Determination and behaviour of thidiazuron in tobacco and soil samples under open fields and laboratory conditions

A simple and sensitive liquid chromatography-tandem mass spectrometry method was developed for the determination of thidiazuron (TDZ), a plant growth regulator, in soil, tobacco leaf (fresh, cured), stem, and root. The detection limits of TDZ ranged from 0.03 mu g/kg to 0.15 mu g/kg, and the limits of quantification ranged from 0.1 - 0.5 mu g/kg. The average recoveries of TDZ in soil, tobacco leaf (fresh, cured), stem, and root were between 75.39% and 98.51% with intra-day relative standard deviations (RSDs) between 1.06% and 4.91% and inter-day RSDs between 1.49% and 7.52%. The valid method was used to determine the amount of TDZ residues in tobacco and soil samples under open field and laboratory conditions. Field experiments were carried out in six agricultural sites of China, and the results showed that the half-lives of TDZ were 9.76 - 12.60 days and 2.04 - 4.81 days in soil and fresh tobacco leaves, respectively. The terminal concentration of TDZ in cured tobacco leaves was <0.50-7.46 mu g/kg. Foliage spray and root irrigation experiments were conducted under laboratory conditions. The results indicated that TDZ can be transferred upward and downward in tobacco plants. The transfer factor (TF) of the root irrigation was approximately 10 times of TF of the foliage spray.