Inorganic ions separation scheme

Analytical chemistry is often described as the area of chemistry responsible for characterizing the composition of matter, both qualitatively (what is present) and quantitatively (how much is present). This description is misleading. After all, almost all chemists routinely make qualitative or quantitative measurements. The argument has been made that analytical chemistry is not a separate branch of chemistry, but simply the application of chemical knowledge. In fact, you probably have performed quantitative and qualitative analyses in other chemistry courses. For example, many introductory courses in chemistry include qualitative schemes for identifying inorganic ions and quantitative analyses involving titrations. 

The birth of a crystal and its growth provide an impressive example of nature s selectivity. In qualitative analytical chemistry inorganic solutes are distinguished from each other by a separation scheme based on the selectivity of precipitation reactions. In natural waters certain minerals are being dissolved, while others are being formed. Under suitable conditions a cluster of ions or molecules selects from a great variety of species the appropriate constituents required to form particular crystals. 

Metal salicylates are occasionally incorporated into mixtures of unknowns for qualitative inorganic analysis. During the conventional group separation, organic radicals are removed by evaporation with nitric acid. When salicylates are present, this can lead to formation of trinitrophenol through nitration and decarboxylation. This may react with any heavy metal ions present to form unstable or explosive picrates, if the evaporation is taken to dryness. The MAQA alternative scheme of analysis obviates this danger. 

This book describes the fundamental operating characteristics of the most common inorganic mass spectrometers. At the heart of this discussion is a description of the various ionization sources that generate a representative analyte population for mass analysis. The initial chapters introduce the mass spectrometric hardware that separates the ionized fractions of analytes, one mass from another. The detection schemes used to measure this ion population, and the data processing systems that permit this information to be of value to the chemical analyst, are also discussed. 

The number of publications involved with the recovery of rubidium from seawater is very limited. Most of the work in this field is by Russian scientists, who have proposed several schemes for the combined recovery of rubidium, strontium, and potassium with natural zeolites [15, 19, 250-253, 257]. A number of inorganic sorbents with high selectivity toward rubidium were also synthesized for the recovery of rubidium from natural hydromineral sources, including seawater. Ferrocyanides of the transition-metal ions were shown to exhibit the best properties for this purpose [258, 259]. Mordenite (another natural zeolite) has recently been proposed for selective recovery of rubidium from natural hydromineral sources as well [260]. A review of the properties of inorganic sorbents applicable for the recovery of rubidium from hydromineral sources has been published [261]. Studies of rubidium recovery fix>m seawater [15, 19, 250-253] have shown that the final processing of rubidium concentrates, especially the selective separation of Rb -K mixtures remains the major problem. A report was recently published showing that this problem can be successfully solved by countercurrent ion exchange on phenolic resins [262]. 

Ion chromatography (IC) was introduced in 1975 by Small, Stevens, and Baumann [14] as a new analytical method. Within a short period of time, ion chromatography developed from a new detection scheme for a few selected inorganic anions and cations to a versatile analytical technique for ionic species in general. For a sensitive detection of ions via their electrical conductance, the effluent from the separator column was passed through a suppressor column. This suppressor column chemically reduces the background conductance of the eluent, while at the same time increasing the electrical conductance of the analyte ions. 

In 1979, Fritz et al. [15] described an alternative separation and detection scheme for inorganic anions, in which the separator column is direcdy coupled to the conductivity cell. As a prerequisite for this chromatographic setup, low-capacity ion-exchange resins must be employed so that low-ionic strength eluents can be used. In addition, the eluent ions should exhibit low equivalent conductances, thus enabling detection of the sample components with reasonable sensitivity. 

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