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201.
Analysis of abamectin residues in avocados by high-performance liquid chromatography with fluorescence detection 总被引:1,自引:0,他引:1
Hernández-Borges J Ravelo-Pérez LM Hernández-Suárez EM Carnero A Rodríguez-Delgado MA 《Journal of chromatography. A》2007,1165(1-2):52-57
In this work an analytical method for the determination of abamectin residues in avocados is developed using high-performance liquid chromatography (HPLC) with fluorescence (FL) detection. A pre-column derivatization with trifluoroacetic anhydride (TFAA) and N-methylimidazole (NMIM) was carried out. The mobile phase consisted of water, methanol and acetonitrile (5:47.5:47.5 v/v/v) and was pumped at a rate of 1 mL/min (isocratic elution). The fluorescence detector was set at an excitation wavelength of 365 nm and an emission wavelength of 470 nm. Homogenized avocado samples were extracted twice with acetonitrile:water 8:2 (v/v) and cleaned using C(18) solid-phase extraction (SPE) cartridges. Recovery values were in the range 87-98% with RSD values lower than 13%. The limits of detection (LODs) and quantification (LOQs) of the whole method were 0.001 and 0.003 mg/kg, respectively. These values are lower than the maximum residue limit (MRL) established by the European Union (EU) and the Spanish legislation in avocado samples. 相似文献
202.
Avelino Martín Miguel Mena Adrin Prez‐Redondo Carlos Ylamos 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(5):m157-m159
The reaction of the imide–nitride complex [{Ti(η5‐C5Me5)(μ‐NH)}3(μ3‐N)] with potassium iodide in pyridine at room temperature affords the adduct di‐μ‐iodido‐1:1′κ4I‐bis{tri‐μ3‐imido‐1:2:3κ3N;1:2:4κ3N;1:3:4κ3N‐μ3‐nitrido‐2:3:4κ3N‐tris[2,3,4(η5)‐pentamethylcyclopentadienyl](pyridine‐1κN)‐tetrahedro‐potassiumtrititanium(IV)}, [K2Ti6(C10H15)6I2N2(NH)6(C5H5N)2] or [(C5H5N)(μ‐I)K{(μ3‐NH)3Ti3(η5‐C5Me5)3(μ3‐N)}]2. The crystal structure contains two [KTi3N4] cube‐type units held together by two bridging I atoms. There is a centre of inversion located in the middle of this unprecedented discrete K2I2 unit. The geometry around K is best described as distorted trigonal prismatic, with three imide groups, two bridging I atoms and one pyridine ligand. 相似文献
203.
Junguang Zhang Ruixia Shi Estrella Diaz 《The Journal of the Operational Research Society》2015,66(9):1555-1565
The improvement to the monitoring and control efficiency of software project effort is a challenge for project management research. We propose to overcome this challenge through the use of a model for the buffer determination and monitoring of software project effort. This software project effort buffer was originally determined on the basis of a risk management factor analysis with total consideration for project managers’ risk preference. The effort buffer was next allocated to different stages according to the buffer allocation cardinal. An effort deviation monitoring and control model was then established based on the grey prediction model, including the establishment of a deviation monitoring and control model, a simulation test of the accuracy and the deviation prediction algorithm flow chart. The method system was eventually applied to an actual project and compared with the actual project data. The results show that the relative error test accuracy of the proposed model is qualified according to the test standard of the grey model, signifying that it could be used for the prediction of effort deviation and decision-making. The proposed model could use the dynamic control system to monitor and control software project effort in an effective manner. 相似文献
204.
