A convenient, cost-effective and fast method using dynamic microwave-assisted extraction and liquid phase microextraction based on the solidification of a floating drop was proposed to analyze organochlorine pesticides in grains including rice, maize and millet. Twelve samples can be processed simultaneously in the method. During the extraction process, 10% acetonitrile-water solutions containing 110 μL of n-hexadecane were used to extract organochlorine pesticides. Subsequently, 1.0 g sodium chloride was placed in the extract, and then centrifuged and cooled. The n-hexadecane drops containing the analytes were solidified and transferred for determination by gas chromatography-electron capture detector without any further filtration or cleaning process. Limits of detection for organochlorine pesticides were 0.97–1.01 μg/kg and the RSDs were in the range of 2.6%–8.5%. The developed technology has succeeded in analyzing six real grains samples and the recoveries of the organochlorine pesticides were 72.2%–94.3%. Compared with the published extraction methods, the developed method was used to analyze organochlorine pesticides in grains, being more environmentally friendly, which is suitable for the daily determination of organochlorine pesticides.

Allium cepa L. var. agrogatum Don (ALAP) is commonly consumed in China as well as other regions and has various beneficial health effects. A novel acidic polysaccharide (named ALAP-21) was obtained from ALAP by ultrasonic and microwave-assisted extraction and purification using DEAE-52 anion exchange and Sephadex G-100 columns. The monosaccharide composition, structural and antioxidative properties of ALAP-21 were investigated by GC–MS chromatography, FT-IR and NMR spectroscopies and three antioxidative activity tests in vitro. The results showed that ALAP-21 was a heteropolysaccharide composed of glucose, galacturonic acid, mannose, galactose, arabinose, rhamnose, xylose, fructose and glucuronic acid with a relative molar ratio of 26.282: 27.546: 11.400: 4.781: 2.467: 2.445: 3.622: 1.106: 1.753, owning (1→4)-α-D-Glcp, (1→4)-α-D-GalAp6Me3OA, (1→4)-β-D-Galp6OMe, (1→2)-α-L-Rhap, (1→4)-β-D-Manp glycosidic linkages. (1→4)-α-D-Glcp and (1→4)-α-D-GalAp6Me3OA residues might be the main components of the sugar chain backbone of ALAP-21. Furthermore, ALAP-21 exhibited high potential for DPPH radicals (82.02%), hydroxyl radicals (53.33%) and superoxide anion radicals (50.28%). These results provide a reference for further research and rational development of ALAP polysaccharides.