) column (150 mm × 2.1 mm, i.d. 5 μm). The mobile phase comprised A = methanol/water with 5 mM ammonium formate (20 : 80) and B = methanol/water
with 5 mM ammonium formate (90 : 20); the gradient programme was: 0–1 min 98% A, 1–8 min 98–5% A, 8–12 min 5% A, 12–13 min 5–98% A and 13–20 min 98% A phases. The column oven temperature was set at 35 °C with a flow rate of 0.4 mL min−1. An aliquot of 10 μL was injected through an auto sampler. Mass spectrometric analysis was performed with electrospray ionization (ESI) in positive (5500 eV) modes for each sample. The nebulizer gas and heater gases were adjusted at 30 and 55 p.s.i., respectively. The ion source temperature was set Autophagy activator at 500 °C. A hybrid triple quadrupole linear ion trap mass spectrometer (QqQLIT) was used by integrating an EMS-triggered IDA-enhanced production (EPI), resulting in enhanced sensitivity at trace level. IDA-EPI
experiments were automatically triggered to obtain product ion mass spectra of these peaks. In the IDA experiment, the parameters included rolling collision energy with scan speed of 4000 amus−1, and dynamic trap selleck fill time as a dependent scan. Chlorimuron-ethyl (50 mg) was dissolved in distilled water (100 mL). The pH of the solution was adjusted to 2.5 by the addition of concentrated sulfuric acid (2 mL). The solution was stirred magnetically for 48 h at 42 °C and then kept for 4 days at room temperature. Products formed were separated by preparative thin-layer chromatography, purified by crystallization from benzene and characterized by spectroscopic methods. The compounds were 4-methoxy-6-chloro-2-amino pyrimidine (III) [IR (cm−1): 3460, 3323, 802; 1H-NMR (CDCl3) δ: 6.2 (s, 1H, aromatic), almost 5.3 (s, 2H, NH2), 3.85 (s, 3H, OCH3); mass spectrum: 159 (M+, 27.7%, 129 (M+ - 30), 94 (M+-66,12.6%) and ethyl-2-(aminosulfonyl)benzoate (IV) [IR (cm−1): 3382, 3278, 2367, 1723; 1H-NMR (CDCl3) δ: 8.15 (d, 1H, aromatic, J = 7 Hz), 7.85 (d, 1H, aromatic, J = 5 Hz), 7.65 (t, 2H, aromatic, J = 5 Hz), 5.84 (s, 2H, NH2), 4.46 (q, 2H, OCH2CH3, J = 5 Hz), 1.46 (t, 3H, OCH2CH3, J = 7 Hz);
mass spectrum: 229 (M+, 8.5%), 212 (10.6%), 184 (100%) and 121]. Fungi isolated from rice rhizosphere soil were allowed to grow in minimal media with chlorimuron-ethyl as the carbon and nitrogen source. Only one fungus survived and grew in medium with chlorimuron as high as 200 mg L−1 (Fig. 1). The mycelia of the isolated fungus were nonseptate with a foot-cell, and conidiophores ended in a terminal enlarged ellipsoidal spherical swelling. This spherical vesicle bearded phialides that covered its entire surface and therefore the head of the conidia was mop-like. They were highly branched; multinucleate mycelia bore a large number of conidiophores, which arose individually as hyphae. Chains of conidia arose on the sterigma, giving the appearance of strings of beads. This fungus was characterized as A. niger.