Milliequivalent Per Litre

A solution containing milligram equivalent (1/1000 g equivalent) of a substance in a litre of solution is expressed as meq/litre. 

The atomic weight of an element may be defined as a number that gives the mass of one atom of that element compared with mass of one atom of oxygen taken as exactly 16 or mass of one atom of carbon taken as exactly 12. 

A gram atom of an element is the quantity of the element, the weight of which in grams is numerically equal to the atomic weight of the element. 

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The Pharmaceutical Codex gives a table of milliequivalents for various ions and also a simple formula for the calculation of milliequivalents per litre (see Box 3.1). 

This formulation is expressed in concentration because the carbonate species are measured values (see Section 2.6). The volume of acid used is a measure of the alkalinity, which is usually expressed as milliequivalents per litre (see footnote to Table 4.10). These units account for the difference in H+ neutralizing power between COf" and HC03-. Note, however, that at pH around 7.5-8, monovalent HC03- accounts for almost all alkalinity (Fig. 5.5) such that at these pH values milliequivalents are essentially the same as millimoles. 

From this graph obtain the sodium concentration of the sample imder analysis in milliequivalents per litre or in ppm. If there is a dilution of the original sample, multiply by the dilution factor. 

Standard solutions for Na are also prepared in meq./l rather than ppm. For this a stock solution of 0.05 (N) NaCl is prepared by dissolving accurately weighed 1.4625 g of dry NaCl in 500 ml distilled water. From this stock 2,4,6,8 and 10 ml solution is diluted to one litre respectively to get working standards containing 0.1, 0.2, 0.3, 0.4 and 0.5 milliequivalents per litre. 

Units of milliequivalents per litre are used here to plot the composition of plasma in Figure 5.2 because the principle of electroneutrality is of interest it demands that the sum of cations in mequiv./litre equals the sum of anions in the same units. Cations and anions are represented as separate bars and the sums of the two are therefore precisely equal in height, reflecting the principle of electroneutrality. The total for each bar is about 150 mequiv./litre. The principal cation quantitatively is sodium, at around 140 mequiv./litre. Potassium is around 4 mequiv./litre and the remainder, magnesium, calcium etc., give the... 

M— molar, i.e. the strength of a solution in moles per litre mEq—milliequivalent(s)... 

Isotonic saline contains 0.9% w/v of sodium chloride (mol. wt. = 58.5). Express the concentration of this solution as (a) molarity (b) molality (c) mole fraction and (d) milliequivalents of Na" per litre. Assume that the density of isotonic saline is 1 g cm... 

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