Dissipation kinetics and residues of florasulam and tribenuron-methyl in wheat ecosystem

The dissipation kinetics and residual levels of florasulam and tribenuron-methyl in wheat field ecosystem were determined using a quick, easy, cheap, efficient, rugged and safe method (QuEChERS) with rapid resolution liquid chromatography tandem mass spectrometry (RRLC-MS/MS). The average recoveries of florasulam and tribenuron-methyl at three spiking levels in wheat plant, soil, wheat straw and wheat grain ranged from 72.8% to 99.2% with relative standard deviations (RSDs) were less than 10.1% and 82.5% to 103.8% with RSDs were less than 9.4%, respectively. The limits of quantification (LOQs) of florasulam and tribenuron-methyl for wheat plant, Wheat straw, wheat grain and soil were 0.01, 0.01, 0.005, 0.005 mg kg(-1), respectively. The field trials results showed that the half-lives of florasulam were 2.76-10.83 d. Half-lives for tribenuron-methyl were found to be 1.27-537 d. The terminal residues in wheat grain were much lower than maximum residue limits (MRLs) set by China (0.01 mg kg(-1) for florasulam and 0.05 mg kg(-1) for tribenuron-methyl), which considered to be safe for human beings. These results will contribute to establishing the scientific basis of the dosage of florasulam and tribenuron-methyl for use in wheat field ecosystems. (C) 2014 Elsevier Ltd. All rights reserved.