diniconazole and tebuconazole

In this work, a core-shell Fe3O4@SiO2@MOF/TiO2 nanocomposite was synthesized and used to as adsorbent for magnetic solid-phase extraction (MSPE) of triazole fungicides from environmental water samples. Five triazole fungicides, namely, triadimenol, hexaconazole, diniconazole, myclobutanil, and tebuconazole, were selected as target analytes for MSPE. These analytes were quantitatively adsorbed on microspheres, and the sorbents were separated from the solution by using a magnet. The analytes were desorbed by methanol and determined through liquid-chromatography coupled with tandem mass spectrometry. The extraction parameters affecting the extraction efficiency were optimized through response surface methodology. The limits of detection and limits of quantification for the selected fungicides were 0.19-1.20ngL(-1) and 0.61-3.62ngL(-1), respectively. The proposed method was applied to determine the concentration of fungicides in actual environmental water samples. The accuracy of the proposed method was evaluated by measuring the recovery of the spiked samples. The satisfying recoveries of the four water samples ranged from 90.2% to 104.2%. Therefore, the magnetic metal-organic framework/TiO2 nanocomposite based MSPE is a potential approach to analyze fungicides in actual water samples.

Topics: Adsorption; Chromatography, Liquid; Fungicides, Industrial; Nanocomposites; Silicon Dioxide; Solid Phase Extraction; Tandem Mass Spectrometry; Titanium; Triazoles; Water Pollutants, Chemical

The amylose-tris(3,5-dimethylphenylcarbamate) chiral stationary phase was synthesized and used to separate the enantiomers of triazole pesticides by high-performance liquid chromatography. The mobile phase was n-hexane-isopropanol applying a flow rate of 1.0 mL/min. Six triazole pesticides were enantioselectively separated. Myclobutanil, paclobutrazol, tebuconazole, and uniconazole obtained complete separation with the resolution factors of 5.73, 2.99, 1.72, and 2.07, respectively, and imazalil and diniconazole obtained partial separation with the resolution factors of 0.79 and 0.77 under the optimized conditions. The effect of the content of isopropanol as well as column temperature on the separation was investigated. A circular dichroism detector was used to identify the enantiomers and determine the elution orders. The results showed the low temperature was good for the chiral separation except for diniconazole. The thermodynamic parameters calculated based on linear Van't Hoff plots showed the chiral separations were controlled by enthalpy.

Topics: Amylose; Chromatography, High Pressure Liquid; Imidazoles; Nitriles; Pesticides; Phenylcarbamates; Stereoisomerism; Temperature; Thermodynamics; Triazoles

In order to establish a fast and accurate method for novel DMIs fungicide screening, lanosterol 14alpha-demethylase of Magnaporthe grisea expressed in E. coli was used as target enzyme and the DMI fungicides diniconazole, tebuconazole, triadimenol and triadimefon were used as representative fungicides, the effects of enzyme activity, enzyme purity and concentration on the binding spectra were investigated. The results showed that active enzyme, elimination of interference of other P450s and proper enzyme concentration were necessary for obtaining accurate binding spectra. The Kd values of diniconazole, tebuconazole, triadimenol and triadimefon were 0.143 micromol/L, 0.24 micromol/L, 0.257 micromol/L and 0.307 micromol/L respectively, which significantly correlated to their 120h-EC50 values on the growth of Magnaporthe grisea. The results indicated that the binding spectra of fungicide and lanosterol 14alpha-demethylase can serve as a reliable and fast method for novel fungicide screening.

Topics: Cytochrome P-450 Enzyme System; Fungicides, Industrial; Spectrophotometry; Sterol 14-Demethylase; Triazoles