Determination of Azole Fungicides in Atmospheric Samples Collected in the Canadian Prairies by LC/MS/MS

2012 ◽  
Vol 95 (5) ◽  
pp. 1350-1356 ◽  
Author(s):  
Renata Raina ◽  
Erika Smith
Keyword(s):  
Gas Phase ◽  
Detection Limits ◽  
Early Summer ◽  
Canadian Prairies ◽  
Agricultural Region ◽  
Air Sample ◽  
Lower Temperature ◽  
Atmospheric Concentrations ◽  
Azole Fungicides

Abstract An LC/MS/MS method has been developed for the determination of azole fungicides in the atmosphere at low pg/m3 concentrations. Detection limits in the range of 0.16 to 1.2 pg/m3 for a weekly air sample were obtained for the 31 fungicides analyzed. This work represents the first detection of propiconazole, prothioconazole-desthio, and trace levels of hexaconazole in gas phase atmospheric samples collected in a Canadian agricultural region. Samples were collected during April–October 2010 at Bratt's Lake, Saskatchewan, in the Canadian prairies where there was known historical use of selected azole fungicides. Atmospheric concentrations were above detection limits only during June–August 2010, with maximum concentrations occurring in July at 77.9 and 37.5 pg/m3 for propiconazole and prothioconazole-desthio, respectively. Gas phase atmospheric concentrations of propiconazole and prothioconazole-desthio increased following a spring and early summer with higher than normal daily precipitation. These azole fungicides showed the largest gas phase concentrations during periods of lower temperature and during sampling events with at least 1 day with no precipitation. The higher atmospheric gas phase concentrations of each azole fungicide were observed on different days, indicating different formulations may be in use in the prairie agricultural region.

scholarly journals Atmospheric Concentrations of Captan and Folpet in the Lower Fraser Valley Agricultural Region of Canada

2009 ◽  
Vol 2 ◽  
pp. ASWR.S2994 ◽  
Author(s):  
R. Raina ◽  
Wayne Belzer ◽  
Keith Jones
Keyword(s):  
British Columbia ◽  
Gas Phase ◽  
Atmospheric Transport ◽  
Early Summer ◽  
Particle Phase ◽  
Transport Pathway ◽  
Agricultural Region ◽  
Lower Fraser Valley ◽  
Atmospheric Concentrations ◽  
Fraser Valley

Two N-trihalomethylthio fungicides were detected in the atmosphere in the Lower Fraser Valley agricultural region of Canada. Captan was detected in both the particle and gas phase with a dominant particle phase fraction observed in both 2005 and 2006 (only total captan atmospheric concentrations were available for 2004). This provides the first evidence of particle transport as a significant atmospheric transport pathway for captan in an agricultural region in Canada. Weekly captan air concentrations reached maximum levels of 13.2 ng m-3 in June 2006, while for folpet total atmospheric levels were lower with maximum reaching 1.7 ng m-3 in August 2004 and generally <1 ng m3 in 2005 and 2006. Folpet is detected in the atmosphere although not previously reported in usage inventories. In the three years examined (2004-2006) captan concentrations observed a seasonal maximum in atmospheric concentrations during spring to early summer coinciding with expected peak usage period on crops in the Lower Fraser Valley agricultural region located in British Columbia, Canada. No usage data is available in Canada beyond 2003 but these seasonal trends show that captan remains a dominant pesticide used in this agricultural region with no decline in atmospheric concentrations during 2004-2006.

scholarly journals Determination of Various Parameters during Thermal and Biological Pretreatment of Waste Materials

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2262 ◽  
Author(s):  
Robert Hren ◽  
Aleksandra Petrovič ◽  
Lidija Čuček ◽  
Marjana Simonič
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Rumen Fluid ◽  
Typha Latifolia ◽  
Waste Materials ◽  
Advantages And Disadvantages ◽  
Before And After ◽  
Ruminal Temperature ◽  
Lower Temperature

