Quantitation stability

Metz(Ref 3) compared Brunswig s Test method with other quantitative stability tests(such as Mayrhofer, Mayrhofer-Will, Hansen and the 85° 110° Hydrolysis Tests) and with qualitative tests(such as Abel the 134.5° Heat Tests). Brunswig s method is indicated to be applicable only to extremely stable powders. For example, if a powd is of moderate stability and just passes other quantitative tests, it might not pass Brunswig s Test. On the other hand, if a powd passes Btunswig s Test it usually passes other quantitative tests but may not pass qualitative tests, such as Abel s, Zinc-Iodide-Starch Test others... 

Beryllium forms an enolate complex with lapachol (11a), a versatile ligand that also forms complexes with a variety of other divalent cations, e.g. Pd(ll) and ZrO(II), and trivalent metallic cations , e.g. In(lll) and Rh(lll), for which there is quantitative stability data. There are no data on related saturated derivatives, e.g. the analogous species 11b, to assess additional stabilization due to jt-metal interactions. 

Reversed-phase chromatography (RPC) Separation by hydrophobicity Quantitative, stability (aggregation), ... 

USP <797> Pharmaceutical Compounding-Steiile Preparations - Storage and Beyond-Use Dating. .. quantitative stability-indicating assays, such as high performance liquid chromatographic (HPLC) assays, would be more appropriate for certain Compounded Sterile Preparations... 

Douglas J.M. 1988. Conceptual Design of Chemical Processes. McGraw Hill, New York. Dupacova J. and Romisch W. 1998. Quantitative stability for scenario-based stochastic programs, Prague Stochastics 98, S. 119-124, JCMF, Praha. 

The possibility of carrying out quantitative stability tests on aqueous preparations of ergot alkaloids, using TLC, has also been reported [85,178] reference may be made too to the semi-quantitative detection of free nicotinic acid in polyvitamin preparations containing nicotinamide [113]. 

During the second year this process is quantitatively stabilized whereas some quantitative changes can be noted. During the first 10 months mainly small and medium sized cracks are observed which further develop into large cracks located perpendicular to the... 

Computational issues that are pertinent in MD simulations are time complexity of the force calculations and the accuracy of the particle trajectories including other necessary quantitative measures. These two issues overwhelm computational scientists in several ways. MD simulations are done for long time periods and since numerical integration techniques involve discretization errors and stability restrictions which when not put in check, may corrupt the numerical solutions in such a way that they do not have any meaning and therefore, no useful inferences can be drawn from them. Different strategies such as globally stable numerical integrators and multiple time steps implementations have been used in this respect (see [27, 31]). 

The theory predicts high stabilities for hard acid - hard base complexes, mainly resulting from electrostatic interactions and for soft acid - soft base complexes, where covalent bonding is also important Hard acid - soft base and hard base - soft acid complexes usually have low stability. Unfortunately, in a quantitative sense, the predictive value of the HSAB theory is limited. Thermodynamic analysis clearly shows a difference between hard-hard interactions and soft-soft interactions. In water hard-hard interactions are usually endothermic and occur only as a result of a gain in entropy, originating from a liberation of water molecules from the hydration shells of the... 

Several alternative attempts have been made to quantify Lewis-acid Lewis-base interaction. In view of the HSAB theory, the applicability of a scale which describes Lewis acidity with only one parameter will be unavoidably restricted to a narrow range of struchirally related Lewis bases. The use of more than one parameter results in relationships with a more general validity ". However, a quantitative prediction of the gas-phase stabilities of Lewis-acid Lewis-base complexes is still difficult. Hence the interpretation, not to mention the prediction, of solvent effects on Lewis-add Lewis-base interactions remains largely speculative. 

You have seen that measurements of heats of reaction such as heats of combustion can pro vide quantitative information concerning the relative stability of constitutional isomers (Section 2 18) and stereoisomers (Section 3 11) The box in Section 2 18 described how heats of reaction can be manipulated arithmetically to generate heats of formation (AH ) for many molecules The following material shows how two different sources of thermo chemical information heats of formation and bond dissociation energies (see Table 4 3) can reveal whether a particular reaction is exothermic or en dothermic and by how much... 

In Figure 7b, the data are plotted as AG yielding a linear function. Extrapolation to 2ero denaturant provides a quantitative estimate of the intrinsic stability of the protein, AG, which in principle is the free energy of unfolding for the protein in the absence of denaturant. Comparison of the AG values between mutant and wild-type proteins provides a quantitative means of assessing the effects of point mutations on the stability of a protein. 

When hydroxypteridines are considered, it must be borne in mind that these compounds exist principally in the pteridinone forms, containing thermodynamically stable amide functions, and consequently have low reactivity. Their stability towards acid and alkali correlates well with the number of electron-donating groups which apparently redress the deficit of ir-electrons located at the ring nitrogen atoms. Quantitative correlations can be seen in the decomposition studies of various pteridinones (Table 7). These results are consistent with the number of the oxy functions and their site at the pteridine nucleus. The... 

The choice of die transporting reagent for a given material is made so diat die reaction is as complete as possible in one direction, in die uptake, and die reverse reaction in die opposite direction at die deposition site. This requires diat not only die choice of die reagent, but also die pressure and temperature ranges under which die reaction is most effectively, or quantitatively, performed, must be calculated (Alcock and Jeffes, 1967 1968). There will always be limitations placed on diis choice by die demands of die chemical ineruiess and temperature stability of die containing materials in which die reaction is canied out. 

An understanding of a wide variety of phenomena concerning conformational stabilities and molecule-molecule association (protein-protein, protein-ligand, and protein-nucleic acid) requires consideration of solvation effects. In particular, a quantitative assessment of the relative contribution of hydrophobic and electrostatic interactions in macromolecular recognition is a problem of central importance in biology. 

The l,2,3-tri-/-butylcyclopropenium cation is so stable that the perchlorate salt can be recrystallized from water. An X-ray study of triphenylcyclopropenium perchlorate has verified the existence of the carbocation as a discrete species. Quantitative estimation of the stability of the unsubstituted ion can be made in terms of its pXn+ value of —7.4, which is intermediate between those of such highly stabilized ions as triphenylmethyl... 

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