Adsorption and degradation of imazapic in soils under different environmental conditions.

Imazapic is widely used in peanut production, and its residues can cause damage to succeeding crops planted in the following year. The planting area of peanut is large in Henan province. Inceptisol is the main soil type in Henan Province and was used in laboratory experiments that were conducted to investigate imazapic degradation in soil under various environmental conditions. The results indicated that the imazapic degradation rate increased with an increase in temperature, soil pH, and soil moisture, and decreased with organic matter content. The use of biogas slurry as a soil amendment accelerated imazapic degradation. The half-life of imazapic in sterilized soil (364.7 d) was longer than in unsterilized soil (138.6 d), which suggested that there was a significant microbial contribution to imazapic degradation. Imazapic adsorption was also examined and was found to be well described by the Freundlich isotherm. The results indicate that soil has a certain adsorption capacity for imazapic.

Simultaneous determination of seven preservatives in food by dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry.

A simple, rapid, inexpensive and environment-friendly method, based on dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry (GC-MS), was developed for the determination of food preservatives including benzoic acid (BA), sorbic acid (SA), dehydroacetic acid and four parabens. Optimum DLLME conditions were determined as follows: extraction solvent (chloroform) volume, 50 µL; disperser solvent (acetone) volume, 0.5 mL; NaCl amount, 0.50 g/4 mL sample solution at pH 4.0. Hydroquinone was selected as the internal standard. The calibration curves were linear in the range 0.05-10 mg L-1 for BA, SA and methylparaben, and 0.02-10 mg L-1, for the remainder. Limits of detection were in the range 0.15-0.50 mg kg-1 with enrichment factors ranging from 25 to 114 for all target analytes. Recoveries were in the range 88.7-110.5% with a relative standard deviation of less than 5%.

An environment-friendly procedure for the high performance liquid chromatography determination of benzoic acid and sorbic acid in soy sauce.

A rapid, accurate and environment-friendly procedure has been developed for the HPLC-based determination of benzoic acid and sorbic acid contents in soy sauce. A C18 column served as the stationary phase, methanol-ammonium acetate buffer (0.02M) (30:70, v/v) was used as the mobile phase, the flow rate was 1mL/min, the UV detector was set at 225nm and cinnamic acid was selected as an internal standard. Under such optimized conditions, benzoic acid, sorbic acid and the internal standard were separated within 8.1min. This newly developed procedure also showed excellent recurrence, with a relative standard deviation of less than 3% and recoveries were 96.1-104.3%.