The aim of this study was to investigate the fate, terminal residues and risk assessment of spirotetramat and its four metabolites in pineapple and pineapple pulp samples. To achieve this goal, a simple, efficient and sensitive method based on QuEChERS technique was developed using LC-MS/MS. The limit of quantification was 0.01 mg/kg for all the target analytes with the average recoveries ranging from 77% to 109%. The validated method was successfully applied to investigate the fate and terminal residue of spirotetramat and its four metabolites in pineapple and pineapple pulp samples in China. The dissipation dynamics of spirotetramat in pineapple were investigated according to first-order kinetics and the calculated half-lives were 4.6 and 2.3 days in the two sampling locations. After two or three applications at the doses of 80 to120 mg a.i./kg, the highest spirotetramat residue (sum of spirotetramat and its four metabolites) that detected in pineapple and pineapple pulp samples were 0.203 and 0.064 mg/kg. The dietary risk assessment of spirotetramat in pineapple was assessed by risk quotients and the calculated risk quotient value was found to be far below 100%, indicating a low health risk to the consumers. As there was no recommended MRL value in pineapple in China, these results should be useful for safe and reasonable usage of spirotetramat in pineapple in China.
Ni Wei,Xin Xu,Jiushun Qin,Wei Lai,Ruoyan Li,Chenhuan Lai,Qiang Yong
Development of green pretreatment strategies with excellent lignin removal ability is particularly important for masson pine biorefinery. γ-Valerolactone (GVL), as a green and recyclable solvent, has unique solvent characteristics to extract lignin. In this study, three acid catalysts, including sulfuric acid (H 2 SO 4 ), hydrochloric acid (HCl) and p -toluenesulfonic acid (TsOH), were used to catalyze γ-valerolactone (GVL) pretreatment of masson pine. Among them, the TsOH-catalyzed GVL pretreatment achieved the highest lignin removal ratio and the best cellulose enzymatic hydrolysis yield. Under the optimized pretreatment conditions (150 ℃, 150 mM TsOH, GVL/H 2 O (4:1, w/w), 1 h), the lignin removal ratio reached 89.0 %, achieving a 72 h glucose yield of 87.1 % from the pretreated residues. The solvent lignins from pretreatment liquid was separated and characterized by NMR analysis. Meanwhile, the hexoses in pretreatment liquid were further converted into levulinic acid (LA) using the TsOH-catalyzed bi-phase reaction systems. This study gives insights into developing a biorefining process for the effective utilization of masson pine.
危险品化学品经营许可证（带存储）