Authentic materials definition

The hydrate formed by photolysis of this substance is one of the few such products (the others are uracil hydrate, 5-fluorouracil hydrate, and uridine hydrate) that have actually been isolated and compared with authentic material of known structure.7 It is nearly the only product formed in the photolysis, is definitely stable at room temperature and neutral pH, and the thermal reversal to dimethyluracil is nearly quantitative. These properties, as Moore observed, make the reaction ideal for mechanistic investigation. Burr and Park have investigated the reaction mechanism by measuring the photolysis rate of dimethyluracil in mixtures of water with several nonaqueous, nonreactive solvents as a function of water concentration.64 The photolysis rate for 10" iM DMU was found to be the same in water-saturated cyclohexane (about 5 x 10-3M in water) as in dry cyclohexane. The photolysis rate in dry, highly purified dioxane was quite insensitive to water, and it was observed that hydrate formation (measured by thin-layer chromatography and by thermal absorbance reversal) became appreciable only at water concentrations above 40%. 

When a bead of a gel-type CFP material is in the dry state, for practical purposes it can be considered as a solid material (thus possessing a mass, a volume and a shape). When in the swollen state, a CFP material can be still considered as a solid from the practical point of view, but this circumstance is now an authentic approximation. In fact, physico-chemical analysis reveals that under some circumstances this alleged solid material is rather a very viscous liquid. More precisely, it is a suspension of interconnected polymer chains in the swelling agent. Each swollen CFP bead can be considered as a drop, which can retain a definite shape owing to the existence of the polymer framework. 

When reviewing a natural products manuscript, I look for novelty, significance, and completeness of the study, so that a definite contribution is being made. It is important that the work of others is appropriately cited and built on as a foundation and that the authors try to answer as many questions in their own work as is feasible. The work must be carried out according to accepted standards in terms of collection and authentication of the biological material and in the rigor with which chemical structures are determined, bioassays performed, and synthetic procedures conducted. 

Performs zero- and double-blind studies. Intralaboratory reproducibility (including ruggedness and robustness for real samples) should be demonstrated additional validation using an authentic standard reference material of the analyte in the sample matrix. Definition of criteria for revalidation. 

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