Volatiles formed on heating clay minerals contain a variety of cations and anions and are highly reactive. Gas chromatograph-mass spectrometer analysis of long-chain n-alkanes exposed to such volatiles showed that some decomposition occurred even <250°C. Reactions with anions donated by the volatiles led to compounds containing atoms other than C and H, e.g., Cl. The products obtained from n-alkanes heated in a stream of clay volatiles to 500°C resembled those produced by corresponding alkane-clay mixtures heated to 250°C. At higher temperatures contact between the alkanes and montmorillonite or halloysite led to changes in the assemblages formed, whereas kaolinite or sepiolite had no effect. Thus, the first reactions that occurred when clays were heated with n-alkanes were apparently induced by the volatiles; at higher temperatures catalysis due to direct contact came into play with some of the clay minerals.

A series of organo-montmorillonites and organo-hectorites was prepared by complete ion-exchange from the pure sodium form of the parent smectites. The organic cations were tetramethylammonium, trimethylated quaternary ammonium derivatives of the lysine and of the ornithine methyl esters, quaternarized polyammonium cations, or tetraphenylphosphonium (TPP). These organo-smectites were used as packing material for gas chromatography columns. Mixtures of light hydrocarbons (methane to n-butane; “C1” to “C4”) could be separated. The degree of separation depends on the presence of micropores or of organophilic mesopores. The BET surface area, the micropore and mesopore volumes, as well as the size distribution of micropores and mesopores were measured for several systems. As a general trend, the retention times of the light hydrocarbons decrease with an increase of the micropore volume. In the case of TPP-montmorillonite, characterized by a large mesopore volume but for which no microporosity could be detected, separation of longer linear hydrocarbons (n-pentane to n-octane) could also be achieved.

A synthetic octahedral-site-vacancy-free annite sample and its progressive oxidation, induced by heating in air, were studied by powder X-ray diffraction (pXRD), Mössbauer spectroscopy, nuclear reaction analysis (NRA), Raman spectroscopy, X-ray fluorescence (XRF) spectroscopy, gas chromatography (GC), thermogravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM), and size-fraction separation methods. For a set heating time and as temperature is increased, the sample first evolves along an annite-oxyannite join, until all H is lost via the oxybiotite reaction (Fe2+ + OH− ⇌ Fe3+ + O2− + H↑). It then evolves along an oxyannite-ferrioxyannite join, where ideal ferrioxyannite, KFe3+8/3□1/3AlSi3O12, is defined as the product resulting from complete oxidation of ideal oxyannite, KFe3+2Fe2+AlSi3O12, via the vacancy mechanism (3 Fe2+ ⇌ 2 Fe3+ + [6]□ + Fe↑). A pillaring collapse transition is observed as a collapse of c near the point where ${\text{Fe}}^{2+}\text{/Fe}=\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$3$}\right.$ and all OH groups are predicted and observed to be lost. Quantitative analyses of H, using NRA, GC, and Raman spectroscopy, corroborate this interpretation and, in combination with accurate ferric/ferrous ratios from Mössbauer spectroscopy and lattice parameter determinations, allow a clear distinction to be made between vacancy-free and vacancy-bearing annite. The amount of Fe in ancillary Fe oxide phases produced by the vacancy mechanism is measured by Mössbauer spectroscopy to be 11.3(5)% of total Fe, in agreement with both the theoretical prediction of 1/9 = 11.1% and the observed TGA weight gain. The initiation of Fe oxide formation near the point of completion of the oxybiotite reaction (${\text{Fe}}^{2+}\text{/Fe}=\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$3$}\right.$) is corroborated by pXRD, TGA, Raman spectroscopy, and appearance of an Fe oxide hyperfine field sextet in the Mössbauer spectra. The region of Fe oxide formation is shown to coincide with a region of octahedral site vacancy formation, using a new Mössbauer spectral signature of vacancies that consists of a component at 2.2 mm/s in the [6]Fe3+ quadrupole splitting distribution (QSD). The crystal chemical behaviors of annite-oxyannite and of oxyannite-ferrioxyannite are best contrasted and compared to the behaviors of other layer-silicate series in terms of b vs. [D] (average octahedral cation to O bond length). This also leads to a diagnostic test for the presence of octahedral site vacancies in hydrothermally synthesized annite, based on a graph of b vs. Fe2+/Fe. The implications of the observed sequence of thermal oxidation reactions for the thermodynamic relevance of the oxybiotite and vacancy reactions in hydrothermal syntheses are examined and it is concluded that the oxybiotite reaction is the relevant reaction in the single-phase stability field of annite, at high hydrogen fugacity and using ideal starting cation stoichiometry. The vacancy reaction is only relevant in a multi-phase field, at lower hydrogen fugacity, that includes an Fe oxide equilibrium phase (magnetite) that can effectively compete for Fe, or when using non-ideal starting cation stoichiometries.

