摘要:

This review deals with a new analytical methodology which successfully combines ion-exchange principles with conductimetric detection. This technique, known as ion chromatography (IC), was introduced in 1975 by Small, Stevens, and Bauman.1IC has proven to be very useful for the determination of aqueous ionic species with pK less than approximately seven. The technique fills the need for simple, rapid, and reliable determination of the common ions (such as SO42-, Cl-, NO-3, etc.) in either simple or complicated matrices. Typical ion chromatograms of anions and cations are shown in Figures 1 and 2. Both organic and inorganic ions have been separated and detected by IC. This review is intended to illustrate IC principles, practice, and instrumentation. The bulk of this work is devoted to the application of IC in air and water pollution, quality control, process sampling, clinical chemistry, microelemental and geochemical analysis, and energy-related areas such as power production.

ISSN:0007-8980    

DOI:10.1080/10408348008542720

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Chemical speciation may be defined as the determination of the individual concentrations of the various chemical forms of an element which together make up the total concentration of that element in a sample. The next decade will certainly see a blossoming of interest from chemists, biochemists, and biologists in techniques for chemical speciation. This is because it is becoming more and more apparent that both bioavailability and toxicity are critically dependent on the chemical form of the substance under test. Measurement of the total concentration of a nutrient or a trace element provides very little information about the bioavailability of the substance, since many vitamins and essential elements are now known to exist in a variety of chemical forms, the assimilability of which vary greatly.1–3For example, niacin and folic acid exist in some foods in bound forms which are unavailable to many species,4and the same is true of a whole range of essential metals, including iron, zinc, cobalt, and chromium. For man, the most assimilable form of iron is heme iron from meat. Inorganic iron salts and simple organic complexes are far less available. The group of chromium-amino-acid complexes known as the glucose tolerance factor1.5provides most of the usable chromium, while cobalamin (vitamin B12) is the only essential chemical form of cobalt.6It has also been suggested that zinc-amino-acid complexes are more available than inorganic zinc.2.7Analysis of a diet for total iron, chromium, cobalt, or zinc, without some information about their chemical forms, is therefore almost worthless because a nutritional deficiency of these elements could exist despite their widespread distribution.

ISSN:0007-8980    

DOI:10.1080/10408348008542721

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor