顶空-气相色谱法同时测定复合膜袋中17种 溶剂残留

采用顶空-气相色谱法对食品包装用塑料复合膜袋中常见的17种溶剂进行了分析。对加热温度、平衡时间进行了优化,采用DB-WAX毛细管色谱柱分离,氢火焰离子化检测器检测方法。结果表明:当温度加热到110℃,平衡40 min条件最优;17种溶剂能完全分离,线性较好,加标回收率为79.64%~91.78%,相对标准偏差(n=6)为2.32%~4.52%,检出限为0.003~0.012 mg/m~2;该方法能满足塑料包装材料中溶剂残留量的分析。     

Human plasma protein binding of water soluble flavonoids extracted from citrus peels

The human plasma protein binding of water soluble flavonoids in the peels of five spices of citrus fruits was studied by ultrafiltration combined with HPLC.The flavonoids were extracted separately by hot and cold water,and higher total flavonoid contents were detected in the former extracts than the latter ones.All the extracts show significant scavenging abilities to both ABTS and DPPH free radicals,which indicates the health benefits of the water extracts of citrus fruits peels.For DPPH radical,the IC50values of hot extract follow as Navel orange（NO）≈Mandarin orange（MO） Lemon（LE） Lo tangerine（LO） Pomelo（PO）,while the rank is NO POLE≈MOLO for ABTS radical.The HPLC results reveal that the kinds and contents of the flavonoids detected in the extracts are different among the species.MO extract has the most neohesperidin dihydrochalcone of 118.76 μmol/L and quercetrin of 211.81 μmol/L of which are much more than the rest extracts.Pomelo extract has the most plentiful flavonoids of naringin with a concentration of 303.28 μmol/L.The high contents of myricetrin and dihydromyricetin which both are potent free radical scavengers may explain the highest free radical scavenging activity of the NO extract.The plasma binding rates decrease with the increasing concentrations of flavonoids,and the flavonoids having plenty hydroxyl groups on both A ring and B ring of the molecular skeleton have relative higher plasma binding rates.In addition,the plasma binding rates of flavonoids with saturated C3-C4 bond decrease significantly with the increasing concentrations.     

顶空气相色谱-质谱法同时检测卫生巾中12种溶剂残留

建立了顶空气相色谱-质谱法检测卫生巾中12种残留溶剂的分析方法。以毛细管柱TR-FFAP(60 m×0.25mm,0.25μm)分离,GC-MS选择离子监测(SIM)模式进行定量分析。在优化的条件下,苯系物在0.2～2.0 mg·m^-2、其他溶剂在1.0～10.0 mg·m^-2浓度范围线性关系良好,相关系数0.9950～0.9996,方法的定量下线(S/N=10)为0.0005～0.01mg·m^-2。加标水平为0.4～13.0 mg·m^-2,RSD为0.2%～6.9%,回收率88.3%～103%。应用该方法测定了40个卫生巾样本,溶剂残留检出率45.0%,最高含量为349 mg·m^-2。