Pretreatment of waste materials could help in more efficient waste management. Various pretreatment methods exist, each one having its own advantages and disadvantages. Moreover, a certain pretreatment technique might be efficient and economical for one feedstock while not for another. Thus, it is important to analyze how parameters change during pretreatment. In this study, two different pretreatment techniques were applied: thermal at lower and higher temperatures (38.6 °C and 80 °C) and biological, using cattle rumen fluid at ruminal temperature (≈38.6 °C). Two different feedstock materials were chosen: sewage sludge and riverbank grass (Typha latifolia), and their combinations (in a ratio of 1:1) were also analyzed. Various parameters were analyzed in the liquid phase before and after pretreatment, and in the gas phase after pretreatment. In the liquid phase, some of the parameters that are relevant to water quality were measured, while in the gas phase composition of biogas was measured. The results showed that most of the parameters significantly changed during pretreatments and that lower temperature thermal and/or biological treatment of grass and sludge is suggested for further applications.

Determination of non-metallic inclusions in metal alloys by spark atomic emission spectrometry (review)

2018 ◽  
Vol 84 (12) ◽  
pp. 5-19
Author(s):  
D. N. Bock ◽  
V. A. Labusov
Keyword(s):  
Spectral Line ◽  
Internal Standard ◽  
Detection Limits ◽  
Radiation Detectors ◽  
Metal Alloys ◽  
Emission Spectrometry ◽  
Direct Production ◽  
Metallic Inclusions ◽  
Dissolved Form

A review of publications regarding detection of non-metallic inclusions in metal alloys using optical emission spectrometry with single-spark spectrum registration is presented. The main advantage of the method - an extremely short time of measurement (~1 min) – makes it useful for the purposes of direct production control. A spark-induced impact on a non-metallic inclusion results in a sharp increase (flashes) in the intensities of spectral lines of the elements that comprise the inclusion because their content in the metal matrix is usually rather small. The intensity distribution of the spectral line of the element obtained from several thousand of single-spark spectra consists of two parts: i) the Gaussian function corresponding to the content of the element in a dissolved form, and ii) an asymmetric additive in the region of high intensity values ??attributed to inclusions. Their quantitative determination is based on the assumption that the intensity of the spectral line in the single-spark spectrum is proportional to the content of the element in the matter ablated by the spark. Thus, according to the calibration dependence constructed using samples with a certified total element content, it is possible not only to determine the proportions of the dissolved and undissolved element, but also the dimensions of the individual inclusions. However, determination of the sizes is limited to a range of 1 – 20 µm. Moreover, only Al-containing inclusions can be determined quantitatively nowadays. Difficulties occur both with elements hardly dissolved in steels (O, Ca, Mg, S), and with the elements which exhibit rather high content in the dissolved form (Si, Mn). It is also still impossible to determine carbides and nitrides in steels using C and N lines. The use of time-resolved spectrometry can reduce the detection limits for inclusions containing Si and, possibly, Mn. The use of the internal standard in determination of the inclusions can also lower the detection limits, but may distort the results. Substitution of photomultipliers by solid-state linear radiation detectors provided development of more reliable internal standard, based on the background value in the vicinity of the spectral line. Verification of the results is difficult in the lack of standard samples of composition of the inclusions. Future studies can expand the range of inclusions to be determined by this method.

Polarographic and voltammetric determination of 6-mercaptopurine and 6-thioguanine

1986 ◽  
Vol 51 (11) ◽  
pp. 2466-2472 ◽  
Author(s):  
Jiří Barek ◽  
Antonín Berka ◽  
Ludmila Dempírová ◽  
Jiří Zima
Keyword(s):  
Detection Limit ◽  
Differential Pulse Voltammetry ◽  
Detection Limits ◽  
Differential Pulse ◽  
Voltammetric Determination ◽  
Differential Pulse Polarography ◽  
Hanging Mercury Drop Electrode ◽  
Pulse Polarography ◽  
Pulse Voltammetry

Conditions were found for the determination of 6-mercaptopurine (I) and 6-thioguanine (II) by TAST polarography, differential pulse polarography and fast-scan differential pulse voltammetry at a hanging mercury drop electrode. The detection limits were 10-6, 8 . 10-8, and 6 . 10-8 mol l-1, respectively. A further lowering of the detection limit to 2 . 10-8 mol l-1 was attained by preliminary accumulation of the determined substances at the surface of a hanging mercury drop.

scholarly journals Recognition of hydrogen isotopomers by an open-cage fullerene

2013 ◽  
Vol 371 (1998) ◽  
pp. 20110629 ◽  
Author(s):  
Yasujiro Murata ◽  
Shih-Ching Chuang ◽  
Fumiyuki Tanabe ◽  
Michihisa Murata ◽  
Koichi Komatsu
Keyword(s):  
Equilibrium Constants ◽  
Equilibrium Mixture ◽  
Size Difference ◽  
Binding Affinities ◽  
Kinetic Isotope ◽  
Molecular Sizes ◽  
Lower Temperature ◽  
Kinetics Of ◽  
Pressure Hydrogen

We present our study on the recognition of hydrogen isotopes by an open-cage fullerene through determination of binding affinity of isotopes H 2 /HD/D 2 with the open-cage fullerene and comparison of their relative molecular sizes through kinetic-isotope-release experiments. We took advantage of isotope H 2 /D 2 exchange that generated an equilibrium mixture of H 2 /HD/D 2 in a stainless steel autoclave to conduct high-pressure hydrogen insertion into an open-cage fullerene. The equilibrium constants of three isotopes with the open-cage fullerene were determined at various pressures and temperatures. Our results show a higher equilibrium constant for HD into open-cage fullerene than the other two isotopomers, which is consistent with its dipolar nature. D 2 molecule generally binds stronger than H 2 because of its heavier mass; however, the affinity for H 2 becomes larger than D 2 at lower temperature, when size effect becomes dominant. We further investigated the kinetics of H 2 /HD/D 2 release from open-cage fullerene, proving their relative escaping rates. D 2 was found to be the smallest and H 2 the largest molecule. This notion has not only supported the observed inversion of relative binding affinities between H 2 and D 2 , but also demonstrated that comparison of size difference of single molecules through non-convalent kinetic-isotope effect was applicable.

Validation of annual growth increments in the Otoliths of two species of Damselfish from the Southern Great Barrier Reef

1992 ◽  
Vol 43 (5) ◽  
pp. 1057 ◽  
Author(s):  
AJ Fowler ◽  
PJ Doherty
Keyword(s):  
Great Barrier Reef ◽  
Direct Determination ◽  
Early Summer ◽  
Barrier Reef ◽  
Annual Basis ◽  
Growth Increments ◽  
Regular Time ◽  
Latitudinal Difference ◽  
Pomacentrus Moluccensis

If the otoliths of fish are to be used as an ageing tool, they must fulfil three criteria: they must display an internal structure of increments, this structure must be relatable to a regular time scale, and the otoliths must grow throughout the lives of the fish at a perceptible rate. These criteria were assessed for two species of damselfish: Pomacentrus moluccensis and P. wardi from One Tree Reef on the southern Great Barrier Reef. Transverse sections of sagittae from both species contained an alternating sequence of opaque and translucent zones that formed an interpretable pattern of increments. Treatment of fish with tetracycline showed that the opaque zones were formed on an annual basis, generally between spring and early summer. The assessment of growth of otoliths from fish treated with tetracycline indicated that those as old as 10 years of age were still laying down increments of regular thickness. Consequently, the otoliths from both species successfully fulfilled the three criteria required for the direct determination of age. Furthermore, this study helped to identify two levels of variation in otolith structure, manifested in the clarity and interpretability of the increments; there was an interspecies difference and a significant intraspecies latitudinal difference.

New method for determination of heats of thermal gas-phase reactions yielding intermediates

1996 ◽  
Vol 45 (1) ◽  
pp. 56-59
Author(s):  
N. N. Buravtsev ◽  
Yu. A. Kolbanovskii ◽  
A. A. Ovsyannikov
Keyword(s):  
Gas Phase ◽  
New Method ◽  
Gas Phase Reactions
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