Edible clays are consumed by diverse groups of people, especially of African descent, living in Africa and abroad, in a behavior known as geophagy. The clays are used topically as an emollient and drying agent and internally to control diarrhea. Scientific information concerning the chemical constituents and toxicity of edible clays is scarce. The aims of the present study, therefore, were to ascertain the chemical composition of white edible clays (WEC) and gray edible clays (GEC); to determine their toxicity profiles using analytical chemical methods; to test the acute and sub-acute toxicity of edible clays in their natural form as consumed; and to compare the raw and processed clays, and also to compare the latter to a proprietary drug known as ‘Mist kaolin’ (Moko®) which contains some clay along with other chemicals. Atomic absorption spectroscopy (AAS) and gas chromatography/mass spectrometry (GC/MS) were used to determine the elements present. White female Wistar mice and rats were used for the acute and sub-acute toxicity analyses, respectively. The results from AAS showed the presence of heavy metals and metalloids in both GEC and WEC, and the GC/MS revealed the presence of contaminants such as indomethacin and ethyl benzene, but quantities were below human toxicity levels. Doses of 100–500 mg/kg of either clay type could be harmful to the digestive system, but all of the tests revealed that edible clay is not toxic to humans unless very large amounts (500–1000 mg/kg of body weight) are consumed.

Major efforts to control the population of Aedes aegypti mosquitoes involve the use of synthetic insecticides, which can be harmful to the environment. Most plant compounds are eco-friendly and some of them have biocontrol potential, whereas a fraction of these compounds is released into the environment through the leaf-leaching process. We evaluated the effects of secondary compounds from Ateleia glazioviana and Eucalyptus grandis senescent leaf leachates on Ae. aegypti larval mortality, adult emergence time, and wing size using a microcosm approach. The microcosms consisted of 10 larvae kept in water (control) and under four treatments with leachates from a combination of plant species and leaching time (7 or 14 days). Chemical analyses of the leachates showed the presence of carboxaldehyde and Heptatriocotanol, which have antimicrobial properties, potentially reducing the food available for larvae. β-Sitosterol, Stigmasterol, α-Amyrin, and Lupeol are compounds with inhibitory, neurotoxic, and larvicidal effects. Both plant species’ leachates increased larval mortality and decreased emergence time due to the presence of compounds toxic to the larvae. Larger organisms emerged in treatments with 7-days leachates, likely due to the high concentration of dissolved organic matter in the leachates. The higher mortality in 7-days leachates may also increase the organic matter from co-specific decomposition, improving adult size. Therefore, if the mosquito population is not locally extinct, compounds present in leaf leachates may act as a resource enhancing larvae growth, potentially increasing survivors’ fitness. In conclusion, biocontrol attempts using urban green spaces may have unexpected outcomes, such as resulting in larger pest organisms.

Seeds kept in long-term storage are essential for maintaining genetic resources of crops and other plant materials in seed banks and national germplasm systems. But seeds undergo chemical changes over time as part of the ageing process that result in reduced germination rates and seedling normalcy. For example, oilseed crops such as peanuts are particularly vulnerable to oxidation and rancidification due to their high oil content. To test the effect of storage time on seed oil in peanuts, we grew different accessions and harvested fresh seeds to compare the oil composition of new seeds with seeds aged in storage for varying lengths of time. Out of the nine fatty acids detected and measured by gas chromatography, five including oleic, gadoleic, behenic, lignoceric and cerotic acids differed significantly between new and old seeds. Additionally, old seeds accumulated up to four oxidation products together averaging about 1% of the total oil composition. The concentration of these oxidation products was positively correlated with the age of the seeds, increasing linearly up to more than 6% of the total in the oldest seeds. The presence and concentration of oxidation products measured using simple chromatography techniques can be used as an initial indication of quality and viability in older seed inventories stored in germplasm repositories.

