科研之友
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摘要
The period covered by this review has seen a number of interesting developments. In a novel technique to preconcentrate analytes in drinking water, metal complexes with 8-hydroxyquinoline were adsorbed onto miniature C-18-bonded silica gel columns on centrifugal microfluidic discs. Centrifugal action forced the fluid through the column and measurements were made directly on the columns by LA-ICP-MS. In a variation on an old theme, carbon nanotubes were used for preconcentration by some workers. An elegant solution was devised to calibrate SEC columns, used to separate metalloproteins, through measuring S, found in virtually all proteins, at the same time as the metal of interest. Separate detection of protein by UV absorbance was thereby unnecessary. In this work interference from (OO+)-O-16-O-16 on S-32 was avoided by measuring SO+ at a m/z ratio of 48. A similar approach to removing polyatomic interferences was seen when methane was included in the collision cell. The (ArAr+)-Ar-38-Ar-40 and (ArAr+)-Ar-40-Ar-40 polyatomic interferences on Se-78(+) and Se-80(+) were avoided and As was measured as (AsCH2+)-As-75-C-12 at m/z 89. The flame furnace technique continues to stimulate innovation. In a system reminiscent of the Delves micro cup technique, pellets of lyophilised blood, mixed with high purity graphite powder, were placed on a quartz holder and introduced into a glass combustion chamber which connected to the flame furnace via a quartz or PTFE tube. Ammonium nitrate solution on paper was placed in the chamber, and with a flow of O-2 and focussed microwave radiation, the sample ignited and the combustion products were led into the flame furnace for measurement of Cd. The commercial development of a high resolution-continuum source spectrometer is leading to some new applications for AAS. In one piece of work P was measured at both atomic and molecular lines within an electrothermal furnace. In another, Zn in a simple slurry of yoghurt was measured by FAAS. UV photo-oxidation for HG-AFS was examined and it was seen that adding organic acids to aqueous samples promotes vaporization. In other work TiO2 nanoparticles considerably enhanced the efficiency of HG from Se-VI and Te-VI. Much of the applications work relates to the structure and function of the measurand(s) i.e. metallomics. Overviews of analytical techniques and methods applied to metallomics were seen in several reviews. A sophisticated example of metallomic research is given by the work with ESI-MS, to identify how Cu progresses from one intra-cellular protein to another in a way that avoids the presence of toxic free Cu ions. Understanding of both As and Se metabolism has been further compounded by the identification of yet more intermediates although the question still remains as to whether these are artefacts produced during extraction and the analytical procedure. The UK Total Diet Study noted that exposure to metals has generally declined over 30 years. Of 24 elements in 20 food groups, with the exception of Al, Ba and Mn, all were found to be similar to, or at lower concentrations than when measured six years earlier.
A comprehensive study of the packaging material for bottled water sold across the European Union was reported which showed that there were significant contributions of metals from plastics and glass and that the colour of the glass also inluenced concentrations. Some particularly critical comment has been included in this review. A few papers have reported results that are clearly wrong. Many others include numerical data with an excessive use of significant figures. This material, appearing in the so-called scientific literature, highlights important failures by authors, referees and editors to ensure that data are quality controlled. Finally, we have to report that this is the last ASU to which Simon Branch will be contributing. Simon has been a mainstay of the writing team for many years but a change in career means that he can no longer be involved. His efficient preparation of the foods table will be much missed.
- 出版日期2011
