory concentrations (MIC) values 125.0 µg/ml against Staphylococcus aureus, Micrococcus luteus and Bacillus cereus. However, it did exhibit no substantial antifungal activity.

Analysis of petroleum contaminated soils by spectral modeling and pure response profile recovery of n-hexane.

This pilot study compared penalized spline regression (PSR) and random forest (RF) regression using visible and near-infrared diffuse reflectance spectroscopy (VisNIR DRS) derived spectra of 164 petroleum contaminated soils after two different spectral pretreatments [first derivative (FD) and standard normal variate (SNV) followed by detrending] for rapid quantification of soil petroleum contamination. Additionally, a new analytical approach was proposed for the recovery of the pure spectral and concentration profiles of n-hexane present in the unresolved mixture of petroleum contaminated soils using multivariate curve resolution alternating least squares (MCR-ALS). The PSR model using FD spectra (r(2) = 0.87, RMSE = 0.580 log10 mg kg(-1), and residual prediction deviation = 2.78) outperformed all other models tested. Quantitative results obtained by MCR-ALS for n-hexane in presence of interferences (r(2) = 0.65 and RMSE 0.261 log10 mg kg(-1)) were comparable to those obtained using FD (PSR) model. Furthermore, MCR ALS was able to recover pure spectra of n-hexane.

The mammalian toxicological hazards of petroleum-derived substances: an overview of the petroleum industry response to the high production volume challenge program.

Petroleum-derived substances are complex and composed of aliphatic (normal-, iso-, and cycloparaffins), olefinic, and/or aromatic constituents. Approximately 400 of these complex substances were evaluated as part of the US Environmental Protection Agency voluntary High Production Volume (HPV) Challenge program. The substances were separated into 13 groups (categories), and all available data were assessed. Toxicology testing was conducted as necessary to fully address the end points encompassed by the HPV initiative. In a broad sense, volatile hydrocarbons may cause acute central nervous system effects, and those that are liquids at room temperature pose aspiration hazards if taken into the lungs as liquids and may also cause skin irritation. Higher boiling substances may contain polycyclic aromatic constituents (PACs) that can be mutagenic and carcinogenic and may also cause developmental effects. Substances containing PACs can also cause target organ and developmental effects. The effects of aliphatic constituents include liver enlargement and/or renal effects in male rats via an α-2u-globulin-mediated process and, in some cases, small but statistically significant reductions in hematological parameters. Crude oils may contain other constituents, particularly sulfur- and nitrogen-containing compounds, which are removed during refining. Aside from these more generic considerations, some specific petroleum substances may contain unusually toxic constituents including benzene, 1,3-butadiene, and/or n-hexane, which should also be taken into account if present at toxicologically relevant levels.

[Pollution characteristics of volatile organic compounds from wastewater treatment system of vitamin C production].

Using a portable gas chromatography and mass spectrometry (GC-MS), the volatile organic compounds (VOCs) pollution in each unit of the wastewater treatment system for vitamin C production was studied, and the species characteristics of volatile organic compounds (VOCs) were analyzed and summarized. The results showed that 32 kinds of volatile organic compounds were identified, and the total mass concentration range of volatilizing VOCs was 0.9629-32.0970 mg x m(-3). The most species and the largest concentration (25 and 32.0970 mg x m(-3)) of volatilizing VOCs were found in grit chamber, which was located in the most front-end of the wastewater treatment system and was in semi-closed state. The proportion of molecular sulfide in the grit chamber was as high as 30.02%; Higher proportions of aromatic hydrocarbons were monitored in the subsequent processing units, with percentages of 21.06%-31.48%. The main types of VOCs monitored were chlorinated hydrocarbons and ketones, accounting for 6.39%-55.80% and 10.40%-58.08% of the total amount, respectively; 14 kinds of VOCs were detected in every unit of the wastewater treatment system: acetone, 2-butanone, n-hexane, chloroform, chlorobenzene etc, among which, vinyl chloride, styrene and 1,3-butadiene belong to the highly toxic substances. The vinyl chloride concentration exceeded the standard of "atmospheric pollutants emission standards" (GB 16297-1996), while 1,3-butadiene and other pollutants have no national standard limits. The results of this study provide a scientific basis for the revision of China's pharmaceutical wastewater VOCs emission standards.

Chemical composition of volatile extract and biological activities of volatile and less-volatile extracts of juniper berry (Juniperus drupacea L.) fruit.

Volatile chemicals in a dichloromethane extract from a steam distillate of juniper berry fruit (Juniperus drupacea L.) and its two column chromatographic fractions (eluted with hexane and ethyl ether) were analyzed by gas chromatography/mass spectrometry. The major compounds in the dichloromethane extract were alpha-pinene (23.73%), thymol methyl ether (17.32%), and camphor (10.12%). A fraction eluted with hexane contained alpha-pinene (44.24%) as the major constituent. A fraction eluted with ethyl ether had thymol methyl ether (22.27%) and camphor (19.65%) as the main components. Three samples prepared from the distillate and two additional samples prepared by petroleum ether and ethanol extraction directly from juniper berry fruits exhibited clear antioxidant activities with dose response in both 1,2-diphenyl picrylhydrazyl and beta-carotene assays. All samples except the hexane fraction showed comparable activities to that of the synthetic antioxidant t-butyl hydroquinone at a level of 200 microg/mL in the two testing systems. The extracts of dichloromethane, petroleum ether, and ethanol exhibited appreciable antimicrobial activities against six microorganisms with minimum inhibitory concentrations ranging from 0.5 mg/mL (volatile extract against Candida albicans ) to 1.2 mg/mL (ethanol extract against Aspergillus niger ). The results of the present study suggest that this fruit could be a natural antioxidant supplement for foods and beverages.

Discrimination of petroleum fluorescence spectra.

This paper presents studies of the total spectra (fluorescence-excitation matrix) of petroleum with regard to the utilization of fluorescence for determining petroleum pollutants. Thorough testing of one group, comprising almost forty lubricating oils in the form of their hexane solutions, points out their discrimination.

Rapid and sensitive determination of two degradation products of flumethrin in honey by ultrasonically assisted extraction and gas chromatography with electron capture detection.

A rapid and sensitive method for the determination of 4-fluoro-3-phenoxybenzaldehyde cyanohydrin (FPBC) and 4-fluoro-3-phenoxy-benzaldehyde (FPB) in honey samples using ultrasonically assisted extraction and gas chromatography with electron capture detection (GC-ECD) has been developed. The different factors affecting the efficiency of the extraction were carefully optimized. The honey sample was extracted with a mixture of hexane and dichloromethane (v/v, 1:1) utilizing the ultrasonically assisted technique and cleaned up by solid-phase extraction on Oasis HLB cartridges. The eluate was evaporated to dryness and residues were reconstituted to 1.0 mL with hexane and determined by GC-ECD. The calibration curves of fortified samples showed acceptable linear response (R(2) >0.99) over a range of 3-100 ng/g for FPBC and FPB in seven replicate determinations of six concentrations, respectively, and analysis of variance (ANOVA) with a lack-of-fit test was performed to validate the regression data. Overall average recoveries ranged from 90.9 to 106.2% for honey samples. The detection limits were 0.9 ng/g for FPBC and 1.0 ng/g for FPB, respectively. This method can be successfully applied to routine determination of two degradation products of flumethrin in honey samples.

Evaluation of solid adsorbent materials for cryogen-free trapping-gas chromatographic analysis of atmospheric C2-C6 non-methane hydrocarbons.

Nine commercial solid adsorbent materials (in order of decreasing surface area: Carboxen 1000, Carbosieve S III, molecular sieve 5A, molecular sieve 4A, silica gel, Carboxen 563, activated alumina, Carbotrap and Carboxen 1016) were investigated for their ability to trap and release C2-C6 non-methane hydrocarbons (NMHCs) in atmospheric samples for subsequent thermal desorption gas chromatography-flame ionization detection analysis (GC-FID). Recovery rates for 23 NMHCs and methyl chloride (CH3Cl) were determined. A microtrap filled with the three adsorbents Carbosieve S III, Carboxen 563 and Carboxen 1016 was found to allow for the analysis of the widest range of target analytes. A detection limit of approximately 3pptC [parts per trillion (carbon)] in a 1l air sample and a linear response over a wide range of volatilities and sample volumes was determined for this configuration. Water vapor in the sample air was found to causes interference in trapping and subsequent chromatographic analysis of light NMHCs. A Peltier-cooled, regenerable water trap inserted into the sample flow path was found to mitigate these problems and to allow quantitative and reproducible results for all analytes at all tested humidity conditions.

A new process for preparation of soybean protein concentrate with hexane-aqueous ethanol mixed solvents.

A new process for the preparation of soybean protein concentrate (SPC) by directly extracting full-fat soy flour with a mixture of hexane and aqueous ethanol was established. Compared with conventional methods, it has some advantages, such as saving energy and reducing protein denaturation caused by heat action during solvent recovery, because this process saves one step of solvent recovery. The effects of aqueous ethanol concentration and the mixure ratio (hexane to ethanol) on the degree of protein denaturation and product quality were investigated, on the basis of which the orthogonal tests were performed. The optimum technical parameters were obtained by analyzing the results of the orthogonal tests with statistical methods. We found that SPC can be obtained by extracting full-fat soy flour under the following conditions: mixture ratio hexane: 90% ethanol, 9:1, v/v; extraction temperature, 45 degrees C; ratio of solid to solvents, (1:2 w/v); and 5 repeated extractions (15 min each time). The results of quality analysis showed that solubility of the product was improved significantly [nitrogen solubility index (NSI) 46.6%] compared with that for ethanol washing of protein concentrate (NSI 8.7%).

Kinetics of catalytic oxidation of benzene, n-hexane, and emission gas from a refinery oil/water separator over a chromium oxide catalyst.

With the advances made in the past decade, catalytic incineration of volatile organic compounds (VOCs) has become the technology of choice in a wide range of pollution abatement strategies. In this study, a test was undertaken for the catalytic incineration, over a chromium oxide (Cr2O3) catalyst, of n-hexane, benzene, and an emission air/vapor mixture collected from an oil/water separator of a refinery. Reactions were carried out by controlling the feed stream to constant VOC concentrations and temperatures, in the ranges of 1300-14,700 mg/m3 and 240-400 degrees C, respectively. The destruction efficiency for each of the three VOCs as a function of influent gas temperature and empty bed gas residence time was obtained. Results indicate that n-hexane and the oil vapor with a composition of straight- and branch-chain aliphatic hydrocarbons exhibited similar catalytic incineration effects, while benzene required a higher incineration temperature or longer gas retention time to achieve comparable results. In the range of the VOC concentrations studied, at a given gas residence time, increasing the operating temperature of the catalyst bed increased the destruction efficiency. However, the much higher temperatures required for a destruction efficiency of over 99% may be not cost-effective and are not suggested. A first-order kinetics with respect to VOC concentration and an Arrhenius temperature dependence of the kinetic constant appeared to be an adequate representation for the catalytic oxidation of these volatile organics. Activation energy and kinetic constants were estimated for each of the VOCs. Low-temperature destruction of the target volatile organics could be achieved by using the Cr2O3 catalyst.