Sodium chloride equivalent

The sodium chloride equivalent of a chemical is defined as the amount of sodium chloride (in grams or grains) that has the same osmotic pressure as that of 1 g of the chemical. The sodium chloride equivalents are symbolized by the letter E. The quantities of two substances that are isotonic equivalents are proportional to the molecular weight of each multiplied by the i value of the other. Thus, if the molecular weight and i value of a given chemical are known, one can calculate the sodium chloride equivalent, E, of that chemical as follows ... 

Calculate the sodium chloride equivalent of a 1% solution of pilocarpine nitrate. 

ISOTONICITY ADJUSTMENTS BY SODIUM CHLORIDE EQUIVALENT METHOD... 

The sodium chloride equivalent method is the most frequently used method in the calculation of the amount of sodium chloride needed to prepare isotonic drug solutions. The sodium chloride equivalent of any drug substance, as discussed earlier, is the amount (in grams) of sodium chloride that is osmoti-cally equivalent to 1 g of the drug. The sodium chloride equivalents for selected compounds are listed in Table 8.2. 

TABLE 8.2. Sodium Chloride Equivalents (E) and Freezing Point Depression (ATI" ") Values of Selected Compounds. 

In the prescription above, 1% atropine sulfate is ordered. The sodium chloride equivalent of atropine sulfate is 0.13 (refer to Table 8.2). This means that 1% solution of atropine sulfate has same osmotic pressure as that of 0.13% solution of sodium chloride. This solution is hypotonic. Addition of 0.77 g (i.e., 0.9 - 0.13 = 0.77) of sodium chloride per 100 mL of the 1% solution of atropine sulfate results in an isotonic solution. To determine the amount of sodium chloride required to render a given solution isotonic, the following steps may be used ... 

Find the quantity of sodium chloride required in compounding the following prescription. The sodium chloride equivalent of cocaine HC1 is 0.16. 

Liso values and sodium chloride equivalents ( ) for drugs and excipients... 

Table 1 Freezing point depressions (7/° °), Ljso values and sodium chloride equivalents (E) for drugs and excipients for adjusting their solutions to isotonicity (Continued)...

The sodium chloride equivalent (E) is the amount of sodium chloride equivalent to 1 g of the drug in exerting the same osmotic effect. The E value for a new drug can be calculated from its Li o value or from the freezing-point depression as shown below. 

Some types of injections must be isotonic with blood serum. This applies particularly to large volume intravenous infusions if at all possible hypotonic solutions cause lysis of red blood corpuscles and thus must not be used for this purpose. Conversely, hypertonic solutions can be employed these induce shrinkage, but not lysis, of red cells, which recover their shape later. Intraspinal injections must also be isotonic to reduce pain at the site of injection so should intramuscular and subcutaneous injections. Adjustment to isotonicity can be determined from either the depression of freezing point or from sodium chloride equivalents. The depression of the freezing point depends on the... 

Alternatively the sodium chloride equivalent, which is produced by dividing the value for the depression of freezing point produced by a solution of the substance by the corresponding value of a solution of sodium chloride of the same strength, may be used. Fuller details of each method may be found in the Pharmaceutical Codex (1993). 

Crude 10% sodium hydroxide containing sodium chloride is purified in a similar manner to the product of the causticization process. The water is evaporated in nickel or nickel-clad steel (to reduce corrosion) multiple-effect evaporators to about 50% sodium hydroxide concentration. At this concentration, sodium chloride is only about 1% soluble (2%, on a dry basis) in the more concentrated caustic so that the bulk of it crystallizes out and is filtered off. This quite pure sodium chloride is recycled to the cells. Lor many purposes, such as for pulp and paper production, this purity of 50% sodium hydroxide is quite acceptable. If higher purities are required, sodium hydroxide may be separated from residual water and salt by chilling to the double hydrate crystals NaOH 2HiO, m.p. about 6°C, or as NaOH 3.5HiO, with a m.p. of about 3°C, or by counter-current extraction [9]. The sodium hydroxide obtained after these steps contains 2-3 ppm sodium chloride, equivalent to the purity of the mercury cell product ( rayon grade ) [10]. Concentrations of 73% and 100% sodium hydroxide (see details, Section 7.5) are also marketed. 

Hammerlund ER. Sodium chloride equivalents, cryoscopic properties, and hemolytic effects of certain medicinals in aqueous solution IV supplemental values. J Pharm Sci 1981 70 1161-1163. 

Osmolality determinations are usually carried out using a cryoscopic osmometer, which is calibrated with deionized water and solutions of sodium chloride of known concentration. Using this technique, the sodium chloride equivalents and freezing point depressions for more than 500 substances have been determined and reported in a series of papers by Hammerlund and co-workers (e.g., see Hammerlund 1981). Figure 6.18 shows the osmolality of mannitol-water solutions. 

Therefore, 58.44 grams of sodium chloride will have the same number of fundamental units as 32.00 grams of O2, and 18.02 grams of H2 O whose formulas describe molecules. So, in the case of substances which exist as molecules, we can call the sum of atomic masses the molecular mass. But how shall we name the mass of sodium chloride equivalent to those masses. We know that the designation, molecule, for NaCl is not appropriate. However, if we describe the mass of the fundamental unit representing the composition of any compound by using the expression formula mass, such difficulties are avoided. Table 4-1 lists the formulas and formula masses of several representative compounds. 

Ionic contamination-expressed in sodium chloride equivalents is primarily used to assess the climatic resistance of electronic assemblies. Ionic measurement is suitable for statistical process control, but it does not furnish an absolute statement concerning the climatic resistance of an assembly. 

Method 3 If no iso-osmotic concentration is known, it can be calculated with the aid of the sodium chloride equivalent, also known as tonicic equivalent or E-value. The sodium chloride equivalent is defined as ... 

This gives a total of at E = 0.527 sodium chloride equivalents. 0.9 g of sodium chloride per 100 mL is iso-osmotic. This means that almost 0.373 g per 100 mL should be added. 

With the exceptions of the nitrate ion and sodium chloride, equivalent quantities of the anions cause the same effect. That the quantities are not exact is to be expected when one considers that the experimental error is large owing to the fact that precipitation depends somewhat on the manner of adding the electrolyte. 

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