Dipl.‐Chem. Inmaculada Mena Dr. E. A. Jaseer Dr. Miguel A. Casado Dr. Pilar García‐Orduña Prof. Fernando J. Lahoz Prof. Luis A. Oro 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(18):5665-5675
The ready availability of rare parent amido d8 complexes of the type [{M(μ‐NH2)(cod)}2] (M=Rh ( 1 ), Ir ( 2 ); cod=1,5‐cyclooctadiene) through the direct use of gaseous ammonia has allowed the study of their reactivity. Both complexes 1 and 2 exchanged the di‐olefines by carbon monoxide to give the dinuclear tetracarbonyl derivatives [{M(μ‐NH2)(CO)2}2] (M=Rh or Ir). The diiridium(I) complex 2 reacted with chloroalkanes such as CH2Cl2 or CHCl3, giving the diiridium(II) products [(Cl)(cod)Ir(μ‐NH2)2Ir(cod)(R)] (R=CH2Cl or CHCl2) as a result of a two‐center oxidative addition and concomitant metal–metal bond formation. However, reaction with ClCH2CH2Cl afforded the symmetrical adduct [{Ir(μ‐NH2)(Cl)(cod)}2] upon release of ethylene. We found that the rhodium complex 1 exchanged the di‐olefines stepwise upon addition of selected phosphanes (PPh3, PMePh2, PMe2Ph) without splitting of the amido bridges, allowing the detection of mixed COD/phosphane dinuclear complexes [(cod)Rh(μ‐NH2)2Rh(PR3)2], and finally the isolation of the respective tetraphosphanes [{Rh(μ‐NH2)(PR3)2}2]. On the other hand, the iridium complex 2 reacted with PMe2Ph by splitting the amido bridges and leading to the very rare terminal amido complex [Ir(cod)(NH2)(PMePh2)2]. This compound was found to be very reactive towards traces of water, giving the more stable terminal hydroxo complex [Ir(cod)(OH)(PMePh2)2]. The heterocyclic carbene IPr (IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene) also split the amido bridges in complexes 1 and 2 , allowing in the case of iridium to characterize in situ the terminal amido complex [Ir(cod)(IPr)(NH2)]. However, when rhodium was involved, the known hydroxo complex [Rh(cod)(IPr)(OH)] was isolated as final product. On the other hand, we tested complexes 1 and 2 as catalysts in the transfer hydrogenation of acetophenone with iPrOH without the use of any base or in the presence of Cs2CO3, finding that the iridium complex 2 is more active than the rhodium analogue 1 . 相似文献
205.
Caballo J García-Castro M Martín A Mena M Pérez-Redondo A Yélamos C 《Inorganic chemistry》2011,50(14):6798-6808
A series of titanium-group 3/lanthanide metal complexes have been prepared by reaction of [{Ti(η(5)-C(5)Me(5))(μ-NH)}(3)(μ(3)-N)] (1) with halide, triflate, or amido derivatives of the rare-earth metals. Treatment of 1 with metal halide complexes [MCl(3)(thf)(n)] or metal trifluoromethanesulfonate derivatives [M(O(3)SCF(3))(3)] at room temperature affords the cube-type adducts [X(3)M{(μ(3)-NH)(3)Ti(3)(η(5)-C(5)Me(5))(3)(μ(3)-N)}] (X = Cl, M = Sc (2), Y (3), La (4), Sm (5), Er (6), Lu (7); X = OTf, M = Y (8), Sm (9), Er (10)). Treatment of yttrium (3) and lanthanum (4) halide complexes with 3 equiv of lithium 2,6-dimethylphenoxido [LiOAr] produces the aryloxido complexes [(ArO)(3)M{(μ(3)-NH)(3)Ti(3)(η(5)-C(5)Me(5))(3)(μ(3)-N)}] (M = Y (11), La (12)). Complex 1 reacts with 0.5 equiv of rare-earth bis(trimethylsilyl)amido derivatives [M{N(SiMe(3))(2)}(3)] in toluene at 85-180 °C to afford the corner-shared double-cube nitrido compounds [M(μ(3)-N)(3)(μ(3)-NH)(3){Ti(3)(η(5)-C(5)Me(5))(3)(μ(3)-N)}(2)] (M = Sc (13), Y (14), La (15), Sm (16), Eu (17), Er (18), Lu (19)) via NH(SiMe(3))(2) elimination. A single-cube intermediate [{(Me(3)Si)(2)N}Sc{(μ(3)-N)(2)(μ(3)-NH)Ti(3)(η(5)-C(5)Me(5))(3)(μ(3)-N)}] (20) was obtained by the treatment of 1 with 1 equiv of the scandium bis(trimethylsilyl)amido derivative [Sc{N(SiMe(3))(2)}(3)]. The X-ray crystal structures of 2, 7, 11, 14, 15, and 19 have been determined. The thermal decomposition in the solid state of double-cube nitrido complexes 14, 15, and 18 has been investigated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) measurements, as well as by pyrolysis experiments at 1100 °C under different atmospheres (Ar, H(2)/N(2), NH(3)) for the yttrium complex 14. 相似文献
206.