Sodium controversy over

Although sodium bicarbonate was once given routinely to reduce the detrimental effects associated with acidosis (e.g., reduced myocardial contractflity), enhance the effect of epinephrine, and improve the rate of deflbrillation, its use for cardiac arrest has been extremely controversial over the past several years. Unfortunately, there are few clinical data supporting sodium bicarbonate use. Furthermore, sodium bicarbonate may have some detrimental effects. " The effect of sodium bicarbonate can be described by the following reaction ... 

Among the most deadly of simple compounds is sodium fluoroacetate. The LD50 (the dose lethal for 50% of animals receiving it) is only 0.2 mg/kg for rats, over tenfold less than that of the nerve poison diisopropylphosphofluoridate (Chapter 12).a b Popular, but controversial, as the rodent poison "1080," fluoroacetate is also found in the leaves of several poisonous plants in Africa, Australia, and South America. Surprisingly, difluoroacetate HCF2-COO is nontoxic and biochemical studies reveal that monofluoroacetate has no toxic effect on cells until it is converted metabolically in a "lethal synthesis" to 2R,3R-2-fluorocitrate, which is a competitive inhibitor of aconitase (aconitate hydratase, Eq. 13-17).b This fact was difficult to understand since citrate formed by the reaction of fluorooxalo-acetate and acetyl-CoA has only weak inhibitory activity toward the same enzyme. Yet, it is the fluorocitrate formed from fluorooxaloacetate that contains a fluorine atom at a site that is attacked by aconitase in the citric acid cycle. 

The essential correctness of the situation was confirmed by single crystal studies The crystals were grown over a four-month period at 1200 °C and therefore reached an equilibrium composition very close to Na3Zr2Si2POi2. The maximum in conductivity is thus correlated with maximum occupancy of the mid-sodium site. The conduction process is thought to be accompanied by a breathing-like motion of the framework in agreement with the dynamic disorder observed in the crystals Space does not permit a detailed discussion of this dynamic disorder or the controversy concerning the stoichiometry of NASICON but the reader is referred to references 41 and 51 for more information on these subjects. 

The most widely used cabinet test is the neutral salt spray (Fog) test (ASTM B 117), which consists of a fog of 5 % sodium chloride within the chamber at 35 C [46. Controversy exists over the validity of B 117 as a performance test because corrosion mechanisms are not always the same as those observed in automobile service. Also, not all materials can be successfully evaluated in the test. However, the value of the salt spray test as a quality assurance test is well documented [46]. Several modifications to the salt spray test have been developed including acetic acid salt spray (ASTM G 85, Annex 1), copper accelerated acetic acid salt spray (ASTM B 368), acidified synthetic seawater fog (ASTM G 43, Method of Acidified Synthetic Seawater (Fog) Testing), and modified salt spray (ASTM G 85). ASTM G 85 also includes cyclic tests. 

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