The objective of this study was to develop a new reverse micelle-based microencapsulation technique to load tetracycline hydrochloride into PLGA microspheres. To do so, a reverse micellar system was formulated to dissolve tetracycline hydrochloride and water in ethyl formate with the aid of cetyltrimethylammonium bromide. The resultant micellar solution was used to dissolve 0.3 to 0.75 g of PLGA, and microspheres were prepared following a modified solvent quenching technique. As a control experiment, the drug was encapsulated into PLGA microspheres via a conventional methylene chloride-based emulsion procedure. The microspheres were then characterized with regard to drug loading efficiency, their size distribution and morphology. The reverse micellar procedure led to the formation of free-flowing, spherical microspheres with the size mode of 88 microm. When PLGA microspheres were prepared following the conventional methylene chloride-based procedure, most of tetracycline hydrochloride leached to the aqueous external phase: A maximal loading efficiency observed our experimental conditions was below 5%. Their surfaces had numerous pores, while their internal architecture was honey-combed. In sharp contrast, the new reverse micellar encapsulation technique permitted the attainment of a maximal loading efficiency of 63.19 +/- 0.64%. Also, the microspheres had smooth and pore-free surfaces, and hollow cavities were absent from their internal matrices. The results of this study demonstrated that PLGA microspheres could be successfully prepared following the new reverse micellar encapsulation technique.

In this study, we aimed to analyze changes in the residual levels of buprofezin during milling, washing, cooking, and processing of rice to make porridge, rice cakes, and cookies. The pesticide residue levels in rice were analyzed using high-performance liquid chromatograph with UV detector. The residual buprofezin level in brown rice was 21.8 mg/kg, and after milling, that in polished rice was 1.73 mg/kg, with elimination of 92.1% of the pesticide residue. The rate of reduction in buprofezin levels during brown rice washing was 21.6-57.3%, and the residual level of buprofezin during polished rice washing decreased by 27.4-67.2%. When brown rice was cooked using an electric cooker and pressure cooker, buprofezin levels reduced by 51.7 and 55.5%, respectively. When washed polished rice was cooked using an electric cooker and pressure cooker, buprofezin levels reduced by 83.6 and 82.3%, respectively. When washed polished rice was soaked for 30 min and then cooked using an electric cooker and pressure cooker, buprofezin levels reduced by 87.1 and 88.0%, respectively. After processing polished rice into porridge, rice cakes, and cookies, the residue level of buprofezin decreased by 89.7, 82.0, and 79.4%, respectively, compared to the residual level in polished rice. In conclusion, various rice processing methods decrease the residue levels of buprofezin.

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The effects of milling, washing, and cooking on etofenprox, flubendiamide, and tebufenozide levels in brown and polished rice were investigated by HPLC using a UV detector. The reduction rates of etofenprox, flubendiamide, and tebufenozide after milling were 68.74–93.16%, 64.49–90.25%, and 69.74–92.58%, respectively, 11.64–41.44%, 31.36–65.37%, and 31.61–73.79%, respectively, after washing brown rice, and 30.85–82.08%, 52.13–83.05%, and 43.04–83.89%, respectively, after washing polished rice. The residue levels of the three pesticides in brown rice decreased after electric and pressure cooking by 56.49 and 54.41%, 75.80 and 73.42%, and 70.01 and 71.27%, respectively, and the corresponding levels in polished rice decreased after electric and pressure cooking by 85.58 and 85.82%, 86.70 and 87.06%, and 89.89 and 89.68%, respectively. In conclusion, various processing methods decrease the residual levels of etofenprox, flubendiamide, and tebufenozide in rice.

This study used gas chromatography combined with the microelectron capture detection method to determine the most effective washing and cooking methods for removing isoprothiolane from rice. The initial isoprothiolane concentrations in brown and polished rice, before washing, were 17.03 mg/kg and 1.67 mg/kg, respectively. Residual concentrations declined with more washing cycles (19.3-59.3% for brown rice; 43.1-66.5% for polished rice); and by increasing the temperature of the washing water from 5°C to 40°C (56.6-63.1% for brown rice; 67.1-74.9% for polished rice). Hand-washing samples using gentle stirring or harsh rubbing reduced pesticide concentrations by 63.1-71.6% for brown rice, versus 75.4-87.4% for polished rice. Reduction in isoprothiolane concentrations varied based on the rice cooker type and whether the rice was pre-soaked. Immediate cooking using an electric- or pressure-cooker showed 78.5% and 78.4% reduction in brown rice, compared with 94.0% and 94.0% for polished rice, respectively. Pre-cooking immersion for 30 min showed similar reductions of 83.4% and 83.4% in brown rice, versus 95.8% and 95.8% in polished rice. The results of this study suggest that the most effective method for removing residual isoprothiolane from both brown rice and polished rice was to wash six times (with vigorous rubbing during the 2nd and 3rd washing) in 7-fold water at 40°C, followed by immersion for 30 min before cooking. Regardless of the type of rice cooker, heating is sufficient to remove an average of 83.4% and 95.8% of isoprothiolane from brown rice and polished rice, respectively.