Total ion content

The specific conductance of a water sample provides a simple method to determine the total dissolved ionic solids present in the sample. It is also an inexpensive technique, which lends itself to continuous monitoring of a river or waste stream for the total ion content (Fig. 4.1), and can be easily used to check the accuracy of analyses conducted for specific ions. Specific conductance is measured via a pair of carefully spaced platinum electrodes, which are placed either directly in the stream to be measured or in a sample withdrawn from it [22]. The water temperature should be 25 °C, or the result corrected to this temperature. Voltages in the 12 to 14 range, and frequencies of 60 to 1000 Hz AC are used, plus a Wheatstone bridge circuit to obtain a conductivity reading in xmho/cm or xS/cm (microsiemen/cm). The response obtained is linear with the total ion content over a wide range of concentrations (Fig. 4.1). Examples of the conductance ranges and seasonal variation of some typical Canadian rivers are... 

Standard test methods and requirements for total ion content and specific ions such as chloride, sodium, fluoride, and potassium are given in Method 5011.4, paragraph 3.8.7.3. ... 

Concept used in sophisticated scaling models, whereby certain ions in aqueous solution are said to associate in pairs (e.g., CaS04, CaHC03-). These ion pairs are then deducted from the total analytical value, to provide an estimate of the free ion content available for seed crystal scaling or growth agglomeration and deposition. 

Ion-selective electrodes have been used for the potentiometric determination of the total cupric ion content of seawater [284], Down to 2 xg/l cupric copper could be determined by this procedure. 

We seek to determine an effective fixed-charge density which influences ion uptake and transport. This may be different from an analytical determination of total carboxyl content because some groups may not be in swollen regions of the polymer and so may not... 

The volatilization of the coal pyrolysed in the mass spectrometer to 500 C corresponds to 30 wt % daf. This end temerature had been selected in such way that the yield of volatilization was comparable with the mobile phase content. The temperature also corresponds to a rapid decrease of volatilization. This is shown in Figure displaying the total ion current on heating the... 

Calculation of Results. The total calcium and magnesium ion content X (in mg-equiv per litre of the water being studied) is calculated by the following formula ... 

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