控温超声提取-高效液相色谱法测定空气PM2.5中16种多环芳烃

剪碎的滤膜经乙腈于35℃超声提取60 min,提取液以12 000r·min~(-1)转速离心10min,采用高效液相色谱法测定上清液中16种多环芳烃的含量。以Agilent Eclipse PAH-C18色谱柱为分离柱,用乙腈和水以不同比例混合的溶液为流动相进行梯度洗脱,用二极管阵列检测器和荧光检测器测定。16种多环芳烃的质量浓度均在0.02～1.00mg·L~(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)为0.05～0.25ng·m~(-3)。以空白滤膜为基体进行加标回收试验,所得回收率为87.8%～103%,回收量的相对标准偏差(n=6)小于5.0%。     

用抗坏血酸法测定含砷钢铁中的磷(借硫代硫酸钠还原掩蔽砷)

铋盐-抗坏血酸-钼兰比色测定钢铁中磷的方法,具有准确、灵敏、快速等优点,是我国目前广泛用于分析钢铁中磷的方法之一。但是砷在测定磷的显色条件下,严重干扰磷的测定。据有关资料介绍,砷磷共存时可在测定砷后从磷的结果中扣除砷,或用氢溴酸挥发除砷来消除这     

Directed transport of coupled systems in symmetric periodic potentials

In this paper, we discuss the damped unidirectional motions of a coupled lattice in a periodic potential. Each particle in the lattice is subject to a time-periodic ac force. Our studies reveal that a directed transport process can be observed when the ac forces acting on the coupled lattice have a phase shift (mismatch). This directed motion is a collaboration of the coupling, the substrate potential, and the periodic force, which are all symmetric. The absence of any one of these three factors will not give rise to a directed current. We discuss the complex relations between the directed current and parameters in the system. Results in this paper can be accomplished in experiments. Moreover,our results can be generalized to the studies of directed transport processes in more complicated spatially extended systems.     

凝胶渗透色谱净化-高效液相色谱法测定辣椒制品中的苏丹红染料

取适量辣椒制品样品用环己烷-丙酮(3+1)混合液超声提取后,离心分离,取上清液,蒸至近干,用环己烷-乙酸乙酯(1+1)混合液溶解并定容至10mL。用凝胶渗透色谱法(GPC)净化,用环己烷-乙酸乙酯(1+1)混合液淋洗,收集22~30min之间的流出液,于40℃吹氮蒸干,用乙腈-水(8+2)溶液定容至1mL。用Waters Symmetry C18柱分离,用不同比例的水及乙腈的混合液进行梯度淋洗。用二极管阵列检测器(PDA)在波长478nm(苏丹红Ⅰ)及520nm(苏丹红Ⅱ、Ⅲ及Ⅳ)处进行检测,上述4种染料的线性范围均在0.1~5mg·L-1之间。4种染料在辣椒油中的检出限为0.02mg·kg-1,在辣椒酱及辣椒粉中的检出限均为0.005mg·kg-1。用标准加入法测得方法的回收率在79.5%~93.8%之间,测定值的相对标准偏差(n=6)在1.9%~8.3%之间。