High-temperature X-ray diffraction with concurrent gas chromatography (GC) was employed in the study of iron disulfide (FeS2) cathode pellets disassembled from thermal batteries. When FeS2 cathode materials were analyzed in an air environment, reaction of the KCl and LiCl salt phases led to the formation of Li2(SO4) and KFe2S3 phases beginning at ~230 °C. These phases subsequently reacted to generate various forms of potassium iron sulfates in the 280–500 °C range, with the final products resulting in a β-Fe2O3 phase and K2(SO4). Independent simultaneous thermal analysis coupled with mass spectroscopy (MS) augmented the diffraction results and supported the overall picture of FeS2 decomposition. Both gas analysis measurements (i.e. GC and MS) from the independent experiments confirmed the formation of SO2 off-gas species during the breakdown of the FeS2. In contrast, characterization of the same cathode material under inert conditions showed the persistence of the initial FeS2 phase throughout the entire temperature range of analysis.

The gas release and speciation of carbon species from irradiated and unirradiated Zircaloy-4 samples, representative for the fuel cladding as used in Belgian nuclear power plants, were studied in a saturated Ca(OH)2 solution in anaerobic conditions. This environment is relevant for the Belgian Supercontainer design, as perceived for the geological disposal of high-level nuclear waste. To achieve this, we performed simple immersion and potentiostatic corrosion tests. Potentiodynamic polarization curves, recorded prior to the potentiostatic tests, revealed that irradiation seems to induce changes on the Zircaloy-4 corrosion behavior, such as a shift of the corrosion potential. Potentiostatic corrosion tests on unirradiated Zircaloy-4 provided a corrosion rate of ~54 nm/yr over a 7 day-experiment, whilst a corrosion rate of only ~4 nm/yr was calculated for the irradiated sample. Gas chromatography revealed that during simple immersion tests, which lasted 195 days, hydrogen, methane, ethane, and CO2 were produced, with methane being the major compound. Assuming that all carbon released from the metal was transformed into gaseous compounds, this yields to a corrosion rate ranging from 57 to 84 nm/yr for the irradiated sample. However, caution has to be taken on these corrosion rate and more tests should be performed to confirm these results.

A suite of coarsely crystalline samples of crinoidal limestone adjacent to a PbS-CaF2-CaCO3 vein in the North Pennine orefield (Greenhow Rake) was analysed by three independent methods [Inductively Coupled Plasma emission spectroscopy (ICP), Mass Spectrometry (MS) and Gas Chromatography (GC)], in order to determine the nature and origin of trace elements and volatiles released on heating and thermal decrepitation, to establish whether fluid inclusions from the host limestone differed in composition from those within the vein, and to assess the value of the results obtained for mineral exploration. The ICP method gave reproducible results for Ca, Na and K, and significant values for Pb and Zn. Na and K correlate with H2O levels determined by MS/volumetric analysis, suggesting their coexistence within fluid inclusions. No such correlation was found for Pb and Zn, suggesting that these elements were derived by volatilisation, perhaps from traces of galena and sphalerite. Methane showed no correlation with H2O and a source other than aqueous fluid inclusions is thought probable for this volatile.

The vein calcite showed much lower K/Na fluid ratios (0.05 cf 0.1–0.2), than the limestones. The limestone-hosted fluids occur predominantly in crinoid ossicles and are believed to represent early pre-mineralisation fluids, unrelated to those associated with veining. Combined ICP and MS techniques may be of value in investigating samples where fluid inclusions are too small for microthermometric and optical analysis.

Fuel-oil contamination of groundwater and waterways is common throughout the world. The fuel components methyl-tert-butyl ether (MTBE) and benzene, toluene, ethylbenzene and o-, p- and m-xylenes (BTEX) compounds are most likely to reach a borehole after a contamination event, and also those that pose the greatest risk.

Various gas chromatography-mass spectrometry (GCMS) methods are available for the analysis of volatile organic compounds (VOCs) but many of these are not suitable for rapid and combined analysis of MTBE and BTEX. Here we describe and validate a simple and reliable method that fulfils these requirements. The method is quick: 48 samples can be analysed in a 24 hour period using the Precept II® autosampler and therefore is suitable for high throughput work. Validation of our experiments is presented in the form of linearity, precision and intra-day repeatability of standards as well as limits of detection and limits of quantification for the range 1—20 μg/l.

