云南晋宁梅树村前寒武系—寒武系界线剖面的磁性地层学研究

本文在晋宁梅树村的前寒武系—寒武系剖面上,较系统地在53个采点上采集了112块岩心标本(249块样品)。磁性地层学研究指出该剖面中一些极性混合带与小壳动物化石群的出现与衰亡的时空位置吻合,反映了地磁场倒转与小壳动物化石群演化的相关性。古纬度信息表明中谊村段主要磷矿层位正是低纬度带控制的古地理环境,文章为晚前寒武纪—寒武纪磁性地层序列研究提供了实际资料。     

MAGNETOSTRATIGRAPHY OF PRECAMBRIANCAMBRIAN BOUNDARY AT MEISHUCUN SECTION, YUNNAN PROVINCE

Magnetostratigraphic studies of 112 cores specimens (249 samples) in a Precambrian-Cambrian section at Meishucun, Jinning County, Yunnan Province reveal the following: (ⅰ) Around the Sinian-Cambrian boundary in the Meishucun section existed a mixed polarity zone in which the Meishucun fauna went through an evolution of appearance—flourish—extinction. (ⅱ) The Meishucun section had a paleolatitude of no more than 20° during the Sinian-Cambrian, The phosphate deposits in this region and in the Zhongyicun Member were formed in the low-latitude environments.     

液相色谱-串联质谱法测定猪肉中咪唑类药物及其代谢物

建立了高效液相色谱-串联质谱同时测定猪肉中29种咪唑类药物及其代谢物残留的检测方法。样品采用乙酸乙酯提取,浓缩复溶后加入乙腈饱和正己烷净化除脂,以0.3%(体积分数)甲酸水溶液和乙腈为流动相,反相C_(18)色谱柱梯度洗脱分离,采用电喷雾正离子(ESI+)源多反应监测(MRM)模式进行检测。29种化合物在0.05~20.0μg/L范围内线性关系良好,相关系数r~20.99。在1.0~5.0μg/kg添加范围内,平均回收率为65.4%~103%,相对标准偏差(RSD)为1.3%~6.8%。方法检出限为0.02~0.3μg/kg,定量限为0.1~1μg/kg。该方法简便、快速、灵敏,适用于猪肉中咪唑类及其代谢物残留的检测。