电热蒸发进样微波等离子体炬原子发射光谱法中共存元素的影响

本文考察了以微波等离子体炬（MPT）为光源，电热钽丝环进样时，溶液中共存元素对发射信号的影响。     

Hair dye distribution in human hair by ToF-SIMS

A single hair sample preparation protocol modified from reported method was developed and used to prepare longitudinally sectioned hair for ToF-SIMS analysis. Preliminary results demonstrate that ToF-SIMS is capable of providing molecular distribution of fragment ions from intrinsic constituents as well as external chemicals like the hair dye ingredients used in this study. The observation of pPDA and H₂PO₄⁻ penetrating into the internal region of hair might initiate a renewed interest in exposure study.     

回归估计样本容量的确定

本文就回归估计量回归系数已知和未知两种情况，给出确定样本容量的方法．     

On-column injection onto capillary columns. Part 2: Study of sampling conditions; practical recommendations

During one year continuous use of on-column injection, the typical advantages described in our first report have fully been confirmed. In addition the analysis of large sample volumes has proved promising. Only minor modifications have been applied to the on-column injector device. Broad evidence has been gathered showing that full separation efficiency of the capillary columns after on-column injection is attained only when cold trapping or the solvent effect, as band shortening mechanisms, are working- While, under the conditions of on-column injection, cold trapping is less efficient than with other injection techniques, the opposite holds true for the solvent effect. Compared with splitless injection, the danger of excessive solvent condensation on the column is increased. A working rule is presented for establishing the optimal chromatographic conditions for handling large sample volumes while ensuring full separation efficiency yet avoiding harm to the column.     

Estimation of a quantile in some nonstandard cases

A necessary condition for the asymptotic normality of the sample quantile estimator isf(Q(p))=F(Q(p))>0, whereQ(p) is thep-th quantile of the distribution functionF(x). In this paper, we estimate a quantile by a kernel quantile estimator when this condition is violated. We have shown that the kernel quantile estimator is asymptotically normal in some nonstandard cases. The optimal convergence rate of the mean squared error for the kernel estimator is obtained with respect to the asymptotically optimal bandwidth. A law of the iterated logarithm is also established.This research was partially supported by the new faculty award from the University of Oregon.     

Analysis and Speciation of Traces of Arsenic in Environmental,Food and Industrial Samples by Voltammetry: a Review

Voltammetric approaches for the determination of arsenic and speciation at trace levels are critically appraised in a review covering the literature from 1970 to 2002. Special attention is devoted to stripping modes and to issues related to the choice of working material and supporting electrolyte. A section is dedicated to the management of real samples and aspects of sample preparation. An extensive compilation, organized by real sample type, gathers essential experimental conditions. Potentiometric stripping analysis is introduced for sake of comparison. The coupling of voltammetric detection or preaccumulation with FIA, chromatography, capillary electrophoresis and ICP techniques is also addressed.     

Retention behavior and solvent optimization of organochlorine pesticides in solid-phase extraction

Summary Plots of capacity factor and retention time vs. elution solvent composition were proved to be useful to interpret the retention behavior of Kepone and its metabolites in a reversed-phase solid-phase extraction and to optimize the elution solvent. The percent recovery of Kepone was largely improved when the solvent was optimized. The standard deviations of the results of extractions were also improved upon the optimization of the solvent.     

基于硒化锌薄膜法的食源性致病菌原位红外光谱检测

食源性致病菌是引发和威胁公众健康的主要因素之一.由于食源性致病菌种类繁多,常规检测方法复杂耗时要求高,因此迫切需要一种更加快速精确的致病菌检测技术.在传统红外光谱检测致病菌的流程中,如经典的溴化钾压片法,除了压片本身的操作之外通常还需对样品进行冷冻干燥(约需2 d)等耗时前处理过程,因而不利于高通量快速检测.本研究利用...     

Monte Carlo simulation of GM probe and NaI detector efficiency for surface activity measurements

This paper deals with the direct measurement of total (fixed plus removable) surface activity in the presence of interfering radiation fields. Two methods based on Monte Carlo simulations are used: one for a Geiger–Muller (GM) ionisation probe and the other for sodium iodide (NaI) detector with lead collimators; equations for the most general case and the geometry models for Monte Carlo simulation of both (GM and NaI) detectors are employed. Finally, an example of application is discussed.     

Some Aspects of the Mobility and Distribution of Toxic Heavy Metal Contaminants Insoil Profiles and River Sediments

Abstract

Investigations of the distribution and mobility of Pb, Ni, Cd and Hg have shown that Pb is strongly associated with humic substances in the top layer of soils and in river sediments, and that Pb shows the highest organophilicity. Ni is very organophilic, and Cd, somewhat less so. The hydrophilicity of Hg highly influences its movement in soil profiles and river sediments. The risk of contamination by these metals is characterized through the environment protection capacity (EPC_G) values which combine humus content and the quality and thickness of the humus layer in one parameter. The risk of contamination is highest at low EPC_G values. Increase of EPC_G decreases the risk of environmental contamination through binding of heavy metals to humic substances, decreasing their mobility.