Elements in Solution

Gr. prasios, green, and didymos, twin) In 1841 Mosander extracted the rare earth didymia from lanthana in 1879, Lecoq de Boisbaudran isolated a new earth, samaria, from didymia obtained from the mineral samarskite. Six years later, in 1885, von Welsbach separated didymia into two others, praseodymia and neodymia, which gave salts of different colors. As with other rare earths, compounds of these elements in solution have distinctive sharp spectral absorption bands or lines, some of which are only a few Angstroms wide. 

AAS is used to quantify the concentration of specific elements in solution. In flame atomic absorption, the analyte solution is introduced into the flame... 

Inductively coupled plasma atomic emission spectrometry (ICP-AES) is used to screen polymers, liquids and solvent extracts for residual metal atoms (catalysts, fillers, etc.). The technique can provide rapid multi-component screening of elements in solution over a wide concentration range (0.1-1,000 pg/ml). 

All mine surface water in direct contact with the tailings is characterized by low pH (2.0-3.5) and a large amount of dissolved solids (1,400-17,000 ppm TDS). Average concentrations of elements in solution... 

In the above example, this would give an MDL value of 1.28 pg ml-1. It should be remembered that, in the example given here, which is the analysis of a solution, the MDL is for that element in solution, and should be converted into an MDL in the original solid sample to give a true picture of the MDL for the analysis. For the analysis of solids, the MDL can be interpreted directly without any further calculation. 

Water samples are amongst the simplest to prepare, simply requiring acidification to keep the sample elements in solution and to matrix-match with the calibration solutions, and the addition of an internal standard. The procedure is as follows. 

Cathode deposit morphology can also be affected by the presence of trace elements in solution. An SEM micrograph of a zinc deposit from a pure or unadulterated electrolyte and time duration of two minutes at 10 mA/cm2 is shown in Figure 3. When U0 parts per billion of antimony was added to this solution, and a similar electrodeposition cycle was performed, an approximate ten-fold increase in crystallite size was obtained (see Figure U). 

Two types of metallic globules were observed in the waste form. These were principally elemental molybdenum with trace elements in solution and elemental palladium with other trace elements in solution. In the case of molybdenum, the silicon... 

Performance is defined by the sensitivity threshold, or the minimum concentration of element in solution that will yield an analytical signal with amplitude equal to twice that of the average background signal. This classical definition leads to optimistic values that can vary from element to element. The limit of detection represents the concentration of an element that can be detected with a 95% confidence limit (cf. chapter 21). In general, measurements are made in a concentration domain that corresponds to 50 times the limit of detection. 

A further method of extraction of the selenium from the mud is based on the solubility of the element in solutions of potassium cyanide, forming selenocyanide. The solution deposits selenium when acidified, and any sulphur is retained in solution as thiocyanic acid.2 Treatment with a solution of an alkali hydroxide, or fusion with sodium carbonate (the latter more especially for the extraction of selenium from the dust of the flues between the pyrites burners and the Glover tower), has also been applied, the mass being extracted with water in the latter case. The resulting aqueous solutions deposit selenium on atmospheric oxidation, whilst any extracted sulphur passes mainly to thiosulphate.3... 

Unlike the other zinc halides, zinc fluoride, Znp2, is only slightly soluble in cold water. The anhydrous halides are prepared by direct union of the elements, In solution, zinc chloride, bromide, and iodide exhibit anomalous conductance properties attributed to undissodated molecules and complex ions. On heating these solutions, halogen acids, HX, are evolved, leaving... 

Redox Reactions. Aquatic organisms may alter the particular oxidation state of some elements in natural waters during activity. One of the most significant reactions of this type is sulfate reduction to sulfide in anoxic waters. The sulfide formed from this reaction can initiate several chemical reactions that can radically change the types and amounts of elements in solution. The classical example of this reaction is the reduction of ferric iron by sulfide. The resultant ferrous iron and other transition metals may precipitate with additional sulfide formed from further biochemically reduced sulfate. Iron reduction is often accompanied by a release of precipitated or sorbed phosphate. Gardner and Lee (21) and Lee (36) have shown that Lake Mendota surface sediments contain up to 20,000 p.p.m. of ferrous iron and a few thousand p.p.m. of sulfide. The biochemical formation of sulfide is undoubtedly important in determining the oxidation state and amounts of several elements in natural waters. 

Tetraphenylimidodiphosphate Complexes of Rare Earth Elements in Solution... 

Since the introduction of the first commercial instrument in 1983, inductively coupled plasma mass spectrometry (ICP-MS) has become widely accepted as a powerful technique for elemental analysis. Two excellent books on ICP-MS have been published [1,2]. ICP-MS provides rapid, multielement analysis with detection limits at single parts part trillion or below for about 40 to 60 elements in solution and a dynamic range of 104 to 108. These are the main reasons most ICP-MS instruments have been purchased. Two additional, unique capabilities of ICP-MS have also contributed to its commercial success elemental isotope ratio measurements and convenient semiquantitative analysis. The relative sensitivities from element to element are predictable enough that semiquantitative analysis (with accuracy within a factor of 2 to 5) for up to 80 elements can be obtained using a single calibration solution containing a few elements and a blank solution. 

Note For each element in solution 1 or solution 2, a mineral or gas phase has to be defined under PHASES that contains this element. Otherwise PHREEQC reports the following problem element is included in solution 1, but is not included as a mass-balance constraint . The modeling can still be continued, however the respective element is not considered for the mass balance. 

The detection limit (or limit of detection) is defined as the lowest concentration of an element in solution which can be detected with 95% certainty. It is therefore the concentration which will produce a deflection equal to twice the standard deviation of a series of readings (typically ten). Historically it has also been defined as the concentration which produces a deflection from the base line of a chart recorder which is equal to twice the peak to peak variability of that base line. The important thing to note with detection limit information is that the method of calculation should be defined when original work is being published. 

At 21-5° C. the heat of formation from sodium hydroxide and the acid is 15 16 Cal.,4 and that from the elements in solution is 198 4 Cal.5 The electric conductivity has been studied by Arrhenius.6... 

Potassium orthophosphates.—The normal salt, potassium orthophosphate, K3P04, is obtained by heating basic slag or native calcium phosphate with charcoal and potassium sulphate. The potassium sulphide simultaneously formed is converted into phosphate by addition of phosphoric acid, or the potassium phosphate is precipitated by addition of alcohol. The aqueous solution of the salt is very alkaline in reaction, owing to hydrolytic dissociation. The heat of formation from the elements in solution is 483-6 Cal.4... 

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