This MTBE/BTEX analytical method developed was used to study the optimization of a modular post-abstraction remediation system incorporating air-stripping and granular activated carbon (GAC) technologies (Hall, 2004), from which a selection of sample data is presented.

The study identified insecticidal effects from the cinnamon and clove essential oils in Tenebrio molitor L. (Coleoptera: Tenebrionidae). The lethal concentrations (LC50 and LC90), lethal time, and repellent effect on larvae, pupae, and adults of T. molitor after exposure to six concentrations of each essential oil and toxic compounds were evaluated. The chemical composition of the cinnamon oil was also determined and primary compounds were eugenol (10.19%), trans-3-caren-2-ol (9.92%), benzyl benzoate (9.68%), caryophyllene (9.05%), eugenyl acetate (7.47%), α-phellandrene (7.18%), and α-pinene (6.92%). In clove essential oil, the primary compounds were eugenol (26.64%), caryophyllene (23.73%), caryophyllene oxide (17.74%), 2-propenoic acid (11.84%), α-humulene (10.48%), γ-cadinene (4.85%), and humulene oxide (4.69%). Cinnamon and clove essential oils were toxic to T. molitor. In toxic chemical compounds, eugenol have stronger contact toxicity in larvae, pupae, and adult than caryophyllene oxide, followed by α-pinene, α-phellandrene, and α-humulene. In general, the two essential oils were toxic and repellent to adult T. molitor. Cinnamon and clove essential oils and their compounds caused higher mortality and repellency on T. molitor and, therefore, have the potential for integrated management programs of this insect.

Leaves absorbed high amounts of clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) as foliar sprays on honey mesquite (Prosopis glandulosa Torr. # PRCJG) as indicated by concentrations of 10 μg/g fresh wt or more in basal stem phloem by 4 days after treatment. Small quantities of clopyralid (< 1 μg/g) were detected in basal stem phloem after spray applications of clopyralid to defoliated plants or roots treated by soil application. When applied to foliated plants, the 0.56 kg/ha of clopyralid killed 60% or more plants, but none were killed when clopyralid sprays were applied to defoliated plants or when 2.2 kg/ha of clopyralid was applied to the soil. Water, diesel oil plus water, or water plus surfactant were equally effective as clopyralid carriers as foliar sprays.

Removing the epicuticular wax from mature pads (cladophylls) of Lindheimer pricklypear increased picloram absorption by four- to sixfold in the laboratory, while the addition of surfactant had little effect on absorption. Absorption decreased with increasing pH of the picloram solution, indicating that picloram diffused through the cuticle as the undissociated molecule. Picloram entered detached pads at the areoles more readily than through the surrounding cuticle. In the glasshouse, whole plants consisting of an old, mature pad supporting a young, growing pad absorbed picloram very slowly whether picloam was applied as a spray to old or young pads or to the soil. About 90 and 80% of the applied picloram remained on the waxy surface of old and new pads, respectively, and about 2% of the applied picloram was recovered from within the epicuticular wax after 30 days. Picloram concentrations within pads treated in the glasshouse were greater when the herbicide was applied to new pads (4.6 μg/g) than old pads (1.9 μg/g) after 30 days. More picloram was translocated basipetally from treated new pads to untreated old pads than in the opposite direction, but concentrations in untreated pads were low (<1 μg/g). Little picloram was absorbed by roots, compared to pads, and little was translocated into or out of roots. These results conflict with the view that the effectiveness of picloram for pricklypear control is attributable to extensive root uptake and acropetal transport. However, observations of plants 6 months after treatment indicated that soil applications were more effective than sprays in the glasshouse.

The soil bacterium Alcaligenes eutrophus is able to degrade phenoxy herbicides such as 2,4-D [(2,4-dichlorophenoxy)acetic acid]. It has been shown that several degradative genes are located on a large plasmid harbored by this organism. We have demonstrated by HPLC and gas chromatography that 2,4-dichlorophenol is a major metabolite resulting from 2,4-D degradation by A. eutrophus. A portion of the large plasmid carrying the 2,4-D catabolic genes has been cloned and mapped by restriction endonuclease digestion. Overlapping subclones have been produced and were used in conjugation experiments in order to identify the first gene involved in 2,4-D detoxification. Once sequenced, this gene will be transferred to dicotyledonous plant cells using available vector systems.

Simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] was applied annually at 4.5 kg/ha to uncultivated sandy loam of peach (Prunus persica Batsch) for 7 yr (orchard A) and 9 yr (orchard B). Simazine and the metabolite, hydroxysimazine [2-hydroxy-4,6-bis (ethylamino)-s-triazine] as determined by gas chromatography (GC) persisted for 40 and 28 months in soil of orchard A and B, respectively. However, no progressive accumulation of either compound in large quantities occurred from repeated annual applications of simazine to the orchard soils. No metabolites other than hydroxysimazine were detected. Hydroxysimazine was degraded more slowly than simazine and the residue levels of hydroxysimazine were at least 40 times those of simazine 40 months and 28 months after the final application in orchard A and B, respectively. Both simazine and hydroxysimazine residues were detected in the upper 30 cm of the soil profile.

In a two-year study involving two sites in western Canada, the dissipation of bromoxynil octanoate alone at 0.35 or 0.42 kg phenol equivalent (pe)/ha and the tank mixture of MCPA iso-octyl ester at 0.28 kg ae/ha plus bromoxynil octanoate at 0.28 kg pe/ha was monitored in postemergence-treated triticale. Initial foliar residues on the day after application (three- to four-leaf stage of the crop) were of the order of 14 and 5 mg/kg for MCPA and bromoxynil, respectively. Residues of both herbicides decreased to less than the limit of quantification (0.025 mg/kg) of the analytical method 21 d after application. At crop maturity, herbicide residues were non-detectable in the straw and seed. There was little or no effect on the dissipation of bromoxynil residues due to tank mixing with MCPA.

Leaves of greenhouse-grown honey mesquite [Prosopis juliflora (Swartz) DC var. glandulosa (Torr.) Cockerell # PRCJG] initially absorbed more triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid} from application of the ester than the amine salt. After 24 h, however, honey mesquite had absorbed 66% of the applied ester formulation and 72% of the amine formulation. Triclopyr was rapidly transported from the treated leaf to other plant parts. Triclopyr concentrations recovered 4 h after treatment in the upper canopy, lower canopy, and roots averaged 0.12, 0.19, and 0.09 μg, respectively. Concentrations of triclopyr recovered after 24 h were not significantly different than after 4 h in the canopy. No ester from ester application was recovered in the canopy, other than that in the treated leaf. Triclopyr recovered from stems of honey mesquite in the field ranged from 0.16 to 0.72 μg/g in phloem and from 0.04 to 0.20 μg/g in xylem from a broadcast spray application of the butoxyethanol ester at 1.12 kg/ha. Concentrations of triclopyr were usually not significantly different in either the upper or lower stems whether sampled 3 or 30 days after treatment.

The leaves of tall morningglory, giant duckweed, and common purslane were treated with nine surfactants at a concentration of 0.1% and examined after 24 hr using cryo-scanning electron microscopy for phytotoxicity as evidenced by tissue damage and epicuticular wax morphology changes. In some instances, tissue damage could be discerned; however, the effects of a particular surfactant were not uniform across the three species. Morphological alteration of epicuticular waxes was not observed. Gas chromatographic analyses of the epicuticular waxes of the species used in the study reveal component differences and may, in part, explain the lack of uniform response across species for a particular surfactant.

Phytotoxicity, absorption, translocation, and metabolism of root-applied norflurazon [4-chloro-5-(methylamino)-2-(3-(trifluoromethyl)phenyl)-3(2H)-pyridazinone] in tolerant narrowleaf and susceptible broadleaf guineagrass (Panicum maximum Jacq. # PANMA) biotypes were examined under greenhouse and laboratory conditions. Dose response studies conducted in the greenhouse showed greater injury to the shoots of broadleaf than narrowleaf biotypes. 14C-norflurazon absorbed was 0.3 and 0.5% and 1.6 and 2.4% of that applied, 3 and 7 days after application for narrowleaf and broadleaf biotypes, respectively. Of the total radioactivity absorbed after 3 and 7 days, 70 and 76% and 57 and 61% were translocated to the shoots of susceptible and tolerant biotypes, respectively. Gas chromatographic analyses revealed that broadleaf shoots had 3.08 μg/g dry wt of the parent compound while its tolerant counterpart had 0.40 μg/g dry wt, 7 days after application. The toxic parent compound was metabolized more rapidly to its non-phytotoxic desmethyl analog by narrowleaf biotypes, thereby preventing its accumulation in the shoots. Differences in absorption, translocation, and metabolism were responsible for the differential response of the two biotypes of guineagrass.